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Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 I 75-26,623 McKENZIE, Donald Chisholm, 1946- CARDIO-RESPIRATORY AND METABOLIC RESPONSES TO SELECTIVE ARM OR LEG TRAINING. The Ohio State University, Ph.D., 1975 Education, physical

Xerox University Microfilmsf Ann Arbor, Michigan 48106 CARDIO-RESPIRATORY AND METABOLIC

RESPONSES TO SELECTIVE ARM

OR LEG TRAINING

DISSERTATION

Presented in Partial Fulfillment of the Requirements for

the Degree Doctor of Philosophy in the Graduate-

School of The -Ohio State University

Donald Chisholm McKenzie, B.Sc.(P.E.),M.P.E.

*****

The Ohio State University

1975

Reading Committee Approved by

E.L. Fox

R.L. Bartels jS.I. Lustick Division of Physical Edudation DEDICATED

To my father, Donald G. McKenzie for the principles and goals which guide my life; and to my wife Barbara, for making it all worthwhile- ACKNOWLEDGMENTS

This study represented a co-operative effort on the part of a large number of individuals. I am parti cularly indebted to Dr. E. L. Fox for his help in the collection and statistical treatment of the data. Ken

Cohen was instrumental in the development of the rebreathing apparatus and also in the collection and reduction of the data; without his assistance this study would not have been possible.

I am also indebted to my 'colleagues', Topper

Hagerman, Bill Steinmetz, John Dusseau, Dan Switchenko, and

Garret Caffrey for their assistance in this study and for making my stay in Columbus a rewarding and cherished exper ience.

Certainly the students who served as subjects for this study must be thanked for their co-operation and effort in all facets of the investigation.

Finally, I especially wish to express my grati tude to my advisor, Dr. E. L. Fox, for his advice and help throughout my graduate program.

This study was supported by the Central Ohio

Heart Chapter (RF 3793-A1).

iii VITA

December 28, 1946 .. Born - Weston, Ontario, Canada

1970 ...... B.Sc.(P.E.), University of Guelph, Guelph,

Ontario, Canada

1970 - 1972 ...... Teaching Assistant, the University of

British Columbia, Vancouver, British

Columbia, Canada

1972 ...... M.P.E., The University of British Columbia,

Vancouver, British Columbia, Canada

1972 - 1974 ...... Teaching Associate, Exercise Physiology

Research Laboratory, The Ohio State

University, Columbus, Ohio

PUBLICATIONS

"Plasma Lipid Variations in Response to Diet and Exercise",

Masters Thesis, The University of British Columbia, Vancouver,

British Columbia, Canada.

"Plasma Lipid Variations in Response to Diet and Exercise",

Fed. Proc. 32: 890 Abs., March 1973.

"Specificity of Training: Metabolic and Circulatory Responses",

with E.L. Fox and K. Cohen, Med. Sci. Sports: Vol. 7, No.l, 1975. FIELDS OF STUDY

Physiology of Exercise Dr. E.L. Fox

Physiology ...... Dr. S.I. Lustick

Human Anatomy ...... Dr. R. Beran

Physiological Chemistry Dr. J. Merola

v TABLE OF CONTENTS Page ACKNOWLEDGEMENTS...... iii

VITA ...... iv

LIST OF TABLES ...... viii

LIST OF FIGURES ...... ix

Chapter

I. INTRODUCTION ...... 1

Statement of the Problem Limitations and Delimitations of the Study Significance of the Study Definitions

II. REVIEW OF THE LITERATURE ...... 6

Introduction Cardio-respiratory Adaptations to Training Adaptations to Arm or Leg Training

III. METHODS AND PROCEDURES ...... 17

Subjects Orientation Experimental Design Training Programs Experimental Procedure a. Calorimetry b. CO2 Rebreathing Procedure

IV. RESULTS AND DISCUSSION ...... 34

Introduction Reliability Arm Training Versus Leg Training Oxygen Consumption Heart Rate Cardiac Output Stroke Volume Blood Lactate Pulmonary Ventilation A-V O2 differences

v i Page V. S U M M A R Y ...... 55

APPENDIX

A. Raw D a t a ...... 60

B. Statistical Results ...... 68

C. Sample Cardiac Output Calculation ...... 75

D. Reliability D a t a ...... 7 7

BIBLIOGRAPHY ...... 78 LIST OF TABLES

Table I Physical Characteristics

Table II Mean Circulatory Changes Following

Training: Arm Trained Group

Table III Mean Circulatory Changes Following

Training: Leg Trained Group

• • • V 3 . l l LIST OF FIGURES

Figure 1. Rebreathing Apparatus 27

Figure 2. Oxygen Consumption: Trained limb vs

untrained limb 39

Figure 3. Heart Rate Responses: Leg trained group 41

Figure 4. Heart Rate Responses: Arm trained group 42

Figure 5. Heart Rate versus VO 2 for Trained and

Untrained limbs 44

Figure 6. Cardiac Output: Trained limb vs untrained

limb 47

Figure 7. Blood Lactic Acid Changes: Arm trained

group 49

Figure 8. Blood Lactic Acid Changes: Leg trained

group 50 CHAPTER I

INTRODUCTION

The importance of the cardio-respiratory system, both at rest and during physical activity, is well known and has been the subject of an enormous number of investiga tions. The cardio-resiratory adaptations to physical train ing: resting and exercise bradycardia, increased stroke volume of the heart, decreased pulmonary ventilation, in creased arterial-venous oxygen differences etc., are also well documented; however, the mechanisms that elicit these adaptations have not yet been completely resolved. Frick et al (27) feel that an intrinsic mechanism within the heart itself is responsible for the resting and exercise brady cardia. They suggest that at rest, the decreased heart rate is due to increased vagal tone, whereas during physical act ivity this influence on the heart is a result of sympathethic inhibition. Other researchers have also concluded that adap tations to exercise by the heart is of an intrinsic nature, the primary change being that of increased stroke volume due to a more powerful contraction of the myocardium (32,39,46).

On the other hand, there is some evidence that the effects of training may be derived from extrinsic factors,

1 2

specifically in alteration in the trained muscles. The ad

justment of the heart rate to the work intensity might be mediated by afferent nervous impulses from working muscles

and by descending impulses from motor cerebral centers, both modifying the brain stem's sympathetic stimulation of the

sinoatrial node (4,32,49). This suggests that the effect of training on the heart would be secondary to changes in

the trained skeletal muscles which reduce the sympathetic

stimulation of the sinoatrial node during exercise performed with these muscles.

Thus, there appear to be two plausible explana

tions of the mechanisms involved in the adaptation of the

cardio-respiratory system to training: an intrinsic or

central mechanism within the heart itself and an extrinsic or peripheral mechanism, the trained skeletal muscles.

STATEMENT OF THE PROBLEM

The purpose of the this study is to evaluate the effects of training the arm or leg muscles on the cardio

respiratory responses to two submaximal work loads.

The following experimental hypotheses will be tested:

1. Training performed by arm exercise on a bicycle 3

ergometer will cause a significant reduction of

heart rate and blood lactic acid, a significant

increase in stroke volume, and no significant

change in cardiac output during submaximal arm

exercise, but not during submaximal leg exercise.

2. Training performed by leg exercise on a bicycle

ergometer will cause a significant reduction of

heart rate and blood lactic acid, a significant

increase in stroke volume, and no significant

change in cardiac output during submaximal leg

exercise, but not during a submaximal arm exercise.

