The Evaluation of Anerobic Power and Capacity in Alpine Ski Racers with Jump Tests

I am thankful for my struggle,

because without it

I wouldn’t have stumbled across my strength.

(Alex Elle)

Doctoral Thesis

THE EVALUATION OF ANEROBIC POWER AND CAPACITY IN ALPINE SKI RACERS WITH JUMP TESTS

submitted to the Faculty of Psychology and Sport Science of the Leopold-Franzens Universität Innsbruck

In fulfilment of the requirements for the degree “Doctor of Philosophy – PhD”.

submitted by

Carson Patterson, M.A.

Supervisor Ao. Univ.-Prof. Dr. Christian Raschner

2nd Supervisor Assoz.-Prof. Dr. Martin Faulhaber

reviewed by Ao. Univ.-Prof. Dr. Christian Raschner Priv. Doz. Hannes Gatterer, PhD

Innsbruck, May, 2020

TABLE OF CONTENTS

___

ACKNOWLEDGEMENTS ...... V

LIST OF PAPERS ...... VI

ABBREVIATIONS...... VII

SUMMARY...... 1

1 INTRODUCTION...... 3

1.1 Aerobic fitness in alpine ski racing...... 3

1.2 Anaerobic fitness in alpine ski racing...... 5

1.3 Fitness and ski racer safety……………….…….……...... 10

1.4 Jumps as testing mode in alpine ski racing……….…...... 10

1.5 The power-load relationship in jumping…...... 11

1.6 Using jumps to detect bilateral force imbalances……...... 12

1.7 Monitoring anaerobic power and capacity in alpine ski racing…….…………...….12

1.8 Aim of the PhD project……………...…………...... 14

2 METHODS...... 16

2.1 Paper I...... 16

Power variables and bilateral force differences during unloaded and loaded

squat jumps in high performance alpine ski racers.

2.2 Paper II...... 23

The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity in

alpine ski racers with loaded countermovement jumps.

2.3 Paper III...... 29

The 2 minute loaded repeated jump test: longitudinal anaerobic testing in elite

alpine ski racers.

3 RESULTS...... 33 iii

3.1 The anaerobic power of elite Austrian female and male alpine ski racers...... 33

3.1.1 Power variables and bilateral force differences during unloaded and loaded

squat jumps in high performance alpine ski racers. (Paper I)……....……...... 33

3.2 The anaerobic power and capacity of elite Austrian male alpine ski racers...... 37

3.2.1 The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity

in alpine ski racers with loaded countermovement jumps. (Paper II).…...... 37

3.3 The longitudinal anaerobic power and capacity of female alpine ski racers..…..….42

3.3.1 The 2 minute loaded repeated jump test: longitudinal anaerobic testing in

elite alpine ski racers. (Paper ……………………………….………..………..42

4 DISCUSSION...... 49

5 CONCLUSION...... 57

6 REFERENCES...... 58

7 EIDESSTATTLICHE ERKLAERUNG...... 72

8 PAPERS I-III...... 74

ACKNOWLEDGEMENTS

I would like to thank some key people for their influence, guidance and help along the way. I know that I will miss a couple – please forgive me; I have been touched by so many. A very special thanks to all! And now at the risk of missing someone… I want to thank Dr. Christian Raschner for suggesting I pursue a PhD and motivating me to finish this. It took a long time - I appreciate your patience Christian. Thank you for your support and so much more! Dr. David Smith – I acknowledge and appreciate the impact you had on me by showing me that one can train scientifically to improve performance. This was a revelation. Dr. Howard Wenger – thank you for showing me that one can work with the world’s best athletes, learn every day and have a great sense of humour. Thanks to Patrick Neary, for your friendship and for all your support in the lab and everywhere else. Could not have done it without you! Dr. Werner Nachbauer – you gave me my first opportunity to work in Innsbruck and my first taste of the Department of Sport Science – thank you! Werner Margreiter, you have my gratitude for taking a chance on me as a conditioning coach for the men’s downhill team and setting me on a path of making Innsbruck my home. Hans-Peter Platzer – thanks for your friendship, honest opinions and your stats expertise. I thank my fellow Olympiazentrum coaches: you have taught and supported me in so many different ways: Hans-Peter, Christoph, Antonio, Lukas, Roland, Mario and Fabian. Thank you to my Olympiazentrum colleagues - Barbara, Lisa, Philipp, Bettina, Caro, Sandra, Simone, Benny, Esi, Caro, Pia and Tom. Thanks for your help and for putting up with me! Thanks to my ISW colleagues who supported me: Martin Burtscher, Martin Faulhaber, Hannes Gatterer, Dieter Heinrich, Barbara Hotter, Elmar Kornexl, Günther Mitterbauer, Martin Mössmer, Armin Niederkofler, Gerhard Ruedl, Kurt Schindelwig, David Weichenberger and Inge Werner. Thanks to Gomer Lloyd for starting this FDC on this international adventure! You are missed! Thanks to all the athletes who have touched me over the years – too many to name – I learned tons from you. Blood, sweat and tears! I am honoured and humbled to know you. Aunt Ruth – you always made me feel special and took me seriously. Thank you! To Vera, thanks for being in my life! You enrich it! I owe much to my sister and brother, Catherine and Clayton. You taught me so much before I started school. You nurtured me. Thank you for giving me a head start. To my Schatzi Regina - you give me wings to fly, and keep my feet on the ground. You have opened my eyes in so many ways. You make my life so beautiful. You gave me a new heimat. You complete me. Thank you with eternal love! To Mom and Dad, to whom I owe so much. Thanks for giving me life, for loving me, for raising me. I dedicate this dissertation to you and your memory, with humble gratitude.

v" " LIST OF PAPERS

The present dissertation is based on the following papers, which are referred to in the text by their roman numerals.

Paper I:

Patterson, C., Raschner, C. and Platzer, H.-P. (2009) Power variables and bilateral force differences during unloaded and loaded squat jumps in high performance alpine ski racers.

Journal of Strength and Conditioning Research, 23 (3), 779-787.

Paper II:

Patterson, C., Raschner, C. and Platzer, H.-P. (2014) The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity in alpine ski racers with loaded countermovement jumps.

Journal of Strength and Conditioning Research, 28 (9), 2611-2620.

Paper III:

Patterson, C., Platzer, H.-P. and Raschner, C. (2019) The 2 minute loaded repeated jump test: longitudinal anaerobic testing in elite alpine ski racers. Journal of Sports Science and

Medicine 18, 128-136.

