Body size and cycling performance
BODY SIZE AND CYCLING PERFORMANCE
Scott Olive, BApplSci (Exercise and Sports Science)
Thesis submitted for the degree of Master of Sports Science (Hons) The University of New South Wales 1996 Body size and cycling performance
ABSTRACT
In many sports body size, shape and composition are major factors which determine performance. In cycling body size is a determinant of both energy supply and energy demand. On the demand side the primary retarding force encountered by cyclists is air resistance, which is directly proportional to the projected frontal area of the cyclist (~)- On the supply side the rate of power production is a function of body size. This study has formed part of a much larger study into the improve ment of cycling performance through the development of a "first-principles" mathematical model of cycling performance. Some of this work has been pub lished recently (Olds, Norton, Lowe, Olive, Reay & Ly, 1995; Olds, Norton, Craig, Olive & Lowe, 1995; Olive, Norton, Olds & Lowe, 1993). In this study extensive laboratory testing was used to measure the power supply and anthropometric variables of 53 cyclists (39 male, 14 female). Relationships were determined between anthropometric characteristics and ~- The rela tionships between power supply variables and body size were also established using both empirical and theoretical models. A mathematical model of cycling performance was then used to simulate the effects of varying body size, shape composition and position on cycling performance. The major findings of this study were:
• The lack of unanimity in previous estimates of ~ is most likely due to technical factors in the measurement process;
• ~ is closely related to height, mass and body surface area (BSA) and particularly to the riding position adopted. Contrary to other investigations, the ratio of ~/BSA was found to be independent of body size. Equations have been developed to predict ~ from anthropometric variables and riding position; • Whilst optimal physique is context dependent, both theoretical and empiri cal models predict that larger riders have a performance advantage over their smaller counterparts in most situations.
2 Body size and cycling performance
"I hereby declare that this submission is my own work and that, to the best of my knowledge and belief, it contains no material previously published or written by another person, nor material which to a substantial extent has been accept ed for the award of any other degree or diploma of the uni versity or other institute of higher learning, except where due acknowledgement is made in the text."
Signed: ......
CERTIFICATE OF ORIGINALITY
I hereby declare that this submission is my own work and to the best of my knowledge it contains no materials previously published or written by another person, nor material which to a substantial extent has been ac:c:epted for the award of any other degree or diploma at UNSW or any other educ:alional institution, except where due acknowledgement is made in the thesis. Any contnoution made to the mean:h by others, wilh whom I have worked at UNSW or elsewhere, is explic:idy acknowledged in lhe thesis.
I also declare that the intellec:tual content of Ibis thesis is the product of my own work, except to the exlent that assistance from others in lhe project's design and conception or in style, presentation and linguistic expression is acknowledged.
(Signed) ···
3 Body size and cycling performance
CONTENTS
1 INTRODUCTION 1.1 The cerodynamics of bicycling 1.2 Anthropometry and bicycling 1.3 Allometric theory and similarity systems 1.4 Modelling the effects of body size on performance 1.5 Statement of the problem
2 METHODS 2.1 Anthropometry 2.2 Measurement of projected frontal area 2.3 Allometric analysis 2.4 Statistical procedures
3 RESULTS 3.1 Anthropometry 3.2 Projected frontal area 3.3 Technical considerations 3.4 Allometric analysis
4 DISCUSSION 4 .1 Anthropometry 4 .2 Projected frontal area 4 .3 Technical considerations 4 .4 Allometric analysis 4.5 Directions for future research
5 APPENDICES 5.1 Documentation
6 REFERENCES
4 Body size and cycling performance
1 INTRODUCTION
1.1 The /Erodynamics of Bicycling 1.1.l Rolling resistance 1.1 .2 Air resistance 1.1 .2. 1 The drag coefficient 1.1 .2.2 The projected frontal area 1.1.3 Maximising cerodynami c efficiency
1. 2 Anthropometry and bicycling 1.2. l The anthropometric profile of racing cyclists 1.2.2 Anthropometry and the projected frontal area 1.2.2.1 Anthropometric prediction of projected frontal area of cyclists
1.3 Allometric theory and similarity systems 1.3. l Geometric similarity
5 Body size and cycling performance
1.3.2 Expressing metabolic data: the problem of scaling
I .4 Modelling the effects of body size on performance
1.5 Statement of the problem
6 Body size and cycling performance
Much of an athlete's potential is determined by their physiological abilities. A great deal of time is expended in laboratories monitoring the power and capacities of the physiological energy systems. One potentially important factor that has received comparatively little scientific attention in the laboratory is the body size of these athletes. The athlete's anthropometric dimensions reflecting body size, shape and composition are variables which may play an important role in determining the potential for success in a chosen sport. Whilst body composition and shape can to a certain extent be manipulated through training, the body size of an athlete is more or less a fixed quantity. The application of anthropometric analysis to sports performance has demonstrated the tendency for individuals to gravitate towards the event to which they are anthropometrically best suited, highlighting the relationship of body size, shape and composition with performance. The existence of optimal body sizes for various sporting events is well documented and has been discussed previously (Ford, 1984). Since a great many factors conspire with physical abilities to create the elite performer, the search for the most suitable body for a sport should ideally be restricted to world class competitors, in whom every detail will be optimised. If an optimal size does exist for a particular sport, the selection process will have eliminated most individuals who do not have the ideal body dimensions. Optimum body sizes are likely to exist in cycling as in other sports, given the relative anthropometric similarities which exist between riders of the same events (McLean & Parker, 1989; Foley, Bird & White, 1989) The differences in the relative size and shape of competitors between events are obvious, and is supported through the identification of anthropometric profiles of these athletes along with both inter- and intra-sport differences. Often a biomechanical advantage is seen to underlie these differences (McLean & Parker, 1989). Research into the identification of optimal body sizes for bicycling has been based on either biophysical first principles or the measurement of energy expenditures of different sized riders (Swain, Coast, Clifford, Milliken & Stray-Gundersen, 1987). The effect of different body sizes on cycling perfor mance is related to the different energy demand and energy supply of the
7 Body size and cycling performance
various sized riders. In general as body dimensions increase both the energy demand and the energy supply of cycling increase. The net effect of these changes in supply and demand determines performance time. The associated effects of changes in the slope of the terrain and the race distance will also need to be considered. In order for a cyclist to move forward work must be done to overcome both rolling resistance and air resistance. There is also a small amount of resistance offered by the mechanical components of the bicycle itself (ie the friction of the gears, chain, bearings etc). Air resistance is by far the largest retarding force experienced by the
cyclist and is a function of the cyclist1s projected frontal area (~), a dimensionless drag coefficient (Co), air density and the relative air velocity. Estimates of the Co have been reported for a range of bodies and it has been suggested that the value of Co remains relatively constant for standard
racing bicycles (Whitt & Wilson, 1982). The ~ of racing cyclists has been calculated previously (Capelli Rosa, Butti, Ferretti, Veicsteinas & di Prampero, 1993; Davies, 1980; McLean, 1994; Pugh, 1974; Swain et al., 1987). The data reported for~ of cyclists in the literature have a large range. This variance in measurements exists because some reports have measured i\>TOTAL (ie rider and bicycle) whilst others have measured ~RIDER only and it is often unclear to determine what they have included in their measurements. Reports that
either measure ~TOTAL or ~RIDER have been found to still differ despite the similar physical characteristics, racing positions and bicycle type of the rid ers between the studies. There is also a lack of technical detail reported, per haps suggesting apparent discrepancies in measurement techniques. Cycling is a sport determined by energy expenditure in direct interaction with a mechanical device. It is also a mass-supported sport where air resistance acts as the principal retarding force. It has been suggested that air resistance (or some more easily measured variable such as~) be used to define the proper size denominator for physiological and cardiovascular energy supply. This has subsequently led to relationships being established between
body size, ~ and related energy requirements.
8 Body size and cycling performance
1.1 THE lERODYNAMICS OF BICYCLING
The mechanical power output generated by a cyclist is used to overcome the external resistance when riding on the flat. The total external resistance (~0 t) retarding motion is equal to the sum of the rolling resistance (~), air resistance (RJ and frictional resistance, which includes the power transmission losses through mechanical parts such as the chain, gears and bearings. Frictional losses are considered negligible in modern racing bicycles · (Sj~gaard, Nielsen, Mikkelsen, Saltin & Burke, 1985, p.9).
1.1.1 ROLLING RESISTANCE
Rolling resistance is very nearly a constant retarding force at normal bicycle speeds. ~ is proportional to the combined mass of the bicycle and rider, and the rolling resistance coefficient (which is dependent on the tyre pressure and tread, wheel diameter and riding surface; Kyle & Van Valkenburgh, 1985).
1.1.2 AIR RESISTANCE
Air resistance is the force exerted by the surrounding air on a body moving through still air, or on a stationary body in moving air (Pugh, 1976) and is by far the greatest of the retarding forces opposing motion, increasing with the square of relative air speed. At speeds of approximately 13 km.h-1 and above, air resistance exceeds the rolling resistance. In fact at racing speeds over 32 km.h-1 air resistance represents over 96% of the total retarding force encountered (Kyle & Burke, 1984; Hill, 1993).
The air resistance is a function of the drag coefficient (C0 ), projected frontal area(~), the air density (p), and the relative air velocity with respect to the cyclist (v) (lngen Schenau, 1982). ~TOTAL for a racing cyclist is the sum of the projected frontal area of both rider and bicycle. ~RIDER is the
9 Body size and cycling performance
projected frontal area of the rider only. ~BIKE is the projected frontal area for the bicycle only.
1.1.2.1 THE DRAG COEFFICIENT
The Co is a dimensionless quantity and is largely determined by the shape and smoothness of the bicycle and rider (Brancazio, 1984). By manipulating the contours of a surface to produce a more streamlined rerodynamic efficient shape, the Co can be reduced. Some of the factors which have been found to determine the relative shape and smoothness of racing cyclists are clothing, frame design, racing accessories, helmets and wheel design (disk wheels, trispokes etc.).
The C 0 for any particular shaped object is a function of its respective Reynolds number. The Reynolds number of an object moving through a fluid is determined by it's relative velocity and diameter. High Reynolds numbers (> 4 x 105) are typically associated with large diameter objects travelling at high relative velocities and turbulent boundary layers producing low rerodynamic drag (Whitt & Wilson, 1982). The Co for racing cyclists though remains independent of its Reynolds number due to the relatively low velocity of the system. Even the fastest racing bicycles and riders are well below the critical Reynolds number, where laminar and partly turbulent airflows separate into fully turbulent airflows. Therefore most rerodynamicists have worked on optimising the system to achieve an efficient laminar flow and reduce drag that way. For example, the importance of rerodynamic equipment and clothing in the reduction of drag is critical (Kyle, 1983), where rerodynamic clothing can contribute an overall reduction between 6-10% in drag over conventional cycling clothing. Estimates of the Co have been reported for a range of bodies. The majority of the literature suggests that the Co remains relatively constant for standard racing cyclists in the order of 0.70-0.90 (Capelli et al., 1993; Davies, 1980; Gross, Kyle & Malewicki 1983; Kyle, 1979; Nonweiler, 1956; Pugh, 1974). Davies (1980) reported AP data and from that estimated a Co of 0.56
10 Body size and cycling performance
for a conventional racing configuration. Similarly Capelli et al. (1993) reported an estimated C 0 of 0.645 for rerodynamic bicycle frames. Olds, Norton, Lowe, Olive, Reay & Ly (1995) reported an estimated value of 0.592. They concluded from their work that the differences in the reported values of Co may be due to differences in the measurement techniques of~- Drag has been traditionally analysed by rerodynamicists using a lumped variable called drag area. The drag area of a cyclist is equivalent to the product of the C O and the ~TOTAL· The Co is usually not reported in wind-tunnel research into sports performance due to the difficulties and limitations associated with the measurement of ApTOTAL (Pugh, 1976). However, the obvious advantage of measuring the two variables as separate quantities is the ability to manipulate and model the various changes of these values on performance. In the absence of elaborate tests such as rolldown, tractive towing or wind-tunnel experiments, ApTOTAL provides a good estimate at the effect of different configurations on fluid resistance. However in modelling both variables independently we cannot assume a mutually exclusive relationship where changes in Co and changes in ~TOTAL can occur independently.
1.1.2.2 THE PROJECTED FRONTAL AREA
The projected frontal area of an object is 11 the area projected in a plane normal to the direction of motion 11 (Pugh, 1976). ~ is often considered as the measure of the size of the object and has been related to the body surface area of the rider, riding position, clothing, accessories, and the bicycle shape (Brancazio, 1984; Whitt & Wilson, 1982). Values between 0.318 and 0.5 m2 for the~ of racing cyclists have been reported. This large range of values exists despite the reported similar physical characteristics of the riders, riding positions used and bicycle configurations used in the various studies. The lack of technical detail reported in the procedures of~ calculation has undoubtedly led to variations in the measurement techniques between different investigators (Olds et al., 1995).
I I Body size and cycling performance
Comparisons between the quantitative data reported for ~ in the literature are shown in Table 1.1. The air resistance recorded for the bicycle alone has been calculated to be approximately 30% of the total drag (Nonweiler, 1956). This represents a i\,BIKE of 0.097 m2 [assuming a Co of 0.93 as reported by Nonweiler, (1956)]. Kyle (1990) also estimated the bicycle to represent 20-35% of the total drag with the remainder due to the body of the rider. The actual air resistance of the bicycle alone is most likely reduced when racing since the rider obscures parts of the frame (Nonweiler, 1956) and it is the ~RIDER alone which constitutes the greatest proportion of drag (Nonweiler, 1956; Sj11.1gaard et al., 1985). Pugh (1976) analysed the various orientations of leg movement during a single crank revolution and the relationship with the ~- It was reported that the variation in 1\, during different phases of the crank revolution were comparatively small.
1.1.3 MAxIMISING JERODYNAMIC EFFICIENCY
With air resistance accounting for up to 90% of the metabolic cost of cycling at racing speeds, an optimisation of the rerodynamics of the bicycle and rider is essential for best performance. A reduction in air resistance will provide a performance advantage to the cyclist, otherwise only gained through physiological training (Pugh, 1976). There are four ways in which air resistance may be reduced besides reducing racing speed: (i) drafting; (ii) reduction of i\,; (iii) reduction of Co; (iv) ascending to altitude (Pugh, 1976). Air resistance is also reduced in hot conditions because air density decreases as temperature and humidity increase. However when riding at sea level in a time trial event (where drafting behind another competitor is not permitted), a reduction in either 1\, or C 0 remain the only ways to lower air resistance. A reduction in 1\, represents the most efficient and cost-effective method of reducing drag. Regardless of the body size of the rider, riding position is the most critical determinant of AP.
12 Body size and ci;cling performance
Nonweiler (1957) 3 0.396 0.326
Pugh (1974) 6 0.470 0.460 0.420
Faria & Cavanagh (1978) 0.500 0.350
Davies (1980) 15 0.500
Gross et al. (1983)b 0 .399 0.362
5c 0.318 Swain et al. (1987)a
5d 0.378
0.600 Neumann (1992)b 0.500 0.400
McLean (1994)<3 10c 0.387
,od 0.465
Capelli et al. (1993) 2 0.394
Wright et al. (1995) 10 0.332
Present studya 17 0.471 0.444 0.347
Present studyb 17 0 .605 0.563 0 .464
Weighted mean 0.51 7 0.444 0.407
Table 1.1 Summary of studies which have reported the projected frontal area Ap (m2) of cyclists in three riding positions. a rider only b rider and bicycle
In all other studies it is not explicitly stated whether the measurements refer to the bicycle only, or to the bicycle plus rider. c smaller riders d larger rider
13 Body size and cycling performance
Consideration of the bicycle shape and the frame design used will also assist to minimise the Co and ~BIKE· Improvements in componentry alone can lead to substantial improvements in cycling performance. Kyle (1990) suggested that the bicycle frames which produce minimum drag use tubing with an airfoil-shaped cross-section streamlined in the direction of airflow, with the most efficient tubing having less than 33% of the drag of the round tubes. This reduction in drag is equivalent to nearly a 60 s reduction over a 40 km distance. The best rerodynamic frames have tubing which is narrow, with all outstanding cables and accessories hidden within the tubes to reduce drag. lErodynamic tubing is unique in mild crosswinds, as the airfoil sections actually cause lift with a concomitant forward force component. With suitable conditions (dependent on the yaw angle of the crosswind) the resultant drag may be lower than if there were no wind present at all (Kyle, 1990). New rerodynamic handlebars have enhanced cycling performance through the modification of riding position and a corresponding reduction in the ~RIDER· Different types of handlebars are now used in road racing, track racing and triathlon competition. The popularity of these handlebars has generated extreme interest in efficient riding positions (Gregor et al., 1991). Apart from being used by triathletes for a number of years, rero style handlebars (eg Scott DH, Profile) have recently been approved for use by the Union Cycliste lnternationale during competitive time trial events. lEro style handlebars differ from the standard drop style handlebars in that the upper body of the rider is typically lowered to a more horizontal position, with the arms extended out in front of the body and the elbows pulled inward. The purpose of this riding position is that the arms are brought forward in front of the midline of the body, which narrows the shoulders and reduces the ApRIDER (Berry, Pollock, van Nieuwenhuizen & Brubaker, 1994). Subsequently the use of these rero style handlebars with their arm rests has now become the most efficient riding technique invented. Kyle (1990a) suggested that these rero style handlebars typically lower drag by about 12% when compared to a racing crouch using upturned cow horn (drop) handlebars. The most rerodynamic and practical racing position is with the rero style handlebars flat or tilted up to 30° with the rider's back flat. The elbows
14 Body size and cycling performance
should be tucked so that the body drafts behind the arms with the hands placed together. More extreme racing positions have been adopted, with the development of new rerodynamic handlebars. Graeme O'Bree [1995 World Champion (4000 m Individual Pursuit) and one-hour record holder in 1994] raced in a position in which his head was pitched far in front of the handlebars and his arms were completely tucked under his chest and resting on the handlebars. O'Bree's radical riding position has now been banned by the Union Cycliste lnternationale because it is unstable and dangerous. Even more radical rerodynamic riding positions are now being adopted by O'Bree and others. The new "superman" position has been trialled with outstanding success at the 1996 Olympic Games, World Track Championships and was used successfully by Chris Boardman in setting a new one hour record. In this position the arms are extended far forward in front of the body with the head and trunk kept down in order to minimise the J\RIDER· Although currently legal it may become banned by the Union Cycliste lnternationale due to even further instability and danger. The typical crouched racing position using conventional drop style handlebars modified the ApRIDER• but unlike the racing positions which have been adopted through the use of rero style handlebars the crouched racing position did not modify the shape of the rider. It sought to lower the position of the upper body only, which left the rider's arms and hands in the standard racing position and did not make for a more rerodynamically shaped and smoother system. The traditional belief was that the crouched racing position was the most optimal position for a compromise between mechanical power production, breathing efficiency and rerodynamics (Borysewicz, 1986; Konopka, 1982). Concerns raised over possible physiological detriments of riding in extreme rerodynamic riding positions are not scientifically supported. Data reported by Johnson and Shultz (1990) suggested that the rerodynamic enhancements afforded by the rero style handlebars are obtained with no apparent physiologic cost. No consistent physiological change was reported in heart rate, V02, tidal volume, ventilation or gross. mechanical efficiency while cycling on an ergometer at an intensity of 80% V02max with either rero style or drop style handlebars. However, these data represented mean responses and
15 Body size and cycling performance
the observed individual variation in the response to handlebar type meant that the potential for reduced gross mechanical efficiency in some individuals should be considered. Further research conducted by Berry et al. (1994) failed to find any statistically significant ventilatory or pulmonary limitations as a result of riding with rero style handlebars. It was reported that although differences in riding time (ie time to exhaustion) were not statistically significant, individual differences in riding times were related to whether subjects had previously trained with rero style handlebars. It was suggested that individuals who race with rero style handlebars should also train with them. Richardson & Johnson (1994) reported on the effects of rero style handlebars during outdoor racing. Their data suggested significant reductions in V02 of approximately 2% and respiratory exchange ratio (RER) values of approximately 4% when racing with rero style handlebars compared with the traditional drop style handlebars. These data are statistically significant and certainly performance significant when it is recognised that a 2% reduction in
V02 in high-level competitive events may determine final medal placings. The choice of bicycle wheels is another important factor towards maximising rerodynamic efficiency. Smaller wheels, fewer spokes, narrower tyres and hubs, rero rims and disk wheels all produce lower drag (Kyle & Van Valkenburgh, 1985). Smaller front wheels in particular have the advantage of allowing closer drafting between riders whilst also reducing the ApRIDER by tilting the rider forward. The ~ and the mass of smaller wheels is less than that of standard wheels also. The disadvantage of using smaller wheels is that they typically have a higher rolling resistance. Olds et al. (1995) have calculated that a bicycle equipped with a 24" front wheel would result in a time reduction over 26 km of 0.2 min (0.5%) over using standard 27" front wheels. Further time reductions were possible when using even smaller front wheels. It is not surprising then that small front wheels are standard in almost all World and Olympic time-trial events.
1.2 ANTHROPOMETRY AND BICYCLING
16 Body size and cycling performance
The physical characteristics of an athlete reflecting body size, shape and composition are often considered to be important variables for determining the potential for successful performance. Certainly at an elite performance level there appears to be a tendency for individuals to gravitate towards the event to which they are anthropometrically best suited. The distinctive body sizes and shapes found within sports today have evolved due to both the natural selection of successful athletic body types over consecutive generations, and as an adaption to the training demands within the present generation. This process has been labelled morphological optimisation (Norton, Olds, Olive & Craig, 1996). The relative importance of anthropometric indices to cycling performance is well documented (Craig et al., 1993; Foley, Bird & White, 1989; McLean & Parker, 1989; Miller & Manfredi, 1987; White, Quinn, Al Dawalibi & Mulhall 1982a, 1982b). Relationships between~ and the anthropometry measurements of cyclists have also been established (Pugh, 1976; Swain et al., 1987; McLean, 1994).
1.2.1 THE ANTHROPOMETRIC PROFILE OF CYCLISTS
In general terms, top class cyclists are ectomorphic mesomorphs with little variation in fatness among the different specialities (Foley et al., 1989; McLean & Parker, 1989). However when the anthropometric measurements of the different specialities are analysed more closely, distinguishing differences in size, shape and composition appear. Generally there is a trend towards a decrease in mesomorphy and a corresponding increase in ectomorphy as the duration of the event increases. Sprint cyclists then are shorter and significantly heavier than other track and road cyclists, and have significantly larger chest, arm, thigh and calf girths. They are also more mesomorphic, less ectomorphic and have a greater sum of skinfolds than the endurance riders (Foley et al., 1989; McLean & Parker, 1989). Craig et al. ( 1993) reported that high performance track endurance cyclists consistently achieve sums of six skinfolds (triceps, biceps, subscapular, suprailiac, front thigh and medial calf) below 40 mm the week prior to a World championship
17 Body size and cycling performance
Endomorphy Mesomorphy Ectomorphy
I I 1.9 3.04 4.1 3.5 4.49 5.5 1.8 2.78 3.8 Sprint - Pursuit - -- Road Time trial
Figure 1.1 Characteristic somatotype ratings (representing body shapes) of elite cyclists specialising in one of four different events. Data are mean ± SD (Foley et al., 1989) plotted in relation to somatotype distributions of a reference population. The reference group is from the Australian Anthropometric Database (AADBase, 1995; n = 70 males 18-29 yr).
or Olympic competition. The time-trialists are the tallest of the cyclists and have longer leg to height ratios compared to the other groups (Foley et al., 1989; Miller & Manfredi, 1987). This reduces the rerodynamic drag of the upper body and also allows the time-trialists to use much higher gear ratios than any of the other cycling groups, probably because they use longer crank arms (Foley et al., 1989). It must be remembered when analysing anthropometric indices that some will vary depending upon the particular training phase of the yearly programme (Craig et al., 1993). The general body shape and somatotype ratings of the different riding groups are illustrated in Figure I.I. Excess metabolically inactive tissue can affect the energy demand of cycling in a number of ways. Firstly, additional mass will increase the energy required to overcome rolling resistance, the requirement to impart kinetic energy and accelerate the bicycle, and the energy required to ride up a grade. Secondly, the greater body mass will increase the body surface area (BSA) of the rider and ~RIDER increasing the energy required to overcome air resistance. In estimating the effect of added mass on an individual pursuit 4000
18 Body size and cycling performance
metre event (IP4000), both Kyle (1991) and Olds, Norton & Craig (1993) have predicted that a 2.7 kg increment in bicycle mass will increase the time to complete the IP4000 event by approximately 0.6 s due to added rolling resistance. The model of Olds et al. (1993) also predicts that an increase of 2.7 kg in body mass will increase predicted IP4000 time by 2.1 s due to the increased ~RIDER· Fat mass was one of the independent variables selected in the prediction of IP4000 time from a physiological statistical regression model developed by Craig et al. (1993), which highlights the importance of body composition to cycling performance.
1.2.2 ANTHROPOMETRY AND PROJECTED FRONTAL AREA
The importance of body size to successful cycling performance is undeniable. Relationships have been established previously between mass, height, BSA and both ~TOTAL and ~RIDER (Table 1.2). Nonweiler (1956) reported that wind-tunnel drag area was 11.8% greater in a large cyclist compared to a small cyclist (0.324 vs 0.290 m2). This was supported by the large cyclist having a BSA 15.6% greater than the small cyclist (2.04 vs 1.77 m 2). Having estimated a Co of 0.93, ~ constitutes a similar fraction of BSA for the large cyclist (17 .1 % ) to the small cyclist (17.6%) showing a relatively independent relationship with body size. Pugh (1976) reported a mean ~/BSA of 21 % for cyclists. Pugh suggested that height and mass be used to predict ~ as an alternative to more elaborate methods, owing to the close relationship of body size for sports such as walking, running and cycling. Di Prampero et al. (1979) in a theoretical analysis of cycling performance assumed ~RIDER to be a constant fraction of BSA (25%). Others investigators have assumed that ~TOTAL is a constant fraction of 25% of BSA (Sj121gaard et al., 1985). A constant relationship seems theoretically correct since similar proportions of individual riders of the sam e shape are likely to be exposed to the same air flow.