LIMITATIONS AND DELIMITATIONS OF THE STUDY

1. Sixteen healthy, untrained, male university stu

dents, aged 18 - 23, served as subjects for the

study.

2. The training period was of five weeks duration

with five workouts per week.

3. The type of training was restricted to sprint and

endurance interval training.

SIGNIFICANCE OF THE STUDY

One of the more important implications of these

findings would be in the planning of physical training pro 4

grams, particularly those indicated for clinical use. For example, since the cardio-respiratory adaptations might be

specific, not all types of exercise programs, regardless of how intense, would have the same benefits in the rehab

ilitation of patients. Inclusion in the training program of specific exercises corresponding to those required for

the patients' daily activities would be mandatory.

Another area which would derive benefits from

these findings is that of athletic training. Franklin Henry has shown that motor skills are task specific rather than

general (41); it is possible that adaptations of the cardio

respiratory system are also specific to the muscle group

employed. This would suggest that in training for cardio

respiratory fitness it is imperative that the muscles used

in competition are those used in acquiring the training ef

fect. This is particularly true in events requiring upper

body endurance.

DEFINITIONS

PaC02 : The partial pressure of carbon dioxide in arterial

blood. This value may be converted to C02 content

(CaC02) in volumes percent by use of the dissocia

tion curve for arterialized blood assuming a normal 5

and constant O 2 content of 97.5 percent saturation.

PvC02: The partial pressure of carbon dioxide in mixed

venous blood.

CO 2 Rebreathing Technique: A simple, painless method of

determining PVCO 2 , necessary for the determination

of cardiac output via the Fick principle. See Chap

ter 3 for details.

Interval Training Program: A system of conditioning or

training, consisting of a series of repeated bouts

of exercise alternated with periods of relief (23).

Submaximal Work: For the purpose of this study, submaximal

work is defined as a work level which ilicits a

heart rate response of approximately 160 beats per

minute or less.

Arm Training: Physical exercise performed on the bicycle

ergometer specifically adapted to allow pedalling

with both arms.

Leg Training: Physical exercise performed on the bicycle

ergometer with both legs. CHAPTER 2

REVIEW OF THE LITERATURE

INTRODUCTION

The review of the literature has been divided into two sections. A brief summary of the cardio-respiratory adaptations to physical activity or training is presented; this is followed by a more thorough consideration of the material relevant to this study, specifically the literature pertaining to the cardio-respiratory and metabolic adapta tions to arm and/or leg training.

CARDIO-RESPIRATORY ADAPTATIONS TO TRAINING

Physical training influences a number of circula tory parameters, the changes often manifested in the resting, submaximal, and/or maximal exercise conditions.

The heart is adaptable to variations in physical activity, the primary response to training being an increase in stroke volume both at rest and during all exercise cond itions (20,52). There seems to be no essential difference in cardiac output at rest or during submaximal work follow ing a training period (7,24,26,33); however, there are studies which indicate that training may cause a reduction in the

6 7

submaximal cardiac output (1,57). Maximal values of cardiac output, following a training period, are significantly in creased (7,20,52). Associated with these changes in cardiac output and stroke volume is the well-known resting and exer cise bradycardia evoked by physical training (20,27,32).

The arterial-venous oxygen difference (A-V oxygen difference) is an extremely important circulatory parameter which is changed as a result of training (43). Saltin et al (52) have shown that training does increase the A-V oxygen dif ference; this is supported by other authors (1,7). At any level of oxygen consumption, the A-V oxygen difference de pends on the percent of cardiac output going to the working muscle (50), thus, the shunting of blood away from inactive areas becomes an important variable. Donald, Bishop, and

Wade (19), in a series of experiments, have shown that train ing does alter the redistribution of blood to the exercising muscle. During maximal exercise, approximately 4 litres per minute more blood was distributed to active muscles in sedentary subjects following training (52). Several hypoth- ises have been advanced to explain how this redistribution is brought about. Muscle biopsies examined by electron microscopy hare shown neither an increase in the number of capillaries per unit area nor a change in size of the ves- 8

sels (52), although other morphological studies in animals

and human subjects have yielded conflicting results (34).

Xenon clearance studies have revealed the same maximal blood

flow in groups of trained and untrained subjects (31) , thus

the flow must be distributed to a laager muscle mass. How

ever, calculations of lean body mass from specific gravity measurements do not reflect a change of sufficient magnitude

to account for the increase in blood flow of 4 litres per minute (52). Thus it appears that the untrained subjects

do not activate all available motor units in the working

muscle; with training, more fibers in the same muscle are

probably activated (51).

Intensive research has been devoted to determin

ing the changes in oxygen consumption associated with train

ing. It is a well-known fact that training will increase

the maximal aerobic power of an individual as well as the

capacity to accumulate a greater oxygen debt (5,20, 22).

Saltin (51) has stated that at maximal exercise, the inc

reased maximal A-V oxygen difference of the same order of

magnitude; however, the factors affecting maximal oxygen

consumption are complex, interrelated, and seem to involve

the cellular machinery as well as the circulatory parameters

(28,29,35). At submaximal workloads trained subjects have 9

a decreased oxygen consumption when compared to untrained individuals, i.e., improved mechanical efficiency (20), al though, at rest, there are no noticeable differences. Values

for pulmonary ventilation parallel those of oxygen consump tion; training increases the maximal value yet decreases the submaximal pulmonary ventilation for a standard workload

(20,51).

Blood lactic acid values at rest are no different regardless of training status; however, the concentrations of lactate in skeletal muscle and in blood are lower in the

trained than in the untrained state during submaximal exer

cise (48,53,54). Recent work by Mole (44) indicates that this could be due to adaptations in the enzymes involved in pyruvate metabolism. In addition, trained individuals have

the capacity to develop higher maximal blood lactate levels

than their untrained counterparts, however, this may merely be a reflection of an improved tolerance to the physical

discomforts of heavy exercise (30).

ADAPTATIONS TO ARM OR LEG TRAINING

The majority of the research relevant to this

study has been done in a series of recent experiments by

Jan Clausen and his co-workers. A study was designed to 10

determine whether the heart rate response to training was dependent upon the muscle groups used for the training (12).

Eight healthy, untrained males were used as subjects. They were divided into two groups; four trained their arms and four trained their legs, using bicycle ergometers specific ally adapted to their type of exercise. The training period consisted-of three, five minute workouts daily for four weeks.

All subjects were tested both during arm and leg exercise at two different work loads before and after the training period. The subjects who trained the arms had, after train ing, markedly decreased heart rates during the arm test, whereas heart rate response during the leg test showed only a small insignificant reduction. Similarly, the subjects who trained the legs showed a decrease in heart rate res ponse to leg exercise but little change when subjected to the arm exercise. Thus when the authors suggested that the primary reason for the decreased heart rate following train ing is of an extra cardiac origin, that is, the trained skeletal muscles may reduce the sympathetic stimulation of the sinoatrial node during exercise performed with these muscles. This reduced sympathetic stimulation may arise from two factors: a decreased efferent discharge in higher motor centers or a decreased excitation of local receptors in the 11

trained muscles.

Clausen carried on with this type of investiga tion in another study designed to determine whether other circulatory changes induced by training are specific to the trained muscle groups (13). Ten subjects trained daily on bicycle ergometers for five weeks; five trained the arm muscles; and five trained the leg muscles. Hemodynamic data were obtained on two submaximal workloads before and after training with both the trained and untrained limbs.