ABBREVIATIONS

ACL anterior cruciate ligament

BW bodyweight

DH downhill

Fmaxdiff maximal force difference between dominant and nondominant leg

FIS International Ski Federation

GPP general preparation period

GS giant slalom

Hz hertz

ICC interclass correlation coefficient kg kilogram

LCMJ loaded counter movement jump

LRJT loaded repeated jump test ml millilitre

MLD Muskel-Leistungs-Diagnose ml.kg-1.min-1 millilitre per kilogram per minute mmol.l-1 millimole per litre ms millisecond

ÖSV Austrian Ski Federation

P average power relative to bodyweight

P01 relative average power in first 100 ms of a jump

P02 relative average power in first 200 ms of a jump

P30 mean relative average power from the start of the LRJT to 30 seconds

vii

P30rel first LRJT 30 second interval expressed as a percentage of PREF

P60 mean relative average power from 31 to 60 seconds

P60rel second LRJT 30 second interval expressed as a percentage of PREF

P90 mean relative average power from 61 to 90 seconds

P90rel third LRJT 30 second interval expressed as a percentage of PREF

P120 mean relative average power from 91 to 120 seconds

P120rel fourth LRJT 30 second interval expressed as a percentage of PREF

P150 mean relative average power from 121 to 150 seconds

P150rel fifth LRJT 30 second interval expressed as a percentage of PREF

PMAX highest average power relative to body weight of the reference counter movement jumps

PREF average power relative to body weight of the reference counter movement jump

SD standard deviation

SE standard error

SG super giant slalom

SL slalom

SPSport SP Sportdiagnosegeräte GmbH

W watt

WC FIS Alpine World Cup

1RM one repetition maximum

%Jump percentage of best jump height

viii

SUMMARY

The complexity of alpine ski racing makes it difficult to quantify the physiological demands of the sport, and there is no consensus as to what physical qualities determine racing success. However, modern ski equipment has made the sport much more dynamic, increasing the importance of strength and power. Ski racers must be powerful, and be able to maintain their power throughout an entire race. Assessing anaerobic power and capacity in ski racers with jump tests can aid in optimizing their physical preparation may be predictive of racing success. The MLD portable jump testing system from SPSport has been used for a number of years to test the anaerobic fitness of the Austrian alpine ski team. The aims of this doctoral thesis were: to evaluate and compare anaerobic power variables in male and female elite Austrian ski racers, to determine the reliability of the MLD loaded repeated jump test (LRJT), to examine the effect of the annual physical preparation on anaerobic fitness, to investigate the development of anaerobic fitness in world class ski racers over 4 seasons, and to explore the predictive value of anaerobic power and capacity tests for ski racing success.

The first part of the project tested anaerobic power of Austrian national alpine ski team members with weighted jumps. Ground reaction force records from 2 force platforms were used to calculate power variables. Twenty male and 17 female athletes jumped with increasing additional barbell loads up to 100% BW in order to evaluate their power-load curve. The men displayed significantly higher values at all loads for power and jump height (p < 0.05). No significant gender differences were found in power reached at 100ms, suggesting that ski racing may not require “fast” power as a ski turn involves a long stretch shortening cycle. Maximum power was reached at light loads

(men at 25% BW and women at 0% BW), and power decreased uniformly thereafter. It is proposed that the load where the power-load deflection point occurs be used as the power training load and not the load at which maximum power is reached.

The second part of the project proved the reproducibility of the 2.5-minute LRJT and the effectiveness of the general preparation period training on anaerobic fitness in elite Austrian male ski racers. Athletes improved in both anaerobic power and capacity from June to October.

The third part of the project investigated the 4-year development of anaerobic power and capacity in female racers in the Austrian national alpine ski team and examined the relationship between the

2-minute LRJT results and ski racing performance (FIS points). Anaerobic power significantly improved from season 1 to 2, but there were no further statistical differences between seasons.

Anaerobic capacity increased up to season 3 by 9.2%, but was significantly higher only when comparing season 4 to seasons 1 and 2. FIS points changed significantly; decreasing by 52% from season 1 to season 4 (lower FIS points indicates better racing results). FIS points had a positive relationship with anaerobic power and capacity only in season 4. Improvements in FIS points from year to year did not correlate with seasonal increases in LRJT results.

The MLD testing system provides reliable test results for anaerobic power and capacity, with male ski racers generally producing higher power and capacity values than their female counterparts.

Anaerobic training adaptations can be monitored with the LRJT but the test results do not correlate with ski racing performance.

1. INTRODUCTION

Alpine ski racing is a complex high-speed sport and the racer who can best manage the physical, psychological, tactical and technical challenges of ski racing will win. The physical demands of alpine ski racing are difficult to quantify due to its complexity (Turnbull et al., 2009). Performance cannot be predicted by any one physiological factor (Bacharach and Duvillard, 1995, Maffiuletti et al., 2006, Turnbull et al., 2009) and there is no consensus as to what physiological parameters dictate success (Gilgien et al., 2018, Impellizzeri et al., 2009, Maffiuletti et al., 2006, Maffiuletti et al., 2012, Neumayr et al., 2003, Neumayr et al., 2006, Turnbull et al., 2009). “Athletes with substantially different physical characteristics can all compete at a high level” (Gilgien et al., 2018), which makes ski racing very interesting and attractive for the athletes. Two reviews of the physiology of alpine skiing (Hintermeister and Hagerman, 2000, Turnbull et al., 2009) stated that there are conflicting opinions as to the relative contribution of anaerobic and aerobic metabolism to skiing performance.

1.1 Aerobic fitness in alpine ski racing

In the 1970s and 1980s, aerobic fitness was thought to be a key factor because many ski racers tested in this period had very high levels of aerobic power (Brown and Wilkinson, 1983; Eriksson et al., 1977, Karlsson, 1984). Eriksson and coworkers (1977) asserted, “anaerobic capacity does not appear to be of any great importance for a good and safe performance in downhill skiing”. The

̇ . -1. -1 VO2max of Sweden’s Ingemar Stenmark was 71 ml kg min (Hintermeister and Hagerman, 2000).

The high aerobic fitness of Stenmark and his Swedish teammates probably influenced the attitude and training programs of many coaches and athletes. However, Karlsson (1984) speculated that the

̇ high VO2maxes of Swedish skiers might have reflected the aerobic training programs of the athletes, and not necessarily the demands of the sport.

Hermann Maier, the great Austrian ski racer, was renowned for his aerobic training, which he performed on a cycle ergometer. Maier even opened the prologue of the Tour de France as a forerunner in 2003. The perception that Maier performed high volumes of aerobic base training had a decisive impact on the training of Austrian alpine ski racers.

The aerobic fitness results of Hermann Maier and his teammates (28 men and 20 women) from

1997 to 2000 were published by the Austrian group (Neumayr et al., 2003), which regularly

̇ performed the spiroergometry tests on the Austrian alpine ski team. WC ranking and VO2max correlated very highly (r2 = 0.96, n = 7), but only in one season (1998).