Other investigators have since reported that ~ /BSA is not independent of BSA. Swain et al. (1987) reported that ApRIDER constitutes a
19 Body size and C1Jcli11g performance
Nonweiler (1956) 3 21 .0 17.3
Pugh (1974) 6 24.3 23 .8 21 .7
di Prampero et al. (1979)a 2 25 .0
Davies (1980) 15 27.0
Swain et al. (1987)a 5c 19.0
5d 17 .8
Capelli et al. ( 1993) 2 20.1
Wrig ht et al. (1995) 10 17.3
Present studya 17 25.7 34.2 18.9
Present stu dyb 17 33 .0 30.7 26 .9
Table 1.2 Summary of studies w hic h have reported Ap/BSA of cyc lists in three riding positions. a rider only
b rider and bicycle
In all other studies it is not explicitly stated whether the measurements refer to t he bi cycle onl y, or to the bicycle plus rider. c sma ller rid ers
d larger ri der
20 Body size and cycling performance
smaller fraction of BSA for larger cyclists (17.8%, mean BSA 2.12 m2) than for smaller cyclists (18.7%, mean BSA 1.68 m 2) and that larger riders are therefore at a relative rerodynamic advantage owing to their ability of a greater reduction in air resistance when assuming a racing position (it was suggested that large riders are able to tuck tighter and reduce ~ of their trunk more effectively). This suggestion has been forwarded on the strength of both indirect evi dence (a lower than expected VO2 in larger cyclists) and direct evidence (measured ~). McLean (1994) reported a lower ~RIDER/body mass ratio in large cyclists. The rerodynamic advantage exists on flat terrain only where drafting is not allowed. In mass road races the presence of undulating terrain and drafting riders will deny the larger competitors this advantage.
1.2.2.1 ANTHROPOMETRIC PREDICTION OF PROJECTED FRONTAL AREA OF CYCLISTS.
McLean (1994) established a relationship between ~RIDER and anthropometric measurements in cyclists. The anthropometric measurements which best predict ~RIDER were mass and height. The inclusion of trunk angle (ie the angle formed between the greater trochanter and the first thoracic vertebra) further improved the prediction of ApRIDER· Small changes in the trunk angle will influence the ~RIDER· Multiple regression equations were subsequently developed in order to predict ~RIDER from the anthropometric measurements of the rider:
~RIDER (m2) = 0.00215M + 0.18964H - 0.07961 (r = 0.90)
~RIDER (m2) = 0.0217M + 0.18437H + 0.07961TA-0.021215 (r = 0.92)
~RIDER (m2) = 0.20956BSA + 0.00384TA - 0.11912 (r = 0.92) where M is mass in kg, H is height in m, and TA is trunk angle in degrees.
1.3 ALLOMETRIC THEORY AND SIMILARITY SYSTEMS
21 Body size and cycling performance
The process of "creating a level playing field" for all body sizes and dimensions is referred to as scaling (Nevill, Ramsbottom & Williams, 1992; Rogers, Olson & Wilmore, 1995). Specifically, scaling has been defined as "an attempt to control for the structural and functional consequences of changes in size or scale among otherwise similar organisms" (Schmidt-Nielsen, 1984). It is important to consider the potential consequences that changes in body size have in terms of function. Physiological measurements are often expressed relative to some mea sure of body size (eg mass, height or BSA). These simple ratios are sometimes referred to as per ratio standards, and are calculated to allow for the comparison of physiological measurements independent of body size and dimension differences. However, the widely used and accepted per ratio standards have been strongly criticised in that they fail to make the measurements truly inde pendent of body size (Katch, 1972, 1973; Katch & Katch, 1974; Nevill, Ramsbottom & Williams, 1992; Rogers et al., 1995; Schmidt-Neilsen 1984; Tanner 1949; Winter, Brookes & Henley, 1991). Many of the per ratio stan dards used fail to render the physiological measurement independent of body size. For example when maximum oxygen consumption (V02max' L.min-1) is expressed per body mass (ml.kg-1.min-1) and then correlated with body mass, a significant negative correlation is usually found. The per ratio standard tends to "over-scale" the data (Nevill et al., 1992). It is also assumed the relationship between the two ratio variables is linear. Nevill et al. (1992) reported that models which describe true linear proportional relationships retain a least squares regression line passing through or close to the origin. The assumption of a zero y-intercept though is rarely satisfied in biological research. If the per ratio method is applied to data exhibiting a non-zero y-intercept spurious conclusions can be drawn in comparing biological data between individuals who differ in body size (Toth, Goran, Ades, Howard & Poehlman, 1993). Statistical correction has often been applied to empirical data where this does not apply (Katch & Katch, 1974). The V02max-to-body mass relationship has repeatedly been shown to fit a curvilinear exponential function (Bergh, Sjodin, Forsberg & Swedenhag, 1991; McMahon, 1975; Nevill et al., 1992; Schmidt-
22 Body size and cycling performance
Nielsen, 1984). The application of simple ratio standards to describe these more complex functions can lead to misleading conclusions regarding differences or similarities between individuals of varying sizes. Apart from per ratio standards, statistical techniques such as linear regres sion models which partition out the effects of covariates, and allometric models that construct power function ratios have been suggested as more appropriate scaling methods. The criticism of most statistical models though is they also assume a linear relationship between the dependent and independent variables (Rogers et al., 1995). Further, regression models tend to produce biased results due to correlated random variation in the dependent and independentvariables (Nevill & Holder, 1995). Physiological relationships can be identified more precisely using allometric models. The strength of the allometric models is that they do not retain these limitations. Scaling physiological variables for body size using allometry involves the application of the general allometric equation. Huxley (1932) and Tessier (1931) developed this powerful model for describing the relative size of two body parts (proportionality). They suggested that proportional relationships could be best described by a single versatile equation:
y = axb (eqn 1) or taking logs of both sides,
In y =Ina + b ln x (eqn 2) where x is the size of some body part or a general measure of body size (usually height or mass), and y is the size of another body part or a body function.
After a log transformation (eqn 2), the variables a and b can can be estimated using linear regression. Nevill et al. (1992) and Nevill (1994) claimed that the log log transformation of the allometric equation is the most statistically correct form to describe such relationships. Further, transformation of the general allometric equation to logs and a linear relationship is more convenient for interpretation and statistical manipulation (Smith, 1980). With traditional linear models (when the variables x and y are plotted against each other) the scores are likely to diverge from
23 Body size and cycling performance
the regression line as the variables increase, because the variation in the scores are usually expressed as a percentage of the mean score. This statistical phe nomenon is known as heteroscedasticity (Rogers et al., 1995). Heteroscedasticity defies an important assumption of linear regression, in that the error term should remain constant throughout the range of variables. Heteroscedasticity is effectively eliminated using log-log transformations. Smith (1980) argued the limitations of allometric analysis, and conclud ed that the general allometric equation (eqn 1) is not an ideal scaling solution. The general allometric equation is limited in that the data fit to the log-log transformation produces a highly distorted goodness-of-fit appearance, and is often only used as an efficient means of altering the distribution of data to meet statistical assumptions of normality and homoscedasticity. In an attempt to apply allometric models to the identification of the scale and strength between different physiological variables, a wide range of allometric exponents have been reported. It is difficult to determine which is the most appropriate model to apply. Physical and physiological variables are known to exist as proportional relationships with linear body dimensions. Different similarity systems have been applied in an attempt to determine the most correct allometric exponent. However, competing similarity systems cannot all always be true. The simplest similarity system and classic allometric scaling model is the geometric similarity model (Ross, Grand, Marshall & Martin, 1982). A competing model of elastic similarity has been proposed by McMahon (1973, 1975).
1.3.1 GEOMETRIC SIMILARITY
Geometric similarity systems (Astrand & Rodahl, 1986; Ross et al., 1982; Weibel, 1984) treat organisms as homogeneous cubes of metabolically active tissue. This treatment though is a gross simplification - surface area: volume ratios and segmental relationships will vary with size and shape; body
24 Body size and cycling performance
tissues are not metabolically homogeneous and variation occurs in dimensionally associated variables due to functional and morphological variability associated with genetic and environmental factors. In large populations these variations may be randomly distributed, and mean values may follow allometrically predicted trends. In highly-selected populations such as elite athletes much of this variability will be minimised (ie athletes will have similar physical and physiological optima). Applications of allometric theory to elite athletes has often produced empirical results which closely match theoretical expectations. Lietzke (1956) analysed world-record performances in different weightlifting classes. He found that the weight lifted varied with the lifter's mass raised to the power 0.67. Since muscle cross-sectional area is expected to also increase with mass raised to the power 0.67, and the force a muscle can exert is proportional to the number of active cross-bridges which depends on the physiological cross-sectional area of the muscle, Lietzke's results reflect geometrical expectancy. These data were supported by the findings of Ross, Drinkwater, Bailey, Marshall & Leahy (1980) who conducted similar analyses. Allometric analysis can also be extremely useful when athletic performance departs from theoretical expectations. The degree that the actual values depart from the theoretical expectancy identifies the extent to which the underlying assumptions are violated. Such situations give clues to important factors which may determine performance. Geometrically similar systems have segmental lengths, breadths, depths and heights proportional to the linear dimension (L). Corresponding areas and area-dependent functions scale as the square of the linear dimension (L2), whilst volumes, masses and mass-dependent functions scale as the cube of the linear dimension (L3). For a large number of physical and physiological variables, different-sized humans are much the same as different-sized cubes (Figure 1.2).
If the length (L) of the size of a cube doubles, it's surface area (L2) quadruples, and its volume (L3) increases eight times. In a similar way human lengths, girths and breadths generally increase linearly with height, surface areas increase with the square of height, and masses and volumes increase with the cube of height.
25 Body size and cycling performa nce
length -·1 2 3 L surface area 6 24 54 L2 volume 8 27 L3
Figure 1.2 Illustration of the principle of geometric similarity. Surface area increases proportionally to the square of length, and volume increases proportionally to the cube of length.
Conversely when mass is used as the reference variable linear dimensions scale as mass to the power 0.33, surface areas to the power 0.67, and masses and volumes to the power 1.00. If a variable scales as massl.OO (M LOO), the variable varies directly proportionally with body mass (ie individuals of different size will have the same value when expressed relative to body mass). A biological example of this linear relationship is blood volume in mammals. The blood constitutes a constant and proportional fraction of the
body mass (McArdle, Katch & Katch, 1991). If a variable is independent of size it then scales as MO (ie no difference exists in the absolute value of the variable between different sizes eg hematocrit in all mammals is independent of size). These relationships are illustrated in Figure 1.3, along with other examples of allometric relationships.
Body surface area (BSA, m 2) is related to mass (M, kg) and height (H, m) through the equation of Dubois and Dubois (1915):
BSA= M0.425 H0.725 0.007184
Since height is proportional to Land mass is proportional to L 3, BSA is proportional to:
26 Body size and cycling performance
1.3.2 EXPRESSING METABOLIC DATA: THE PROBLEM OF SCALING
Both cerobic and ancerobic energy supply are dimensionally-dependent.
Metabolic rate (V02, L.min-1) has been taken as being proportional to M 0-67 or L2 (Astrand & Rodahl, 1986; Secher 1990). The variables determining maximal ancerobic capacity (oxygen deficit in L; Medbo, Mohn, Tabata & Sejersted, 1988) are all volume related (stored oxygen, phosphocreatine stores, buffer capacity) and would be expected to increase in proportion to L3 or M 1.00 (Secher & Vaage, 1983). Limited data are available on maximal accumu lated oxygen deficit (MAOD), which is a common physiological expression of maximal anaerobic capacity. Figure 1.4 summarises the results of 21 studies (n
= 565) using MAOD to quantify maximal ancerobic capacity in males (Astrand & Saltin, 1961; Astrand, Hultman, Juhlin-Dannfelt & Reynolds, 1986; Bangsbo, Gollnick, Graham, Juel, Kiens et al., 1990; Gastin, Krzeminski, Costill & McConnell, 1991; Graham & McLellan, 1989; Green, 1990; Hermansen & Medb!IS, 1984; Karlsson & Saltin, 1984; Linnarsson, Karlsson, Fagraeus & Saltin, 1974; Medb!IS & Burgers, 1990; Medb!IS & Tabata, 1989; Medb!IS, Mohn, Tabata, Bahr, Vaage et al., 1988; Olds, 1994; Olds et al., 1993; Olds et al., 1995; Olesen, 1992; Scott Roby, Lohman & Bunt, 1991; Szogy & Cherebetiu, 1974; Weyand, Cureton, Conley, & Higbie, 1993; Weyand, Cureton, Conley, Sloniger, & Lin Liu, 1994; Withers Sherman, Clark, Esselbach, Nolan et al., 1991). A statistically significant relationship exists between ln(body mass) and ln (MAOD) (r = 0.363, p:::; 0.0001). The slope of the log-log regression line (which corresponds to the allometric exponent) for male subjects is 1.160 (95% Cls = 0.913 - 1.406). V02max is the traditional physiological measure of cardiorespiratory fitness. It has become convention in exercise physiology, to express metabolic rate or V02 relative to body mass ie Ml.OO_ This makes the assumption that VO2 is directly proportional to body mass. Use of this expression is almost universal, and is used to "correct" the energy metabolism of individuals who differ in body size in the aim of creating a "level playing field" between
27 Slope= 1 Slope> 1 .,,,,,, , X=Y
►tl0 ,,,,' ►tl0 .3 .3 ,, Skeleton of mammal ,, increases out of Blood volume increases ,." proportion to body size in proportion to body (b = 1.10) size (b = 1.00)
LogX LogX
Slope= 0 Slope< 1 ,,,, ,,,, X=Y ►tl0 ►tl0 ,, .3 .3 , Hematocrit in all ,'Metabolic rate mammals is ,, increases with body size, independent of body ,,' but less than proportional size (b = 0.00) 4" to body size (b = 0.75)
LogX LogX
Slope< 0
X=Y ►tl0 .3
Heart rate decreases with increasing body size (b = --0.25)
LogX
Figure 1.3 Illustration of different allometric relationships with some physiological consequences used as examples. An allometric exponent of 1 is indicative of a variable which increases in direct proportion with increasing body size. Allometric exponents of O typically identify variables which are independent of body size. Redrawn from McArdle et al. (1991).
28 2.2 y' = 1.160x - 3.475 r = 0.363 p :s; 0.0001 2 • • 1.8 ••• ••• • N • • • 0 ,. _.J . 1.6 0 0 •• 4.15 4.2 4.25 4.3 4.35 4.4 4.45 4.5 In (mass; kg) Figure 1.4 Means of ln(MAOD, LO2) on ln(body mass, kg) reported in 21 studies (n = 565) for supramaximal exercise (107-149% V02max> of 1-6 minutes duration. The regression was calculated using weighted means. The slope of the log-log plot is 1.160 (95% confidence limits 0.913-1.406). Exercise was performed on either ergocycles, arm-leg ergometers or treadmills. 29 Body size and cycling performance individuals. This relative denominator however does not provide the most valid criterion of cardiorespiratory fitness for inter-individual comparison. The majority of the literature provides no conclusive evidence for the use of any one of the most common theoretical models. It is theoretically expected that V02max should scale to M 0-67. This relationship tends to hold extremely well for trained athletes (Astrand & Rodahl, 1986; Secher 1990). Weibel and Taylor (1981) reported that in animals ranging in body mass from 7 g to 260 kg the V02max measured during treadmill running scaled to M0.7S_ Ford (1984) suggested that Ml.OO is still probably the most accurate and sim ple denominator. When comparing individuals of varying levels of obesity, lean body mass (LBM) with the addition of a correction factor for fat mass may be a more accurate denominator. The selection of the most theoretically correct size denominator may also be related to other factors such as the cross-sectional area of the primary muscles or limbs involved or the force of gravity against a given mass, and might have enough of an effect on energy requirements to cause a shift in the theoretical exponent expected. Additionally, the influence of body mass on energy expenditure during rest as opposed to weight-bearing exercise is not completely clear (Rogers et al., 1995). Although numerous studies (Nevill, Ramsbottom & Williams, 1992; Katch, 1973; Tanner, 1949) have presented critical arguments against the use of per ratio standards, a clear alternative has not yet been developed. One major problem is that of sample size. Determining an overall relationship requires a very large sample, and the greatest variation in exponents occurs when using small sample sizes. When large sample sizes are analysed together, the results tend to be much closer to those reported in the zoology literature and those determined geometrically (Nevill et al., 1992). Decisions on which exponent to use must be made on the basis of large sample sizes, and relationships that are physiologically and statistically valid (Rogers et al., 1995). In modelling the energy demands of the cyclist, di Prampero et al. (1979) assumed the ~RIDER to be proportional to the BSA. It has been assumed in later investigations (Swain 1994), that air resistance is then 30 Body size and cycling performance proportional to BSA and scales as M 0-67. An allometric exponent of less than 1.00 places larger cyclists at a relative advantage over smaller cyclists in terms of energy demand (as predicted by di Prampero et al., 1979). Of course the degree to which this advantage exists for either large or small riders will also be a function on the scaling of the physiological energy supply systems. Some investigators have since suggested that since air resistance is the primary retarding force to cyclists at racing speeds, physiological. measurements used to monitor performance such as VO2 should be normalised to ApRIDER (V02/~RIDER; L.min-1.m-2) (Swain et al. 1987). These suggestions have been based based on empirical data, which demonstrated that large cyclists have a lower V02/mass than smaller cyclists (22% lower, p < 0.01) travelling at the same speed on level ground. The ratio of BSA to body mass of the large cyclists was 11 % lower than that of the smaller cyclists (p < 0.001). The ratio of the~ to body mass however was 16% lower in the larger cyclists (p < 0.001). These data not only indicate that ~RIDER is not a fixed fraction of BSA, but that large cyclists are at a distinct advantage in terms of V02/mass while riding on level terrain mainly due to their lower ApRIDER/mass ratio. Swain (1994) calculated the allometric exponent between submaximal VO2 and body mass during outdoor cycling to be 0.32. Similar data collected by McCole et al. (1990) and analysed by Swain (1994) elicited an allometric exponent for submaximal VO2 during outdoor cycling of 0.31. Swain (1994) using data from Swain et al., (1987) concluded that when comparing the VO2max of cyclists on level terrain, then the best denominator for proper size comparison should be expressed as ml.kg-0.32.min-1. Comparing V02max scores on undulating terrain requires analysis using different allometric exponents. These recommendations do not consider the different allometric trends between V02 at submaximal and maximal intensities. Allometric analysis of the measured ~RIDER of the ten subjects studied by Swain et al. (1987) revealed that ~RIDER (using the drop style handlebars position) scaled as MO.SS (r = 0.91), which is less than M0.67 (which would be expected on the theoretical grounds of geometric similarity). McLean (l 994) reported a similar allometric exponent for ApRIDER• scaling as 31 Body size and cycling performance M0.53 with both samples in a similar riding position. No confidence limits were reported for either set of allometric exponents, although both would be expect ed to be large given the small sample sizes used in both studies. If submaximal V02 in outdoor cycling scales at M 0-32 then cyclists might be adopting a greater "tuck" (trunk angle) outdoors than they do in the laboratory. Further, is the possibility that the bicycles of large cyclists (~BIKIU are not much larger than those of the small cyclists ie the ~BIKE comprises a smaller fraction of ~TOTAL for large cyclists than for small cyclists. Swain et al. (1987) reported that the small subjects rode bicycles which had a mass 17% of their rider's body mass. Comparatively, the large subjects rode bicycles which had a mass 12% of their respective body masses. The actual mean difference of ~BIKE between small and large cyclists though is likely to be relatively small. 1.4 MODELLING THE EFFECTS OF BODY SIZE ON PERFORMANCE Mathematical modelling and computer simulation are highly applicable to sports which involve continuous locomotion. Modelling sports performance can produce precise, unambiguous, and quantitative descriptions of reality. One of the main uses of mathematical models in sports performance is in the quantification of the effects on performance of changes in given physiological variables, and the ways in which these variables interact with each other in the elaboration of "what if'' scenarios (Olds et al., 1993). Sj!Zlgaard et al. (1985) modelled the theoretical expectancies of body dimensions and their relationship with cycling performance (using geometrically similar relationships). Differences in the physical and physiological capacities of small and large cyclists were modelled using these allometric relationships. The analysis concluded that during cycling on level terrain at a constant speed, body size does not play an important role in performance. Their analysis was supported in that the main determinants of energy supply (V02 max) and energy demand (air resistance) both theoretically scale to BSA (M0-67). Smaller cyclists though will be at a relative advantage through the lesser demands of rolling resistance, kinetic energy 32 Body size and cycling performance demand for acceleration and riding uphill since all three are dependent upon body mass and scale as M l.OO. However at racing speeds the work required to overcome rolling resistance constitutes only a small fraction of the total power output. Larger cyclists will be at a relative advantage riding downhill since the change in gravitational potential energy for the vertical component of descending a hill is dependent on the total mass of the rider and bicycle and not on ~TOTAL· 1.5 STATEMENT OF THE PROBLEM On the basis of the problems identified from the literature review, the following aims were subsequently developed. Specifically: (l) to provide quantitative data of the ~TOTAL (and associated cerodynamic indices) for cyclists of different body size in different racing positions; (2) to compare three direct methods of measuring ~TOTAL and identify the assumptions and limitations of each of these methodologies; (3) to examine the relationships between the ~RIDER of the racing cyclist and their respective anthropometric characteristics. Further, to identify the best anthropometric predictors of ~RIDER and subsequently develop regression equations for the prediction of ~RIDER; (4) to conduct a theoretical analysis applying allometric assumptions to a mathematical model of cycling performance, to determine the effects of different body size, body shape and body composition on cycling performance. 