The arm trained group, in response to the arm test, showed a significant decrease in heart rate, cardiac output and oxygen uptake. The arterial-venous oxygen difference was increased as was the hepatic blood flow. The only effect of arm train ing that was carried over to any extent, to the work performed with non-trained leg muscles, was a decrease in heart rate, whereas all other parameters remained unchanged. The response to the leg trained group was not as dramatic. Heart rate, after training, was decreased as was cardiac output, although only at the lower submaximal load. Hepatic blood flow (HBF) increased but the A-V oxygen difference was not changed.

During work with the non-trained limb (arms) , heart rate was reduced to a similar degree as that of the trained limb, car diac output was increased at the heavier workload, HBF or 12

A-V C>2 debt were not changed.

These results led the author to suggest that "The very pronounced reduction in heart rate obtained by arm training depends primarily on local changes in the trained arm muscles. Leg-training seems in addition to modify the central circulatory adaptation to exercise also when the work is performed with untrained muscles."

In another publication (14), although the same study as previously mentioned (12), Clausen et al presented the changes in arterial-venous lactate, pulmonary ventil ation, oxygen uptake, and pH in response to selective arm or leg training. After arm training and during arm work the oxygen consumption, the pulmonary ventilation, and the resp iratory exchange ratio (R) were decreased, while no change was seen in the leg work. Arterial and venous lactate values in arm work were decreased by 10 - 21 mgs. % while the decrease in leg work was only 1 - 4 mgs. % . No change in arterial pH was seen during arm work, while venous pH showed a marked increase. In leg work a decrease in arterial and venous pH was evident at the lower workload, however, at the higher workload both values were increased. After leg training during leg work the oxygen consumption was decreased at the highest workload, while no change was found in the low workload. There was no change in oxygen uptake with arm work. 13

R and pulmonary ventilation were decreased during leg work;

the R was slightly decreased in arm work. Arterial and ven

ous lactate values were significantly decreased at both work

loads during leg exercise; however no change was noted in

response to arm work. The authors feel that these results

indicate;

a predominant peripheral training effect of leg training and arm training respectively since practically no changes were found in arm work after leg training and vice versa.

The most comprehensive study relative to the

specificity of training on the cardio-respiratory system was again work of Clausen and his collegues (15). The sub

jects were 13 healthy untrained men; five subjects formed

an arm training group, the remaining eight trained with leg muscles. The training period was of five weeks duration with workouts five days per week. The workout periods con

sisted of a 15 minute warm-up followed by four exercise bouts

of five minutes, with equal resting periods. The subjects were tested, before and after the training program, on two

submaximal arm and leg exercises. Arterial and venous cath

eters were inserted and the following parameters were meas

ured; oxygen uptake, cardiac ouput, A-V C>2 difference, indo-

cyanine green clearance (ICG clearance), aortic blood pres

sures, and heart rate. After training, heart rate was reduced 14

significantly at rest and during both types of exercise in all subjects. The reduction in heart rate during exercise with trained muscles was most pronounced after arm training.

In comparison the heart rate decrease with non-trained muscles was significantly greater after leg training. The difference between exercise with trained and untrained muscles was most obvious in the arm training group. Cardiac output was de creased during exercise with the trained muscles except dur

ing the heavy leg exercise; however, when these changes were compared to the changes in oxygen uptake, they were not significant. Stroke volume was increased after training,

in both the trained and untrained muscle groups. Arm train

ing caused an increase in A-V difference in both sub maximal arm tests but no change occurred during exercise with the untrained legs. Following leg training, A-V © 2 difference was changed only during heavy submaximal work with trained legs as well as with untrained arms; ICG clear ance was used to provide an estimate of hepatic-splanchnic blood flow. After training ICG clearance was reduced to

a lesser amount during exercise with the trained muscles.

During exercise with non-trained muscles, ICG clearance was unchanged. After arm training, systolic, diastolic, and mean blood pressures decreased during exercise with the

trained limb; no changes were observed during exercise with 15

the untrained leg muscles. After leg training no changes were observed when exercising the leg muscles, however, all aortic blood pressures were increased during the heavier submaximal exercise with the non-trained arm muscles. The concentration of resting hemoglobin was unchanged by arm training but reduced in the leg trained group. The authors felt that these results indicated "training is not an abso lute event that affects on the central circulation nonspec- ifically; it also causes important peripheral circulatory variations". It appears that the central and peripheral adaptations act together with respect to heart rate reduction but they tend to counteract each other in their actions on cardiac output and arterial blood pressure. The fact that the peripheral and central circulatory changes were more pronounced in the arm exercise after arm and leg training was interpreted as indicating that arm muscles have a great er potential for local improvement and that central circ ulatory changes are more dependent upon the muscle mass used during the training.

Research on arm and leg exercise is not confined solely to that of Clausen et al. Other workers have studied circulatory response to exercise with variations in the type of work and the muscle groups involved. 16

During arm exercise, heart rate and ventilation has been reported to be higher than during leg exercise at a given oxygen uptake (2,16). Bevegard et al (8) have shown that with arm exercise there is an increase in the systolic, diastolic, and mean pressures in the aorta, in relation to the cardiac ouput, as compared to arm and leg work. These

authors attribute the differences in circulatory adaptation

to arm versus leg exercise as a higher sympathetic tone during arm exercise. Freyschuss and Strandell (25) indicate

a higher lactate production in relation to oxygen uptake

during arm exercise which they attribute to the smaller muscle mass engaged in arm work. During maximal exercise with arms, maximal oxygen consumption and cardiac ouput (dye-

dilution technique) were 66% and 80% respectively, of the

values attained during maximal leg work. At a given submaximal oxygen consumption, heart rate, intra-arterial blood

pressure, and pulmonary ventilation were significantly higher

during arm work than leg exercise (56). Astrand and Saltin

(6) have demonstrated that the maximal values of oxygen

consumption, heart rate, pulmonary ventilation, and lactic

acid are less during arm cycling than during leg cycling. CHAPTER 3

METHODS AND PROCEDURES

SUBJECTS

Sixteen, untrained, male students at the Ohio

State University volunteered for the nine week study. Prior to the commencement of the study each student was required to complete a medical examination to ensure that all physio logical and biochemical variables were within the normal limits. The medical examination was performed at the Stu dent Health Center of the Ohio State University. See Table I for the description data on the subjects.

ORIENTATION

In order to minimize any 'learning' factors in volved with the testing sessions or the training period, and to familiarize each subject with the equipment used for testing, an orientation program was devised. This program consisted of a minimum of two sessions in the laboratory and involved practice of the rebreathing technique as well as exercise on the bicycle ergometers. At the commencement of the pre-testing period the subjects were at ease with the rebreathing apparatus and familiar with the procedures and

17 18

TABLE 1

PHYSICAL CHARACTERISTICS

Subject Age Height(cm) Weight(kg)

1 18 167.6 59.09

2 19 180.3 77.73

3 18 172.7 66.82

4 23 182.2 94.55

5 19 184.2 77.73

6 19 182.9 70.91

7 19 181.6 84.77

8 18 181.6 70.23

9 19 180.3 72.73

10 18 167.0 63.86

11 19 174.0 67.27

12 19 167.0 76.02

13 22 182.9 94.32

14 19 174.0 68.18

15 22 182.9 72.50

mean 19.4 177.45 74.45

St.Dev. ± 1.59 6.31 10.22 19

equipment involved in the tests.