̇ Table 1 Reported VO2max values of alpine ski racers

̇ . -1. -1 Authors Year Nation Competition Level VO2max (ml kg min ) Female Male Rusko et al. 1978 Finland WC 63.8 ± 4.5 Haymes et al. 1980 USA WC 52.7 ± 4.1 66.6 ± 5.4 Song 1982 Canada FIS 65.6 ± 5.0 Brown et al. 1983 Canada WC 63.1 ± 1.3 Karlsson et al. 1984 Sweden WC 67 Veicsteinas et al. 1984 Italy WC 52.4 ± 7.8 Saibene et al. 1985 Italy Military Ski Team 58.9 ± 2.2 Andersen 1988 Canada FIS 55.6 ± 0.8 White et al. 1991 USA FIS 53.4 Duvillard et al. 1995 USA FIS 58.0 ± 4.7 Vogt et al. 2000 Switzerland WC 53.3 ± 2.3 Linda et al. 2001 USA FIS 53.0 ± 2.8 52.9 ± 7.2 Neumayr et al. 2003 Austria WC 55 ± 3.5 59.5 ± 4.7 Gross et al. 2009 Switzerland Europa Cup, FIS 55.2 ± 5.2 Nikolopoulos et al. 2009 Greece FIS 56.5 ± 5.3 Breil et al. 2010 Switzerland FIS 51.6 ± 6.5 58.3 ± 2.7 Impellizzeri et al. 2009 Italy WC 56.5 ± 4.2 Gomez-Lopes et al. 2012 Spain FIS 43.7 ± 4.9 51.6 ± 4.2 Polat 2016 Turkey FIS 51.4 ± 2.7 Nilsson et al. 2018 Sweden FIS 48.4 ± 2.3 58.2 ± 4.4

1.2 Anaerobic fitness in alpine ski racing

There is no agreement among scientists that the metabolic demands of ski racing are predominantly aerobic. In an early study of energy demands in alpine ski racing with Italian male WC racers, it was determined that in SL and GS training, energy sources were about 70 - 75% anaerobic, and 30

- 35% aerobic (Veicsteinas et al., 1984). In 1995, Tesch did not attempt to quantify the relative contribution of aerobic and anaerobic metabolism, but stated that high demands were placed on 5 both energy systems. In a muscle biopsy study of Swiss ski racers, glycogen reduction was greater in Type I fibers during and after SL training (16 runs), leading to the conclusion that endurance training is important and that high muscle oxidative capacity and muscle hypertrophy were the best predictors in alpine ski racing (Vogt et al., 2003).

Scientists have shown that aerobic fitness did not differentiate between different levels of ski racers

(Haymes and Dickinson, 1980, Brown and Wilkinson, 1983, Nilsson, 2018, White and Johnson,

̇ 1991, Impellizzeri et al., 2009). Haymes and Dickinson (1980) did find that VO2max correlated

̇ with DH race performance, but not GS or SL. Song (1982) found that VO2max correlated with DH performance in youth ski racers. The aforementioned work by Neumayr and colleagues (2003) could only show a very high correlation between aerobic power and DH and SG WC ranking in one season. The paper from Neumayr (2003) was strongly criticized by Italian and Swiss sport scientists (Maffiuletti et al., 2006) who believed that the anaerobic component is substantial.

Hydren et al. (2013) reviewed the practice of strength and conditioning for ski racing and emphasized the importance of anaerobic fitness in ski racing. Before the introduction of carving skis and the new racing technique, Bosco (1997) stated that speed endurance (measured with repeated jumps) was the most important physical factor in racing success. His data indicated that the best Italian male and female SL and GS racers at that time (they were also the best in the world) had higher “speed endurance” (anaerobic fitness) compared to their Italian teammates. Bosco however, did not statistically compare jump test results with racing performance.

Impellizzeri and colleagues (2009) examined the physiological profiles of Italian national team

̇ alpine ski racers and found that neither Bosco’s 45 s jump test nor VO2max tests distinguished top athletes (top 15 in FIS WC rankings) from their lower ranked teammates. They did find that SL and GS racers had higher relative eccentric strength in knee extension and flexion.

Koller and Schobersberger (2019) in an editorial maintained that the currently available preseason aerobic and anaerobic tests have limited value as predictors of ski racing performance.

A longitudinal study (10 years) of elite male Swiss ski racers (European cup and WC level),

̇ Maffiuletti and coworkers (2012) presented interesting findings. VO2max increased, single jump power and knee extension strength decreased, and 45-second jump test results did not change. In

2006, Maffiuletti and some of the same colleagues (Maffiuletti, et al., 2006) maintained that alpine ski racing was more anaerobic than aerobic. Their 2012 study however, showed a “shift” from an anaerobic to a more aerobic physiological profile. They also stated that the ski racers and coaches were emphasizing aerobic training with some of the athletes competing in 100 – 150 km cycling races. This may be a case as aforementioned (Karlsson, 1984) that the fitness levels reflect the training, and not the demands of the sport. They speculated that the physiological profile was due to changes in skis (less stiffness, more sidecut and shorter) which have greatly influenced ski racing technique, in turn requiring less muscular strength and anaerobic power in carving turns.

The changes in ski shape and ski technique starting in the late 1990s (Supej and Holmberg, 2019) influenced the evolution of ski racing technique from turning to “carving” (Müller and

Schwameder, 2003). The smaller sidecut radius allows for a shorter turn radius, which increases ground reaction forces (Spörri et al., 2016) which could lead to the conclusion that a racer needs more leg and core strength to handle these larger forces. Müller and Schwameder (2003) have shown that in carving turns there is more co-loading of the inner leg than in traditional turns, which may mean that even with greater net forces the demands on each individual leg are less with the modern carving technique.

The exact physical demands of alpine ski racing are open to debate but it is a high intensity sport

(Polat, 2016, Stöggl et al., 2018). Measuring blood lactate concentration is a common method to determine intensity of exercise (Goodwin et al., 2007). Mader and coworkers (1976) introduced 7 the terms “lactate threshold” and “aerobic-anaerobic threshold". The field of transition between the mere aerobic and the partially anaerobic muscular energy metabolism performance under production of lactate is called "aerobic-anaerobic threshold". An increase of lactate up to 4 mmol.l-

1 in peripheral blood can be rated as a criterion for the assessment of the aerobic-anaerobic threshold, for example, by a gradual increase of work rates" (Heck et al., 1991). Blood lactate concentration in alpine ski racing has been investigated. Table 2 illustrates that blood lactate concentrations can be as high as 15 mmol.l-1, indicating that alpine ski racing is a high intensity sport, with a high anaerobic component.

Table 2 Reported blood lactate values of alpine ski racers

9.0 > 10 Male 9 - 13 7.1 ± 1.6 6.8 ± 0.9 10.1 ± 0.4 8.0 - 15.7 12.4 ± 1.9 11.7 ± 2.7

Female 6.0 ± 1.7 5.7 ± 2.2 Blood lactate concentration (mmol.l-1) GS 1700m 1800m SL 55 s SL 45 s GS 93 s GS 70 s GS 62 s 90 s DH - 3500m Conditions Review article GS 82 s altitude GS 76 s altitude SL altitude 3000 FIS WC WC WC WC WC WC Youth Europa Cup, FIS Military Ski Team Military Ski Team Competition Level Italy Italy Italy Italy USA France Nation Turkey Finland Sweden Slovenia Switzerland Year 1988 1984 1984 1984 1985 1985 2000 1993 2013 2016 2018 Polat Authors Vogt et al. Grenier et al. Saibene et al. Saibene et al. Tomazin et al. Karlsson et al. Richardson et al. Veicsteinas et al. Veicsteinas et al. Anderson & Montgomery 1.3 Fitness and ski racer safety

The relative contribution of anaerobic metabolism to ski racing performance may be debatable, but the ability to maintain high muscular power throughout a race is essential for an athlete’s safety.