33 Body size and cycling performance 2 METHODS 2.1 Anthropometry 2.1.1 Body mass and stretch stature 2.1.2 Skinfold thicknesses 2.1.3 Heights 2.1.4 Breadths 2.1 .5 Girths 2.2 Measurement of projected frontal area 2.2. 1 The photographic weighing method 2.2.2 Planimetry 2.2.2. 1 Digital planimetry 2.2.2.2 Manual planimetry 2.2.3 Trunk angle 2.2.4 Technical consid erations 34 Body size and cycling performance 2.2.4 .1 Comparisons between different methods 2.2.4.2 The focal length of the camera 2.2.4.3 The relative position of the reference dimension 2.2.4.4 The position of the camera relative to the cyclist 2.3 Allometric analysis 2.3.1 Scaling for energy demand and supply 2.3.1.1 Body dimensions and energy demand 2.3.1.2 Body dimensions and energy supply 2.3.2 Allometric models of analysis 2.3.3 Changing body size covaried with slope 2.3.4 Changing body size covaried with race distance 2.3.5 Changing body composition 2.3.6 Effects of variation in segmental proportions 2.3.7 Effects of changing riding position 2.4 Statistical procedures 2.4.1 Anthropometry 2.4 .2 Projected frontal area 2.4 .3 Technical considerations 2.4.4 Allometric analysis 35 Body size and cycling performance Fifty-three subjects (39 male, 14 female) who were all experienced cyclists participated in the study. Informed consent was obtained in accordance with the established protocol for human subjects at the University of New South Wales. The subjects were divided into road or track riders on the basis of their preferred competitive event. 2.1 ANTHROPOMETRY Anthropometric profiles were recorded in accordance with the recommendations of Ross and Marfell-Jones (1991) unless otherwise indicated. The anthropometrist was a nationally accredited LSAS/ISAK (Australian Sports Commission Laboratory Standards Assistance Scheme/International Society for the Advancement of Kinanthropometry) Level Three Instructor with an intra-tester TEM (technical error of measurement) of 4.3%. and inter-tester TEM of <7.5% (Gore et al., 1996). These measurements had been validated against those of an !SAK-trained (criterion) anthropometrist. 2.1.1 BODY MASS AND STRETCH STATURE Body mass (kg) Body mass was measured on a calibrated Avery beam balance scale and recorded to the nearest 0.1 kg. The subjects were weighed first in minimal clothing (this mass was recorded as body mass). They were then weighed in full racing attire whilst holding their bicycles above the ground. From this mass, the mass of the time trial bicycle was determined. Stretch stature (cm) Stretch stature was measured using a wall stadiometer of custom design (Human Bioenergetics Laboratory, UNSW, Sydney). The subject's head was 36 Body size and cycling performance placed in the Frankfort plane (ie when the orbitale is in the same transverse plane as the tragion). Whilst keeping the head in the Frankfort plane the anthropometrist applied gentle upward lift through the mastoid processes. The head board was placed firmly down on the vertex (ie the most superior point on the skull), and the hair crushed as much as possible. The measurement was always taken at the end of a deep inspiration. 2.1.2 SKINFOLD THICKNESSES Skinfold thicknesses were measured using a set of calibrated Harpenden calipers (British Indicators Ltd, London). Two skinfold measurements were taken at each site. The mean of these two trials was taken as the measure. If a variation of more than 5% existed between the two trials a third trial was then completed, and the median of the three trials was taken as the measure. Triceps skinfold (mm) The caliper was applied 1 cm distal from the left thumb and index finger, raising a vertical fold at the marked mid-acromiale-radiale line on the most posterior surface of the arm. Subscapular skinfold (mm) The caliper was applied 1 cm distal from the left thumb and index finger, raising a fold that is oblique to the inferior angle of the scapula in a direction running obliquely downward and laterally at an angle of about 45° from the horizontal. Biceps skinfold (mm) The caliper was applied 1 cm distal from the left thumb and index finger, raising a vertical fold at the marked mid-acromiale-radiale line on the anterior surface of the right arm. 37 Body size and cycling performance Iliac crest skinfold (mm) The caliper was applied 1 cm anterior from the left thumb and index finger, raising a fold immediately superior to the iliac crest at the mid-axillary line (ie above the crest on the midline of the body). Supraspinale skinfold (mm) The caliper was applied 1 cm anterior from the left thumb and index finger, raising a fold at the point where the line from the iliospinale to the anterior axilary border intersects with the horizontal line of the superior border of the ilium at the level of the iliocristale. The fold follows the natural fold lines run ning medially downward at about a 45° angle from the horizontal. Suprailiac skinfold (mm) The caliper was applied 1 cm anterior from the left thumb and index finger, raising a fold 4 cm above the anterior superior iliac spine with the fold parallel to the fibres of the external obliques (Telford, Egerton, Hahn & Pang, 1988). Abdominal skinfold (mm) The caliper was applied 1 cm inferior to the left thumb and index finger raising a vertical fold that is raised 5 cm lateral to and at the level of the omphalion (midpoint of the navel). Abdomen skinfold (mm) The caliper was applied 1 cm inferior to the left thumb and index finger, raising a vertical fold which is adjacent to the umbilicus (Telford et al., 1988). Front thigh skinfold (mm) The caliper was applied 1 cm distally to the left thumb and index finger, raising a fold on the anterior of the right thigh along the long axis of the femur when the leg is flexed at a 90° angle at the knee. The mid-thigh position for this measure is the estimated half-distance between the inguinal crease and the anterior patella. 38 Body size and cycling performance Medial calf skin/old (mm) The caliper was applied 1 cm distal to the left thumb and index finger, raising a vertical fold on the relaxed medial right calf at the estimated greatest circumference. Pectoral skin/old (mm) The caliper was applied 1 cm medial to the left thumb and index finger, raising an oblique fold running in line from the nipple to the manubrium process 5 cm. from the nipple. This measurement was performed on males only. Axilla skin/old (mm) The caliper was applied 1 cm distal to the left thumb and index finger, raising a vertical fold on the mid-axillary line at the level of the xiphi-sternal junction. This measurement was performed on males only (Telford et al., 1988). Juxta-nipple skin/old (mm) The skinfold is an oblique fold located 2 cm from the right nipple in a line running from the nipple to the manubrium process of the sternum. This measurement was performed on males only (Withers, Craig, Bourdon & Norton, 1987). 2.1.3 HEIGHTS Skeletal heights were measured using a broad blade anthropometer (Siber-Hegner GPM, Switzerland). Acromiale (cm) The height from the base to the point marked as the most superior lateral aspect of the acromion process. 39 Body size and cycling performance Radiale (cm) The height from the base to the point marked as the most superior and lateral border of the head of the radius. Stylion (cm) The height from the base to the point marked as the most distal point of the processus styloideus radius. Dactylion (cm) The height from the base to the most distal point of the longest finger. Tibiale (cm) The height from the base to the point marked as the most proximal point of the lateral border of the head of the tibia. Spinale (cm) The height from the base to the spinale. Trochanterion (cm) The height from the base to the point marked as the most superior point of the greater trochanter. Sitting Height (cm) The stretch stature taken from the anthropometry box where the subject was seated to the vertex with the head held in the Frankfort plane. 2 .1.4 BREADTHS Skeletal breadths were measured using a broad blade anthropometer (Siber-Hegner GPM, Switzerland). Bone breadths (biepicondylar humerus and biepicondylar femur) were measured using custom designed small sliding calipers from a Mitutoyo (Sydney) engineering caliper. 40 Body size and cycling performance Bideltoid breadth (cm) The distance between the most lateral aspect of the bideltoid muscles. The subject stood relaxed with minimal pressure applied to the site by the anthropometer. Biacromial breadth (cm) The distance between the most lateral points on the acromion processes with the subject standing erect and arms hanging at the side of the body. Biepicondylar humerus breadth (cm) The distance between the medial and lateral epicondyles of the humerus with the arm raised forward to the horizontal and the forearm flexed to a right angle at the elbow. Transverse chest breadth (cm) The distance between the lateral points of the thorax at the level of the most lateral aspect of the fourth rib. Biiliocristal breadth (cm) The distance between the most lateral points on the superior border of the iliac crests. The branches of the caliper point upward at a 45° angle and firm pressure applied to the caliper branches over the iliac sites. Bitrochanteric breadth (cm) The distance between the lateral and superior aspects of the trochanterion. Biepicondylar femur breadth (cm) The distance between the medial and lateral epicondyles of the femur, when the subject is seated and the leg flexed at the knee to form a right angle with the thigh. The small bone caliper was applied pointing downward to bisect the right angle formed at the knee, and the caliper pressure plates were then 41 Body size and cycling performance applied firmly. Anterior-posterior chest depth (cm) The distance measured between the curved branches of the anthropometer when applied at the level of the mesosternale. The subject was seated in an erect position with measurement taken end-tidal. 2.1.5 GIRTHS Circumferences were measured to the nearest 0.1 cm using a flexible steel tape (Lufkin W606PM, USA). Head girth (cm) Measured in a horizontal plane at a level 2 cm above the brow, with the tape was pulled tight to compress the hair. Neck girth (cm) Measured just superior to the cricoid cartilage with the head in the Frankfort plane. Relaxed arm girth (cm) Measured at the level of the mid-acromiale-radiale. The tape was held parallel to the long axis of the humerus with the arm muscles relaxed and arms hanging by the side of the body. Flexed arm girth (cm) Measured at the maximum girth of the upper arm with the biceps muscle fully flexed and tense, and the elbow flexed to an angle of 45°. Forearm girth (cm) Measured at the site of maximum circumference of the forearm with the arm muscle relaxed. 42 Body size and cycling performance Wrist girth (cm) Measured distal to the styloid processes at the site of minimal circumference. Chest girth (cm) Measured end-tidal at the level of the mesosternale (the mid-point of the sternum at the level of the articulation of the fourth rib with the sternum). Waist girth (cm) Measured at the level of the narrowest point between the lower costal border and the iliac crest. If no obvious narrowing was apparent then the measurement was taken at the mid-point between these two landmarks. Gluteal girth (cm) Measured at the level of the greatest posterior protuberance, corresponding to about the level of the symphysis pubis. Thigh girth (cm) Measured 2 cm below the level of the gluteal fold, perpendicular to the long axis of the femur. Calf girth (cm) Measured at the site of maximum circumference of the calf muscles with the foot placed on a box and the knee flexed to 90°. Ankle girth (cm) Measured at the site of minimal circumference in the region superior to the ankle joint. 43 Body size and cycling performance 2.2 MEASUREMENT OF PROJECTED FRONTAL AREA Projected frontal area was determined for forty subjects (30 male, 10 female) only. Unfortunately researchers have previously reported very few technical details of their procedures and almost never quantify their precision, reliability or accuracy. It was therefore not possible to replicate or report on the technical detail of previous investigations. There have been three commonly-used methods of determining projected frontal area: photographic weighing and manual and digital planimetry. All three methods involve pho tographing the subject along with a reference area or dimension, usually a board, rod or some measured dimension of sporting equipment. 2.2.1 THE PHOTOGRAPHIC WEIGHING METHOD The photographic weighing method is the classic method used for the calculation of~ and has been used in a number of investigations (Pugh, 1974; Swain et al., 1987; Capelli et al., 1993). It is the criterion measure of ~TOTAL> ~RIDER and ~BIKE· Firstly, the subject assumed a preferred racing position on their own bicycle with the rear wheel mounted to a windload simulator in the laboratory (Magnetrainer, Sydney). The front wheel was subsequently raised so that both wheels were level. The bicycle was configured by the cyclist for racing conditions (ie water bottles, bicycle pumps etc were all attached). The reference area (in this study, a wooden board) was placed immediately adjacent to the rider and bicycle in a position halfway between the rider's trochanterion and acromiale (Figure 2.1). This position for the board was measured once the rider assumed their preferred racing position. The dimensions of the board were 90.2 x 60.1 mm (0.542 m2). The camera used to take the photographs was a Pentax-A Asahi K 1000 (Japan) with a zoom lens and focal length set to 35 mm. The tripod was a 323B Exelas (Japan), and the film was standard Kodak Colour 100 ASA 24 exposure. The camera was placed at a distance of approximately 2 m from the 44 01..10 O'o a aero O'o 0 0 1I LerlO 0 0 .b. (J) . . '\ ..,, .,.~....t..,:' • .,-·- OJ ~ ""';;; · "' "' ~ ... ooara oo 0 "£: ~ "'3 "' ~0 Figure 2.1 Relative positioning of the reference area (board) to the cyclist. Both skeletal landmarks (trochanterion and acromiale) were firstly 3 ::: identified and then the front surface of the board was placed coincident with the midpoint of these two landmarks. ~ Body size and cycling performance front wheel of the bicycle in line with the headstem of the frame. Photographs were taken of the subject in their preferred racing position. The subject was instructed to pedal their bicycle for about 30 s before the photograph was taken so they could best obtain their preferred racing position. The negatives of the film were enlarged using standard exposure techniques on a Meopta Axomat 4a Enlarger (Czechoslovakia) onto Ilford MGIV multi-grade 4 21.3 x 18.4 cm photographic paper (Mt Waverly, Australia). Using the enlarged photographs the outline of the subject (rider and bicycle) and the outline of the reference area were cut out with a razor blade and weighed on a Sauter scale (Wiirttemburg, Germany), sensitive to 0.001 g. Since the actual area of the reference area is known, the ratio of the mass of the subject to the mass of the reference area can be used to estimate the ApTOTAL· The same process was used to calculate ~RIDER (where the bicycle was cut away from the rider) and the ~BIKE· The ~BIKE represented those parts of the bicycle which were not covered by parts of the rider's body. Those parts of the bicycle which were covered by the rider's body were included as ~RIDER· The ~TOTAL> ~RIDER and ~BIKE were calculated in 17 (14 male, 3 female) of the 40 subjects in whom projected frontal area was determined in three commonly used racing positions: (i) in a racing position using standard drop style handlebars; (ii) in a racing position using rero style handlebars, and; (iii) in a racing position with the hands placed on the brake hoods. Comparisons were quantified across the three racing positions as absolute and relative changes in projected frontal area. 2.2.2 PLANIMETRY In planimetry the outline of the subject is traced and a triangulation method is used to calculate the area inside the outline. Planimetry can be 46 Body size and cycling performance performed using either digitised or manual systems. 2.2.2.1 DIGITAL PLANIMETRY Digital planimetry has been used previously to calculate ~ (McLean, 1993). ~TOTAL was calculated in eleven (11) subjects using Claris CAD software (Claris Corporation Inc., Mountain View CA) interfaced with a Kurta IS/ADB digitising tablet (Kurta Corporation, Phoenix AZ) on an Apple Power Macintosh 6100/66 personal computer (Apple Computer Inc., Cupertino CA). 2.2.2.2 MANUAL PLANIMETRY Manual planimetry has also been used previously to calculate ~ (Hill, 1927; Pugh, 1976). ~TOTAL was calculated in eleven (11) subjects using a Planix 5 Tamaya Digital Planimeter (Tamaya Technics Inc., Tokyo, Japan). 2.2.3 TRUNK ANGLE The angle of trunk inclination was measured for each racing position at the iliac crest and at the trochanterion using a standard goniometer. The two trunk angle measures were the included angles of a line drawn through the C7 vertebra formed with the horizontal at the level of the iliac crest and the trochanterion respectively (Figure 2.2). 47 · · ~ ~ ;:,: ;:,: 3 3 ...... ::, ::, 0 0 "' "' Q_ Q_ ;:,: ;:,: "'- ::, ::, "' "' ;:; Vl Vl tx:, tx:, 0 0 "'=I "'=I S, S, ~ ~ --2 --2 ~ ~ formed. formed. trochanteric) trochanteric) and and crest crest (iliac (iliac angles angles trunk trunk relative relative and and landmarks landmarks skeletal skeletal the the wing wing sho cyclist cyclist a a of of view view Lateral Lateral 2.2 2.2 Figure Figure A A 00 00 Body size and cycling performance 2.2.4 TECHNICAL CONSIDERATIONS 2.2.4.1 CoMPARISONS BETWEEN DIFFERENT METHODS The J\TOTAL of a subset of 10 cyclists was calculated from photographs on two occasions using each measurement method, so that repeated measurements could be compared. The specific questions addressed were: • Are there significant differences between the mean values for J\TOTAL measured on the same cyclists using the three different methods? • Are there significant differences between the mean values for J\TOTAL determined on the first and second measurement occasions for each of the three methods? • What are the correlations between J\TOTAL values determined on the first and second measurement occasions for each method, and what are the relative technical errors of measurement? 2.2.4.2 THE FOCAL LENGTH OF THE CAMERA The effects of changing the focal length of a camera lens were analysed by empirical measurement. A single male cyclist in the "reros" position was photographed using 6 different camera focal lengths ranging from 28 to 70 mm. The placement of the reference dimension and the camera setup was as described above, except that the distance between the camera and the cyclist was set at 6 m and did not change. The area of both the cyclist and the reference dimension were determined by photographic weighing. 2.2.4.3 THE RELATIVE POSITION OF THE REFERENCE DIMENSION The effects of changing the position of the reference area were modelled theoretically, and the model verified by empirical measurements. For 49 Body size and cycling performance both the theoretical and empirical studies, a baseline position of the reference board was adopted, and the board and camera moved relative to that position. In the baseline position, the camera was placed 3 m directly in front of the board. Photographs were taken and the ~ of the reference board (~BOARD) was determined as described above. Three types of deviation were analysed (Figure 2.3): (i) deviation in the frontal plane, as the board was moved closer to and further away from the camera. ~BOARD was determined with the board at baseline, and at 2.0, 1.5, 1.0 and 0.5 metres behind the baseline, as well as 0.5, 1.0 and 1.5 metres in front of the baseline. Caution was taken to ensure the board was centered relative to the camera lens, and a spirit level was used to ensure there was no degree of tilt on the board; (ii) angular deviation, as the camera was moved in an arc about the centre of the board. ~BOARD was determined with the camera directly in front of the board, and at acute angles of -30°, -20°, -10°, +10°, +20° and +30° in an arc of a circle of radius 3 m with its centre at the mid-point of the baseline. A spirit level was used to ensure there was no degree of tilt on the board; (iii) lateral deviation, as the board was moved from side to side. ~BOARD was determined with the board at baseline, and at 0.25, 0.50, 0.75 and 1.0 metres either side of the baseline. The analysis for lateral deviation will also apply for the vertical displacement of the camera. 2.2.4 .2 THE POSITION OF THE CAMERA RELATIVE TO THE CYCLIST To determine the effects of changing viewpoint on perspective, a single male cyclist in the "ceros" position was photographed with the camera 3, 3.5, 4, 4 .5 and 5 m from the plane of the reference dimension directly in front of the cyclist. The camera focal length was set at 35 mm, the focal length used during the initial set of photographs. The cyclist and the reference dimension were set up as described. The area of both the cyclist and the reference dimension were determined by photographic weighing. 50 Body size and cycling performance E Q) 0 u 0 C N ~ Cl. I Q) <( 4- 4- ~ 0 4- ....., 0 C E Q) 0 ....., If) "'u E Q) ~ ::t:: :J Q) "'(1J Q) Q) ..c....., E E Q) Q) ..c....., 0 ~"' (1J C 0 C (1J 0 .....,0 '@' Q) ""O Q) E (1J :J"' u Q) E E E E E E E E "'C ..c....., 0 If) 0 If) If) 0 If) 0 .Q....., r--- If) N If) 0 0 N r--- 0 (1J ....., 0 0 0 0 0 0 u 0 Q) + + + + I I I -~ Q) ....., ..c....., (1J 4- ~ 0 CJ) C C I I I I I I I I I I .....,Q C I I 0 I I I I I I .....,~ :~ I I I I I I E "':J "'0 ,' I I Q. I I I I I I I I I \ -~....., \ ~ I I I ', 0 (1J (1J I I I \ I + \ 0 1' ,' I I \ \ E .0 I I I \ E I / I ~ \ \ Q:! I / I I \ ~ \ I / I CJ) (1J I I I \ ~E I \ I I I \ \ -~ ~ ' O (1J ,' I I 0 \ \ 0 I I I \ \ I I I \ \ I I I \ \ rt? I I I + \ \ N I I \ I \ \ QI I I I \ I I \ ... I \ \ I I \ :::, I I \ I \ I I I E \ Cl \ I I I \ 0 \ \ u::: ,' I I I If) \ \ I I \ \ I I I \ I \ I I \ \ I I I + \ \ I I \ I I \ I I I I \ \ \ I I I \ I I \ I 'I \ I I \ I I \ I I E \ I \ \ \ ,' I I 0 I \ \ I I I 0 I \ \ I I I \ \ \ I I I N I \ \ I I I I \ \ I I I + I \ \ \ I I \ I I I \ I \ I I I I \ \ I I I I \ I I I I \ \ I \ \ I I I I I I \ \ I I \ \ I I I I I \ \ '-( I \ \ I I I \ I I \ I \ I y I \ 0 I E I \ 0 I I 0 \ (Y) I I \ -!.... I 0 I 0 + 0 I (Y) I >-" I (Y) -!.... I 0 + .-I- 0 0 N 0 0 N + 0 0 I 0 + ~ I 51 Body size and cycling performance 2.3 ALLOMETRIC ANALYSIS A model has been developed which accounts for the various physiological, biophysical and environmental factors in predicting cycling performance time (Olds et al., 1993; Olds et al., 1995). Physiological and anthropometric data were collected on all 30 male subjects used in the analysis of~- These data represented the baseline values which were entered into the model to predict the effects on cycling time. The effects of changing body dimensions were analysed by systematically scaling the baseline values across a range of masses from 50 kg to 100 kg (50, 60, 70, 80, 90, 100 kg) using the procedures described below. The baseline data are summarised in Table 2.1. 2.3.1 SCALING FOR ENERGY DEMAND AND SUPPLY As body dimensions increase, both the energy demand and the energy supply of cycling increase. The specific question addressed is the net effect of these changes in supply and demand on predicted performance time. 2.3.1.1 BODY DIMENSIONS AND ENERGY DEMAND Dimensional variables will affect the energy demand of cycling in the following ways (di Prampero et al., 1979; Pugh, 1974; Olds et al., 1993): (i) rolling resistance is proportional to the combined mass of the cyclist and the bicycle. The mass of the bicycle (and the ApBIKE) will be more or less constant for different sized cyclists, as most componentry is similar for large and small bicycles; (ii) air resistance is proportional to the ~TOTAL· A relationship exists between the anthropometric measurements of a rider and their projected frontal area; (iii) the energy required to ride up a grade and the kinetic energy imparted to 52 Body size and cycling performance maximal ~robic power V02max L.min-1 4.915 ± 0.636 fractional ut il isation of V0 2max f 0.752 ± 0.084 gradient of the VOrWR regression grad L. min-1.w-1 0.0 11 7 ± 0.00 11 intercept of t he VOr WR regress ion int L.min-1 0.4291 ± 0.2330 nude mass of the cyclist M kg 73.5 ± 7. 9 hei ght of the cycli st H cm 178.7 ± 6.6 prerace 02 uptake V02init L. min-1 0.751 ± 0.097 maximal accumulated 0 2 deficit MAOD L 4.345 ± 0.677 time-constant for vo2 kinetics '! s 40.02 time-constant for deficit kinetics 'def s 25 .02 bideltoid bre adth cm 46.3 ± 1.9 anterior-posterior chest depth cm 19.5±1.4 t hi gh length "2" cm 53 .3 ± 3.4 lower leg length cm 46.7 ± 3.1 thig h girth cm 56.6 ± 3. 