EXPERIMENTAL DESIGN

The sixteen subjects were randomly assigned to two equal groups; an arm training group and a leg training group. These two groups were then subdivided initially into sections of four, depending on the type of training program used. One subject acquired an injury, unassociated with the study, which necessitated dropping him from the training program. Thus this arm trained group was reduced to seven individuals; furthermore, the sprint or anaerobic training group was reduced to three subjects in the arm section. As two methods of training were used, sprint and endurance, this study became representative of a 2 x 2 factorial design as represented below.

TRAINING PROGRAM GROUP

ARM LEG

SPRINT 3 4

ENDURANCE 4 4

TRAINING PROGRAMS

Two interval training methods were used; A sprint- type program designed to tax the anaerobic energy system 20

and an endurance-type program which emphasized the aerobic system. Both methods have been used successfully in this laboratory and are established interval training methods

(22,23). The programs remained progressive throughout the entire five week training period, that is, the resistance was increased, when necessary, to maintain a heart rate response of near 180 beats per minute at the end of each work interval. Heart rates were recorded for each work

interval and immediately prior to the beginning of the next exercise bout. In the event that the subject's heart rate did not return below 120 beats per minute prior to the sched uled start of the next work interval, the subject was given additional rest time or instructed to stop the workout.

All workouts were supervised and lasted for approximately

50 minutes, five days per week for the five week training

period.

An example of the sprint training program might

be as follows: 21 x 30 sec. 90 sec. rest 150 watts 90 RPM.

This would read as: 21 repetitions of 30 seconds duration,

90 revolutions per minute, with a resistance of 150 watts,

the rest interval between repetitions is 90 seconds. The

heart rate would be recorded at the end of the 30 second

work bout and at the end of the 90 second rest period. 21

Total work done in this workout would be 1575 watts. A comparable endurance program would be: 8 x 2 min. 6 min. rest 100 watts 60 RPM. This is interpreted as: 8 repeti tions of 2 minutes duration, 60 revolutions per minute, 6 minute rest between repetitions, and a resitance of 100 watts. Total work done is equivalent to 1600 watts. Both programs have elicited a heart rate response of near 180 bpm in untrained subjects, the total work done is virtually equivalent, and the work/relief ratio is equal; i.e. 1/3.

A metronome was used to pace the work bout at the required revolutions per minute.

EXPERIMENTAL PROCEDURE

Each subject was tested on 4 submaximal workloads:

63 watts and 83 watts for the arm tests and 100 watts and

125 watts for the leg tests. Each test consisted of a six to seven minute workout at the resistance mentioned above.

An Electronome metronome was used to pace the subject at 50 revolutions per minute. Two tests were generally done on one visit to the laboratory; that is, both submaximal arm or leg tests were completed in one session with approximately a twenty-five minute rest between the lower test and the heavier test. All pre-tests were completed in 10 days. At the end of the five week training period these tests were performed again, identical to the pre-test procedure.

The experimental procedure can be divided gener

ally into two parts:

A. Indirect Calorimetry

B. CO2 Rebreathing Technique

A- CALORIMETRY The equipment used in the collection of the ex pired gases and the recording of the heart rate was placed

to the right of the subject working on the ergometer. Upon

arriving at the laboratory the subject was weighed and the

barometric pressure recorded. Bipolar leads connected to

a Hewlett Packard 1500A electrocardiograph were used to

pick up heart rate. The number of QRS complexes in a fif-

teen second period were counted and this number was multi

plied by four to give heart rate in beats per minute. A

bicycle ergometer (Jaquet model - distributed by Instrument

ation Associates) was used for all tests. The subject breath

ed through a two-way J valve distributed by Warren E. Collins

Incorporated; the expired gas was collected in a chain-comp

ensated gasometer with a capacity of 120 liters, also from

the W.E. Collins Company. A meter stick, attached to the 23

side of the gasometer, indicated the amount of water dis

placed. Initial and final readings were subtracted and multiplied by the conversion factor of 133.2 cc/mm. The

temperature of the water in the gasometer was recorded and

used in the gas volume calculations.

The subject exercised on the ergometer until

'steady state' was reached, generally five to six minutes.

At this time the expired gas was collected for exactly 60

seconds and the heart rate was recorded for the last 30 sec

onds of this one minute period. As quickly as possible the

rebreathing technique was used to record the curves for the

calculation of PvCC>2 .

One leter, rubber sample bags were used to trans

port the expired gas to the analyzers. The Beckman Oxygen

Analyzer, model E-2, was used to obtain the expired oxygen

concentration. For purposes of calibration, 100% nitrogen

was used to zero the analyzer; room air was utilized as the

span. The Beckman Medical Gas Analyzer, model LB-1, measured

the expired carbon dioxide percentage. A known gas concen

tration of 4.275% C02 was used to provide a span; the 100%

N2 was again used to zero the LB-1. The percentage of nitro

gen in the expired gas was calculated through simple sub

traction. 24

B. C02 REBREATHING PROCEDURE

i. The Principle Underlying the Technique

The C02 rebreathing technique is simply an adap tation of the Fick Principle. This classical theory states that the flow of blood through an organ can be determined by measuring the amount of a substance removed by, or added to, the organ per minute and dividing by the change in concent ration of the substance in the blood. For our purposes the flow of blood through the heart, and thus through the lungs, was desired. The transport of carbon dioxide provided a con venient indicator agent. The amount of CC>2 produced per minute was calculated from the expired gas sample. The Bohr formula was used to estimate the PaCC>2 which was then converted to C02 content in volumes percent by use of the dissociation curve for arterialized blood assuming a normal and constant

02 content of 97.5 percent saturation. The concentration of

CC>2 in the mixed venous blood was determined using the re breathing technique which is described fully later in this chapter. With these variables the cardiac output can be calculated via the Fick Equation:

VC°2 q = where CvC02 - CaC02 25

Q = Cardiac output (ml/min.)

VC02 = Carbon dioxide produced per minute (ml)

CvCC>2 = Concentration of C02 in mixed venous blood (ml/100 mis.

blood.)

CaC02 = Concentration of C02 in arterial blood (ml/100 mis

blood.)

ii. Brief History

Christiansen et al (11) were the first to introduce the rebreathing method to determination of cardiac output.

Prior to this technique the direct Fick procedure and Stewart's dye-dilution method (36) were the only techniques available.

Both procedures require catheterization of veins and arteries, which introduces trauma and anxiety in the subject and may

alter physiological functions. The rebreathing technique developed by Christiansen et al involved determination of

the partial pressure of carbon dioxide in mixed venous blood by breath analysis of the CC>2 concentration in a bag while

rebreathing from that bag. The arterial pressure of carbon dioxide (PaCC>2) was assumed to be identical to the carbon dioxide pressure in end-tidal air. Analysis of the expired

gas gave the total carbon dioxide produced per minute and thus

all variables necessary for the calculation of cardiac output 26

via the Fick equation were available.

These measurements were made at rest and it was not until 1928 that the rebreathing technique was applied to cardiac output measurement during work (10). Since then research involving CC>2 rebreathing has been extensive (17,21,

40,55) and with excellent results.