In 2013, Johan Clarey of France reached a speed of 161.9 km.h-1 on the Lauberhorn FIS WC DH course in Wengen, and Austrian Anna Veith was clocked at 137.6 km.h-1 during an International

Ski Federation (FIS) Alpine WC women’s DH race in Lake Louise. The experts define high speeds as a risk factor for injuries in alpine ski racing (Spörri et al., 2012).

In all alpine ski racing events, a racer must have the physical strength and power to maintain a carved turn and resist gravitational forces (g-force) while maintaining edge control and balance.

Navigating jump landings, bumps, and ruts require rapid force production, or power. The ability to maintain this power throughout the entire race is not only critical to racing performance; it can also determine if a racer loses control and crashes, or arrives safely in the finish area. Thus, ski racing demands high levels of anaerobic power and capacity. The anaerobic power and capacity of ski racers must be evaluated and monitored.

1.4 Jumps as testing mode in alpine ski racing

Kornexl (1977) provided the first documented use of the high box jump test; which was implemented to test the Austrian alpine ski team. This test was validated as a test of anaerobic endurance for ski racers by McGinnis (1981) and Shea (1984) and has been reported to correlate with ski racing performance (Anderson and Montgomery, 1987, Shea, 1984). Forms of the high box jump test are used in Austria (Raschner et al., 2013), Canada (Alpine Canada, 2016),

Switzerland (Vogt, 2013) and the United States (U.S. Ski and Snowboard, 2017). Gross and colleagues (2014) found that a 90-second box jump test is a good simulation of the metabolic demands of ski racing. This test is easy to administer but only measures the number of jumps an athlete can perform in a set test duration or partial duration thus evaluating anaerobic capacity.

There is no objective measure of anaerobic power and it does not allow for single jump analysis or analysis of forces.

Jumps in various forms have been used to evaluate anaerobic power and capacity in ski racers.

From relatively simple jump tests, such as a jump and reach test (Thomas, 1992) to jumping mats

(Bosco, 1994, 1997, Emeterio et al., 2010) to sophisticated laboratory tests using force platforms

(Jordan et al., 2014, Pernitsch, 2001), ski coaches and scientists have attempted to find ways to predict performance, improve fitness and prevent injury in alpine ski racers. Karlsson (1978) stated that the major muscle groups used in skiing (legs and core) are the same muscle groups active in jumping.

Vertical jumps are accepted methods to assess anaerobic power (Bosco, 1994, 1997, Jordan, 2015,

Pernitsch 2001, White and Johnson, 1992), and anaerobic capacity in ski racers (Bosco, 1994, 1997,

Pernitsch 2001). Bosco et al. (1983) demonstrated that the 60-second continuous jump test is highly reproducible (r = 0.95), and others have found that continuous jump tests based on Bosco’s test design were reliable (all parameters had an r of at least 0.93) (Hespanhol, 2007).

Alpine ski racers have also been tested with loaded jumps (Bosco, 1994, 1997, Pernitsch 2001), in which case a barbell is placed on the back as in a back squat. The external forces that a ski racer absorbs on snow can be at to 4 times bodyweight in SL and up to 3.2 times bodyweight in GS

(Gilgien et al., 2018). Supej and Holmberg (2019) reported that the external load on a ski racer can be as high as 5 times body weight in SL.

Jumping tests should be able to measure anaerobic power and capacity, determine the ideal load to train for anaerobic power, and evaluate force imbalances between legs.

1.5 The power-load relationship in jumping

In order to analyse anaerobic capacity, anaerobic power must be tested so one can see how power drops off during the test. Tests can also determine the optimal load to use to train power. Power

11 output changes with the load used during jumps, this is known as the power-load relationship.

Many researchers agree that the optimal load with which to train power is the load at which maximum power is reached (Kaneko et al., 1983, Kawamori and Haff, 2004, Moritani et al., 1987,

Moritani, 1993, Wilson et al., 1993). However, research has shown that maximum power output can occur anywhere from unloaded jumps to jumps with loads up to 70% 1 repetition maximum

(1RM) (Baker et al., 2001, Cormie et al., 2007, Cronin and Sleivert, 2005, Stone, et al., 2003).

Comparisons between studies are difficult because the collection and reporting of power data is inconsistent (Cormie et al., 2007, Cronin and Sleivert, 2005, Dugan et al., 2004).

1.6 Using jumps to detect bilateral force imbalances

Jumping tests can be performed on two force platforms so that one can also test for force imbalances between legs. Ideally, a ski racer should have neuromuscular balance between legs - in other words, strength and coordination is the same for both right and left legs. Measuring bilateral force differences during jump testing can evaluate the progress of an injury rehabilitation program and may aid in injury prevention. Twenty-five to 30% of elite ski racers have suffered at least 1 anterior cruciate ligament (ACL) injury in their careers (Ekeland, 1999, Pujol et al., 2007), and female racers are more susceptible to ACL injuries than men (Tecklenburg et al., 2000). It has been reported that women injure the left ACL more, but no relationship was found between leg dominance and ACL injury (Negrete et al., 2007), whereas other work has suggested that leg dominance may increase ACL injury risk (Gerber et al., 2002). Differences between average and peak forces produced by the right and left legs during 2-legged squats in female softball players have been examined (Gerber et al., 2002), but there has been no published data comparing bilateral forces in loaded and unloaded 2-legged jumps.

1.7 Monitoring anaerobic power and capacity in alpine ski racing

In sports with standard distances such as athletics and swimming, it is very simple to monitor

12 anaerobic power and capacity. For example, a sprinter can perform 30m and 300m sprints at various times in the preparation phase. Ski racing training is not performed under consistent conditions. The environmental factors (temperature, wind, snow quality, etc.) as well as training at various ski resorts with different terrain make it impossible to perform standardized tests on snow.

Snow training intensifies in the late summer and early fall, but preseason training cannot simulate the length of winter ski races. The longest women’s DH race is typically in Lake Louise, and is about 1 minute 50 seconds. The longest women’s SL is usually under a minute, but Bormio in 2008 hosted a women’s SL with a winning time of just over a minute. On the men’s side, the longest DH is the Lauberhorn course in Wengen, which can be as long as 2:30. The longest GS course is

Adelboden, and can see winning times of approximately 1:15. SL races are about 50 seconds to one minute long.

The offseason snow conditions rarely allow training courses to be as long as the winter races, so coaches have no real standard to evaluate the race endurance of an athlete. Therefore, it is important to have a standardized test to assess anaerobic capacity.