2 ca lf girth cm 36.4 ± 2.5 front thig h skinfold mm 10.7 ± 2.9 medial calf skinfold mm 7.4 ± 2.9 tyre pressure p psi 117.7±16.5 ambie nt temperature T K 289.2 ± 4.9 barometric pressure Ps mmHg 758 .7 ± 3.7 re lative wind ve locity Vw m.s-1 0.0 ± 0.0 mass of bicycle and accessories Mb kg 11 .0 ± 1.3 relative humidity RH % 76.1 ± 12.1 Table 2.1 Measured and assumed variables used in the model as base line va lues . The subject dependent variables (n = 30) were systematically scaled across masses ranging from 50 to 100 kg. Thi s study is a component of a much larger study into the improvement of cycling performance The va riable s measured and/or used in this study were also used in the development of a "first-principles" mathematical model of cycling performance as reported by Olds et al. 1995. 53 Body size and cycling performance the bicycle during acceleration are both proportional to the mass which must be elevated or accelerated. Changes in energy demand were modelled using the ~RIDER· A diagrammatic representation of ~RIDER was used (Figure 2.4) to manipulate body dimensions. The rider was drawn using rero style handlebars, and the ~BIKE was assumed to be independent of body size as the baseline values were scaled up and down. This assumption seems reasonable considering the small absolute differences which exist between bicycle mass for large and small riders and the similar size and shape of most componentry. Mean ~BIKE using rero style handlebars had previously been deter mined for twenty of the thirty male subjects used in this allometric analysis A relationship was also established between ~BIKE and BSA (Figure 2.5). BSA was calculated using the algorithm of Dubois & Dubois (1915). The gradient of the regression line between the two variables is not significantly different from zero, and ~BIKE was taken as being independent of body size (0.1486 m2). This constant ~BIKE was added to the ApRIDER (as mass was systemati cally varied between 50 and 100 kg) and the ~TOTAL was derived for the size-corrected cyclists. 2.3.1.2 BODY DIMENSIONS AND ENERGY SUPPLY Energy supply is the work derived from aerobic and anaerobic energy sources and converted into external work. The. calculation of available. energy is related to maximal oxygen consumption V02max• initial (pre-race) V02 (V02init), and to the anaerobic capacity [quantified by the "maximal accumulated oxygen deficit" (MAOD). The procedures used in the collection of the energy supply variables have been published previously as part of a much larger study into the improvement of cycling performance (Olds et al., 1995). The amount of internal energy which must be produced to perform the required external work is considerably greater due to the relative inefficiency of human locomotion. Gross mechanical efficiency can be determined by 54 Body size and cycling performance ,______bideltoid breadth ------, ..c +-'a. (I) "'O +-' VI (I) ..c u c.. N I ...... <( : N ..c +-' : Cl N C ..!!:! ..c ..c +-' Cl Cl C ..c (I) +-' ..c .QI ..c thighgirthht calf girth/1t Baseline values used to calculate ApTOTAL: height= 178.7 cm bideltoid breadth = 46.3 cm A-P chest depth= 19.5 cm thigh length "2" = 53.3 cm lower leg length = 46. 7 cm thigh girth = 56.6 cm calf girth = 36.4 cm ApBIKE = 0.1486 m2 ApRIDER = (1t • A-P chest dth • bideltoid bth) + (1.5 • thigh Ith • thigh gth) + (2 • lower leg Ith • calf gth) 2 2 1t 1t Figure 2.4 Diagrammatic representation of a cyclist using c:ero style handlebars in the fully dropped position, illustrating segmental contributions to ApRIDER· Thigh length "2" is the measured distance between the iliospinale and tibiale laterale. 55 Body size and cycling performance .2 • . 19 . 18 • N- . 17 5 • w • ~ • cii a. .16 <{ • . 15 • • • . 14 • •• • •• • • . 13 •• • 1.7 1.8 1.9 2 2.1 2.2 2.3 BSA (m2) Figure 2.5 Relationship between the ApBIKE (m2) and BSA (m2). y = 0.038x + 0.076 RMSR = 0.019 r = 0.255 p = 0.2779 n = 20 56 Body size and cycling performance . regressing V02 against work rate (WR) at a range of submaximal work rates (Olds et al., 1995). They-intercept of this regression equation is taken to represent the metabolic rate required for loadless pedalling. It is assumed that other determinants of energy supply such as delta mechanical efficiency, anaerobic threshold (fractional utilisation), V02 kinetics and Ordeficit kinetics are independent of body size. As mass was systematically varied from 50 to 100 kg the baseline values for the subject dependent variables, were covaried according to their allometric relationships with mass. The dimensionally adjusted values were then entered as model variables and predicted time was determined as slope, distance and body composition changed. 2.3.2 ALLOMETRIC MODELS OF ANALYSIS Two different allometric models were used to systematically scale the baseline values across the range of rider masses from 50 to 100 kg (in 10 kg increments). The first model scaled energy demand and energy supply variables using the dimensional relationships of geometric similarity (Astrand & Rodahl, 1986). This model was the "expected model".. As. mass was systematically varied from 50 to 100 kg, body mass, V02max' V02init' they-intercept of the V02-work rate regression, MAOD and ~RIDER were covaried according to their allometric relationships with mass. The allometrically-corrected values were then entered into the model as variables, and predicted time was determined as body dimensions, slope, distance and body composition changed. The second model scaled the model variables using allometric exponents calculated from laboratory data. This model was the "empirical model". Exponent analyses (using log-log regression) were applied to both the energy supply and demand variables to calculate mass exponents for V02max' V02init' MAOD and ~RIDER to determine whether the laboratory data matched theoretical expectations. The expected and empirical mass exponents 57 Body size and ci;cling performance ApRIDER (n = 20) 0.67 0.44 (0.06-0.81) VO2max (n = 30) 0.67 0.67 (0.29-1.07) . VO2init (n = 61 ) 0.67 0.55 (0.29-0.81 ) MAOD (n = 565) 1.00 1 . 16 (0. 91-1 .41) int (n = 39) 0.67 0.08 (-1.41 -1.57) Table 2.2 Expected and empirical mass exponents used to scale model demand and supp ly variables to masses of 50, 60, 70, 80, 90 and 100 kg. The allometrically correct values were then entered into the model, and predicted time was determined as body dimensions, body composition, slope and distance changed. 58 Body size and ci;cling performance Supply variables V02max L.min-1 4.9 15 3.798 4.291 4.758 5.203 5.630 6. 042 V0 2in it L.min-1 0. 751 0.580 0.656 0.727 0.795 0.860 0.923 MAOD L 4.345 2.956 3.548 4.139 4. 730 5.32 1 5.9 13 int L.min-1 0.429 0.332 0.375 0.415 0.454 0.491 0.527 Demand variables H cm 178. 68 157.36 167 .12 175.84 183.76 191.05 197.81 bideltoid breadth cm 46.3 40.77 43.3 45.55 47.61 49.49 51 .24 A-P chest depth cm 19.5 17 .18 18.25 19 .20 20.07 20.86 21 .60 thigh length "2" cm 53.3 46.90 49.81 52.40 54.77 56.94 58.95 lower leg length cm 46.7 41 .11 43.66 45.94 48.01 49.91 51 .68 thigh girth (corrected) cm 56.7 49.88 52.98 55.74 58.25 60.56 62 .70 cal f gi rt h (corrected) cm 36.4 32 .07 34.05 35.83 37 .45 38.93 40.31 ApRIDER m2 0.3231 0.2497 0.2821 0.3128 0.3421 0.3702 0.3972 ApTOTAL m2 0.4717 0.3983 0.4307 0.4614 0.4907 0.5188 0.5458 Supply va riables V02max L. min-1 4.915 3.790 4.287 4.757 5.205 5.636 6.051 V02init L.min-1 0.751 0.608 0.672 0.731 0.787 0.839 0.889 MAOD L 4.345 2.780 3.434 4.107 4.795 5.497 6.211 int L.min-1 0.429 0.416 0.422 0.427 0.432 0.436 0.440 Demand variables ApRIDER m2 0.323 1 0. 2729 0.2956 0.3 163 0. 3354 0. 3532 0.3699 ApTOTAL m2 0.4717 0.4215 0.4442 0.4649 0.4840 0.5018 0.5185 Table 2.3 Allometrically-corrected values for both the expected and empirical models. The baseline su pply variables were all laboratory data obtained from other research (Olds et al., 1995). The baseline demand variables (ApRIDER) were calculated from anthropometric measurements of the male subjects used in the Ap analysis. Both supply and demand variables were scaled to the expected and empirical mass exponents (Table 2.2). ApTOTAL was calculated by the addition of ApBIKE (ie 0.1486 m2) in both models. 59 Body size and cycling performance together with scaled values for each model are given in Tables 2.2 and 2.3. The empirical model differed to the first on the energy demand side of the model only, with ApRIDER scaled using an empirical mass exponent of 0.44. All supply side variables continued to be scaled using the known theoretical expectancies. The ApRIDER was scaled using both the expected and empirical mass exponents. ~TOTAL was calculated by the addition of ApBIKE to the allometrically-corrected values. ~BIKE was assumed to be constant (0.149 m2) since it is relatively independent of rider size (Figure 2.5). 2.3.3 CHANGING BODY SIZE COVARIED WITH SLOPE Riding through undulating terrain is common to most road racing events with the exception of time trials which are often restricted to level terrain. The combined effects of allometrically correcting the energy demand and supply variables to masses of 50 and 100 kg through a gradient range of -10% to +10% was modelled and changes in predicted performance time calculated. The ratio of the predicted times for the smallest rider 50 kg (M5O) to the predicted time for the largest rider 100 kg (Ml 00) was plotted for a range of slopes (±2.5%, ±5.0%, ±7.5%, ±10%) over a distance of 4 km. The algorithms of Aunola, Alanen,. Marniemi and Rusko (1990) which relate fractional utilisation of V02max and time to exhaustion were used as an estimate of the fractional utilisation over the 4 km race distance as slope changed. When the ratio of the predicted times for the smallest rider weighing 50 kg (M50) to the predicted time for the largest rider (M100 ) was equal to 1, no difference existed in the predicted time between the small and large rider. 2.3.4 CHANGING BODY SIZE COVARIED WITH RACE DISTANCE 60 Body size and cycling performance The ratio of the predicted times for the smallest rider (50 kg, M50) to the predicted time for the largest rider (100 kg, M 100) were plotted for a range of race distances from 1 to 40 km (in 1 km increments). When the ratio was equal to 1, no difference existed in the predicted time between the small and large rider. Over race distances ranging from 2000 to 7000 metres (approximately. 3-10 minutes) cyclists can elicit and maintain oxygen uptakes close to VO2max (Peronnet & Thibault, 1987). This time is also suitable for the full expression of the MAOD, although time periods of only 60 seconds may be sufficient (Withers et al. 1991). V02max increases with M0-67, whilst the O2-deficit increases with mass. As the distance increases to 7000 metres, V02max becomes the chief determinant of energy supply. As distances get shorter, O 2-deficit will become increasingly important. Distances over 7000 metres are dependent upon the fractional utilisation of VO2max· As distances continue to increase, the fractional utilisation of VO2max decreases. in an undetermined manner. As an estimate of the fractional utilisation of VO2max. the algorithms of Aunola et al., (1990) which relate fractional utilisation of VO2max and time to exhaustion (min) were used: . fraction of VO2max = 1.42 - 0.17 ln(time) 2.3.5 CHANGING BODY COMPOSITION Excess metabolically inactive tissue (fat mass) is detrimental to sports performance and affects the energy demand of cycling in a number of ways (Craig et al., 1993). Firstly additional mass will increase the kinetic energy required to accelerate the system. Secondly increased mass will increase the energy required to ride up a grade since the gravitational potential energy of a system is proportional to mass. Thirdly, the rolling resistance of the system will be increased because rolling resistance is proportional to the mass of the sys tem. Finally, greater body mass will increase BSA and ~RIDER which determines the drag created by the system. 61 Body size and cycling performance To quantify the different effects of a changing body composition (ie fat mass:fat-free mass ratio), simulated 40 km time trials were performed on level terrain (thus removing the effects of slope): (i) using combined changes in body mass and }\RIDER while holding all other baseline values constant. Changes in predicted performance time will therefore reflect changes in rolling resistance, kinetic energy demand and air resistance. The }\RIDER was allometrically-corrected by scaling for the appropriate changes in body mass. (ii) Using changes in bicycle mass, while holding all other baseline values constant. This model represents the effect of increased mass on rolling resistance and kinetic energy requirements only, without any effects on air resistance. All remaining energy supply and demand variables retained their baseline values as described in Table 2.1. 2.3.6 EFFECTS OF VARIATION IN SEGMENTAL PROPORTIONS The effects on }\RIDER of varying segment lengths, girths, breadths and skinfolds ±0.5, ± 1.0, ± 1.5, and ±2.0 standard deviations outside the anthropometric baseline values were assessed. Four different segmental configurations were analysed: (i) deep chest vs. shallow chest (ie anterior-posterior chest depth was varied ±0.5, ±1.0, ±1.5, and ±2.0 SDs outside the anthropometric baseline); (ii) broad shoulders vs. narrow shoulders (bideltoid breadth was varied ±0.5, ±1.0, ±1.5, and ±2.0 SDs outside the anthropometric baseline); (iii) long legs vs. short legs [thigh length "2" and lower leg length (Ross & Marfell-Jones, 1991) were added together and varied ±0.5, ±1.0, ±1.5, and ±2.0 SDs outside the anthropometric baseline]; (iv) thigh and calf skinfolds were varied ±0.5, ±1.0, ±1.5, and ±2.0 SDs outside the anthropometric baseline. All remaining energy supply and demand variables retained their baseline values as described in Table 2.1. 62 Body size and cycling performance 2.3.7 EFFECTS OF CHANGING RIDING POSITION Changes in riding position were modelled over 1 to 40 km race distances. All simulations were modelled on flat terrain. Three different riding positions were modelled with the rider using: (i) rero style handlebars; (ii) drop style handlebars, and (iii) hands on top of the brake hoods. The three riding positions were described by the concomitant change in mean ~TOTAL of the same subject group (n = 14) in three racing positions [ie rero-style handlebars ~TOTAL = 0.5 l l .m2; drop style handlebars ~TOTAL = 0.584 m2; brake hoods ~TOTAL = 0.623 m2 ]. All remaining energy supply and demand variables retained their baseline values as described in Table 2.1. 2.4 STATISTICAL PROCEDURES 2.4 .1 ANTHROPOMETRY The anthropometric profiles for both track and road subjects were presented as means ± SDs. The data were normally distributed about the means. Unpaired t-tests were used to test for differences between track and road riders for both male and female subjects for skinfold thicknesses, girths, lengths, breadths, sum of skinfolds, estimated percent body fat and somatotype. Repeated measures ANOVA was used to test for differences in mass, height and body mass index (BMI) between riders of different ability (ie recreational, club, state). An alpha level of 0.05 was adopted for all analyses. 2.4 .2 PROJECTED FRONTAL AREA 63 Body size and cycling performance i\,TOTAu i\,RIDER• i\,BIKE• i\,TOTAIJ'BSA and i\,RIDER"BSA were presented as means ± SD for male and female subjects using rero style handlebars, drop style handlebars and brake hoods. The data were normally distributed about the means. Unpaired t-tests were used to test for differences between genders. Repeated-measures ANOVA was used to test for significant differences between riding position for the subjects analysed in all three riding positions. In the event of a significant F-ratio, post-hoe analysis was performed using Student's paired t-test with Bonferroni-corrected alpha values. Simple regression analysis was used to establish relationships between i\,TOTAL' i\,RIDER• i\,BIKE• i\,RIDER"BSA, i\,BIKWi\,TOTAL and BSA, and to establish a relationship between bicycle mass/rider mass and rider mass. Simple regression analysis was also used to identify zero-order anthropometric predictors of i\,RIDER in all three riding positions. Stepwise multiple regression analysis (F-to-Enter level= 4, F-to-Remove level= 3.996) were then used to develop equations for predicting i\,RIDER from simple anthropometric measures. Only those anthropometric measurements which were theoretically expected and relatively easy to measure were used in the stepwise analysis. These measurements were mass, height, BSA, bideltoid breadth and biacromial breadth. The other zero-order anthropometric predic tors of i\,RIDER were not used in the stepwise analysis as their relationship was either not as strong, or they were considered as unlikely theoretical predictors of i\,RIDER· 2.4 .3 TECHNICAL CONSIDERATIONS The technical error of measurement (TEM; Pederson & Gore, 1996) and the mean coefficient of variation within trials were used to quantify the precision of the measurement methods, while the intra-class correlation coefficient (ICC; Pederson & Gore, 1996) was used to quantify reliability. Student's paired t-test was used to decide whether there were significant differences between mean i\,TOTAL values for the initial and retest trials using 64 Body size and cycling performance each of the three methods. Repeated-measures ANOVA was used to test for significant differences between the mean ~TOTAL values determined using each of the three methods. In the event of a significant F-ratio, post-hoe analysis was performed using Student's paired t-test with Bonferroni-corrected alpha values. Linear regression was used to determine the relationship between the focal length of the camera and measured ~TOTAL, and between the camera viewpoint and measured ~TOTAL· The strength of the relationships were quantified using the Pearson product-moment correlation coefficient. The relative position of the reference area was quantified using both theoretical and measured values. The theoretical analysis was completed using trigonometry. ICCs were applied to test for differences between the theoretical and measured values. 2.4 .4 ALLOMETRIC ANALYSIS For a full account of the algorithms used, the reader is directed to Olds et al. (1993) and Olds et al. (1995). 65 Body size and cycling performance 3 RESULTS 3.1 Anthropometry 3.2 Projected frontal area 3.2. 1 Comparisons between riding positions 3.2. 2 Relationships between Ap and BSA 3.2.3 Anthropometric prediction of projected frontal area 3.3 Technical considerations 3.3.1 Comparisons between different methods 3.3.2 The focal length of the camera 3.3.3 The relative position of the reference dimension 3.3.4 The position of the camera relative to the cyclist 3.4 Allometric analysis 3.4. 1 Effects of height and mass 3.4 .2 Effects of riding on slope 66 Body size and cycling performance 3.4.3 Effects of race distance 3.4 .4 Effects of altered mass 3.4 .5 Effects of proportionality 3.4.6 Effects of changing riding position 67 Body size and C1Jcling performance 3.1 ANTHROPOMETRY The heights, masses and body mass index (BMI) of all male and female subjects are shown in Table 3.1. Male track riders were taller and heavier, had a higher BMI and lower percentage body fat than road riders, but the differences were not significant. Female track riders were taller and heavier, had a lower BMI and hig her percentage body fat than road riders, but the differences were not significant. male track 5 mean 179.3 78.9 24.4 s 9.47 14.07 2.46 road 35 mean 178.4 72 .8 22 .9 s 5.89 6.71 1.85 all 40 mean 178.5 73 .6 23.1 s 6.28 7.95 1.96 female track 3 mean 170.6 59.9 20.8 s 7.74 7.20 3.93 road 10 mean 164.8 58 .8 21.6 s 5.65 8.39 2.51 all 13 mean 166.1 59 .0 21.4 s 6.35 7.85 2.73 Table 3.1 Comparison of height, mass and BMI between male and female track and road riders. Table 3.2 shows that in general the sum of skinfolds and estimated percentage body fat decrease as we move up the ability scale. Significant differences in the sum of skinfolds and estimated percentage body fat between male state and recreational riders exist (p :=:;: 0.05). All other differences were non-significant. 68 Body size and cycling performance male state 9 63 .7 ± 13.46 8.9 ± 1.66 club 26 70.8 ± 19.60 9.7 ± 2.56 recreation a I 5 87.2 ± 19.66 11 .7 ± 2.60 female state 5 80.7±11.09 17 .0±1.52 club 2 103.2 ± 29.06 19 .5 ± 4.24 recreational 6 95.0 ± 30.91 18.4 ± 4.21 Table 3.2 Comparison of sums of skinfolds (I.SF, mm) and estimated percent body fat (est. %BF) between riders of different ability levels. The data are shown as means± SDs . Tables 3.3-3.8 show the skinfold measures, girths, heights, lengths and breadths measured on male and female track and road riders respectively. No significant differences were found between track and road riders for either male or female subjects for any of the anthropometric measurements. Heath-Carter anthropometric somatotypes were calculated for each subject. The results are shown in Table 3.9. Male track riders had a significantly higher mesomorphy rating than their road counterparts (5.62 vs 4.68; t = 2.09, p = 0.043). Common anthropometric indices were derived from the measurements. The results are shown in Table 3.10. All of these results were non-significant. 69 Body size and cycling performance 002S 73.2 170.4 7.4 11. 7 3.3 14.1 13 .3 18.0 13 .1 5.8 10.4 97.2 12 .7 061S 91.1 188.4 8.4 8.4 4.1 9.2 5.9 8.2 11 .6 7.2 5.7 68.7 9.5 052S 80.0 177.2 10.6 11.2 4.7 11. 7 9.1 10.9 13.4 8.9 6.8 87.4 12.1 050S 58.1 170.5 7.6 5.7 2.6 4.1 2.8 4 .5 4 .. 6 3.1 3.2 38.1 5.6 054S 92 .2 19}0 5.3 9.0 3.3 9.6 6.7 10.9 8.3 4.7 7.3 65.1 8.5 mean 78.9 179.3 7.9 9.2 3.6 9.7 7.6 10.5 10.2 6.0 6.7 71.3 9.7 14.1 5 9.5 1.9 2.4 0.8 3.7 3.9 5.0 3.7 2.2 2.6 22.8 2.9 065T 72 .5 175.6 7.6 7.9 3.8 6.5 5.3 9.2 11. 7 7.6 5.9 65.6 9.4 008NT 66.9 1792 4.8 9.6 3.2 8.6 6.1 8.1 7.2 4.6 5.3 57.5 7.7 048T 80.0 183.9 9.4 11 .2 4.6 17.5 11.4 18.4 12 .9 7.1 12 .6 105.1 13.1 030NR 78.1 183.0 6.4 9.2 3.7 15.5 9.8 13.3 10.8 7.9 8.9 85.5 10.7 018NR 68.3 178.8 5.5 6.2 2.8 4 .6 3.8 5.1 6.7 4.5 4.3 43.3 6.2 058NT 81.5 187.7 17 .2 12 .2 6.4 10.2 5.3 17.1 13.7 12.1 9.9 104.2 14.7 040NT 66.2 170.3 17.1 9.7 5.4 13.3 8.0 11.5 10.4 7.7 8.7 91.8 12 .2 041NR 75.7 186.0 5.7 6.6 2.5 8.1 4.1 9.6 13.2 4.9 4.8 59.4 8.3 053R 65.7 100.5 7.7 6. 5 3.2 7.9 6.5 6.7 11 .4 9.4 4.6 63.8 9.1 028R 67.0 174.8 4.2 6.9 2.8 5.2 3.6 47.7 7.3 6.0 3.3 44.2 6.4 035NR 80.2 178.0 4.6 9.1 3.3 8.6 4.1 6.8 10.3 7.2 4.6 58.5 8.1 009NT 69.0 170.0 4.7 7.2 3.4 7 .1 5.2 5.8 6.2 5.2 4.3 49.2 6.8 045NT 66.3 181.3 6.3 8. 1 3.5 9.3 5.5 8.3 7.3 5.5 5.3 59.1 7.9 033NR 80.6 181.2 10.5 9.5 4.9 11 . 1 9.9 13.3 12.6 9.9 7.6 89.4 12.4 036NT 72.0 182.0 5.3 6.5 3.1 6.5 4 .6 5.2 7.2 5.0 4.2 47.8 6.7 013NR 78.0 193.3 6.0 8.3 3.5 7.5 4.8 6.4 7.7 5.6 4.9 54.7 7.5 045NT 65.0 164.8 8. 1 6.8 3.2 10.1 8.0 13 . 1 12 .8 8.4 5.6 76.0 10.6 034NR 76.1 178.6 7.9 11. 1 4.0 10.1 7.0 15.7 9.3 4.3 8.8 78.3 10.4 70 Body size and C1Jcling performance 037NT 80.0 177.2 5.6 15 .3 2.9 11 .9 9.9 15 .0 6.8 5.2 11 .5 84.0 10.7 049NT 72.9 172.3 6.1 6.0 2.8 10.4 7.0 7.8 12.0 7.3 5.6 65.0 8.7 060NR 58.3 170.8 10.8 6.9 4.5 6.2 5.2 6.6 11 .8 9.6 5.1 66.5 9.7 029R 66.1 173.2 5.8 7.8 4.0 9.5 5.2 7.4 9.6 6.1 4.9 60.2 8.1 044NT 68.3 170.9 6.2 6.5 3.3 6.6 5.1 6.7 10.0 8.6 4.1 57.1 8.2 032NR 71.4 182.0 7.3 7.6 4.1 7.4 4.2 7.7 11.5 5.8 5.7 61.2 8.5 003NR 73 .1177.816.0 12.7 5.2 15.9 12 .2 19.9 18.1 10.0 12 .1 122.2 16.5 016NR 70.2 100.4 6.9 7.3 3.6 8.1 6.1 8.8 12.1 6.6 5.4 64.9 9.1 066T 83 .4 175.6 8.7 9.9 4.8 11 .2 7.9 14.9 9.6 8.0 7 .1 82.0 11 .2 051NR 83.1 181.9 8.0 9.6 5.8 13.8 6.0 15.1 12.6 8.9 7.5 87.3 11.6 055T 65.5 173.4 8.1 9.2 4.1 9.9 6.5 12 .9 15.4 8.2 7.5 81.8 11.3 056NR 75.6 187.5 7.1 8.0 4.0 8.6 5.0 7.5 10.9 10.9 5.5 67.4 9.4 064R 63 .7 181.0 6.4 6 3.5 5.7 4.2 6.1 8.4 6.3 4.3 51 .1 7.3 057R 73.1 174 6.8 9.6 3.9 9.4 7.2 8.9 8.9 4.9 6.7 66.3 8.9 059NR 73.0 179.5 9.6 9.6 3.5 9.0 5.3 11.8 11 .8 6.2 5.5 72.3 10.2 062NR 74.8 174.7 8.7 8.4 4.1 13.0 10.0 15.6 20.1 18.3 8.5 106.7 14.9 011 NR 87.3 182.6 8.1 8.0 3.1 5.2 4.5 6.7 13 .6 9.6 5.4 64.3 9.5 mean 72 .8 178.4 7.8 8.6 3.8 9.4 6.4 10.2 10.9 7.5 6.5 71.2 9.8 s 6.7 5.9 3.2 2.1 0.9 3.1 2.3 4.2 3.1 2.7 2.4 19.0 2.5 mean 73 .6 178.5 7 .9 8. 7 3.8 9.5 6.6 10.3 10.8 7 .3 6.5 71.3 9.8 s 8.0 6.3 3.1 2.1 0.9 3.2 2.5 4.3 3.2 2.7 2.4 19.2 2.5 Table 3.3 Values for body mass (kg), stretch stature (cm), individual skinfolds (mm), sum of skinfolds (I.9 SF) and estimated percentage body fat (est.% BF, Withers et al., 1987a) for the male subjects . Tri = triceps; Sub = subscapu lar; Bi =biceps; IC = iliac crest; Sup = supraspinale; Ab = abdominal; Th = front thigh; C = medial calf; Ax = mid-axilla. 