Studies comparing the three procedures by Jernerus

(37), Klausen (38), Asmussen and Neilsen (3) and Muiesen (45), have shown that the rebreathing technique is a valid and reproducible method for the determination of cardiac output.

It is easy to administer, bloodless, and in exercise provides volumes comparable to the dye-dilution and direct Fick methods.

iii. The Apparatus

The rebreathing technique used in this study is an adaptation of the method devised by Defares (18). The equip ment used and the set-up is represented graphically in

Figure 1. The subject sat so he was in a comfortable position in which to pedal the ergometer. A Collins 5-way (P-318) control valve with a dead space of 175 mis. was used to connect the subject to the rebreathing bag. The rebreathing bag was a simple rubber sample bag with a three liter capa city and was attached directly to the 5-way valve so that it 27

100%

Vitalometer {61.) Electronome Metronome (100 bpm.) LB-1 , Pickup__ Head Tubing \ \ Bicycle Ergometer

Rubber Sample (31.) Bag Pump rubber_ 600 mis/min. tubing

Collins 5-way (P-318) Control Valve — 2 way Analyzer I J-valve Mouthpiece

I Gasometer U20Z. ) LB-1 Subject Linearizer

Grass HP 1500 A Polygraph Electrocardiograph

Figure 1. Rebreathing Apparatus 28

hung in a vertical position. From the rebreathing bag ran two attachments; a short span (12 inches) of rubber tubing, of approximately 0.5 - 0.4 ccs. diameter, to a Beckman LB-1 pickup head, and a longer piece (36 inches) of the same tubing to a Beckman microcatheter sample pump which operated at

600 mls/minute. The tubing was attached to the pickup head and the pump just prior to the rebreathing procedure. The pickup head was connected to the Beckman Medical Gas Analyzer model LB-1. After the gas sample from the rebreathing bag passed through the C02 pickup head it was returned to the rebreathing bag via the pump. The instantaneous recording of C02 concentration in the rebreathing bag after each breath was transferred to a Grass Model 7 Polygraph. As the LB-1 has a logarithmic scale a Beckman BL-1 Linearizer was used to change the reading to a linear scale. Thus as the sample went from the C02 head, it was recorded on the LB-1 in a logarithmic scale, changed to a linear value by the Linearizer and recorded on the Grass Polygraph.

The Grass Polygraph was connected only to the

LB-1 Linearizer, there was no direct attachment to the LB-1

Analyzer itself. The signal from the Linearizer came to the

Grass D.C. driver amplifier Model 7DAB, from here it was recorded on the Grass Ink Writing Oscillograph Model 7WC 12PA. 29

Two pens were in operation; one monitored the C02 signal from the Linearizer, the other provided a time scale each second.

iv. Calibration

As a graphical representation of the C02 concen tration of the mixture in the rebreathing bag was required on a breath to breath basis, it was necessary to calibrate both the LB-1 Analyzer and the Grass Polygraph to be certain that the signal recorded by the Analyzer was the same value, after linearization, that appeared on the Polygraph. As the rebreathing technique was only used during exercise conditions a scale from 4.00 to 10.00 percent C02 in expired gas, was chosen. To calibrate the LB-1 for the rebreathing procedure

100% nitrogen was used to zero the Analyzer. Then a known gas concentration of 6.76% C02 was passed through the pick up head. The scale on the Analyzer was adjusted with the screw on the pickup head until it coincided with the known sample. The calibration of the LB-1 Analyzer was now complete, and, as the scales on the Analyzer and Polygraph are not identical, it was not uncommon to note that they did not agree with each other. The Grass Polygraph was calibrated as follows. A known concentration of C02 (4.275%) was passed 30

through the pickup head. Using the *Baseline Position*

adjustment, the pen monitoring the CO 2 concentration was moved so that it coincided with 4.275 on the scale on the recording paper. A second known gas concentration (6.75%) was introduced into the pickup head. With the 'Driver Sensi tivity' adjustment the pen was moved so that it read 6.75 on the scale. Often it was necessary to alternate these gas samples until the required range was achieved. The set

ting on the 1/2 amp. high freq. was 0.5; the paper speed was 10 mm/sec. Due to the sensitivity of the apparatus and the relatively high CC^ gradients it was necessary to recal ibrate the LB-1 Analyzer and Polygraph with fresh gas samples prior to every rebreathing attempt.

v. The Rebreathing Procedure

The expired gas collection and heart rate re cording preceded the rebreathing procedure. During the in

itial 4 to 5 minutes of exercise as the subject reached a

'steady state’ condition, the gasometer was washed out a number of times. During these wash outs it was a simple procedure to determine the approximate tidal volume of the

subject. This was necessary in fixing the volume of gas placed in the rebreathing bag. A Collins Vitalometer with 31

a 6 liter capacity was filled with 100% oxygen. The tidal volume plus approximately 300mls. of oxygen was pushed into the rebreathing bag using the longer hose attachment.

As the expired gas was being collected in the gasometer and the heart rate being recorded, the number of breaths per minute by the subject was counted and recorded. Immediately after the gas collection was completed the two rubber hose attachments to the rebreathing bag were connected to the pickup head and the microcatheter pump. The shorter hose to the pickup head came from the bottom of the rebreathing bag, while the gas was returned via the longer tubing to the neck of the bag. The Polygraph recorder was placed in gear so that the paper was moving at the required speed.

An Electronome metronome, set at 100 beats per minute, was used throughout the entire laboratory procedure; to pace the subject at 50 rpm's on the ergometer and to guide the rebreathing rate at 50 breaths per minute.

The subject was instructed to exhale normally and then signal with his finger that he had done so. Im mediately, the Collins 5-way control valve was turned so that the subject's next inhalation would draw gas from the rebreathing bag. The subject then rebreathed at a constant rate of 50 breaths per minute with normal depth until a 32

plateau was reached on the curve, generally 6 - 8 seconds.

The desired curve and an example of the calculations neces sary to determine cardiac output are contained in the Appendix.

Two minutes after the end of the exercise a blood sample was taken by venipuncture from the antecubital vein. Two mis. of the blood were combined with 9 cc. of trichloroacetic acid and frozen. These samples were sub sequently transported to the Community Laboratories of Col umbus Ohio for lactate analyses. This laboratory was also responsible for the pre and post training resting blood analyses for hematocrit and hemoglobin values.

vi. Reliability

It was necessary to test the consistency or reliability of the rebreathing procedure used in this study.

This was done in two different ways. During the training period the subject would come in on two consecutive days and perform the lower submaximal test. Data were collected similar to the pre-test sessions. As the training effect was negligible the cardiac output measurements would be tested easily for reliability. The other method involved administering the two submaximal tests during one session in the laboratory. As the lower workload was used and an 33

adequate relief interval was allowed before the second test, the consistency of the measurement technique was determined.

During these reliability measurements blood was not taken.

STATISTICAL TREATMENT

The statistical analysis followed a specific pattern for each variable (see Appendix B). The students t test was used to compare the pre-post values for each subiect for each submaximal workload. This statistical test examined the response to the training program for each vari able and for each exercise test.

Next, all the trained limbs (arms and legs) were combined and tested in the same pre-post pattern for each of the two submaximal workloads. A similar procedure was repeated using the combined untrained limbs (arms and legs).

An additional group of t tests was performed to test the training response of the trained limb to that of the untrained limb. This analysis could be broken down further to arm trained group, trained limb (arm) versus untrained limb (leg) and similar treatment of the leg trained group.