Anaerobic capacity can be tested with jumps. Bosco and his group developed jump tests that were used by the Italian alpine ski team (Bosco 1994, 1997), one of which consisted of 60 continuous jumps in 60 seconds. Continuous jumping tests the efficiency of the stretch shortening cycle (Bosco et al., 1983), but skiing is not an “explosive” sport and is dominated by slow eccentric contractions

(Berg and Eiken, 1999, Berg et al., 1995, Hydren et al., 2013). Kröll and colleagues (2013) agreed with Berg et al. (1995) that skiing is predominantly eccentric, but stated that some isometric and concentric muscular work is also present. The Bosco test is more suited to athletes in sports in which the stretch-shortening cycle is important (Sands et al., 2004). WC SL has an approximate turn rhythm of 1 - 1.5 seconds (race time divided by number of gates); GS, this is 1.5 - 2 seconds and 2.4 - 3 seconds in SG. Guidelines for anaerobic capacity tests recommend that the tests mimic

13 the duration and cadence of the athlete’s event (Finn et al., 2000, Harley and Doust, 1994).

Therefore, jump tests for ski racers should be “slower” with noncontinuous jumps. The longest DH race for men is about 2.5 minutes long, and so an anaerobic capacity test for male racers should reflect this. SL duration is much shorter (about 1 minute) but FIS WC SL races normally have about 60 turning gates, and GS races about 50 gates, therefore anaerobic capacity tests for

“technical skiers” (SL and GS competitors) should simulate 60 turning gates. A test for women should be 2 minutes long. With loaded counter movement jumps every 2.5 seconds, ensuring that there is a short pause between jumps, the men would perform 60 jumps and the women 48, close to the number of gates men have in SL and GS (50 – 60) and to the number of gates women often have in GS (about 50).

The anaerobic capacity test with jumps developed by Pernitsch (2001) at the University of

Innsbruck is 2 minutes long for women and 2.5 minutes long for men. The women jump with a loaded barbell equivalent to 20% of their body weight, and the men jump with 40%. These tests are part of the Austrian Ski Federation fitness testing battery for alpine ski racers with tests early and late in the GPP, similar to Bosco’s timing in tests with Italian ski racers (Bosco 1994, 1997).

This literature review reveals that there is little published work investigating anaerobic power and capacity in alpine ski racers. Further research should compare male and female ski racers in various power variables, the power-load relationship and force imbalances. The test variables measured in anaerobic power tests are reliable (Pernitsch, 2001) but it is not known if the LRJT is reliable or if it can detect changes in anaerobic fitness. It is also unknown if the LRJT test results can predict ski racing performance.

1.8 Aim of the PhD project

The literature up to this point investigating anaerobic power and capacity in alpine ski racers leads to a three-part aim for the current PhD project:

Aim of Paper I

To examine the anaerobic power of elite Austrian female and male alpine ski racers using unloaded and loaded squat jumps. Specifically, to compare power variables and bilateral force imbalances between sexes, and to investigate the power-load relationship.

Aim of Paper II

To investigate the anaerobic power and capacity of Austrian alpine ski racers. To determine if the repeated loaded jump test is reliable, and if the general preparation period (summer training) produces changes in racers’ anaerobic fitness.

Aim of Paper III

To investigate the long term (4 year) development of anaerobic fitness in elite female Austrian alpine ski racers and determine if anaerobic fitness measures correlate with ski racing performance.

2 METHODS

The Institutional Review Board of the Department of Sport Science of the University of

Innsbruck and the Sport Science Committee of the Austrian Ski Federation approved the studies. These bodies focus on ethics and quality of research, but the ski federation was also concerned with the practical applications of the tests for athletes and coaches. All testing was performed according to the Declaration of Helsinki. All athletes in Paper I were apprised of the risks of participation before giving informed consent. For Papers II and

III all subjects and athletes were informed of the study aims, requirements and risks before providing written informed consent.

Statistical analyses were performed with SPSS 18.0 for Windows. Level of significance was set at p ≤ 0.05 (Papers I and II) and α = 0.05 (Paper III). A detailed description of the statistical analyses of each study is provided in each of the 3 papers.

2.1 Paper I

Experimental Approach to the Problem

This study used an acute repeated-measures design to compare power variables and force imbalances between male and female ski racers and to determine the effect of load on power variables in unloaded and loaded SJ. During the testing session, each subject completed 3 jumps under each of 5 different load conditions: unloaded and with loads of

25, 50, 75, and 100% BW. The subjects started with unloaded SJ, and the loaded SJ were performed always from lightest to heaviest.

Subjects

Men (n = 20) and women (n = 17) who were members of the junior and European Cup alpine ski teams of the Austrian Ski Federation were tested. The mean age, height,

16# # and FIS ranking are presented in Table 3. FIS ranks all athletes in each alpine ski racing event, and the best single event ranking for each athlete was used.

Table 3 Age, height, body mass, and International FIS ranking (mean ± SD)

Group Age (y) Height (cm) Body mass (kg) FIS Rank

Women 19.2 ± 2.3 166.3 ± 3.0 63.3 ± 4.7 156 ± 97.5

Men 19.9 ± 1.9 180.0 ± 4.8 80.4 ± 5.8 171 ± 100.9

FIS ranks all skiers together, meaning that all skiers are compared with the world’s best, but when compared with other young racers, these subjects are elite. This group has won a total of 19 medals at world junior championships, as well as medals in European Cup races and top 3 positions in European Cup season standings. All skiers tested were experienced with strength training, with at least 4 years squatting experience, and were injury free. This test is part of the fitness testing program of the Austrian alpine ski teams.

The athletes were tested in September before the fall preseason ski training period. All the skiers had performed the same protocol in testing at least once before, except for 2 women, who performed the test for the first time. Each athlete is medically screened by a physician before each season to insure that there are no contraindications to participation in ski racing or any physical activity with the team. The Sport Science Committee of the

Austrian Ski Federation gave previous approval for the testing, and testing was performed according to the Declaration of Helsinki.

Data Collection Equipment

The hardware (MLD-Station Evo2) and software (MLD 2.0) from SpSport were used to collect data. The vertical ground reaction forces were measured with two separate force platforms. Each platform is solid aluminum, and the outer surface is anodized. The

17 platforms measure 400 x 600 x 80 mm and contain 4 one-dimensional force transducers, able to measure a maximum functional force of 7.5 kilonewtons. The sampling rate is 1000 Hz. The transducer signal is directly amplified in the platforms to reduce interference. The measurement precision is 0.1% of the end result.

The software version MLD 2.0 calculates vertical power and other variables. The software uses the ground reaction force record obtained from the force platforms to calculate variables, as described by Linthorne (2001). The subject’s initial velocity must be

0 in order for this system to function.

Test-Retest Reliability

To assess test-retest reliability during the development of this testing system, 11 physical education students were tested twice, with the second testing session completed 3 days after the first session. Intraclass correlation coefficients for variables used in this study were between ICC = 0.944 and ICC = 0.981 (Pernitsch, 2001).