71 Body size and cycling performance 005TE 67 .9 HS6.116 .81 5.6 7.9 16.7 12 .9 14 27 .7 12.1 123.8 22 .5 025S 54.0 179.5 10.6 7.4 4.7 8.7 7.7 11 .6 20.3 11 .7 82 .7 16.5 001TE 57 .7 166.1 11.9 9.9 4.4 8.5 8.3 12.4 19.1 13.1 87.8 18.5 mean 59.9 170.6 13.1 11.0 5.7 11.3 9.6 12.7 22.4 12 .3 98.1 19.2 s 7.2 7.7 3.24 4.23 1.94 4.78 2.86 1.24 4.64 0.75 22.40 3.05 002NR 69.9 176.6 15.4 10.6 4.6 9.3 4.8 8.2 13.5 11.3 77.7 18.1 063NR 51.9 160.0 14.2 9.3 5.7 8.8 6.8 12 .4 25.5 9.6 92.5 17.4 043NR 57 .1 161 .9 12 .5 6.1 3.3 6.8 4.7 5.8 14.1 10.3 63.6 15.0 020NR 54.6 161 .6 15.6 8.4 3.9 8.9 8.6 13.6 20.8 9.1 88.9 18.0 031NR 54.5 161.8 14.6 9.1 3.7 7.6 5.7 6.9 19.8 11 .6 79.0 17.8 015NT 50.4 164.0 11 .8 7.8 6.2 7.6 5.3 7.5 16 6.6 68.8 14.1 007NT 58.8 162.7 11 .6 9.6 6.2 11 .7 11 .1 14.3 23.2 12.8 100.6 19.1 012NT 75.5 1642 15.6 18.9 10.9 15.1 17 .8 20.1 33 .8 21 .9 154.1 26.1 010NT 51 .6 161.5 12 .2 9.1 6.4 7.7 5.8 11 18.8 7.4 78.5 15.4 040NR 63.5 173.8 13.2 7.9 3.3 6.9 6.1 11 .1 24.9 8.4 81 .9 15.8 mean 58.8 164.8 13.7 9.7 5.4 9.0 7.7 11.1 21.1 10.9 88.5 17.7 s 8.4 5.6 1.60 3.47 2.28 2.57 4.07 4.316.144.32 25 .4 3.38 mean 59.0 166.1 13 .6 10.0 5.5 9.6 8.1 11 .5 21.4 11.2 90.7 18.0 s 7.9 6.3 1.93 3.51 2.13 3.09 3.80 3.80 5.68 3.80 24.22 3.25 Table 3.4 Values for body mass (kg), stretch stature (cm), individual skinfolds (mm), sum of skinfolds (IS SF) and estimated percentage body fat (est. % BF, Withers et al., 1987b) for the female subjects. Tri = triceps; Sub = subscapular; B =biceps;IC = iliac crest; Sup = supraspinale; A= abdominal; Th = front thigh; C= medial calf. 72 Body size and e1;c/ing performance 002S 58 .2 39 .5 29.3 32.2 27.9 16.9 93.4 81.1 99.4 57.5 36.3 21.7 061S 57.4 40.2 32 .2 33.5 29.2 18.6 107.8 85 .8 104.8 60.8 41.9 24.5 052S 59 .6 38.2 31.7 34.9 29.1 18 .0 99 .3 79 .8 99 .8 62 .0 39 .0 22.9 050S 56.6 34.2 25 .6 28.2 25.6 15.8 89.4 67 .7 87 .7 49.5 35.7 20.9 054S 57 .8 39 .4 34.3 37 .3 31.6 18.4 108.9 86.8 106.0 64.3 39.0 23.8 mean 57.9 38.3 30.6 33 .2 28.7 17.5 99.8 80.2 99.5 58.8 38.4 22 .8 s 1.11 2 .40 3.32 3.38 2.17 1.17 8.61 7.62 7.24 5.77 2.48 1.48 065T 56 .5 40.8 30.2 32 .8 28.5 18.0 97 .7 77 .7 94.2 57.4 36 .0 23 .6 008NT 59.4 37.7 26.7 30.2 26.2 16.2 88.2 74.6 92 .6 54.4 34.4 21.6 048T 58.7 36.6 28.8 32 .2 27.0 17 .5 103.5 80.8 99.7 61 .4 38.0 22 .8 030NR 57.4 40.1 28.6 32.4 29.4 17.4 95.9 82.4 99.1 57.7 36 .2 22 .7 018NR 55 .2 35 .1 28.7 32.3 27.0 17 .5 90.4 69.7 92 .6 54.2 31 .8 21 .6 058NT 57.4 39.7 30.0 31 .1 27 .3 17 .1 97 .6 83.3 100.1 57.5 37.5 23 .8 040NT 56 .7 37.5 29.1 31 .1 26.0 16.8 89.6 74.8 92 .3 53 .9 34.2 21 .4 041NR 55 .5 37.8 28.7 31 .1 28.0 17.7 93.2 78.2 99.6 56.7 35.6 22 .1 053R 56.3 36.5 25.4 28.5 25.8 16.8 88.5 70 .4 90.6 53 .4 35.8 23 .1 028R 57.0 35.7 26.6 29.0 26 .0 16.5 90.1 74.3 97 .0 56.7 37.4 22 .2 035NR 56 .3 40.0 31.1 33.7 28.6 18.6 98.2 81.6 100.1 58.4 39.1 23.4 009NT 57 .0 38.8 32.4 36 .3 28.4 17 .9 89.7 75 .3 90.5 55.5 32 .8 21 .7 045NT 56 .5 36.8 28.2 30 .9 26.0 16.5 90.3 72.9 89 .8 51 .7 34.2 21.1 033NR 56.9 37.2 30.2 35 .2 28.1 17 .1 99 .7 85 .1 98.3 59 .3 34.9 21 .1 036NT 56 .7 36.5 28.0 30.5 26.1 16.6 93.9 76.9 95.6 55 .0 37.5 21 .8 013NR 58.6 37.4 27.9 31 .3 27.6 17.6 90 .8 75.2 98.1 55.3 35 .0 23 .2 045NT 56.5 38.1 29.4 31.9 26.3 16.9 90 .5 74 .4 92 .2 57.0 34.7 22 .2 034NR 57.0 36.4 28.4 31.4 25.3 16.4 98.2 82.2 98.3 58.7 35.2 21.6 73 Body size and cycling performance 03 7NT 57.9 37 .4 30.4 32 .6 27.8 17.6 101 .5 87 .3 98.6 58. 5 39 .0 22 .7 049NT 57.3 34.5 30.5 34.0 27 .1 17.2 102 .9 79 .3 94.1 56.5 36.5 22.6 060NR 55 .3 34.8 27 .3 29.5 25.8 17 .4 85 .6 67 .4 88.8 51 .5 34.5 22.4 029R 56.8 38.1 29.1 31.2 26.9 17.6 90.3 72.9 90.6 51.6 34.4 21 .1 044NT 54 .2 37 .0 30. 1 31 .9 27 .9 17 .3 97 .2 76.4 91 .8 55 .8 34.8 21.5 032NR 54.1 35 .9 29.4 31 .8 27 .8 17. 0 87 .8 71 .6 96.6 58 .6 37 .7 22.7 003NR 57.2 34. 2 27.3 29.8 26.6 16 .8 90.9 79.9 94.1 54.9 34.5 23.2 016NR 57 .1 36.1 27.9 30.0 26.6 15 .9 87 .8 73.5 94.3 56.6 33.5 21 .9 066T 58. 3 39.3 33 .0 36.5 29.5 18.8 104.7 86.3 100.9 62.5 38.6 23.2 051NR 58.0 38.5 31 .2 32.6 28.8 18.4 108.0 82 .4 99.3 59.7 38.4 22.6 055T 55.6 37.5 28.9 31.2 25.4 16 .5 92.7 73 .8 90.2 54.0 34.5 20.4 056NR 55 .8 38.0 27.5 30.5 27.1 16.4 93.3 79.4 96.3 55.9 37 .0 22.0 064R 57 .8 34.3 26.1 29.5 27 .0 17 .1 88.7 73 .6 90.4 49.3 43.8 21.5 057R 59.4 37.1 32 .0 35.5 28.5 16 .7 102.3 80.8 94.8 57.3 35.2 21 .2 059NR 58 .9 37 .7 30.8 33.4 28.0 17 .0 90.7 75.8 95 .8 56 .5 36 .9 22 .2 062NR 58.7 38.8 29.1 32 .5 27.0 16.9 95.9 78.0 98.8 61.4 37.8 23.5 0 11 NR 58 .8 39.7 32.1 35 .7 31 .3 18.9 101.4 83 .1 104.9 62 .9 41.5 24.5 mean 57 .1 37.4 29.2 32 .0 27 .3 17 .2 94.5 77 .5 95.5 56.5 36.2 22 .3 s 1.34 1.69 1.82 2.03 1.31 0.72 5.80 4.86 3.96 3.96 2.41 0.93 mean 57 .2 37.5 29.4 32 .2 27 .5 17 .3 95.2 77 .8 95.0 56.8 36.6 22.4 s 1.33 1.78 2.06 2.22 1. 48 0.78 6.32 5.23 4.57 3.53 2.49 1.00 Table 3.5 Girth measurements (cm) for male subjects. H = head ; N = neck; AR = arm (re laxed); AF = arm (flexed); F = forearm; Wr = wrist; Ch = che st; W = waist, G = gluteal; T = thigh; C = calf; A = ankle. 74 Body size and cycling performance 005TE 58 .6 33.2 28.4 29.5 25 .5 15 .6 86.4 79.8 96 .6 60.6 36.1 21 .6 025S 52.6 31.9 26.4 28.7 25.0 14.9 82 .7 65.9 92 .9 56.0 33 .6 19.5 001TE 58 .4 30.9 26 .0 27.3 24.4 15 .2 80.1 67.6 90.5 54.0 30.8 19.2 mean 56.5 32 .0 27 .0 28.5 25.0 15 .3 83 .1 71 .1 93.3 56.9 33.5 20.1 s 3.41 1.15 1.27 1.13 0.58 0.35 3.17 7.59 3.07 3.38 2.65 1.31 002NR 57 .4 32 .4 27.7 28.9 24.5 16 .0 88.1 72.3 105.7 60.4 37.0 21 .6 063NR 54.5 30.5 23 .3 24.6 22.7 16.8 78.2 66.1 91.5 53.9 31 .9 19.1 043NR 53.5 31.2 26.5 27.7 23.7 14.8 84.2 66.6 93.7 56.2 32 .6 19.9 020NR 54.3 30.9 23 .2 24.6 22 .8 14.7 79.9 62 .6 95.4 52.7 34.3 20.6 031NR 56 .1 31 .7 25 .2 26.9 23 .8 14.6 84.8 65.3 88.2 53 .5 33.7 20.2 015NT 54.7 30.1 23.0 24.5 22.2 14.6 75.5 59.6 90.9 50.7 33.5 20.8 007NT 54.6 32 .3 25.5 27 .1 22.8 14.6 83.6 66.2 95 .7 55.4 36.2 20.7 012NT 55 .9 36.0 30.3 31 .8 26.1 14.5 94.4 80.0 104.6 65.6 40.3 22.4 010NT 52 .5 31 .9 25 .9 27.0 22.7 14.5 81 .6 63 .6 92 .3 53 .4 32.8 19.9 040NR 53 .0 31 .2 25 .1 26.7 24.0 14.9 86.1 66.9 92.3 58.4 37.4 21.8 mean 54.6 31 .8 25 .6 27.0 23.5 15.0 83.6 66.9 95 .0 56.0 35.0 20.7 s 1.50 1.64 2.25 2.23 1.16 0.77 5.35 5.64 5.76 4.40 2.67 0.98 mean 55 .1 31.9 25.9 27.3 23.9 15.1 83.5 67.9 94.6 56.2 34.6 20.6 s 2.08 1.50 2.11 2.09 1.21 0.69 4.82 6.07 5.20 4.07 2.63 1.04 Table 3.6 Girth measurements (cm) for female subjects. H = head; N = neck; AR = arm (relaxed); AF = arm (flexe d); F = forearm; Wr = wrist; Ch = chest; W = waist, G = gluteal; T = thigh; C = calf; A = ankle. 75 Body size and ci;cling performance 002S 33.6 22.7 19.2 91.8 85.0 44.140.941 .2 27.8 - 87.5 31.5 19.8 7.05 9.98 061S 35.6 26.2 20.9 111 .9 99.4 45.6 53.8 42.6 31 .0 30.1 102.0 33.5 20.6 7.67 10.21 052S 32.8 25.0 19.4 98.6 92 .2 46.5 45.8 39.8 27.5 27.5 94.5 31.4 22.5 7.4 10.40 050S 33.0 22.4 17.6 97.0 88.4 43.1 45.3 40.5 25.4 25.7 89.4 29.3 18.0 6.65 9.25 054S 33.2 24.2 19.5 105.3 97.2 46.5 50.7 37.3 28.8 27.8 99.9 32.1 22.5 8.17 10.65 mean 33.6 24.1 19.3 100.7 92.4 45.2 47.3 40.3 28.1 27.7 94.7 31.6 20.7 7.39 10.1 5 1.13 1.59 1.17 7.80 5.98 1.50 5.03 1.96 2.04 1.83 6.33 1.52 1.92 0.58 0.53 065T 34.2 22.5 20.4 97.4 90.6 44.3 46.3 41 .0 29.4 27.5 96.1 31 .8 20.3 7.36 9.98 008NT 32.7 28.7 20.7 101.4 93.4 46.3 47.1 40.1 27.4 - 93.6 32.1 19.0 7.3 9.40 048T 31.9 25.9 20.4 100.5 93.8 46.1 47.7 41 .0 28.4 - 95.0 32.6 21.0 7.1 10.40 030NR 35.9 24.2 18.3 104 94.9 - 45.0 39.5 29.3 -- 33.4 19.0 7.05 10.35 018NR 33.5 24.5 19.6 100.3 90.5 - 43.8 40.3 27.8 -- 31 .8 17.0 7.15 9.55 058NT 38.1 27.8 22.2 105.8 97.6 - 50.5 44.4 31.1 27.2 100.4 34.4 18.0 7.55 10.05 040NT 32 .8 20.520.5 94.8 87.4 44.742.739.928.1 - 87.5 28.618.87.15 9.40 041NR 35.1 26.6 21 .0 100.6 89.5 38 51.5 39.8 29.1 - 99.5 31.4 19.5 7.25 10.5 053R 32.7 23.9 20.6 101 .7 95 .8 47.3 48.4 39.9 27.9 27.3 91.8 38.5 17.5 7.2 9.95 028R 33.0 23.3 18.1 95.9 86.0 37.5 48.5 39.3 26.4 - 92.5 29.8 20.5 6.85 9.55 035NR 33 .9 24.5 19.7 99.3 88.7 42 .9 45.8 40.1 29.0 - 90.5 30.6 20.4 7.25 10.40 009NT 29.5 23.7 19.5 92.8 83.8 40.9 42.9 39.4 27.5 - 89.0 32.2 18.8 7.00 9.25 045NT 31.6 25.1 17.7 100.2 83.5 37.146.436.2 27.1 - 96.0 30.4 18.0 6.9 9.15 033NR 35.6 25.6 21 .1 104.8 97.3 51 .1 46.2 41 .1 26.8 - 97.0 32.0 20.8 7.05 9.35 036NT 33 .2 28.6 22.4 100.4 93.4 46.9 46.5 42.4 28.5 - 96.0 32.2 19.0 7.45 10.40 013N R 34.2 27.6 19.1 108.7 102.3 52 .7 49.7 40.6 30.2 - 100.5 30.7 20.3 7.45 10.25 045NT 30.5 24.3 16.8 91.3 85.5 44.5 41.0 39.6 28.4 - 86.0 31 .6 18.8 7.1 5 9.65 034NR 31.6 28.1 18.1 98.7 92 .1 47.3 44.8 40.4 27.1 - 95.0 33.1 18.0 7.05 9.25 76 Body size and cycling performance 037NT 34.2 23.6 19.5 99.2 92.9 48.0 44.9 41 .1 28.6 - 94.0 34.8 21.5 7.00 9.95 049NT 34.1 22.5 19.0 92.7 87.0 41 .7 45.3 41 .4 29.3 25.6 88.7 36.4 19.8 6.95 9.45 060NR 32 .1 25.4 20.2 99.2 91.7 44.1 47.6 38.8 26.2 26.9 90.0 30.5 16.8 6.95 9.70 029R 32 .1 24.1 18.9 90.0 82.5 35.7 46.8 39.0 25.5 - 91.5 29.2 20.5 6.95 9.45 044NT 32.5 23.8 19.9 97 .4 91.9 45.4 46.5 39.5 27.4 - 91.0 32 .5 20.0 7.15 9.75 032NR 32.5 36.4 19.9 89.7 79.4 30.5 48.9 41.0 27.0 - 93.0 27.9 20.5 7.25 9.85 003NR 37.6 21 .8 18.9 98.2 90.3 45.5 44.8 39.0 27.2 - 89.7 30.3 20.0 6.95 10.05 016NR 32 .2 26.4 18.4 99.5 88.2 42.8 45.4 41 .8 26.8 - 92.6 32.4 19.0 7.05 9.75 066T 34.5 22 .1 25.0 98.8 90.6 45.8 44.8 41 .9 27.5 27.5 91.4 35.8 20.5 7.44 9.65 051NR 34.2 23.7 21.5 99.7 92.3 44.3 48.0 38.6 27.7 27.0 98.8 33.2 18.7 7.25 10.65 055T 32.2 24.5 18.9 94.7 88.5 44.9 43.6 36.4 25.7 24.4 92.3 31.5 18.3 7.15 9.90 056NR 35.6 36.6 10.4 105 98.4 48.7 49.7 40.9 27.0 27.3 95.3 32.4 19.0 7.05 9.05 064R 37.1 24.6 21 .2 104.3 97.3 47.5 49.8 38.8 29.1 27.2 95.8 30.9 19.8 7.17 9.43 057R 35.2 21 .2 19.8 94.0 87.9 45.1 42.8 39.6 26.7 - 90.6 34.0 21.5 6.97 9.30 059N R 33 .5 26.4 19.2 102.3 95.2 47.5 47.8 42 .0 28.7 - 93.3 32.1 18.5 7.00 9.50 062NR 34.1 21 .2 21 .2 99.3 91 .7 44.2 47.5 39.3 26.9 27.7 93.8 32.0 20.5 7.31 9.74 0 11 NR 36.2 27.1 20.6 97.2 92.9 46.6 46.4 39.2 29.5 27.7 98.9 29.3 22 .0 7.73 9.94 mean 33.7 25.3 19.7 97.4 91 .0 44.2 46.4 40.1 27 .9 26.9 93.5 32.1 19.5 7.16 9.77 s 1.93 3.50 2.23 9.81 4.92 4.53 2.41 1.55 1.28 0.97 3.69 2.17 1.29 0.20 0.42 mean 33.7 25.2 19.6 97.9 91.2 44.4 46.5 40.1 27.9 27.1 93.7 32 .0 19.6 7.19 9.81 s 1.84 3.33 2.12 9.57 5.00 4.25 2.78 1.58 1.36 1.21 4.03 2.09 1.41 0.27 0.44 Table 3.7 Meas urements of heights, lengths and breadths for male subjects. All measurements are in cm. AR = acromiale-radiale; RS = rad iale-stylion; MD = mid-stylion-dactylion; I = iliospinale height; T = trochanteric height; TTL= trochanterion-tibiale laterale; TL = tibiale laterale; BA = bia cromial breadth; BI = bi iliocristal brea dth; FL = foot length; SH = sitting height; TC = transverse chest, AP = an terior-posterior chest depth; H = biepicondylar humerus; F = biep icondylar fem ur. 77 Body size and cycling performance 005TE 32.1 21.4 27.0 90.1 80.0 40.4 39.6 35.3 26.7 - 84.0 30.7 20.2 6.20 9.20 025S 28.2 21 .0 17.3 85.7 78.7 39.6 39.1 36.1 28.7 - - 26.8 17.0 6.35 8.35 001TE 31.6 24.9 17.7 92.9 86.5 46.140.432.5 25.1 - 87 .6 26.7 17.0 6.05 8.95 mean 30.6 22.4 20.7 89.6 81 .7 42.0 39.7 34.6 26.8 • 85.8 28.1 18.1 6.20 8.83 s 2.12 2.15 5.49 3.63 4.18 3.54 0.66 1.89 1.80 • 2.55 2.28 1.88 0.15 0.44 002NR 33.8 23.5 19.3 96.5 89.2 45.5 43.7 39.3 27.9 - 91.0 29.3 16.7 6.45 9.30 063NR 32.2 22.5 17.5 93.4 85.9 42.1 43.8 35.0 28.3 22.7 86.1 26.5 16.7 6.11 8.75 043NR 31.4 18.7 18.0 90.4 83.4 - 40.6 34.9 26.6 -- 28.3 16.5 6.00 8.55 020NR 28.8 20.4 16.6 86.3 80.3 42.7 37.6 35.8 26.4 - 82.0 27.8 16.5 6.05 9.65 031NR 28.4 22.8 16.0 84.7 79.5 41 .6 37.9 34.9 26.1 - 81 .0 28.8 15.2 6.15 8.75 015NT 30.5 18.9 17.9 89.1 82.9 43.5 39.4 34.1 26.5 - 83.5 25.6 15.7 6.00 9.05 007NT 30.2 20.2 16.0 87.1 81.5 42.4 39.1 36.2 25.2 - 84.5 28.5 19.0 6.05 8.65 012NT 31 .0 23.0 18.1 92.5 84.0 43.6 40.4 36.0 31.1 - 88.2 31.8 17.5 6.50 9.95 010NT 34.0 22.7 18.4 83.2 74.3 33.2 41 .1 34.4 27.5 - 81 .0 25.9 17.5 5.85 8.30 040NR 31.8 24.7 18.8 97.6 91 .7 46.147.036.5 26.0 25.0 93.4 27.5 17.5 6.06 9.17 mean 31 .2 21.7 17.7 85.1 83.3 42.3 41.1 35.7 27.2 23.9 85.6 28.0 16.9 6.12 9.00 s 1.85 2.04 1.13 13.80 4.95 3.73 2.97 1.49 1.67 1.63 4.44 1.82 1.05 0.20 0.51 mea n 31 .1 21 .9 18.4 86.1 82.9 42.2 40.8 35.5 27 .1 23.9 85.7 28.0 17 .2 6.14 9.00 s 1.84 2.00 2.78 12.20 4.66 3.52 2.65 1.58 1.63 1.63 4.03 1.83 1.30 0.19 0.49 Table 3.8 Measurements of heights, lengths and breadths for female subjects. All measurements are in cm. AR = acromiale-radiale; RS = radiale-stylion; MD = mid-stylion-dactylion; I = iliospinale height; T = trochanteric height; TTL= trochanterion-tibiale laterale; TL = tibiale laterale; BA = biacromial breadth; BI = biiliocristal breadth; FL = foot length; SH = sitting height; TC = transverse chest, AP = anterior-posterior chest depth; H = biepicondylar humerus; F = biepicondylar femur. 78 Body size and cycling performance male track 5 mean 2.20 5.60 2.12 s 0.97 0.79 0.93 road 35 mean 2.17 4.68 2.74 s 0.69 0.95 0.97 all 40 mean 2.17 4.80 2.66 s 0.71 0.98 0.97 female track 3 mean 3.60 3.93 1.83 s 1.06 1.68 1.05 road 10 mean 3.25 3.96 2.60 s 0.84 1.01 0.94 all 13 mean 3.33 3.93 2.42 s 0.86 1.11 0.98 Table 3.9 Mean ± SD val ues for endomorphy, mesomorphy and ectomorphy for all subject s. 79 Body size and cycling performance male track 5 mean 32 .2 51.5 52 .8 71 .6 104.7 102 .0 s 1. 15 1.09 1.04 3.78 9.71 2.45 road 35 mean 33 .1 51 .0 52.5 75.4 106.3 103.0 s 1.60 2.29 1.09 11 .1 14.9 4.52 all 40 mean 33 .0 51.0 52 .5 74.9 106.1 102 .9 s 1.56 2.17 1.08 10.54 14.19 4.31 female track 3 mean 31.2 48.0 51.7 73.3 94.8 102 .8 s 3.41 4.12 1.53 6.15 6.21 3.13 road 10 mean 32.1 50.5 51 .8 69.8 97.8 102 .6 s 1.62 2.32 1.54 6.47 11 . 1 2.7 8 all 13 mean 31 .9 49.9 51 .8 70.6 97.1 102.6 s 2.02 2.87 1.47 6.33 9.93 2.69 Table 3.10 Mean ± SD values for derived anthropometric indices for all subjects. Arm: ht = arm: height ratio; leg : ht = leg: height ratio; sit ht: ht = sitting height: stature ratio; brachia! = brachia! index (ratio of the length of the forearm to the length of the upper arm); crural = crural index (ratio of the length of the lower leg to the length of the upper leg); seat: leg = sea t height to trochanterion height ratio. 80 Body size and cycling performance 3.2 PROJECTED FRONTAL AREA The ~TOTAL> ApRIDER• ~BIKE> ~TOTAdBSA and ApRIDERf'BSA of all male and female subjects in the three riding positions are shown in Tables 3.11-3.13. Male riders had a significantly higher ~TOTAL using rero style handlebars (0.506 vs 0.41 l; F = 4.69, p :5 0.0001), drop style handlebars (0.580 vs 0.451; F = 5.74, p :5 0.0001) and brake hoods (0.616 vs 0.518; F = 4.51, p :5 0.0001). Male riders had a significantly higher ~RIDER using rero style handlebars (0.357 vs 0.279; F = 4.94, p :5 0.0001), drop style handlebars (0.462 vs 0.345; F = 5.60, p :5 0.0001) and brake hoods (0.481 vs 0.398; F = 4.33, p = 0.0002). ~BIKE was higher for male riders in all three riding posi tions and significant using drop style handlebars (0.118 vs 0.107; F = 2.48, p = 0.0194) and brake hoods (0.135 vs 0.120; F = 2.61, p = 0.0148). ~TOTAdBSA was higher in males in all three riding positions and significant using drop style handlebars (0.303 vs 0.279; F = 2.33, p = 0.0275). ~RIDERf'BSA was higher in males in all three riding positions and significant using rero style handlebars (0.190 vs 0.173; F = 2.23, p = 0.0357) and drop style handlebars (0.241 vs 0.213; F = 3.50, p = 0.0016). 81 Body size and cycling performance 008-NT 1.844 0.546 0.296 0.363 0.197 0.183 018-NR 1.858 0.490 0.264 0.355 0.191 0.135 040-NT 1.770 0.460 0.260 0.32 6 0.184 0.134 041-NR 2.008 0.583 0.290 0.412 0.205 0.171 028-R 1.8 17 0.425 0.234 0.297 0.163 0.129 037-NT 1.974 0.530 0.269 0.389 0.197 0.141 029-R 1.790 0.430 0.240 0.300 0.167 0.131 036-NT 1.929 0.460 0.239 0.330 0.171 0.130 045-NT 1.715 0.459 0.268 0.324 0.189 0.135 044-NT 1.798 0.519 0.289 0.367 0.204 0.152 064-R 1.819 0.534 0.294 0.376 0.207 0.159 065-T 1.881 0.512 0.272 0.368 0.196 0.144 054-S 2.205 0.509 0.231 0.341 0.155 0.168 058-NT 2.074 0.578 0.279 0.412 0.199 0.166 060-NR 1.680 0.493 0.293 0.343 0.204 0.149 066-T 1.996 0.528 0.264 0.394 0.197 0.134 056-NR 2.005 0.529 0.264 0.387 0.193 0.142 055-T 1.785 0.473 0.265 0.336 0.188 0.137 053-R 1.839 0.530 0.288 0.333 0.181 0.197 062-NR 1.899 0.525 0.277 0.387 0.204 0.138 mean 1.884 0.506 0.269 0.357 0.190 0.149 s 0.129 0.044 0.020 0.034 0.151 0.019 022-NR 1.859 0.423 0.228. 0.289 0.155 0.134 043-NR 1.601 0.400 0.250 0.270 0.168 0.131 020-NR 1.569 0.431 0.275 0.296 0.189 0.134 010-NT 1.54 0.390 0.253 0.268 0.174 0.121 063-NR 1.525 0.410 0.269 0.274 0.180 0.136 82 Body size and cycling performance mean 1.619 0.411 0.255 0.279 0.173 0.131 s 0.137 0.017 0.018 0.013 0.013 0.006 mean 1.831 0.487 0.266 0.342 0.186 0.145 s 0.167 0.055 0.020 0.044 0.016 0.019 Table 3.11 Measurements of projected frontal area and derived anthropometric ratios for male and female subjects using c:Ero style handlebars. BSA = body surface area (m 2); ApTOTAL = projected frontal area of the rider and bicycle (m 2); ApTOT/BSA = ApTOTAL to BSA ratio; ApRIDER = projected frontal area of the rider only (m2); ApRlo/BSA = ApRIDER to BSA ratio; ApBIKE = projected frontal area of the bicycle only (m2 )_ 83 Body size and cycling performance 0025 1.847 0.535 0.290 0.429 0.232 0.106 030NR 2.000 0.571 0.285 0.464 0.232 0.107 040-NT 1.770 0.522 0.295 0.414 0.234 0.108 041-NR 2.008 0.687 0.342 0.553 0.276 0.134 033-NR 2.012 0.562 0.279 0.446 0.222 0.115 013-NR 2.082 0.583 0.280 0.467 0.224 0.116 029-R 1.790 0.490 0.274 0.381 0.213 0.109 016-NR 1.891 0.539 0.285 0.412 0.218 0.127 035-NR 1.986 0.574 0.289 0.474 0.238 0.100 036-NT 1.929 0.578 0.299 0.471 0.244 0.107 045-NT 1. 715 0.512 0.298 0.399 0.233 0.113 044-NT 1.798 0.563 0.313 0.435 0.242 0.128 064-R 1.819 0.566 0.311 0.440 0.241 0.128 065-T 1.881 0.578 0.307 0.464 0.247 0.113 054-5 2.205 0.601 0.273 0.486 0.220 0.116 058-NT 2.074 .0689 0.332 0.561 0.270 0.129 060-NR 1.680 0.541 0.322 0.418 0.248 0.123 066-T 1.996 .0575 0.288 0.462 0.231 0.113 056-NR 2.005 0.649 0.3 24 0.527 0.262 0.122 055-T 1.785 0.580 0.325 0.444 0.249 0.136 057-R 1.874 0.598 0.319 0.470 0.2 51 0.129 053-R 1.839 0.591 0.321 0.463 0.252 0.128 059-NR 1.916 0.623 0.325 0.495 0.258 0.128 062-NR 1.899 0.585 0.308 0.465 0.245 0.120 06 1-5 2.181 0.6 18 0.283 0.510 0.234 0.107 mean 1.919 0.580 0.303 0.462 0.241 0.118 s 0.135 0.048 0.020 0.044 0.016 0.010 84 Body size and ci;cling performance 022-NR 1.859 0.480 0.258 0.380 0.204 0.100 025-S 1.528 0.416 0.272 0.309 0.202 0.107 010-NT 1.540 0.425 0.276 0.315 0.205 0.110 001-TE 1.657 0.449 0.271 0.345 0.208 0.104 063-NR 1.525 0.487 0.32 0.374 0.245 0.114 mean 1.622 0.451 0.279 0.345 0.213 0.107 5 0.143 0.032 0.024 0.032 0.018 0.005 mean 1.870 0.559 0.299 0.442 0.236 0.116 s 0.175 0.066 0.022 0.061 0.019 0.010 Table 3.12 Measurements of projected frontal area and derived anthropometric ratios for male and female subjects using drop style handlebars. BSA = body surface area (m2); ApTOTAL = projected frontal area of the rider and bicycle (m2); ApTOT/BSA = ApTOTAL to BSA ratio; ApRIDER = projected frontal area of the rider only (m2); APR10/BSA = ApRIDER to BSA ratio; ApBIKE = projected frontal are of the bicycle only (m2). 85 Body size and cycling performance 041-NR 2.008 0.707 0.352 0.546 0.272 0.161 028-R 1.8 17 0.564 0.31 0 0.440 0.242 0.124 033-NR 2.012 0.590 0.293 0.459 0.228 0.131 034-NR 1.943 0.576 0.297 0.441 0.227 0.136 037-NT 1.974 0.626 0.317 0.496 0.251 0.129 029-R 1.790 0.529 0.296 0.404 0.225 0.126 035-NR 1.986 0.601 0.303 0.494 0.249 0.107 03 6-NT 1.929 0.603 0.312 0.476 0.247 0.127 045-NT 1.715 0.546 0.319 0.424 0.247 0.123 044-NT 1.798 0.585 0.325 0.449 0.250 0.136 064-R 1.819 0.632 0.347 0.484 0.266 0.148 065-T 1 .881 0.616 0.328 0.495 0.263 0.121 058-NT 2.074 0.707 0.341 0.568 0.274 0.139 060-NR 1.68 0.576 0.343 0.445 0.265 0.131 066-T 1.996 0.653 0.327 0.503 0.252 0.150 056-NR 2.005 0.731 0.365 0.588 0.293 0.143 055-T 1.785 0.591 0.331 0.454 0.254 0.137 057-R 1.874 0.613 0.327 0.470 0.250 0.145 053-R 1.839 0.639 0.348 0.500 0.272 0.140 059-NR 1.916 0.641 0.334 0.496 0.259 0.145 062-NR 1.899 0.603 0.318 0.474 0.250 0.129 mean 1.892 0.616 0.325 0.481 0.254 0.135 s 0.106 0.052 0.020 0.045 1.659 0.012 022 -NR 1.859 0.524 0.282 0.406 0.219 0.118 043-NR 1.60 1 0.463 0.289 0.349 0.218 0.114 03 1-NR 1.570 0.508 0.323 0.367 0.234 0. 141 012-NT 1.822 0.585 0.321 0. 454 0.2 49 0.131 86 Body size and cycling performance 010-NT 1.540 0.485 0.315 0.362 0. 235 0.123 063-NR 1.525 0.556 0.364 0.434 0.284 0 .. 122 007-NT 1.627 0.507 0.311 0.412 0.253 0.095 mean 1.649 0.518 0.315 0.398 0.242 0.120 s 0.136 0.041 0.027 0.039 0.023 0.014 mean 1.843 0.591 0.323 0.460 0.251 0.131 s 0.175 0.065 0.022 0.057 0.019 0.014 Table 3.13 Measurements of projected frontal area and derived anthropometric ratios for male and female subjects with the hands placed on the brake hoods. BSA = body surface area (m2); ApTOTAL = projected frontal area of the rider and bicycle (m2); ApTOT/BSA = ApTOTAL to BSA ratio; ApRIDER = projected frontal area of the rider only (m2); ApRID/BSA = ApRIDER to BSA ratio; ApBIKE = projected frontal are of the bicycle only (m2). 87 Body size an d cycling performa nce 3.2. l COMPARISONS BETWEEN RIDING POSITIONS Seventeen (14 male, 3 female) subjects were analysed in the three different racing positions (ie using cero style handlebars, drop style handlebars and the brake hoods respectively) to determine the quantitative effects of changing riding position. Tables 3.15-3.17 show the ~TOTAu ApRIDER and ApBIKE of the subjects in each riding position. Significant differences were found between each of the three riding positions for ApTOTAL (F = 136.09, p $ 0.0001), ApRIDER (F = 176.18, p $ 0.0001) and ~BIKE (F = 33.39, p $ 0.0001). ceros vs drops -0.071 -9.79 :s; 0.0001 ceros vs hoods -0.112 -14.43 :s; 0.0001 drops vs hoods -0 .042 -7.68 :s; 0.0001 ceros vs drops -0.097 -12 .42 :s; 0.0001 ceros vs hoods -0.124 -15.81 :s; 0.0001 drops vs hoods -0.027 -5.73 :s; 0.0001 ceros vs drops 0.026 7.58 :s; 0.0001 ceros vs hoods 0.012 3.12 0.0066 drops vs hoods -0.015 -6 .70 :s; 0.0001 Table 3.14 Qu antitati ve differences between riding positions .. Al so show n are the post-hoe d (mea n differe nce), Stude nt 's t-ratio, and the associated probability (p). 88 Body size and cycling performance 041-NR 0.583 0.687 0.707 029-R 0.430 0.490 0.529 036-NT 0.460 0.578 0.603 045-NT 0.459 0.512 0.546 044-NT 0.519 0.563 0.585 064-R 0.534 0.566 0.632 065-T 0.512 0.578 0.616 058-NT 0.578 0.689 0.707 060-NR 0.493 0.541 0.576 066-T 0.528 0.575 0.653 056-NR 0.529 0.649 0.731 055-T 0.473 0.580 0.591 053-R 0.530 0.591 0.639 062-NR 0.525 0.585 0.603 mean 0.511 0.584 0.623 s 0.044 0.057 0.060 063-NR 0.410 0.487 0.556 022-NR 0.423 0.480 0.524 010-NT 0.390 0.425 0.485 mean 0.408 0.464 0.521 s 0.017 0.034 0.036 mean 0.464 0.563 0.605 s 0.034 0.071 0.069 Table 3.15 Repeated measurement of ApTOTAL of the same subject group in three different riding positions. 89 Body size and cycling performance 041-NR 0.412 0.553 0.546 029-R 0.300 0.381 0.404 036-NT 0.330 0.471 0.476 045-NT 0.324 0.399 0.424 044-NT 0.367 0.435 0.449 064-R 0.376 0.439 0.484 065-T 0.368 0.464 0.495 058-NT 0.412 0.561 0.568 060-NR 0.3 43 0.417 0.445 066-T 0.394 0.462 0.503 056-NR 0.387 0.527 0.588 055-T 0.336 0.444 0.454 053-R 0.333 0.463 0.500 062-NR 0.387 0.465 0.474 mean 0.362 0.463 0.486 s 0.035 0.053 0.053 063-NR 0.274 0.374 0.434 022-NR 0.289 0.380 0.406 010-NT 0.268 0.315 0.362 mean 0.277 0.356 0.401 s 0.011 0.036 0.036 mean 0.347 0.444 0.471 s 0.046 0.065 0.060 Table 3.16 Repeated measu rement of ApRIDER of the same subject group in three different riding positions. 90 Body size and cycling performance 041-NR 0.171 0.134 0.161 029-R 0.131 0.109 0.126 036-NT 0.130 0.107 0.127 045-NT 0.135 0.113 0.123 044-NT 0.152 0.128 0.136 064-R 0.159 0.128 0.148 065-T 0.144 0.113 0.121 058-NT 0.166 0.129 0.139 060-NR 0.149 0.123 0.131 066-T 0.134 0.113 0.150 056-NR 0.142 0.122 0.143 055-T 0.137 0.136 0.137 053-R 0.197 0.128 0.140 062-NR 0.138 0.120 0.129 mean 0.149 0.122 0.136 5 0.019 0.009 0.011 063-NR 0.136 0.114 0.122 022-NR 0.134 0.100 0.118 010-NT 0.121 0.110 0.123 mean 0.131 0.108 0.121 s 0.008 0.007 0.003 mean 0.146 0.119 0.134 s 0.019 0.010 0.012 Table 3.17 Repeated measurement of ApBIK E of the same subject group in three different riding positions. 9 1 Body size and cycling performance 3.2.2 RELATIONSHIPS WITH BODY SIZE All of the data analysed are for both male and female subjects. Strong linear relationships between ~TOTAL and BSA, ~RIDER and BSA (p ~ 0.0001) are evident in all three riding positions. As BSA increases measured ~ increases (see Figures 3.1-3.2). The slope of the regression on i\,RIDERJ'BSA vs BSA is not significantly different from zero (p > 0.05) in all three riding positions ie ~RIDER is a constant fraction of BSA (see Figure 3.3). The mass of larger riders' bicycles represents a significantly (p ~ 0.0001) smaller proportion of their body mass (approximately 12%) than do the bicy cles of smaller riders (approximately 20%; see Figure 3.4). The ~BIK~~TOTAL ratio is smaller in large cyclists in all three riding positions, and a significantly smaller proportion (p < 0.01) when riding in the drops and hoods position (see Figure 3.5). 