Under certain conditions when it was advantageous to look at the effects of sprint versus endurance training, a 2 x 2 analysis of variance was used. CHAPTER 4

RESULTS AND DISCUSSION

INTRODUCTION

The subjects performed their workouts as designed.

Attendance was nearly 100%; if a workout was missed it was made up so that each subject completed a minimum of 24 work outs during the five week training period. The post-test was identical to the pre-test and was completed within one week. The data received was reduced and the appropriate statistical tests were applied. The 2 x 2 analyses of vari- ence used to compare sprint training to endurance training resulted in no significant difference for any of the variables tested. It was apparent that the small number of subjects

(3 or 4) within each subgroup was largely responsible for the lack of significance. With this in mind the sprint and endurance subgroups were combined which lead to a comparison between the arm trained group and the leg trained group.

RELIABILITY

The data for the reliability testing of the cardiac output measurement via the CO 2 rebreathing technique are con tained in Appendix D. The correlation coefficient for relia bility between the two determinations was +.835; the means for the two trials were 11.83 and 11.46 (p>.10).

34 35

ARM TRAINING versus LEG TRAINING

The mean circulatory changes following training, for both the arm trained group and the leg trained group are contained in Tables 2 and 3 respectively. It is apparent that the magnitude of the post-training changes is greater when the trained limb is used to perform the sub maximal tests, thus indicating that the controlling mechanisms for such changes are largely influenced by the status of the muscle performing the task. Nevertheless, the response to the tests while using the untrained limb suggests also a central adaptation to training.

The contribution of the local changes in the trained muscle to the total circulatory or metabolic response to training is discussed separately for each variable. See Appendix B for the statistical treatment.

OXYGEN CONSUMPTION

Following training, there was a significant decrease in oxygen requirements for the standard tasks, for all groups, at each level. That is, the leg trained group showed a significant change in the arm tests as well as the leg tests; this standard response to both tests was also true for the arm trained group. In addition, when the untrained limbs and the trained limbs were considered as separate groups, pre minus post analyses indicated a signifi cant decrease in oxygen consumption regardless of the trained state.(Figure 2). However, when the oxygen consumption 36

TABLE 2

CIRCULATORY CHANGES FOLLOWING TRAINING:

ARM TRAINED GROUP

Trained Limb Untrained Limb Oxygen Consumption (mis)

Load I -237 ± 90* -147 ± 155* Load II -236 ± 235* -133 ± 117*

Heart Rate (bpm)

Load I -31.4 ± 26.5* -8.1 ± 13.3 Load II -29.9 ± 22.1* - 10.1 ± 11.8

Cardiac Output (1/min)

Load I -2.16 ± 3.2 -0.38 ± 2.7 Load II -0.96 ± 0.7* -0.24 ± 3.4

Stroke Volume (mis)

Load I +4.43 ± 26.1 +1.74 ± 13.6 Load II +9.56 ± 14.7 +3.95 ± 25.6

A-V Oxygen Difference (mls/100 mis blood)

Load I -0.18 ± 2.8 -0.67 ± 1.8 Load II -2.12 ± 1.8* -0.75 ± 2.5

BTPS (l/min)

Load I -9.28 ± 9.8* -6.07 ± 9.8 Load II -11.31 ± 9.6* -8.42 ± 7.7*

Lactate (mg%)

Load I -23.4 ± 14.0* -0.71 ± 6.0 Load II -32.0 ± 15.0* -5.70 ± 5.8

Values are mean + S.D.

* = statistically significant p<.05 TABLE 3

CIRCULATORY CHANGES FOLLOWING TRAINING:

LEG TRAINED GROUP

Trained Limb Untrained Limb Oxygen Consumption (mis)

Load I -308 ± 108* -134 ± 261 Load II -273 ± 85* -177 ± 152*

Heart Rate (bpm)

Load I -22.0 ± 8.2* -3.6 ± 14.1* Load II -25.9 ± 5.9* -20.1 ± 14.7*

Cardiac Output (1/min)

Load I -2.02 ± 1.7* -1.40 ± 1.8 Load II -0.38 ± 2.1 +0.70 ± 2.3

Stroke Volume (mis)

Load I +3.21 ± 12.2 -1.27 ± 19.3 Load II +17.41 ± 14.4* +15.33 ±16.3

A-V Oxygen Difference (mis /100 mis blood)

Load I -0.08 ± 1.4 -0.76 ± 3.8 Load II -2.65 ± 1.8* -2.83 ± 3.5

BTPS (1/min)

Load I -8.07 ± 8.0* -10.80 ± 17.1 Load II -12.25 ± 7.3* -15.24 ± 9.4

Lactate (mg%)

Load I -10.4 ± 5.5* -16.1 ± 18.1* Load II -12.6 ± 6.2* -21.0 ± 14.9*

Values are mean + S.D.

* = statistically significant p<.05 38 response to the submaximal bicycle tests by the untrained limb is compared to the response of the trained limb there is a statistically significant difference. This suggests that changes in the trained muscle are primarily responsible for the changes in oxygen consumption. There also appears to be a central adaptation to training as evidenced by the signi ficant change in oxygen consumption when the untrained muscles were tested; however, this is definitely secondary to the local, peripheral muscle changes. This view is consistent with that of Clausen and his co-workers (15, 48) who also feel that the decrease in oxygen consumption following train ing is due to local changes in the trained muscle. Their data show very little change in oxygen consumption following exercise with the untrained muscle and a decrease of approxi mately 100 mls/min in V02 following tests using the trained muscle. The data from this study show qonsiderably greater changes in oxygen consumption; approximately 275 mls/min with the trained limb and 150 mls/min with the untrained limb

(Figure 2). This change in V02 with the untrained limb is difficult to explain. It is possible that variation in the technique, intensity, and duration of the training periods was responsible for this V02 response. In addition, the subjects in this study were completely familiar with the apparatus and thus a habituation effect is possible. Also,

Clausen's subjects had three indwelling catheters during the experimentation, a factor often associated with increased OXYGEN CONSUMPTION (MLS) Pre- Post Values -200 -275 -125 -50 Figure 2. Oxygen Consumption: Trained limb vs untrained limb untrained vs limb Trained Consumption: Oxygen 2. Figure Trained Limb 275 x Load I Load II Load I Load xx Untrained L s T p<.05 UTL vs TL x x p<.05 X -161 Limb x

Trained -255 Limb x Untrained -156 Limb x VO w 40 anxiety and alteration of physiological function.

HEART RATE

A significant bradycardia following training was evident in the leg trained group in both the leg and arm tests at both work levels (Figure 3). The arm trained group showed a significant decrease in heart rate in the submaximal tests performed with the arms; however, there was no statisti cally significant decrease in the heart rate values when the tests were repeated using the legs. This pattern was con sistent at both workloads (Figure 4). The leg trained group showed a significant training-induced bradycardia regardless of the muscle group used in the tests, thus supporting the hypothesis that adaptation of the heart to training is of an intrinsic nature. The arm trained group, however, demonstrated a significant decrease in heart rate only when the trained limb was used to perform the two workloads, thereby introduc ing evidence supporting the extrinsic mechanism of adaptation.