Spotting system1

A system of jump testing has been developed at the University of Innsbruck’s Department of Sport Sciences in which athletes are safely tested with loads as high as 150% BW

(Figures 1 and 2). Loads of 50% BW and higher were spotted with this system. The power rack had been customized by the researchers and had a height of 2.75 m. An aluminum framework above the power rack built with Item (Item Industrietechnik

GmbH, Germany) aluminum profiles supported the spotting system. The bar was attached to 2 climbing ropes via 2 carabineers with climbing slings. The ropes passed perpendicular to the floor over the power rack through 2 double blocks (2.72 m above the ground) and then traveled behind the bar parallel to the floor through 2 fiddle blocks with cam cleats. The ropes then dropped perpendicular to the floor and were

18 then controlled by a spotter. The spotter was behind the subject and power rack holding the two ropes. When the subject descended into the starting position, the spotter allowed the ropes to travel with the bar. When the subject and bar were at the peak of the jump, the spotter snapped the ropes tight, and the cam cleats clamped them. The bar then remained in the air, and the subjects landed without the bar.

Figure 1 Customized power rack with spotting system for loaded squat jumps (SJ). The spotter is behind the subject holding the 2 ropes. The 2 light beam units next to the power rack for SJ starting position are circled.

Figure 2 Set up for the spotting system for loaded squat jumps. The spotter is behind the subject holding the 2 ropes. When the subject descends into the starting position, the spotter allows the ropes to travel with the bar. When the subject and bar are at the peak of the jump, the spotter snaps the ropes tight and they are clamped by the cam cleats.

The bar then remains in the air and the subject lands without the bar.

Procedures

This test is part of a battery of tests used by the Austrian Ski Federation alpine ski teams. Before the battery of tests, the athletes performed a standardized warm-up, including 10 minutes of cycling on a cycle ergometer, and then a specific warm-up for each test. Before the SJ test, the athletes completed 2 to 3 series of light squats with a weight of their choice and then performed a few jumps with no weight.

The bar height for the SJ starting position was individually standardized before the test. After warming up, the athlete descended into a squat with an aluminum bar on the shoulders until the bar was at the height where a 90-degree knee angle was reached. The landmarks of greater trochanter, lateral intercondylar notch, and lateral malleolus were used to determine knee angle. Two light beam units connected to the power rack were then adjusted so that a tone signal sounded when the bar broke the beam at the point the athlete reached the designated squat depth. The athlete executed

20 a SJ by descending slowly to a 90- degree knee angle (signalled by a beep tone from the light beam units), pausing briefly (ca. 0.5-1 second) and then jumped without a counter movement.

A loaded barbell was on the shoulders for the loaded SJ, and the 0% BW jumps were performed with an aluminum bar weighing 600 grams so that jump technique was identical to the trials with a barbell. SJ were performed with 0, 25, 50, 75, and 100% BW as additional loads on the bar.

Figure 3 Testing protocol used for the squat jump tests.

The software calculated the positive displacement of the center of gravity of the subject. The displacement-to-time record was obtained by numerically integrating the velocity-to-time record

(Linthorne, 2001). The velocity at the start position of the squat jump was zero, and the vertical height was set to zero at that point. The software used the maximal velocity as the take off velocity, and the displacement difference between the initial velocity (zero) and the maximal velocity was the positive displacement. The positive displacement obtained for the 0% BW trials was used to standardize the displacement for the subsequent trials. Jumps with a positive displacement of more

21 than ± 3 cm of that measured with 0% BW were not included in the data analysis. Jumps with a countermovement were also not used. Athletes achieved at least one valid SJ at each load.

Each subject performed 3 jumps at each load or more if a valid SJ was not achieved with 3 jumps.

There was a 1-minute pause between trials. A 3-minute rest interval was given when the load was increased (Figure 3).

Variables

The variables examined were relative average power (P), relative average power in the first 100 ms of the jump (P01), relative average power in the first 200 ms of the jump (P02), jump height, percentage of best jump height (%Jump), and maximal force difference between dominant and nondominant leg expressed as a percentage of the nondominant leg (Fmaxdiff). The power variables and jump height were calculated by the software. The power variables used in this study were not peak power measurements, but power was averaged from the initiation of the push-off phase to the point where maximum velocity was reached or from the initiation of the push-off phase to the end point of the defined time segment (either 100 or 200 ms). Post-test calculations were made to determine %Jump and Fmaxdiff at each load. Percentage of the best jump height = (jump height - best jump height) / best jump height × 100. Fmaxdiff = absolute difference (maximum force right leg

2 maximum force left leg)/maximum force nondominant leg × 100).

Statistical Analyses

For data analysis, the jump with the highest relative average power for each load was used. The mean and SD were determined for each variable at each load for women and men. A 2-way repeated-measures analysis of variance (ANOVA) design was used to test the effect of load on each variable, to determine if there was an interaction between load and sex, and if sex had an effect on each of the 6 variables. Independent t tests were used to examine differences between the

22 men and women (at all loads) for the variables that were affected by sex. Level of significance was set at p ≤ 0.05.

2.2 Paper II

Experimental Approach to the Problem

This paper consists of 2 studies. The first investigated the reliability of the LRJT: physically active young men performed 2 LRJTs with 7 days between testing sessions. A repeated-measures design was used to compare the 2 testing session results. The second study tested elite male ski racers with the LRJT in June and October to determine whether GPP training improved anaerobic fitness. A repeated-measures design analysis of variance (ANOVA) and paired t-tests were used to compare anaerobic power and capacity variables from June and October. In all testing sessions, each subject completed 60 LCMJs with a loaded barbell equivalent to 40% BW.

Study 1: Loaded Repeated Jump Test Test-Retest Reliability

Subjects. Thirteen young men were tested. The mean age, height, and weight of the subjects are presented in Table 4. All were physically active and trained regularly with squats and high intensity anaerobic exercise. Eight of the subjects were current or former sport science students, 5 of the subjects were members of a commercial fitness training group.

Table 4 Physical characteristics of subjects in LRJT reliability study (mean ± SE), n = 13.

Age (y) Height (cm) Body mass (kg)

28.9 ± 1.3 180.0 ± 1.1 78.8 ± 1.6

Data Collection Equipment. The MLD system described for Paper I was used, with an updated version of the software, MLD 3.2. The software used the ground reaction force record obtained from the force platforms to calculate parameters as described by Linthorne (2001). The subject’s initial velocity must be zero in order for this system to function.

Procedures. The warm-up started with 10 minutes of riding a cycle ergometer or jogging at a self- selected intensity. This was followed by 10–15 minutes of stretching and mobility exercises. The subject then completed 2 sets of squats (8–12 repetitions): one with only the bar (20 kg) and the other with 40 kg total load. Subjects then performed single LCMJs with an aluminum bar (600 g) and were instructed to jump as explosively and as high as possible, with 100% effort. The subjects were instructed that the bottom of the countermovement should elicit a 90° knee angle. Subjects were given feedback regarding their technique, power, and the countermovement depth of the

LCMJ. When the subject’s technique was satisfactory, a 20-kg bar was then used and 3–5 LCMJs were performed, dependent on the subject’s ability to jump with a consistent countermovement depth.