92 Body size and cycling performance .75 • .:Eros o drops • . 7 • hoods •0 • .65 •• . 6 "'.s ...J ~ . 55 0 • I-c. <{ .5 • .45 • •• • . 4 • • 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 BSA (m2) Figure 3.1 Relationship between ApTOTAL and BSA for three riding positions. aeros: y = 0.240x + 0.048 • RMSR = 0.039 r = 0.724 p ~ 0.0001 n = 25 0 drops: y = 0.296x + 0.005 RMSR = 0.042 r=0.781 p ~ 0.0001 n = 30 hoods: y = 0.333x - 0.019 RMSR = 0.040 r = 0.792 p ~ 0.0001 n = 28 93 Body size and cycling performance .6 • .Eros o drops • ~ .55 • hoods i .5 • 0 • 0 N..s .45 • a:: w • 0 i:2 • o a. .4 • <( .35 • • . 3 •• • • 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 BSA (m2) Figure 3.2 Relationship between ApRIDER and BSA for three riding positions. aeros: y = 0.193x + 0.012 • RMSR = 0.031 r = 0.732 p s; 0.0001 n = 25 0 drops: y = 0.290x + 0.010 RMSR = 0.035 r = 0.830 p s; 0.0001 n = 30 hoods: y = 0.295x - 0.081 RMSR = 0.034 r = 0.805 p s; 0.0001 n = 28 94 Body size and cycling performance 30 • ceros o drops 28 • A hoods • i ~ 26 • • • • 0 24 <( V) ...... co er: w 22 Cl ii: c. 0 <( o. •• 0. 20 c9 ,• • • • ••• . 18 • • • • 16 • •• • • 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 BSA (m2) Figure 3.3 Relationship between ApRIDER/BSA and BSA for three riding positions. aeros: y = 0.073x + 0.173 • RMSR = 0.016 r = 0.091 p = 0.7155 n = 25 0 drops: y = 0.033x + 0.174 RMSR = 0.019 r = 0.022 p = 0.1020 n = 30 hoods: y = 0.023x + 0.209 • RMSR = 0.019 r = 0.023 p = 0.3337 n = 28 95 Body size and cycling performance .24 0 0 .22 .2 0 00 V, V, 0 ru .18 E 00 ,._ 0 0 Cl/ "'C oO ·;:: 98 ~ .16 0 V,ru 0 E 0 Cl/ 0 u 0 f >, u .14 0 :0 § 80 0 Oo 0 .12 0 0 .1 cP 50 55 60 65 70 75 80 85 90 95 rider mass (kg) Figure 3.4 The relationship of bicycle mass as a fraction of rider mass and rider mass. y = 0.319 - 0.002x RMSR = 0.019 r = 0.778 p ~ 0.0001 n = 53 96 Body size and cycling performance .4 • ~ros o drops .375 A hoods • .35 .325 • • • __. • ~ 0 .3 I- a. -:::!: w .275 ~ co c. <( • •• . 25 ~ • .225 .2 .175 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 BSA (m2) Figure 3.5 Relationship between ApBIKE/ApTOTAL and BSA for three riding positions . aeros: y = 0.399 - 0.055x • RMSR = 0.026 r = 0.341 p = 0.0957 n = 25 0 drops: y = 0.410 - 0.064x RMSR = 0.012 r = 0.848 p ~ 0.0001 n = 30 hoods: y = 0.340 - 0.064 RMSR = 0.018 r = 0.484 p = 0.0091 n = 28 97 Body size and cycling performance 3.2.3 ANTHROPOMETRIC PREDICTION OF PROJECTED FRONTAL AREA Regression analysis was conducted in order to identify anthropometric zero-order predictors (p ::;; 0.05) of the ~RIDER only. The zero-order predic tors are listed in Table 3.18 for each of the three riding positions with Pearson product-moment correlation coefficients (r) and associated probability (p). Stepwise regression analysis retained the best predictors of ~RIDER in each of the three positions examined (see Table 3.19). Only those independent variables with a theoretical basis for inclusion and which were relatively easy to measure were analysed. BSA, height and bideltoid breadth were retained and used as the independent variables within the regression equations. ApRIDER was used as the dependent variable as as it was not considered appropriate to predict ~TOTAL from anthropometric measurements of the rider. 98 Body size and cycling performance mass 0.700* 0.778* 0.714* height 0.685* 0.802 * 0.811* BSA 0.732 * 0.830 * o.805* triceps 0.328 0.295 0.298 subscapular 0.194 0.425 0.086 biceps 0.192 0.340 0.112 iliac crest 0.190 0.061 0.102 supraspinale 0.100 0.218 0.065 abdominal 0.279 0.018 0.161 front thigh 0.366 0.497* 0.295 medial calf 0.031 0.191 0.080 mid-axil la 0.401 0.083 0.189 head 0.516* 0.439 * 0.442 * neck 0.725* 0_733* 0.703* arm (rela xed) 0.528* 0.513* 0.413* arm (flexed) 0.611 * 0.542 * 0.47 1 * forearm 0.715* 0.675* 0.684* wrist 0.625* 0.636* 0.587* chest 0.666* 0.667* 0.560* waist 0.726* 0.741* 0.662 * gluteal 0.247 0.329 * 0.329 thigh 0.277 0.189 0.189 calf 0.511 * 0.563* 0.493* ankle 0.685 * 0.728* 0.670* acromiale-radiale 0.640* 0.684 * 0.684* radiale-stylion 0.447 * 0.502* 0.630* 99 Body size and cycling performance mid-stylion-dactylion 0.327 0.173 0.173 iliospinale 0.748* 0.784* 0.824* trochanterion 0.721* o.750* 0.776* troch .-tib .-lat. 0.484* 0.447* 0.480* thigh length "2" 0.601 * 0.582 * 0.627* tibiale-laterale 0.625* 0.776* 0.751* sitting height o.715* 0.795* o.775* bideltoid 0.636* 0.557* 0.575* biacromial 0.722 * 0.706* 0.739* transverse chest 0.693 * 0.707* 0.651 * biliocristal 0.451* 0.459 * 0.489* trochanteric 0.519* 0.699* 0.669 * AP chest depth 0.476* 0.477* 0.417* foot length 0.748* 0.642 * 0.538 humerus 0.714* 0.769* 0.748* femur 0.576* 0.713* 0.627* Table 3.18 Zero-order correlation between ApRIDER and anthropometric measurements for male and female subjects in three riding positions. * Significant at 95% (p::; 0.05) 100 Body size and ci;c!ing performance ApRIDER = 0.1929(X 1)- 0.0 11 8 0.732 0.031 ApRIDER = 0.1511 (X1) + 0.0034(X3) - 0.0832 0.828 0.026 ApRIDER = 0.2898(X1) - 0.0995 0.830 0.035 ApRIDER = 0.2528(X1) + 0.0029(X3) - 0.1597 0.867 0.032 ApRIDER = 0.0058(X2) - 0. 5506 0.8 11 0.034 ApRIDER = 0.0049(X2) + 0.0028(X3) - 0.5262 0.850 0.031 X1 = body surface area (m2) x2 = standing height (cm) X3 = bideltoid breadth (c m) Table 3.19 Multiple regression equations predicting the ApRIDER in three racing positions. The independent variables used in the prediction of ApRIDER were the mean measurements of the subjects (male and female) in the respective racing positions. The physiological and environmental data used in the simulations were the allometric baseline values described in Table 2.1. 101 Body size and Cljcling performance 3.3 TECHNICAL CONSIDERATIONS 3.3.1 COMPARISONS BETWEEN DIFFERENT METHODS Table 3.20 shows the test-retest statistics for the three different methods of calculating ApTOTAL· The reliability of each technique was tested by calculating the technical error of measurement (TEM) and intraclass correlation coefficient (ICC). All three methods were highly reproducible, with the best results obtained using the photographic weighing method (%TEM = 2.9%, ICC= 1.0) Repeated measures ANOVA showed that there were significant differences between ApTOTAL determined by the three meth ods (F = 8.79, p = 0.0022). Post-hoe analysis showed the differences to be located between manual planimetry and both photographic weighing and digital planimetry. However, the mean differences were quantitatively small (2.9 and 2.2% respectively). manual planimetry 0.446 0.063 0.959 0.008 1.57 0.15 2.90 digital planimetry 0.455 0.064 0.997 0.003 2.18 0.06 0.83 photographic weighing 0.459 0.069 1.000 0.001 1.62 0.14 0.25 Table 3.20 Mean values for ApTOTAL using three different methods of measurement. Also shown are the test-retest statistics for each method: ICC (intraclass correlation coefficient), d (mean difference), Student's t-ratio, and the associated probability (p), as well as the percentage intra-tester technical error of meas urement. 102 Body size and cycling performance 3.3.2 THE FOCAL LENGTH OF THE CAMERA A significant relationship (r = 0.909, p = 0.0121) was found between the focal length of the camera lens and measured ~TOTAL (see Figure 3.6). As the focal length became shorter (ie as the camera lens angle became wider), the measured ~TOTAL became smaller. The measured ~TOTAL varied >8% for focal lengths ranging from 28 to 70 mm . . 52 .515 .51 0 .505 N .5 .s 0 ....J ~ .495 0 I- a. <( .49 .485 .48 0 .475 .47 20 30 40 50 60 70 focal length (mm) Figure 3.6 The relationship between the focal length of the camera lens and ApTOTAL· y = 0.0009 + 0.4508 RMSR = 0.008 r = 0.909 p = 0.0121 n=6 103 Body size and cycling performance 3.3.3 THE POSITION OF THE REFERENCE AREA When the area of the reference board was cut out, it was weighed five times for each photograph. When all measurements were considered together, there was a very close correlation between theoretical and measured area ratios and the difference between the mean values was not significant (r = 0.9996, p ~ 0.0001; mean difference = -0.02). For frontal deviation, the correlation was r = 0.9998 (p ~ 0.0001) and the mean difference -0.05, which was not significant (see Figure 3.7). For angular deviation, the correlation was r = 0.98 (p ~ 0.0001), the ICC 0.97, and the mean difference -0.004 (not significant; see Figure 3.8). For lateral deviation, the correlation was not significant (r = 0.065, p = 0.85) and the mean difference of -0.016 was significant (t = -2.37, p = 0.04; see Figure 3.9). This is probably because of the very small scatter in area ratios for the lateral deviations examined (99-103% of the baseline value), and because of the complicating effects of distortion at the margin of the image when the board was shifted to extreme lateral posi tions. Frontal deviation in the modelled and measured range resulted in very large differences (measured range 261 %, theoretical range 253%). In particular, the measured frontal area became much larger as the board was moved towards the camera (see Figure 3.10). Angular deviation in the mea sured range resulted in quite large differences (measured range 16%, theoreti cal range 14%). Angular deviation of the camera affects not only the apparent area of the reference board, but also the measured ~TOTAL· As the camera swings around from a head-on position more of the lateral aspect of the cyclist becomes exposed. The change in the apparent ~TOTAL will vary according to the size and shape of the cyclist and the riding position they adopt. In the present study, as the camera was swung in an arc of ±30°, the measured ApTOTAL varied by ±46% (see Figure 3.12). This is due not only to changes in the apparent area of the reference board (see Figure 3.11), but also due to the fact that the actual area of the cyclist and bicycle changes, as we see progressively more of the lateral aspect of the cyclist. Lateral deviation in the range measured made very little difference to the measured frontal area (mea sured range 3%, theoretical range 5%; see Figure 3.13). 104 Body size and cycling performance C Figure 3.7 Theoretical analysis of the effect of frontal displacement of the reference dimension. The camera (C) is placed d m from the board, which has a half width of b m. The board subtends an angle (equal to twice angle BCA) at the camera lens. If the board were moved back Xf m from the baseline position, it would need to be larger to subtend the same angle, and hence to appear as wide as the baseline board in the photograph. In fact, it would need to have a half-width of DE m. Since triangles CBA and CDE are similar, DE b or b d d DE A similar analysis applies to the height of the board. Therefore the ratio of the apparent area of the board in the baseline position to that of the board in the frontally displaced position (we will designate this ratio rf) will be The ratio of the apparent areas of the bicycle-rider system will be the inverse of this ratio. 105 Body size and cycling performance D ...... 0 ...... 0 .... ,...... , ...... o ...... o ... ····· .. •···o· C B A Figure 3.8 Theoretical analysis for angular deviation. The camera is shifted to position C' at an angle a.0 from the baseline position C. AB is a segment perpendicular to the segment C'D. Since the angle C'DC equals a. 0 , angle C'DB equals (90-a.) 0 , and angle ABD also equals a. 0 • ABD is a right triangle whose hypotenuse BD is equal to b, the half-width of the board. From the point of view of the camera, b appears to be as long as AB, which is equal to b cos a.. The height of the board is not affected by angular deviation. Therefore the ratio of the apparent area of the board in the baseline position to that of the board in the displaced angular position (ra) will be ra = cos a. 106 Body size and cycling performance x, 14············· ...... ~ 8 b A d x, ...... ---,------,.A' C C Figure 3.9 Theoretical analysis for lateral deviation. From the baseline position, the board has been displaced x1 m to the right. DB' is a perpendicular from the segment CA'. The triangles CAA' and BDA' are similar. From the point of view of the camera, b appears to be as long as DB'. Since the ratio of the apparent area of the board in the baseline position to that of the board in the displaced lateral position (r 1) is equivalent to the ratio of DB' to b, 107 Body size and cycling performance 3 0 0. cc 2.5 QI C 2 0. c( rear wheel + 61 o/o (0 .8 1) I!! 1.5 "::, Ill "'QI E -0 .2., hand le bars -25 o/o (0 .38) I! .5 -2 -1.5 -1 -0.5 0 +0.5 + 1 + 1.5 fro nta I displacement ( m) ca.mera. O O 6 0 Figure 3.10 The effect of frontal deviation on the ratio of measured Ap to Ap in the base line position. The solid line shows the theoretical relationship, and the open circles measured values. The small insets at the bottom show overhead views of the position of the camera and reference board relative to the cyclist when the board is set at the front wheel, handlebars, seat and rear wheel. 108 Body size and cycling performance 1.16 1 . 14 c. < a, c:. 1.12 a, VI ..0"' 1. 10 ...0 c. ,,< 1.08 l!! ~ VI 1.06 "'a, E 1.04 -0 .2... :! 1.02 1.00 0 -30 -20 -10 0 + 10 +20 + 30 a ng u lard isp la cement ( 0 ) ./...... ··:::::l'\<::··· ...... c •m• r• ···o::::::::::::~::: ...... :...1~-···0-···•>b .. :-.... i~:::::~:::~:::~· Figure 3.11 The effect of angular deviation on the ratio of measured Ap to Ap in the baseline position, taking into account only the effect of deviation on the apparent area of the reference board. Note that as the angular deviation increases, the apparent area of the reference board decreases, making the apparent area of the cyclist appear relatively larger. The solid line shows the theoretical relationship, and the open circles measured values. The small inset at bottom shows the position of the reference board relative to the camera. 109 Body size and cycling performance 1 .5 c. CICI -L. -30 -20 -10 0 10 20 30 angular displacement ( 0 ) -:,,£:::•· . .... ············: .. ·'·.. / ···=<'·... ·.::::·· ...... ~ : ' ~ c•m • r• ··~::::<:::~::::: ...... :... i···-O·····>\(>.:_ .... ::::::::::::::::oo·· Figure 3.12 The effect of angular deviation on the ratio of measured Ap to Ap in the baseline position, taking into account the effect of deviation on both the apparent area of the reference board and the apparent area of the cyclist. The solid line is a curve of best fit. 110 Body size and cycling performance 1.05 Cl. < QI C: QI 1.04 VI,,, ..Q .,0 c. 1 .0 3 < -a 2! :, 1.02 ,,,VI QI E -0 1.01 .Q., :! 1.00 0 -1 -0. 7 5 -0 . 5 -0. 2 5 0 + 0 .2 5 + 0 . 5 + 0 . 7 5 + 1 latera I displacement (m) 9I -·-1 !9 ---t-9 9i- 9I ~ ~ ~ ! ~ ! ~ ~ ~ i ca.mera. l l l l l Figure 3.13 The effect of lateral deviation on the ratio of measured Ap to Ap in the baseline position. The solid line shows the theoretical relationship, and the open circles measured values. The small insets at bottom show the position of the reference board and camera relative to the cyclist for deviations of -1.0, -0.5, +0.5 and + 1.0 m. 111 Body size and cycling performance 3.3.4 THE POSITION OF THE CAMERA RELATIVE TO THE CYCLIST As the position of the camera relative to the cyclist (viewpoint) increased from 3 m directly in front to 5 m directly in front, the measured ApTOTAL decreased in an approximately linear fashion (r = 0.955, p = 0.0057, I-tailed) by about 9% - a decrease of about 5% for every m the camera was moved away from the cyclist (see Figure 3.14). The areas of the upper body (above the waist) and lower body (below the waist) of the cyclist were deter mined separately, and while there was little change in the area of the lower body, there was a linear decrease in the area of the upper body, which was closer to the camera than was the reference board, as the distance increased (r = 0.954, p = 0.0060, I-tailed; see Figure 3.15). 112 Body size and cycling performance .48 .47 N.s .46 _J ~ 0 I- 0.. <{ .45 .44 .43 3 3.5 4 4.5 5 viewpoint (m) Figure 3.14 The relationship between the position of the camera relative to the cyclist and ApTOTAL· y = -0.0215 + 0.5423 RMSR = 0.006 r = 0.955 p = 0.0057 n = 5 113 Body size and cycling performance .24 Ap upper body .235 •0 Ap lower body .23 • .225 • 0 N .22 $ a. <( .215 0 .21 0 .205 0 .2 3 3.5 4 4.5 5 viewpoint (m) Figure 3.15 The relationship between the position of the camera relative to the cyclist and the Ap of the upper body (filled circles) and lower body (open circles). • y = -0.0195 + 0.2971 RMSR = 0.006 r = 0.954 p = 0.006 n=5 O y = -0.0043 + 0.2291 RMSR = 0.008 r = 0.454 p=0.2212 n = 5 114 Body size and cycling performance 3.4 BODY SIZE AND CYCLING PERFORMANCE: AN ALLOMETRIC ANALYSIS 3.4 .1 EFFECTS OF HEIGHT AND MASS On level terrain an inverse relationship exists between body size and predicted 40 km cycle time (ie as mass and height increase, predicted time decreases). Figures 3.16 and 3.17 show the predicted times under the assumptions of both the expected and empirical models. Predicted performance times decrease for both mass and height in both models, indicating a significant performance advantage for larger cyclists. Using the expected model, predicted 40 km cycle time decreases from 64.02 to 61.01 minutes as mass increases from 50 to 100 kg, representing a range of 3.01 min (180.6 s) or 4.84% of the baseline time (62.17 min). Using the empirical model, predicted 40 km cycle time decreases from 66.33 to 59.33 minutes as mass increases from 50 to 100 kg, representing a range of 7.00 min (420 s) or 11.26% of the baseline time. 115 Body size and cycling performance 68 • expected model o empirical model 67 66 c 65 l QJ 64 E ·.;:::; E ~ 63 0 'Q" "O QJ 62 +-'u '6 ~ a. 61 60 59 50 60 70 80 90 100 110 mass (kg) Figure 3.16 Predicted 40 km cycle time (min, ordinate) plotted against rider mass (kg, abscissa) for riding on level terrain. 116 Body size and cycling performance 68 • expected model O empirical model 67 66 c 65 l QJ 64 E ·.;:::; E ~ 63 0 '<:l" "C QJ 62 +-'u '6 ~ a. 61 60 59 160 165 170 175 180 185 190 195 200 height (cm) Figure 3.17 Predicted 40 km cycle time (min, ordinate) plotted against rider height (cm, abscissa) for riding on level terrain. 117 Body size and cycling performance 3.4.2 THE EFFECT OF RIDING ON A SLOPE The differences in predicted cycle time between riding on a slope as opposed to level ground are dramatic. When riding uphill, predicted cycle time increases as the height or size of the cyclist increases (ie small cyclists are at a relative advantage). The situation is reversed when riding downhill (ie large cyclists are at a relative advantage). These trends occur under the assumptions of both models. Figure 3.18 shows the ratio of the predicted cycle time for a cyclist of mass 50 kg (M50) to the predicted cycle time for a cyclist of mass 100 kg (M100) across a range of slopes from -10% to +10%. A ratio of 1 represents no advantage to either the small or large rider. This occurs at a slope of +2.93% for the expected model, and at slope of +5.55% for the empirical model. The rate of change of advantage as slope changes is not linear. The relative advantage to small cyclists uphill begins to level off with slopes >7.5%. The relative advantage to large cyclists downhill begins to level off at -5%. The steepest part of the curves occur in the region where most slopes encoun tered in real life are graded (-5% to +5%), indicating that body size will influ ence performance on undulating terrain. 118 Body size and cycling performance 1.2 • expected model 1.15 o empirical model 1. 1 0 0 1.05 I I I I I I I ------,------I .95 .9 -10 -7.5 -5 -2.5 0 2.5 5 7.5 10 slope(%) Figure 3.18 The ratio of the predicted time for a cyclist of mass 50 kg (M 50) to the predicted time for a cyclist of mass 100 kg (M 100), plotted against a range of slopes from -10% to +10%. A ratio of 1 indicates no advantage to either small or large cyclists. Both model predictions are shown. 119 Body size and cycling performance 3.4.3 EFFECTS OF RACE DISTANCE Both models predict that large cyclists (M 1oo) will perform better than small cyclists (M5o) on flat terrain over distances from 1 to 40 km (see Figure 3.19). Both models predict that the relative advantage to the large cyclist will become less as race distance increases up to 8 km. For distances ranging from 8 to 40 km, a relatively constant advantage of 5% in performance time is pre dicted for the large cyclist by the expected model. The empirical model pre dicts that the relative advantage of the large cyclist will increase as race dis tance increases from 8 to 40 km. The advantage to the large cyclist under this model are even more substantial with a 10.1 % advantage after 9 km, and a 10.6% advantage after 40 km. 120 Body size and cycling performance 1.14 • expected model 0 empirical model 1.12 1 .1 0 0 ~ "6 LI) ~ 1.08 0 ·.;::::; ~ 1.06 1.04 5 10 15 20 25 30 35 40 distance (km) Figure 3.19 The ratio of the predicted time for a cyclist of mass 50 kg (M50) to the predicted time for a cyclist of mass 100 kg (M 100), plotted against race distances ranging from 1 to 40 km. A ratio of 1 indicates no advantage to either small or large cyclists. Both model predictions are shown. 121 Body size and cycling performance 3.4.4 EFFECTS OF ALTERED MASS Figure 3.20 shows the effects of changing body and bicycle mass. An increase of 5 kg in body mass (all fat mass) will increase predicted 40 km cycle time by 49.8 seconds, whilst a decrease of 5 kg in body mass (all fat mass) will decrease predicted 40 km time trial performance by 51 s. These changes in body mass are essentially linear. Therefore each kilogram of fat mass either lost or gained is equivalent to a change of approximately 10.1 s in predicted cycle time. Approximately 18.5% of the total change in predicted cycle time is a consequence of changing mass on rolling resistance and kinetic energy demands. Therefore each kilogram of mass either added to or subtracted from the bicycle will give approximately a 1.9 s change in predicted 40 km cycle time. By far the most dramatic consequence of altered mass is due to the effects on ApRIDER· Each kilogram added or subtracted to the rider as fat mass will change predicted 40 km cycle time by approximately 8.2 s. 122 Body size and cycling performance • A time (total) A time (mass only) .8 ■ 0 A time (ApRIDER only) .6 c .4 l E .2 ·.;:::; E ~ 0 ,;:f" "'O ~u -.2 i5 ~ a. <:] -.4 -.6 -.8 -1 -6 -4 -2 0 2 4 6 A mass (kg) Figure 3.20 Effects of altered mass on predicted 40 km cycle time for the baseline subject (height 178.68 cm, mass 73.48 kg). The filled circles represent the changes in overall time. The filled squares represent the effects of increased mass on rolling resistance (Rr) and kinetic energy (EK) alone, disregarding changes in projected frontal area (ApRIDER)· The open circles (obtained by subtraction) represent the effects of increased mass on ApRIDER alone, disregarding changes in and Rr and EK· 123 Body size and cycling performance 3.4 .5 EFFECTS OF PROPORTIONALITY Different anthropometric configurations were modelled independently whilst holding all other physical and physiological variables constant. ~ was most sensitive to changes in the legs when thigh length and tibiale laterale were varied ±2 SDs around the baseline measure. The effects of modelling the various anthropometric configurations are shown in Figure 3.21. Table 3.21 shows the variation in predicted 40 km cycle time when the anthropometric measurements are varied ±2 SDs around the baseline measure. Variations in regional fat deposition or fat patterns even without changes in fat mass will affect skinfold thicknesses, and hence girths and ~RIDER· Modelled changes in proportion and segmental configuration should be analysed with caution, as they assume that segment lengths can vary independently of each other, of height and mass, and of functional variables such as the V02max and MAOD. 124 Body size and cycling performance e A-P chest depth 0 bideltoid breadth .8 ■ thigh length □ lower leg length .6 c • front thigh skinfold thickness ll. medial calf skinfold I .4 Q) E ·.,::; Q) .2 u>, u E 0 ~ 0 s;t "'O Q) -.2 -~+-- "'O ....Q) a. -.4 <] -.6 -.8 -1 -2 -1.5 -1 -.5 0 .5 1.5 2 SDs away from mean Figure 3.21 Effects of deviations in proportionality from the anthropometric means of the male subject group. The abscissa indicates the deviation (SDs) from the baseline means of the subject group. The ordinate shows predicted variation in time (min) from the baseline 40 km time. 125 Body size and cycling performance f1 time f1 time f1 time f1 time f1 time f1 time f1 time f1 time (s) (%) (s) (%) (s) (%) (s) (%) A-P chest depth 6.9 0.19 14.1 0.38 20.7 0.56 27.6 0.74 bideltoid breadth 5.1 0.14 8.1 0.22 12.3 0.33 16.2 0.43 thigh length 12 .9 0.35 25.8 0.69 38.7 1.04 51.6 1.38 lower leg length 9.9 0.27 20.1 0.54 29.7 0.80 39.9 1.07 thigh skinfold 3.3 0.09 6.3 0.17 9.9 0.27 12.9 0.35 calf skinfold 3.9 0.11 7.5 0.20 11 . 