The trained limbs and untrained limbs were con sidered as separate groups and the heart rate values were analyzed statistically. These results show that there was a significant bradycardia at both workloads when the trained limb was compared to the untrained limb. However, this comparison is misleading as further breakdown of these groups, i.e., trained limb vs. untrained limb - arm trained group and trained limb vs. untrained limb - leg trained group, indicates that the significant bradycardia mentioned HEART RATE (BPM) 175 150 125 100 Figure 3. Heart Rate Responses: Leg trained group trained Leg Responses: Rate Heart 3. Figure r Ps Pe Post Pre Post Pre R WORK ARM P<.OI pc.oi 9 od II load load I load E WORK LEG p <01p HEART RATE (BPM) 100 175 125 150 Figure 4. Heart Rate Responses: Rate Heart 4. Figure Pre R WORK ARM P<.02 \ Post od II load od I load Arm trained group trained Arm Pre E WORK LEG S N Post NJ 43 above was, in fact, due only to the significant decrease in the arm trained group. Therefore, the hypothesis that train ing-induced brachycardia results from stimuli originating in the working skeletal muscle (33) is supported by the data of the arm trained group. The leg trained group, however, does not show the same specificity. This may have been due to the fact that the legs are usually more well trained than the arms, and thus the training effect on the legs is less pronounced. In addition, this effect would be magnified by the fact that the arm muscles are generally very poorly train ed and thus have a greater potential for change. On the other hand, as suggested by Clausen and others, the decreased specificity with the leg muscles might be related to differ ences in the size of the arm and leg muscle masses.

In view of the consistent changes in heart rate and oxygen consumption, these variables were plotted against each other. In Figure 5, the heart rate is plotted on the ordinate against VO 2 on the axis for both the arm trained group and the leg trained group. In both cases it is clear that the bradycardia induced by training when exercising with the trained limbs is greater than would be expected

from a decrease in VO 2 . This is shown by the difference in elevation of the pre and post regression lines and is inde pendent of whether the trained limb is arm or leg. By the same token, the common regression line for the pre and post data of the untrained limb indicates that in this case the iue . er Rt s VO vs Rate Heart 5. Figure HEART RATE (beats/min) 100 120 140 160 100 8 r~ 180 160 180 140 120

- i (ARM) -

. 12 . 16 . 20 2.2 2.0 1.8 1.6 1.4 1.2 1.0 RIE LIMB TRAINED . 12 . 16 . 20 2.2 2.0 1.8 1.6 1.4 1.2 1.0 L Limbs i I iI NRIE LIMB UNTRAINED PRE(A)+ POST(A) PRE(A)+ (ARM) 1 D(D AM TRAINED ARM ) A ( _ E TRAINED LEG V 02 , liters , /min 02 V i i J L i I i I j

2 For Trained and Untrained and Trained For I i i I i I i J NRIE LIMB UNTRAINED PRE(A)+P0ST(A) (LEG) RIE LIMB TRAINED (LEG)

45 bradycardia effect was totally related to the decreased VO 2 .

This, too, is independent of whether the untrained limb is the arm or the leg. In other words, for a given VO 2 , the heart rate is lower after training only when exercising with the trained limbs.

CARDIAC OUTPUT

Values for cardiac output were significantly decreased following training in only two instances: the arm- trained group at the highest workload during the arm tests, and the leg trained group at the lower work level using the trained limb. In addition, when the trained limbs were considered as a separate group and analyzed statistically, the cardiac output was significantly decreased, following training during the lighter workload. This reduction was not, however, carried over to the higher work level.

When the untrained limb was compared to the trained limb, there was no significant difference in the cardiac output values at either workload, after training

(Figure 6). It is possible that the training program was not of sufficient intensity and/or duration to ilicit a response; however, since the test bouts of exercise were of submaximal intensity a change in the status of cardiac output is not expected at this work level following a training period (7,24,26,34). It is, therefore, striking to notice any significant decrease in the cardiac output values. Clausen (13,15) has shown a decrease in cardiac 46 output during exercise with trained muscles at a submaximal workload except during heavy leg exercise. These changes were not significant when the cardiac output was related to the oxygen consumption. In the same studies, exercise with the untrained muscles produced no significant change in the cardiac output values following training, with the exception of the arm tests at the higher work level following leg training. In this instance cardiac output was elevated by

12%.

In the light of the data contained in Clausen's papers (13, 15) and the results of this study, there appears to be no consistent pattern of response of the cardiac out put variable with respect to trained and untrained masculature, although a trend towards a more peripheral training response is evident.

STROKE VOLUME

In light of the relatively unchanged cardiac output and the significant decrease in heart rate in response to training, an increase in the stroke volume following training is not surprising and is shown in Tables

2 and 3. The post-training changes are greater when the tests are performed with the trained limb; however, when these values are examined statistically there is no significant change when the trained limb is compared to the untrained limb. A statistically significant increase in stroke volume followed the leg tests at the highest work CARDIAC OUTPUT (1/min) Pre-Post Values - - - 2.00 1.50 1.00 .50 Figure 6. Cardiac Output: Trained limb vs untrained limb untrained vs limb Trained Output: Cardiac 6. Figure Trained limb - 2.08 Load I Load II Load I Load Untrained N.S. . 9 -.8 limb Trained limb Untrained N.S. limb - j 48

level with the trained limb. In addition, when the trained

limbs were considered as a group, pre- post training analyses

showed a significant increase in stroke volume during ex ercise performed at the highest work level; all other changes

in stroke volume were statistically non-significant. There

fore the observed increases in stroke volume are not of

sufficient magnitude to be of statistical significance,

although in the two instances where signficance was reached

the local changes in the trained muscle appear to be

responsible.

Clausen (15) reports similar increases in stroke volume following training although these changes are seen

during submaximal exercise performed with the untrained

as well as with the trained muscle groups. In fact, the

greatest increase in stroke volume occurred during heavy

submaximal work with the untrained limb indicating that

the central circulatory adaptation to training is also

important in mediating stroke volume responses.

BLOOD LACTATE

The changes in venous blood lactate values

following training are presented in Tables 2 and 3. The arm

trained group showed a significant decrease in the lactate

values following training when the exercise was performed with the trained limb, but not when the untrained limb was

used (Figure 7). The leg trained group, however, exhibited

a significant decrease in the lactate values post-training. VENOUS BLOOD LACTATE (MG%) 5 4 30 0 6 15 Figure 7. Blood Lactic Acid Changes: Arm trained group trained Arm Changes: Acid Lactic Blood 7. Figure Pre R WORK ARM p<.oi \ ot Pre Post od II load od I load E WORK LEG Post VO VENOUS BLOOD LACTATE (MG%) 45 0 6 30 IS Figure 8. Blood Lactic Acid Changes: Leg trained group trained Leg Changes: Acid Lactic Blood 8. Figure r Ps Pe Post Pre Post Pre R WORK ARM p<.o load load II load p<.oi E WORK LEG p <.oip O in 51 regardless of the muscle group used in the tests (Figure 8).

When the trained limbs are considered as a separate group and compared to pre-training values, the venous blood lactate is significantly decreased at both workloads. An identical procedure for the untrained limbs shows a significant decrease only at the higher workload.

A comparison of the response by the trained limb to that of the untrained limb results in no significant difference at either workload. Further breakdown, i.e.,

Arm Trained: trained limb vs untrained limb, and Leg

Trained: trained limb vs untrained limb, shows a signifi cant difference within the arm trained group. The leg trained group shows no difference when the trained limb is compared to the untrained limb.