The subjects then performed 3–8 single LCMJs with a loaded barbell (equivalent to 40% BW) to create a reference power output for the LRJT LCMJs. The average power (P) relative to BW from the single 40% LCMJ that produced the highest P with an appropriate depth was used as the reference P (PREF) for the LRJT. P was not a peak power measurement, but the relative power averaged from the bottom of the countermovement to the point where maximum velocity was reached. After establishing the PREF for the LCMJ, the subject was then given a rest, the LRJT was again described and explained, and when the subject was ready, the LRJT was performed.

To allow comparisons between LCMJs, a consistent countermovement depth was necessary. The

MLD software calculated the positive displacement of center of mass for each LCMJ. The following assumptions were used: the lowest point of the center of mass was at the bottom of the countermovement, when the velocity was momentarily zero; and the highest point of the center of mass was at takeoff, when the velocity was maximal. Using the ground reaction force data, the velocity-time record was numerically integrated to obtain the displacement-time record (Linthorne,

2001). The calculated displacement difference between zero velocity and maximal velocity was

24 the positive displacement of the center of mass. The positive displacement obtained from each subject’s reference LCMJ was used to standardize the countermovement depth for each subject’s

LRJT. Every LCMJ was controlled for countermovement depth, and jumps with a positive displacement of less than 90% of the reference jump were not used in the data. A shallow countermovement will result in a high-power output because the force will be high and the time is reduced.

The LRJT consisted of each subject performing 60 LCMJ on 2 force platforms (left and right) with a loaded barbell equivalent to 40% of the subject’s BW. The subjects jumped every 2.5 seconds

(the test duration was 2.5 minutes), pausing briefly between jumps to avoid reaction jumps. A computer monitor in front of the subject assisted in LCMJ timing with a countdown progress bar for each jump.

The second testing session was conducted 7 days later, and each subject was tested at the same time of day. Subjects were instructed to attempt to duplicate their activity and diet from the 2 days before the first LRJT test before the second test so that test conditions were similar. Warm-up from the first testing session was recorded and duplicated for the second. Test procedures for establishing

PREF and the LRJT were identical.

Statistical Analyses. The PREF and P for each LCMJ in the RLJT were calculated for each subject.

Each jump was numbered, and the p values for all valid jumps were recorded. Data sets were created for each subject with missing values in the cases of invalid jumps. A regression line was calculated for 60 LCMJs with missing values with Excel (Microsoft) for each subject’s LRJT. The missing values for each subject were then calculated with the regression equation and replaced.

Each subject then had p values for 60 LCMJs. The mean P for the complete test was calculated from the 60 values (Pmean). The 60 values were divided into intervals of 30 seconds (12 LCMJ), and a mean was calculated for each 30-second interval, eliciting P30, P60, P90, P120, and P150. The 25 reproducibility of P variables (PREF, Pmean, P30, P60, P90, P120, and P150) was analyzed using SPSS

(18.0 for Windows) to compute the ICC using a 2-factor mixed-effects model and type consistency

(19). Statistical significance was set at p ≤ 0.05.

Study 2: Evaluation of General Preparation Period Training on Anaerobic Power and Capacity

Subjects.

Nine male alpine ski racers were tested to evaluate anaerobic power and capacity before and after the GPP training period. All 9 athletes were members of the men’s junior alpine ski team of the

Austrian Ski Federation. The mean age, height, and weight for the athletes are presented in Table

5. All skiers tested were experienced with weight training, particularly in squatting, and were injury free. The LRJT is part of the fitness-testing program of the Austrian alpine ski teams.

Table 5 Physical characteristics of the ski racers (mean ± SE), n = 9.

Test session Age (y) Height (cm) Height (cm)

June 18.0 ± 0.3 178.7 ± 1.5 82.0 ± 2.2

October 18.3 ± 0.3 178.7 ± 1.5 82.7 ± 2.1

Data Collection Equipment. The MLD system used to test the alpine ski racers was identical to that used in the reliability study.

Procedures. The conditions for testing for the Austrian Ski Federation are controlled and remain very similar for each testing session. Coaches instruct athletes regarding activity and diet before the tests so that testing conditions are standardized. Each athlete undergoes sport medicine tests

̇ (cycle ergometer VO2max, body composition, and blood work) in the morning and then reports to the sport science laboratory in the afternoon. Before the battery of tests the athletes performed a

26 standardized warm-up, including 10 minutes of cycling on a cycle ergometer, and then a specific warm-up for each test. The LRJT is the last test in the battery.

Before the LRJT, the athletes completed 1–2 series of squats (8–12 repetitions) with a weight of their choice. The athletes then performed single LCMJs with an aluminum bar and loaded barbells exactly as in the reliability study. They were given feedback regarding their technique, power, and the countermovement depth of the LCMJ. When the athlete’s technique was satisfactory, 3–6 individual LCMJs with a loaded barbell (equivalent to 40% bodyweight) were then performed

(single jumps) to determine PREF to compare with the LRJT LCMJs.

The athlete then took rest, the LRJT was again described and explained, and when the athlete was ready, the LRJT was performed. The LRJT protocol was exactly the same as that used with in the test-retest reliability study.

General Preparation Period Training. This was not a training study, but an evaluation of the effectiveness of the off-season training on anaerobic fitness. Coaches received the results of tests, and were given feedback and guidelines for training prescription. The planning of training was the responsibility of the conditioning coach. The GPP (May 1–November 30) consisted of 214 days.

Athletes and coaches met on a regular basis at ski camps or condition camps (at least 74 days during the GPP), and the conditioning coach often visited the athletes where they lived and trained. Two of the 9 athletes attended a ski boarding school where national team coaches were also school coaches, and 3 athletes in the group attended other ski boarding schools where training was monitored. An outline of the training plan and periodization is given in figure 4. Only endurance and strength training are outlined in the figure, but the training program also had a strong focus on agility, speed, coordination, and flexibility. The most important element of training was skiing. Ski camps normally had skiing in the mornings, with regenerative training in the afternoons, consisting

27 of light training (core, speed, agility, and flexibility) and introduction to new exercises and/or programs for home training. Table 6 illustrates the breakdown of training days in the GPP.

Figure 4 Periodization plan for endurance and strength in the general preparation period.

For the evaluation of the GPP training of the junior ski racers, tests were conducted in June and

October of 2009.