1 0.30 14.7 0.39 Table 3.21 Effects of deviations in anthropometric measurements from the baseline measurements. The changes in predicted 40 km cycle time (fl time) are expressed in seconds (s) and as percentage (%) of the baseline time of 62 min 17 s. 126 Body size and cycling performance 3.4.6 EFFECTS OF CHANGING RIDING POSITION Figure 3.22 shows the effects of changing riding position (and hence the ~ of the subject) on predicted 4 and 40 km cycle time. Using the rero style handlebars reduces predicted 4 km cycle time by 14 .4 s or 4 .10% of the baseline time which uses drop style handlebars (5 min 51.6 s). Racing with the hands placed on the brake hoods increases predicted 4 km cycle time by 7.2 s or 2.05% of the baseline time. Using the rero style handlebars reduces predicted 40 km cycle time by 186 s (3 min 06 s) or 4.62% of the baseline time using drop style handlebars (67 min 03.6 s). With the hands placed on the brake hoods predicted 40 km cycle time is increased by 93.6 s (1 min 33.9 s) or 2.33% above the baseline time. 127 Body size and cycling performance o2ros drops hoods o2ros 4000 0.511 5: 37 .2 - 4.10 drops 4000 0.584 5: 51 .6 0 hoods 4000 0.623 5: 58 .8 + 2.05 o2ros 40 000 0.511 63 : 57.6 -4.62 drops 40 000 0.584 67: 03.6 0 hoods 40 000 0.623 68: 37.2 + 2.33 Figure 3.22 Effect of riding position on predicted performance time. The three riding positions were described by the concomitant change in mean Ap of the subject group (n = 14) in the three racing positions. 128 Body size and e1;cling performance 4 DISCUSSION 4.1 Anthropometry 4 .2 Projected frontal area 4.2. 1 The problem of scaling 4.2.2 Anthropometric prediction of projected frontal area 4 .3 Technical considerations 4 .3.1 Comparisons between different methods 4.3.2 The relative position of the reference dimension 4.3.3 Perspective and distortion in photography 4 .4 Allometric analysis 4 .5 Directions for future research 129 Body size and cycling performance 4 .1 ANTHROPOMETRY The anthropometric profiles of this group of cyclists are similar to cyclists profiled in other studies specifically, and the wider athletic population generally. Both male and female track and road riders have similar body mass, height and BMI measurements to those recorded for national level riders (Craig et al., 1993; Foley et al., 1989; McLean & Parker, 1989; Telford, Hahn, Pyne & Tumilty, 1990; Telford, Egerton, Hahn & Pang, 1988; Van Handel, Baldwin, Puhl, Katz, Dantine & Bradley, 1987; Withers, Craig, Bourdon & Norton, 1987a). The sum of skinfolds and estimated percent body fat data for male and female state level riders is comparable to data recorded previously for state and national level riders (Telford et al., 1988; Withers et al., 1987a; Woolford, Bourdon, Craig & Stanef, 1993). Relative fatness decreases as we move up the ability scale from recreational to state level riders. Fat mass was shown to be an important predictor of 4000 m individual pursuit performance, due to its retarding effects on rolling resistance, energy required to impart kinetic energy on the system and increased ~RIDER (Craig et al., 1993). Low fatness is a typical characteristic of high performance athletes, and the leanest riders are found at the highest ability levels (Foley et al. 1989; Withers et al., 1987a). Olds (1996) performed Monte Carlo simulations on a large body of anthropometric data pooled from 55 studies on cyclists of different riding ability (n = 3158). For the purposes of meta-analysis, the cyclists were divided into three broad classes: Class 1 (international competitors, Olympians, professional stage-race cyclists); Class 2 (state-level competitors, minor professional tours, elite juniors, national representatives in age-group events, USCF Category l); Class 3 (dub-level competitors and well-trained recreational cyclists and triathletes, USCF Categories 2-3). An interesting aspect of the data in Table 4 .1 is that the variability of anthropometric measures tends to decrease as ability level increases. Male riders are ectomorphic mesomorphs and there is little variation in endomorphy between track and road riders. This agrees with the findings of Foley et al. (1989) and McLean & Parker (1989) who also found a small variation in fatness among riders of different specialities. Female riders are 130 Body size and cycling performance endomorphic mesomorphs, and again there is little variation in the somatotype components between the track and road riders (Figure 4.1). As with most athletes both the male and female riders rate highly in the mesomorphy component (Withers, Craig & Norton, 1986; Withers, Whittingham, Norton & Dutton, 1987c). In a study of the somatotypes of Olympic athletes it was found that there is a trend towards decreased mesomorphy and increased ectomorphy as race distance increased (de Garay, Levine & Carter, 1974). Higher mesomorphy components for the track riders reflect increased morphological development which is required for higher-output shorter-dura tion cycling events. The tendency for ectomorphy to increase with racing distance is typical of power versus endurance athletes (Tanner, 1964) with the higher ectomorphy component of the road riders. The small differences in endomorphy which do exist between track and road riders is attributed to the emphasis given to the lesser demands of endurance training and racing placed on the track riders at these ability levels (ie recreational, club and state). Track riders competing at an elite competition level are set heavy endurance training programmes (riding up to 38 000 km.year-1), and it is not surprising that some of these riders are the leanest of all athletes (Craig et al. 1993). The mean percentage of seat height to trochanterion height of 102.9% for male riders and 102.6% for female riders agree quite closely with the val ues determined previously by Nordeen-Snyder (1977) of 100% for optimal oxygen efficiency and Hamley and Thomas (1967) of 102% for optimal power production. McLean and Parker (1989) found that national track riders have a mean seat height to trochanterion height of 99%, and are subjectively able to determine their optimal seat height. Similarly, most riders in this study chose their seat height through a random process of trial and error, and were able to achieve a seat height which was close to optimal. A methodological consideration for the determination of correct seat height is the difficulty in identifying the location of the trochanterion. Anthropometrists completing LSAS/ISAK anthropometry accreditation courses have consistently found the trochanterion to be one of the most difficult skeletal landmarks to locate. There is a common tendency to locate and mark this landmark proximal to its true location (Chris Gore, personal communication, 29 August 1996). Such 131 Body size and cycling perfo rma nce Class 1 males µ 176.0 70.6 10.9 cr 4.40 6.49 3.26 n 1517 1568 363 Class 2 males µ 176.2 71.4 10.1 cr 8.39 8.73 2.74 n 213 213 70 Class 3 males µ 176.8 69.2 13.1 cr 6.83 8.22 3.25 n 445 445 422 females µ 165.7 57.9 20.6 cr 7.23 8.18 6.42 n 99 99 27 Table 4.1 Estimates of mean va lues and standard deviations for height (cm), mass (kg), and estimated percentage body fat (est. %BF) for Class 1, 2 and 3 male and female cyclists based on Monte Carlo simulations. Also shown is the number of data points in each si mulation (reproduced from Olds 1996). 132 Body size and cycling performance 13 3 "'-'----, 1, 11 7 14 \ ~ 2 6 12 15 94 16 10 /I \, ', / \ / 5 \ l 11/"' \ /~_ De Garay et al ., (1974) 1 male TE 19 1.8, 5.1, 2.6 De Garay et al., (1974) 2 male R 67 1.8, 4.9, 2.7 Stepnicka (1977) 3 male R 25 1.5, 5.5, 2.9 1/2 Carter et al., (1982) 4 male R 18 1.7, 4.8, 3.1 Singh & Malhotra, (1982) 5 female R 9 5.2 , 3.2, 2.6 1/2 White et al., (1982) 6 male R 5 1.6, 4.7, 2.7 Withers et al. , (1986) 7 male R 11 2.0, 5.2, 2.9 2 Singh & Malhotra ( 1988) 8 male TE 11 2.9, 3.6, 3.5 2 Singh & Malhotra ( 1988) 9 male R 10 2.4, 4.0, 3.4 2 McLean & Parker (1989) 10 male TE 17 2.1, 4.7, 2.9 Foley et al. , (1989) 11 male TE 7 2.2, 5.3, 2.9 1/2/3 Foley et al., ( 1989) 12 male R 16 2.1, 4.8, 3.5 1/2/3 Present study 13 male TE 5 2.2, 5.6, 2.1 2/3 Present study 14 male R 35 2.2, 4 .7, 2.7 2/3 Presen t st udy 15 female TE 3 3.6, 4.7, 2.7 2/3 Present study 16 female R 10 3.3, 4.0, 2.6 2/3 Figure 4.1 Somatochart showing the soma topl ots of male and fema le (fill ed circ les) track (TE) and road (R) subgroups, and reference data. 133 Body size and cycling performance technical error would effectively decrease seat height as a fraction of trochanterion height. 4 .2 PROJECTED FRONTAL AREA 4.2.1 THE PROBLEM OF SCALING Recent investigations suggest that large cyclists are at an advantage on flat terrain due to a lower ~RIDE~BSA (Swain et al., 1987; McLean, 1994). In these studies ~RIDER scaled as M0.5S and M0.53 respectively, which did not agree with the theoretical mass exponent of geometric similarity for areas and area-dependent functions of M 0-67. The present study found that ApRIDER does scale to M 0-67 (M0-66, M0.78 and M 0-65 for the reros, drops and hoods riding positions respectively), and ~RIDER is a constant fraction of BSA for all cyclists. This was expected since no relationship was found between ~RIDE~BSA and BSA when measured directly (see Figure 3.3). Male cyclists generally have a larger Ap because they are taller and heavier. Body shape also changes between male and female cyclists, and will also contribute to differences in~ and BSA. Objects of different shape (eg cubes and cylinders, males and females) have different A/BSA ratios. However, provided that objects are internally geometrically similar (eg large females are simply blown-up versions of small females and large males are sim ply blown-up versions of small males), then all objects scale to the same exponent b but different co-efficients a under a geometric similarity system. This study has shown that males have a significantly greater (p < 0.05) ApRIDER/BSA than females in the reros and drops riding position. The same non-significant trend also applies in the hoods riding position (p < 0.15). This is expected because males and females are not geometrically similar, and scale to different allometric co-efficients. The weighted mean exponent for the ApRIDER of male cyclists only was M0.50 (M0.44, M0.53 and M0.51 for the reros, drops and hoods riding positions respectively), which was close to the exponents reported by Swain et al. (1987) and McLean (1994) but was not 134 Body size and cycling performance significantly different (p > 0.05) from M 0-67. Similarly, measured ~RIDE~BSA ratios for all three riding positions were not significantly differ ent (p > 0.05) between small and large cyclists (see Figure 4.1). ~RIDER is a constant fraction of BSA because the BSA of male cyclists in this sample scaled to MO.SB (M0-58, M 0-60 and MO.SS for the reros, drops and hoods riding positions respectively), and which are all not significantly different (p > 0.05) from M0.67. Height and mass data of elite Tour de France cyclists [Le Tour 1996 (WWW document; www2.letour.fr)] was analysed, which confirmed the theoretical relationship between BSA and mass. In this sample BSA scaled to M0.64 (r = 0.96; see Figure 4.2). As with other populations male cyclists scale geometrically (ie BSA a M 0-67), but are likely to differ in shape to other pop ulations because they scale to different allometric co-efficients. The fact they are traditionally high in ectomorphy may provide some clues to the differences in their shape. 1996 Tour de France cyclists had a mean ectomorphy compo nent of 3.40 ± 0.68 (n = 164). The mean ectomorphy component for the gener al adult male population is 2.03 ± 1.20 (n = 993; AADBase, 1995). The rerodynamic advantage of larger riders on flat terrain is gained primarily through their significantly smaller ~BIKW~TOTAL (see Figure 3.5). Large cyclists are not more effective at reducing ~RIDE~BSA than small cyclists. In the allometric analysis of this study, two different similarity systems were used to study the effects of body dimensions on cycling perfor mance. One model used the theoretically expected exponents, and the second model empirical mass exponents to determine the effects of changes in body size on energy supply and demand variables. The empirical model uses the exponents calculated for the energy supply and demand variables on different samples of male cyclists, none of which are significantly different (p < 0.05) from the theoretical expectants. Since cyclists scale geometrically this model is not a likely similarity system. The differences between the expected and empir ical models do highlight the importance of allometric considerations to performance, especially in the correct determination of scaling relationships. 135 Body size and cycling performance 21 y = 23.064 - 2.175x ,. r=0.186 20 • • p = 0.4334 V'l 0 '- n = 20 f\l 19 Figure 4.1 ApRIDER/BSA ratios for male riders only in three riding positions. The top panel is the cEros position, the middle panel is the drops position and the lower panel the hoods position. 136 Body size and cycling performance .8 .75 .7 N .65 E .55 .5 • 4 4.1 4.2 4.3 4.4 4.5 In (body mass; kg) Figure 4.2 Regression of In (BSA, m2) on In (body mass, kg) for 1996 Tour de France competitors. The slope of the regression line 0.64 (95% confidence intervals, 0.61-0.67) is the estimated exponent (b) of the general allometric equation. y = 0.639x - 2.079 RMSR = 0.015 r = 0.960 p ~ 0.0001 n = 164 137 Body size and cycling performance 4.2.1 ANTHROPOMETRIC PREDICTION OF PROJECTED FRONTAL AREA Since ~RIDER is undoubtedly related to the size and shape of the rider, anthropometric prediction equations have been developed to estimate ~RIDER using some simple body measurements. The anthropometric prediction of ~RIDER is an alternative to the time-consuming and expensive methods of photographic analysis. Dubois and Dubois (1915) established a prediction equation for BSA from height and mass. Since ~RIDER is approximately a constant fraction of BSA, height and mass should also be predictors of the size and shape of a rider and ~RIDER· Pugh (1976) was one of the first to establish a relationship between projected frontal area (in their case ~TOTAV and height and mass. It is more theoretically correct to predict ~RIDER rather than ~TOTAL from anthropometric measurements, since APBIKE is independent of body size. Equations developed in this study were specific to three different racing positions, since different body regions are exposed for each riding position and may change ~RIDER· BSA, mass and height were three of the strongest zero-order predictors of ApRIDER in each riding position. This supports the findings of Pugh (1976) and those of McLean (1994) whose analyses retained BSA, mass and height in similar predictive equations. Anthropometric variables which are more complex to measure (eg iliospinale height) do not necessarily significantly improve the prediction of ~RIDER· Trunk angle was not retained as a zero-order predictor of the ~RIDER in this study. Intuitively trunk angle would be expected to be related to ~RIDER· The result could be from some larger riders adopting very rerodynamic riding positions. 4.3 TECHNICAL CONSIDERATIONS The range of data reporting~ in the literature is large. These differences exist despite using homogeneous samples, riding positions and bicycle configurations. The differences are undoubtedly due to variation in 138 Body size and cycling performance measurement technique, particularly in the choice and the relative location of a reference dimension when photographic methods are used. Most studies have failed to report any technical details of their measurement processes. Measurement techniques have to be standardised so that data may be compared. Numerous problems exist with any method that uses photographic analysis. As observed by Swain et al. (1987) photographs taken in the laboratory may not accurately reflect true riding position. We found that the riders "posed" for the photographs, which might not be the same position as their racing positions. Ideally the cyclists need to be analysed under racing conditions, however the relative positioning of a suitable reference dimension would be critical and very difficult. Photographic analysis of~ does not consider fluid dynamics and three dimensional body shapes. Photographs do not account for the type and the direction of air flow around a moving object. The lack of an accurate method to measure ~ is one reason why rerodynamicists traditionally measure a lumped drag area (ie ~TOTAL Co) rather than measuring both variables independently. Another reason is that drag area is the variable useful for practical application. It is not useful simply knowing ~TOTAL if the drag characteristics of a system (ie relative shape, smoothness) are not available. The exact relationship which exists between ApTOTAL and Co remains unclear, but it is doubtful that both variables are mutually exclusive as measures of size and shape and smoothness respectively. 4.3.1 CoMPARISON BETWEEN DIFFERENT METHODS The photographic weighing method showed the best reliabilty and precision, where meticulous measurement can reduce the technical error of measurement for repeated weighings to 0.25%. Planimetry is usually preferred because it is more time efficient and cost-effective. Once the photograph has been taken and developed the approximate time required to perform photo graphic weighing was 25 min, compared to 10 min for manual or digital 139 Body size and cycling performance planimetry. Digital planimetry particularly provides nearly the same level of reliability and precision as photographic weighing and will become even less time-consuming with the advent of more sophisticated software applications. 4 .3.2 POSITIONING THE REFERENCE DIMENSION The measured ~ is sensitive to frontal, angular and lateral displacement of the reference dimension. There was generally good agreement between the theoretical and empirical estimates of how the relative position of the reference board to the cyclist affects measured ~TOTAL· Frontal deviation has by far the most dramatic effect (see Figure 3.12). Displacing the board from the baseline position (mid-acromiale-trochanterion) to the acromiale (roughly at the level of the handlebars) decreases the measured ~TOTAL by 25%. Assuming a baseline ~TOTAL of 0.5 m2 (with the board placed mid acromiale-trochanterion), this shift would reduce measured ~TOTAL to 0.38 m2. Moving it further forward to the front wheel-tip, would decrease ApTOTAL by 54% to 0.27 m2. The apparent enlargement of the board will subsequently diminish the ~TOTAL of the cyclist. Moving the board back to the trochanterion (roughly at the level of the seat), ~TOTAL is increased by approximately 28% to 0.64 m2. Moving the board back to the rear wheel-tip increases ApTOTAL by 61% to 0.8lm2. The apparent reduction in the size of the board will subsequently increase the ~TOTAL of the cyclist. Few investigators have reported the location of their reference dimension. Pugh (1974) used the height and width of the handlebars as the reference dimension. In a relatively forward position, ~TOTAL is effectively decreased because the handlebars appear large relative to the cyclist. Pugh's measured values for ApTOTAL in the reros, drops and hoods positions were 0.42, 0.46 and 0.47 m 2 respectively. Correcting for the relative placement of the reference dimension in the frontal plane, the mean ~TOTAL of cyclists reported by Pugh (1974) in the rero, drops and hoods positions were 0.560, 0.613 and 0.627 m2 respectively. These corrected data compare favourably with the mean ~TOTAL reported in this study for the same riding positions of 0.506, 0.580 and 0.616 m2 respectively. The small size of handlebars as a 140 Body size and cycling performance Figure 4.2 Standardised position of the system (rider and bicycle) and the reference dimension (board). 141 Body size and cycling performance reference dimension would also reduce the precision with which ApTOTAL can be measured. McLean (1994) and Swain et al. (1987) measured ~RIDER· The data reported by McLean are consistent with the measurements obtained in the present study. McLean (1994) used a vertical linear reference 1 metre in length placed at the level of the bicycle bottom bracket and approximately 40 cm to the side (Brian McLean, personal communication, 11 June 1996). ~RIDER in the drops position yielded measured values of 0.387 and 0.465 m2 for small (mass = 62.0 ± 3.9 kg) and large (mass = 87.1 ± 10.5 kg) cyclists respectively. Swain et al. (1987) used an A4-size cardboard rectangle placed "mid-body" as a reference dimension (David Swain, personal communication, 8 October 1996). ~RIDER in the drops position measured 0.318 m2 and 0.378 m2 for small (mass= 59.4 ± 4.1 kg) and large (84.4 ± 3.2 kg) cyclists respectively. The ~RIDER for male cyclists in the drops in the present study was 0.463 m2. The mass of these riders was 70.7 ± 7.2 kg. Both samples are relatively homogeneous and the relative location of the reference dimensions are similar. Lateral (or vertical) displacement and angular deviation has a smaller effect on measured ~- A shift of the reference dimension 1 m to the right or left changed the~ by only 3% (measured) or 5% (modelled), while even a 5° change in the camera arc angle resulted in variations of< 1.5%. Therefore even gross lateral or angular misalignments are unlikely to cause major errors. Given the importance of the placement of the reference dimension, it is easy to understand how different investigators have arrived at such widely varying estimates of Ap for similar bicycle-rider systems, and hence varying estimates of the coefficient of drag. 4 .3.3 PERSPECTIVE AND DISTORTION IN PHOTOGRAPHY The apparent relationship between the size, shape and position of visible objects in an image is termed perspective. The perspective of a photograph is determined by the viewpoint (ie the position of the camera in relation to the subject, or more specifically the ratio that the depth of the subject bears to its distance from the camera). Perspective is independent of 142 Body size and cycling performance the focal length of the lens and remains constant if the viewpoint is fixed. When viewpoint is altered, perspective is changed. Altering the focal length of the lens without changing the viewpoint, alters image size only leaving perspective unchanged (Horder, 1975). Photographs which use a close viewpoint are steep in perspective and characteristically show a great disparity between the apparent size of fore ground and background objects. Foreground objects will have increased prominence and background objects reduced prominence (see Figure 4.3). Objects close to the camera appear larger [eg nearer portions of the body (the hands and head particularly) appear exaggerated in size against diminutive legs and more distant parts (see Figure 4 .4)]. This is reflected in the results, where the measured area of the upper body decreased as the cam era was placed further away from the rider. In theory we should see an increase in the measured area of the lower body as distance increases, since the reference board is nearer the camera than the lower body. However, the mea sured area of the lower body only varied very slightly, probably because the distance between the reference board and the plane of the lower body was very small, and because the area of the upper body was preponderant. Therefore the change in total area was largely a function of the change in the upper area of the body. The magnitude of the variation in the measured range (9.1 %, or about 5% of measured~ for every m the camera is moved) could be of practical importance. The difference in measured areas depends on the ratio of the distance between the camera and the plane of the upper body and the plane of the reference board. The degree of apparent size imbalance and distortion will be determined by the depth of the subject and therefore vary with the riding position. In extended riding positions where the body is in a horizontal position, the effect will be most pronounced, since there is a greater distance between the reference board, and the closer and more distant ends of the cyclist. This will have some consequence for analyses relating anthropometric measurements to ~- As the upper body will be relatively enlarged when a close viewpoint is used, the importance of upper body dimensions 143 i i tx, tx, ;:, ;:, U) U) ~- ;:t ;:t i i ~ ~ ~ ~ t t ~- 'a, 'a, i i to to and and EF EF appear appear of of AD AD C2 C2 at at ~- .: .: ratio ratio cyclist cyclist - the the cyclist cyclist of of the the apparent apparent parts parts the the 2 2 c through through distant distant more more passing passing position position the the and and C 1 1 C to to camera camera closer closer From From gets gets point CD:AD. CD:AD. perpendicular perpendicular is is view view AD AD planes planes the the to to as as EF EF two two of of ratio ratio Therefore Therefore Consider Consider greater. greater. A A apparent apparent D D viewpoint. viewpoint. the the on on 1 1 c somewhat somewhat is is position position smaller. smaller. perspective perspective F F which which of of camera camera relatively relatively BD:AD, BD:AD, is is From From be be EF. EF. AD AD to to Dependence Dependence 4.3 4.3 Figure Figure A A A A ...... Body size and cycling performance Figure 4.4 Steep perspective in this photograph is the result of a close viewpoint (2 m) with a wide-angle lens (35 mm). The upper body of the rider (eg hands, head) appears disproportionately large compared to distant objects (eg legs). 