These results clearly indicate the specific nature of the adaptation to training by the arm trained group. Only when the trained limb was used to perform the sub-maximal tasks did the lactate values decrease significantly. It is apparent from these data that local changes in the trained muscle are responsible for the lactate response to arm training.

The leg trained group responded in a non-specific manner: the blood lactate values were significantly decreased following training, regardless of the limb used during the exercise tests. This is a peculiar finding as it demonstrates that the untrained muscles (arms) have responded in a 52 trained manner. In fact, data contained in Table 3 show that the blood lactate values were decreased to a greater magnitude when exercise was performed with the untrained limbs. As the blood lactate concentration is derived from the exercising muscle only, it is difficult to explain the significant decrease in the arm tests following leg training.

Although the technique used for leg training was specifically designed to eliminate a training effect on the arms it is possible that the arms did receive a small amount of exercise per day either through a fault of the technique or due to the fact that the training program was sufficiently strenuous to require upper body contractions to maintain balance and/or rhythm. In sedentary individuals, the arm muscles have a greater potential for local improvement and therefore these minor training stimuli could possibly mediate a significant response in the arm muscles to explain the lactate decrease. The site of the blood sampling also could be responsible for the changes. As the blood was always taken from the arm veins the values during arm work would be representative of the working arm muscle. On the contrary, values taken from the arm during leg exercise would not necessarily approach the values in the working leg muscle.

It is also apparent from the low initial lactate values during leg exercise that the potential for change in the leg muscle is much lower than in the arm. 53

PULMONARY VENTILATION (BTPS)

Pulmonary ventilation was significantly decreased,

following training, in the a m trained group at both work

loads with the trained limb and the higher workload with the untrained limb. The leg trained group showed a significant decrease, following training, only when the trained limb was used to perform the submaximal tests. When all the trained

limbs were combined and compared to the initial pre-training values, a significant decrease was observed for both workloads.

Similar tests on the untrained limbs also resulted in

statistically significant decreases in pulmonary ventilation.

Consequently, when the trained limb group was compared to the untrained limb group there was no significant difference in

the changes post-training.

These results indicate a combination of central and peripheral training effects on the ventilation response

to exercise. The leg trained group, which decreased pul monary ventilation significantly only when the legs were

used in the tests, demonstrates the peripheral effect of

training. Stimuli arising from the trained muscle are

responsible for the decrease in pulmonary ventilation

following training. The values of the leg trained group are

in line with those of Clausen (14) and Rasmussen (48) which

also indicate a predominatly peripheral training effect on pulmonary ventilation.

Post-training changes in pulmonary ventilation 54 were more non-specific in the arm trained group as evidenced by the response of the untrained limb at the highest sub maximal work level. In addition, the BTPS values for the untrained limb were significantly reduced following training indicating a central adaptation to regular exercise as well as the peripheral training effect.

A-V OXYGEN DIFFERENCES

Following training the A-V O 2 difference was significantly decreased during the submaximal tests performed with the trained limb for both the arm trained and the leg trained groups at the highest workload. Consequently, when these two groups were combined and tested versus pre-training values the A-V O 2 difference was again significantly decreased at the highest workload. All other changes in this variable were statistically non-significant.

These findings are surprising as it has been shown that training increases the A-V O 2 difference (7,52).

Similar findings, however, are shown in a paper by Clausen

(15). Following leg training, a decrease in the total A-V O 2 difference was observed during submaximal exercise with the legs. These results are difficult to explain although it must be noted that these values represent total A-V O 2 differences and not the regional changes which may in fact be of a different nature (15). CHAPTER 5

SUMMARY

The purpose of this study was to evaluate the effects of training the arm or the leg muscles on the cardio-respiratory responses to two submaximal workloads.

Of particular interest was the contribution of local muscle changes to the cardio-respiratory adaptation to training.

Fifteen healthy, untrained, male university students volunteered for the nine week study. The subjects were randomly assigned to two groups; an arm trained group of seven subjects and a leg trained group of eight subjects.

Prior to the training program each subject was tested on four submaximal workloads: 63 watts and 83 watts for the arm tests and 100 watts and 125 watts for the leg tests. Each test consisted of a six to seven minute workout at the resistance mentioned above. During these submaximal tests the following variables were determined: oxygen comsumption

(open circuit), pulmonary ventilation, heart rate (EKG), cardiac output (CO2 rebreathing), stroke volume, A-V oxygen difference, and venous blood lactate.

Two types of interval training were used in each group: a sprint program designed to tax the anaerobic energy system and an endurance program which emphasized the aerobic

55 56

energy system. The programs remained progressive throughout the five week training period. Following the training pro gram the submaximal tests were performed again, identical to the pre-test procedures.

Following training, there was a significant de crease in oxygen requirements for the standard tasks at each work level, regardless of the limb used to perform the tests.

In addition, when the untrained limbs and the trained limbs were considered as separate groups, pre minus post analyses indicated a significant decrease in oxygen consumption re gardless of the trained state. However, when the oxygen consumption response to the submaximal bicycle tests by the untrained limb is compared to the response of the trained limb there is a statistically significant difference. This suggests that changes in the trained muscle are primarily responsible for the changes in oxygen consumption. There also appears to be a central adaptation to training as evidenced by the significant change in oxygen consumption when the untrained muscles were tested. However, this is definitely secondary to the local, peripheral muscle changes.

With regards to heart rate response to training, the leg trained group showed a significant bradycardia regardless of the muscle group used in the tests. These 57

findings support the hypothesis that adaptation of the heart to training is of an intrinsic nature. The arm training group, however, demonstrated a significant decrease in heart rate only when the trained limb was used to perform the two workloads. Therefore, the hypothesis that training-induced bradycardia results from stimuli originating in the skeletal muscle is supported by the data of this group.

Cardiac output measurements following training tended to be decreased although this was statistically significant in only two instances: the arm trained group at the highest work level using the arms and the leg trained group at the lower work level also with the trained limb.

It is a well known fact that the cardiac output values remain unchanged, following training, when the exercise is of submaximal intensity and thus significant changes are not to be expected.

Stroke volume, following training, was increased in both groups. The post-training changes are greater when the tests are performed with the trained limb although these changes were not statistically significant. In the two instances where significance was reached: the leg trained group at the highest work level with the trained limb and the trained limbs considered as a group and compared to 58

pre-training values, it would appear that local changes in the trained muscle are responsible.

Blood lactate responses to training were similar in pattern to those of heart rate. The leg trained group showed a significant decrease in the lactate values regard less of the muscle group used in the tests, whereas, the arm trained group demonstrated a significant decrease in lactate only when the trained limb was used. These results clearly indicate the specific nature of the adaptation to training by the arm trained group; it is apparent that local changes in the trained arm muscle are responsible for the decrease in venous blood lactate values. In addition, the lactate data shows the increased potential for local improvement within the arm muscle; within the leg trained group the blood lactate values for the untrained limb were decreased to a greater extent than those of the trained leg muscles.

BTPS values indicate a combination of central and peripheral training effects on the ventilation response

to exercise. The leg trained group, which had decreased pulmonary ventilation only when the legs were used in the

tests, demonstrates the peripheral training effects. The

arm trained group showed a non-specific response to training,

indicating a central adaptation to regular exercise as well 59

as the peripheral training effect.

Total body arterial-venous oxygen differences were significantly decreased following training; a sur prising result contrary to the usual response to training.

It is possible that regional measurements would not show