145 Body size and cycling performance (eg biacromial breadth, bideltoid breadth) will be exaggerated. It is better to shoot from a longer camera distance and enlarge the images, or use a longer focal length lens to give reasonably flat perspective. Different focal lengths produce their own inherent characteristics. Shape (wide-angle) distortion of wide-angle lenses is due to the wide angle of view, because a lens projects its image on a flat film plane (Figure 4.5). Spheres and cylinders at the edge of the field appear elongated or elliptical eg faces become egg-shaped, with the elongation stretching the proportions away from from the centre of the image. This is noticeable in the exaggerated ellip soid shape of the head (see Figure 4.6) and "keystoning" of the reference board (ie a rectangular board will appear trapezoidal, as the edge closest to the edge of the film is distorted; see Figure 4.7). Measured¾ decreases with focal length, perhaps because the distortion of the reference board is greater than that of the cyclist at short focal lengths. Choosing the correct focal length to minimise distortion is important. In the range measured in this series of tests (focal lengths ranging from 28-70 mm, a relatively moderate spread) the variation in measured ¾TOTAL was >8%. Incorrect perspective and shape distortion will also bias the relationship between certain anthropometric measurements and ¾· If the head is distorted (a zero-order predictor of ¾RIDER) for example, this may bias the importance of head girth as a predictor of¾· 4.4 ALLOMETRIC ANALYSIS Allometric considerations have been used in conjunction with a model of cycling performance to predict the effects of changes in body dimensions on cycle time. Predicted cycling performance times will reflect dimensional changes according to how those changes affect the different components of the energy supply and energy demand of cycling. Dimensional changes have been modelled both independently and conjointly with changes in slope, distance and body mass. It has been assumed that some factors influencing energy sup ply and energy demand (including mechanical efficiency, fractional utilisation, 146 Body size and C1Jcling performance ' ' ' ,(D' ' '',,, ' ' ' ' ' ' ' ' ' ' '' ' ' '' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' ' _o ~:---:-__ :_-:-:::::::~~------:::~~c''~ ' ' ' ' ' ' , ' , , , , , ,' , , , , , , , , , , , , , , , , / ,, / ,' ,," , , , , 0 , , ' , , , , , , Figure 4.5 Di stortion of objects at edges of wide-angle photographs. Because the image of the object must be projected onto a flat film surface, light rays which fall obliquely onto the film will tend to elongate images (Redrawn from Horder, 1975). 147 Body size and cycling performance Figure 4.6 Illustration of the distortion created by changing the camera focal length and viewpoint. These images were created in a computerised figure-posing programme, Poser 1.0. The figure on the left shows the view taken by a camera with a simulated long focal length (60 mm) and far viewpoint (ie the camera is placed a long way from the cyclist). The figure on the right uses a simulated short (15 mm) focal length and near viewpoint. In the figure on the right, the head and hands are markedly enlarged relative to the lower body, and parts of the body near the edge of the image (eg the head) are abnormally extended. 148 Body size and C1Jcling performance . "' Figure 4.7 Photograph of the reference board using a short focal length lens (35 mm). The keystoning of the rectangular reference board to a trapezoid shape has occ urred due to distortion at the edge closest to the edge of the film. 149 Body size and cycling performance the time constant for V02 kinetics and 02 deficit kinetics, i\,BIKE and bicycle mass) are unaffected by body dimensions. The two allometric models used in this study produced similar trends which indicated that large cyclists will be substantially advantaged when riding on flat terrain. Both models predict an energy demand advantage to the large cyclist because the i\, of large bicycles is not significantly greater (p > 0.05) than the i\, of small bicycles (see Figure 2.5). The mean i\,BIKE for males using reros style handlebars was 0.149 m2. The i\,BIKE/i\,TOTAL for 50 kg riders was approximately 36%, and the i\,mKEfi\,TOTAL for 100 kg riders was approximately 27%. The smaller i\,BIKE/1\,TOTAL is the primary advan tage of larger riders on flat terrain over 40 km. The empirical model predicts an even greater energy demand advantage to the large cyclist because this model scales i\,RIDER to MD.44. Since i\, is proportional to air resistance, the energy demand of large cyclists will be relatively smaller. Anecdotal and empirical evidence suggests that smaller sized cyclists generally perform better in hill and stage races (Stovall, Swain, DeBenedetti, Pruitt & Burke, 1993). The differences exist primarily because energy demand and energy supply scale to different mass exponents. When energy demand (which is largely determined by ApTOTAL) scales to a lower mass exponent than energy supply (which is largely determined by V02mru) on the flat, large cyclists are favoured. When energy supply (V02mru,) scales to a lower mass exponent than energy demand during hill climbing (which is largely deter mined by M + Mb) small cyclists are favoured. During downhill riding large cyclists retain their advantage because energy supply (ie the gravitational potential energy of the system) scales to a higher mass exponent than energy demand. Both models used in this study predicted that large riders would retain an advantage uphill to slopes of 2.9% (expected) and 5.5% (empirical). This occurred because a 4 km uphill course was used for the simulations. On such courses the performance advantage is to the large cyclist for two reasons. Firstly, over relatively short distances the 02-deficit becomes a major factor to energy supply. Since mass is the chief determinant of energy demand when riding uphill, and MAOD scales as M 1 (expected) and Ml.16 (empirical) then large cyclists will be equal to small cyclists using the expected model and at a 150 Body size and cycling performance relative performance advantage using the empirical model. Secondly, large cyclists retain the relative advantage of energy demand in both models because of their lower bicycle mass:rider mass. Of course most tours and road races include hills which are longer and steeper, where the chief determinant of energy supply is some fraction of V02max scaling at an exponent < M 1, and placing the small cyclist at the relative performance advantage. Both models predict that large cyclists will be at a performance advantage over distances from 1 to 40 km on flat terrain. It is essentially the lower ~BIKWApTOTAL which provides this edge. The empirical model predicts even better race times for large cyclists because ~RIDER scales to M0.44 (empirically) and M0.67 (expected), providing a lesser relative energy demand. The relative advantage to the large cyclist will become less as race distance increases up to 8 km, because O2-deficit becomes less important and· V02max becomes the chief determinant of energy supply. Over very short distances, the large cyclist is at an even greater advantage because O2-deficit [ scaling as M 1 ( expected) and M 1.1 6 (empirical)] contributes significantly to energy supply. For distances ranging from 8 to 40 km, a relatively constant advantage of 5% in performance time is predicted for the large cyclist by the expected model. The empirical model predicts the advantage to the large cyclist will increase slightly as race distance increases from 8 to 40 km, because they-intercept of the VOrWR regression line scales as MO.OS (ie there is no significant difference in the oxygen cost of loadless pedalling between small and large cyclists). The advantage to the large cyclist under this model is 10.1% after 9 km and 10.6% after 40 km. The ratio M50:M100 increases suddenly in both models at an 8 km distance. This is due to the concomitant drop in the fractional utilisation of energy supply where riders cannot sustain oxygen uptakes close to VO2max for longer than approximately 10 minutes (Aunola et al., 1990). The large cyclist (M100) is able to ride 9 km on flat terrain approximately 1 min faster than the small cyclist (M50). This allows the large cyclist to sustain an intensity close to V02max for nearly all of the distance. The small cyclist will complete more of the 9 km distance at a lesser fraction of V02max which will increase the advantage of the large cyclist over this distance. 151 Body size and cycling performance Swain (1994) estimated that differences in body mass account for approximately 10-20% of performance variability between elite cyclists. Each kg of fat mass either lost or gained is equivalent to a change of approximately 10.1 sin predicted performance time over 40 km on the flat. Nearly 80% of this change in predicted performance time will be accounted for through changes in ~RIDER· The remaining change is due to the effects of increased mass on rolling resistance and the kinetic energy demands required to accelerate the system. Segmental dimensions will also change the ~RIDER· In general, riders with narrow shoulders, shallow chests and short legs will perform better than their heavily-torsoed, long-legged counterparts. Most of these predicted variation are small (0.3-1.4% of predicted performance time), but would be significant from a performance perspective. Even a 0.1 % change in the baseline time is equivalent to 3.7 s or a distance of 40 m. The importance of using rero style handlebars to achieve a more rerodynamic riding position should not be under-estimated. Predicted performance time was lowered more than 4% of the baseline time (186 s) over 40 km using rero style handlebars compared to the conventional drop style handlebars. The use of rero style handlebars represents an efficient and immediate means of improving cycling performance, especially when considering the time and expense of laboratory testing which usually achieves only marginal performance gains immediately. A number of studies have used statistical techniques to establish relationships between physiological and anthropometric characteristics to cycling performance (Miller & Manfredi, 1987; Craig et al., 1993). Empirical evidence suggests that elite time trialists are tall (186 cm) and lean (77 kg) (Foley et al., 1989), and it is this body size and shape which supports the best riders and the theoretical findings of both models. Miller and Manfredi (1987) found that the upper- to lower-body circumference ratio was a significant predictor of 15 km time trial performance, supporting the importance of segmental dimensions to cycling performance. Increasing mesomorphy (eg broad shoulders, deep chest) increases ~RIDER and is disadvantageous over longer distances. Craig et al. (1993) found that fat mass was one of the vari- 152 Body size and cycling performance ables retained in stepwise multiple regression prediction of 4000 m individual pursuit performance, supporting the modelled importance of changes in adiposity. Foley et al. (1989) reported the supposed importance of leg length as a significant anthropometric variable associated with cycling performance. Sprinters for example have significantly shorter legs which enables them to generate high pedal cadences through a biomechanical advantage (Astrand & Rodahl, 1986; Foley et al., 1989). Time trial riders have significantly longer legs than riders of other events, which enable them to gain a similar biomechanical advantage and utilise higher gear ratios with longer crank arms. The biomechanical rationale for this is not fully understood. Our models predict that the optimal time trialist will be large but with relatively short legs. Obviously it will be a trade off between the biomechanical advantages associated with long-legged riders and the contribution of long-legs to ApRIDER· It is doubtful that the relationship between size and predicted cycle time is open-ended for both models. The empirical data on the size of elite riders strengthens this suggestion, although the appearance of large riders is becoming more commonplace. Riders competing in the 1996 Tour de France had a mean height 179.0 ± 5.72 cm and mass 68.9 ± 5.53 kg. Six riders were taller than 190 cm, and three of these riders weighed more than 80 kg [Le Tour 1996 (WWW document; www2.letour.fr)]. Larger riders may now be appearing due to either secular trends in growth and also the possibility of new morphological optima which might accompany changes in equipment design and alter the type of rider which is best suited to an event (Norton et al., 1996). Perhaps other factors have traditionally contributed to the suppres sion of large riders. Heat transfer might be an important consideration both in conduction and dissipation, and may place large riders at a disadvantage in hot, humid environments. More likely is that most cycling tours involve a mix of both flat and hilly terrain, and that it is the disadvantages of riding in undulating terrain which limits the performance of large riders. Mechanical efficiency for both models was considered independent of body size. The relationship between rider size and mechanical efficiency is not fully under- 153 Body size and cycling performance stood and has traditionally been regarded as negligible (Astrand, 1960; Williams, Wyndham, Morrison & Heynes, 1966). These assumptions may not hold when dealing with a large number of subjects with heterogeneous masses. Berry, Storsteen & Woodard (1993) reported significant negative relationships between gross and net cycling efficiency and body mass, and that these effects are most likely related to the effects of large subjects having to move increased leg mass and increased body size on resting metabolism. The data of both models are determined by the mass exponent used in the allometric scaling process. Firstly both the rerobic and the anrerobic energy supply systems are dimensionally dependent. The empirical model mass exponents for energy supply all fall within the 95% confidence intervals and closely match the expected mass exponents for area and volume dependent functions. The empirical model mass exponents support the. use of geometrical similarity when reporting metabolic data. As an example, VO2max should be expressed in ml.kg-0-67.min-1 as it is proportional to M 0-67. This provides a more valid comparison in comparing V02max between individuals of different body size. This data of Vaage and Hermansen (in Astrand & Rodahl, 1986, p 400), the data of Coyle (in Swain 1994) and the data of Secher (1990) support the use of M 0-67 as the best-fit size denominator. Figure 4.8 shows that when V02max is expressed in relative terms as ml.kg-1.min-1 small cyclists have greater values than large cyclists. The lower panel of this figure shows that when V02max is expressed in relative terms as ml.kg-0-67.min-1 it becomes independent of body size (ie the slope of the regression line is not statistically different. from zero) and may therefore be used as a meaningful size denominator. VO2max was also expressed for the same subjects in relative terms as ml.kg-0.75.min-1 which is another proposed size denominator (Bergh et al., 1991; Kleiber, 1947; Nevill, 1994). The slope of the regression line was more negative than that for VO2max expressed in relative terms as ml.kg-0.67.min-1 although it was not statistically different from zero. Both models have used male data only due to the shape differences which are likely to exist between males and females. The increased fat mass of female subjects may change the shape of the rider and the ~RIDER• and the mass exponents of energy supply. Both genders should be analysed as separate 154 Body size and cycling performance 7 y = 0.038x + 2.166 r = 0.498 6.5 • p !5: 0.0001 ~ I 6 .EC • 5.5 d X CU 5 E N 0 4.5 ·> 4 3.5 90 y = 97.371 - 0.405x r = 0.415 ~ 85 I p = 0.0009 .EC 80 75 I Ol ~ 70 --= -S 65 X CU 60 E N 55 0 ·> 50 • 45 • 360 y = 313.334 - 0.421x r = 0.113 I 340 C p = 0.3872 .E 320 /Y)...... • N I 300 Ol ~ 280 E 260 -X CU E 240 N 0 • ·> 220 • 200 250 y = 235.544 - 0.518x r = 0.196 ~ 240 I C 230 p=0.1309 .E 220 ~ • /Y) 210 I Ol 200 ~ 190 E 180 -X CU 170 E • N 160 • 0 • ·> 150 • 140 • 55 60 65 70 75 80 85 90 95 . Figure 4.8 Maximal oxygen uptake (V02max) for a group of male cyclists ranging in ability from recreational to world-class (n = 61) expressed as L.min-1 (top panel), ml.kg-1.min-1 (second panel), ml.kg-2/3_min-1 (third panel) and as ml.kg-3/4_min-1 (bottom panel). 155 Body size and cycling performance populations when allometrics are considered for energy supply and demand variables. If females do differ in body shape compared to males, then applying the geometric model of ApRIDER used in this study would make it difficult to model the disproportionately large anterior-posterior chest depth of the female. 4 .5 DIRECTIONS FOR FUTURE RESEARCH An understanding of the importance of body size to performance is an essential component in the physiological preparation of an athlete. Anthropometry and sports performance is an area of exercise science which has received comparatively little research attention. A more complete understanding of the consequences of body size are required. Specific to this study are: • Due to competing selection pressures, only those performers with the most optimal body dimensions become world-class competitors. Anthropometric data needs to be collected which describes the differences between competitors of different ability classes. These data may give some clues to the selection pressures placed on these performers at different competition levels. • Very little anthropometric and physiological data exists on female cyclists. More descriptive data are required across heterogeneous populations so that a better understanding can be obtained of the allometry and particularly the size and shape differences between genders. • The determination of projected frontal area using traditional methods is unsatisfactory and has many technical problems, particularly in the choice and location of a reference dimension. Some purer method of isometric projection needs to be developed. • A major problem not only in cycling but inthe area of fluid dynamics is 156 Body size and cycling performance to model flow patterns. Recently, discrete particle mathematics has emerged as a possible solution. Such methods may give a better understanding of the relationship between the size, shape and smoothness of riders. • The influence of body size on energy supply variables in not clear. The effects of body size on mechanical efficiency has recently been described as significant (Berry et al., 1993). Further work is needed to more carefully describe the relationships. between body size and fractional utilisation, MAOD, V02 kinetics and 02 deficit kinetics. • Determine the effect of the transverse and lateral planes of the body on cycling performance. This relationship is critical to a complete understanding of the cross-wind analysis problem. 157 Body size and cycling performance 5 APPENDICIES 5.1 Documentation 5.1.1 Personal details 5. 1.2 Informed consent 5.1 .3 Anthropometric details 1 5. 1.4 Anthropometric details 2 158 Body size and cycling performance 5.1.1 PERSONAL DETAILS 159 ID No.: Personal Details Category: Experienced Road Surname: ···········~······...... First Names: ...... Address: ...... Postcode: ...... Phone: (day) ...... (evening) ...... Age: ...... Sex: ...... Height: ...... Weight: ...... Seat Height: ...... V02max: ...... Experience (yrs): ...... Avg km/yr: ...... TEST DATES: 1 ...... 2 ...... 3 ...... Comments: ••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••'"••••••••••••••••••••••••••••••••••••••••• ...... Body size and cycling performance 5.1.2 INFORMED CONSENT 161 Informed Consent Form I understand that the research you propose will involve the measurement of height, weight, skin/old thickness and various bone measures, and taking photographs for analysis. In addition, you will be carrying out a variety of fitness tests sometimes involving all-out efforts, and the taking of small amounts of blood from the fingertip. 1 The testing package you have volunteered for involves a variety of tests on the stationary bicycle. While some are quite mild, others involve all-out exercise to exhaustion. The screening procedure you will undergo, along with the nature of the testing procedures, mean that the risk of serious accident is minimised. Even so, you should be aware that such tests have in very unusual circumstances led to cardiovascular complications, and in extremely rare cases to death. If you should feel any unusual symptoms during the test, inform the researchers and we will stop at once. If you suffer unpleasant after-effects, contact both your G.P. and the researchers. 2 To analyse blood characteristics, some blood will be taken from the fingertip. As with any invasive measurement, there is a slight risk of infection. However, strict aseptic procedures will be followed and paramedically-trained personnel will be available at all times. I authorise details of my performance and personal details to be recorded, tabulated and reviewed by the University for the purpose of statistics, research and advancement of education, apart from which such details will remain confidential. I hereby exempt, release and discharge the University, its servants, agents and contractors liability for any injury, loss, damage or expense sustained as a result of my participation in the programme, whether by reason of negligence of the University, its servants, agents, or contractors or for any other reason whatsoever and howsoever caused. I do not suffer from any physical and medical disability affecting my capacity to undertake this series of tests. This application is made and the authority exemption and release are given to the University and its servants, agents or contractors. Date this ...... day of ...... 199 ...... Name ...... Signature ...... Witness ...... Body size and cycling performance 5.1.3 ANTHROPOMETRIC DETAILS 1 163 lLJ No.: ...... Anthropometric Details 1 Surname: ...... First Names: ...... Date: ...... Time: ...... Height: ...... Weight: Nude: ...... Clothed: Bike & Rider Wt: ...... Trunk Ang le: Position Trochanteric Iliac Angle Angle Aerobars Racing Drops Brake Hoods Type of Tyre Front Rear Type of Tyre Normal Pressure Other Information Comments: ...... Body size and cycling performance 5.1.4 ANTHROPOMETRIC DETAILS 2 165 ID No.: ...... Anthropometric Details 2 Name: Date: ...... Trial 1 Trial 2 Trial 3 Mean Heiehts Acromial (cm) Radial Stylion Dactylion Iliospinal Tibial Trochanteric Sitting Widths Bideltoid (cm) Biacromial Biiliocristal Femur Humerus Transverse Chest Anterior-Posterior Chest Depth Foot Length Bitrochanteric Girths Head (cm) Chest (end tidal) Flexed Ann Waist Gluteal Girth Thigh Girth Neck Girth Calf Girth Foreann Relaxed Ann Ankle Wrist Skinfolds Triceps (mm) Subscapular Pectoral (men) Biceps Supraspinale Suprailiac Abdominal Abdominal* Iliac Crest FrontThi~h Calf Mid-Axilla (men) Juxta-Nipple Comments: ...... Body size and e1;c/ing performance 6 REFERENCES 167 Body size and cycling performance AADBase (1995). Australian Anthropometric Database. School of Sport and Leisure Studies, The University of New South Wales, Sydney, Australia. Astrand, P.O., Hultman, E., Juhlin-Dannefelt, A. & Reynolds, G. (1986). Disposal of lactate during and after stenuous exercise in humans. Journal of Applied Physiology, 61, 338-343. Astrand, P.O. & Saltin, B. 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