Table 6 Breakdown of training and recovery days in the GPP

Training Component May June July August September October November Total

Skiing 5 4 8 13 8 8 12 58

Intense Conditioning 17 16 14 9 10 10 4 80

Regeneration 6 4 5 6 8 10 10 49

Full rest 3 6 4 3 4 3 4 27

Total 31 30 31 31 30 31 30 214

Statistical Analyses. The data collected from the ski racers were treated with the same methods as in the reliability study. The PREF was calculated for each athlete. LRJT data sets were created for P so each athlete had p values for 60 LCMJs. The Pmean for the complete LRJT was calculated and a mean was calculated for each 30-second interval, eliciting P30, P60, P90, P120 and P150. The first valid

LCMJ of the LRJT was compared: with PREF (percent of P150) as a control that the test was performed with maximal effort. The P of each 30-second interval was also expressed as a percentage of PREF: P30rel, P60rel, P90rel, P120rel and P150rel.

A 1-way repeated measures ANOVA with (SPSS 18.0 for Windows) was used to determine the effect of testing session (June and October) on P30, P60, P90, P120, and P150 if fatigue affected these variables (did they decrease with test duration), and if there was an interaction between test session and fatigue. Paired t-tests compared June and October results in the following variables: PREF, the percentage of the first LCMJ P relative to PREF, Pmean, P30, P60, P90, P120, and P150. Paired t-tests were also utilized to compare June and October values for P30rel, P60rel, P90rel, P120rel, and P150rel to determine whether the relative effect of fatigue changed. Level of significance was set at p ≤ 0.05.

Statistical power calculated post hoc for the paired t-test with G*Power 3.1, according to Franz et al. (2009).

2.3 Paper III

Participants. The same ten female Austrian national alpine ski team athletes were tested prior

(August – October) to each of the 2010, 2011, 2012 and 2013 FIS alpine ski racing seasons. Seven had achieved at least a top 10 placing in a FIS WC race prior to or during the seasons examined, and collectively this group had won 60 FIS WC, 5 FIS world championship and 3 Olympic medals.

All skiers tested were experienced with weight training, particularly in squatting. The mean age, height, weight and Body Mass Index for the athletes are presented in Table 7. 29

Table 7 Physical characteristics of the ski racers (mean ± SD), n = 10.

Season Age (y) Height (cm) Body mass (kg) Body Mass Index (kg.m2)

2010 20.0 ± 2.7 167.3 ± 3.5 66.3 ± 4.0 23.7 ± 2.2

2011 21.1 ± 2.7 167.3 ± 3.5 67.0 ± 4.6 24.1 ± 2.2

2012 22.0 ± 2.6 167.3 ± 3.5 66.5 ± 4.6 23.9 ± 1.8

2013 23.1 ± 2.7 167.3 ± 3.5 65.4 ± 5.3 23.6 ± 2.3

Data Collection Equipment. The same MLD system was used to collect data.

Calculation of Power Output and Counter Movement Depth. To allow comparisons between

LCMJs, a consistent countermovement depth was necessary. The MLD software calculated the positive displacement of center of mass for each LCMJ. This is described in the methods of Paper

II.

Procedures. The testing conditions for the Austrian Ski Federation were controlled and remained very similar for each testing session. Test procedures were the same as in Paper II, with the exceptions that the female subjects performed single LCMJs with a loaded barbell equivalent to

20% BW as opposed to 40% used by the males, and the females performed 48 jumps in 2 minutes.

Subjects were given feedback regarding their technique, power, and the countermovement depth of the LCMJ. When the subject’s technique was satisfactory, 3-5 individual LCMJs were performed (single jumps with rests between) to determine the reference LCMJ to compare with the

LRJT jumps. The single 20% LCMJ that produced the highest average power relative to body mass with an appropriate depth was used as the reference power (PMAX) for the LRJT. After establishing the PMAX, the athlete then took a rest of at least 3 minutes.

The LRJT was again described and explained, and when the subject was ready, the LRJT was performed. The test was 2 minutes long and the load was 20% BW. The subject jumped every 2.5

30 s, (48 LCMJ) pausing briefly between jumps to avoid reactive jumps. A computer monitor in front of the athlete assisted in LCMJ timing with a visual countdown for each jump.

Ski Racing Performance Analysis. Ski racing performance was based on FIS points. FIS points up to the 2019-2020 season were organized so that the best in the world in each discipline had 0 points and the 31st in the world had 6 points. Occasionally everyone’s FIS points were adjusted to ensure that this was the case. Thus, a racer’s FIS point were a measure of how he / she compared with the rest of the world. A racer’s FIS points were the average of the racer’s best 2 races in that discipline in the last 13 months. Lower FIS points indicated better performance. For each season, the discipline with the lowest FIS points was used for each athlete.

Data Treatment. The relative calculated the power of all jumps for each athlete. Each jump was numbered, and the power values for all valid jumps were recorded. Data sets were created for each athlete with missing values in the cases of invalid jumps. In the event of missing jumps, a regression line was fit to the jump data so that missing data points could be interpolated. Each athlete then had power values for 48 CMJs. A mean power for the complete test (P0-120) was also calculated from the 48 values.

The first valid LCMJ (LCMJrel) of the LRJT was compared to PMAX (percentage of PMAX) as a control that the test was performed with maximal effort.

PMAX was defined as the measurement of anaerobic power, P0-120 as the measurement of anaerobic capacity, and fatigue index (FI) as the indicator of anaerobic fatigue.

FI as a control parameter was determined by taking the percentage difference between PMAX and the average of the relative power of the last 12 jumps (30 seconds duration) of the LRJT (P120.).

FI = 100

The seasons 2010, 2011, 2012 and 2013 were designated as season 1, season 2, season 3 and season

4. 31

The changes between seasons in the measures of PMAX, P0-120 and FIS points were also assessed, eliciting six season differences (1 and 2, 1 and 3, 1 and 4, 2 and 3, 2 and 4, and 3 and 4).

Statistical Analysis. Differences between seasons were calculated for all outcome measures. The linear relationship between the outcome measures and the seasonal differences in the outcome measures were assessed using Pearson correlation coefficients for each season and each season-to- season comparison. Analysis of variance (ANOVA) with repeated measures (SPSS 18.0 for

Windows) was performed to detect differences. Pairwise comparisons were made using student t- tests. Scatter plots were made for each season to compare the following: PMAX with FIS points, P0-

120 with FIS points, changes in PMAX with changes in FIS points and changes in P0-120 with changes in FIS points. Statistical significance was set at α = 0.05.

3 RESULTS

3.1 The anaerobic power of elite Austrian female and male alpine ski racers

3.1.1 Power variables and bilateral force differences during unloaded and loaded squat jumps in high performance alpine ski racers. (Paper I)

The ANOVA showed that load affected all variables except Fmaxdiff. There were no significant differences between men and women for the variable P01 (Figures 5–10). Separate t-tests indicated that men had significantly higher values at all loads for P and jump height, and in P02, the men were significantly higher at all loads except 75% BW. The men had higher values for % Jump, showing significantly higher percentages at 25, 75, and 100% BW. The males and females had no significant differences in Fmaxdiff.

The trend for each variable, excluding Fmaxdiff, was to decrease as load increased. This trend was similar for men and women, with the exception that the men reached maximum P at 25% BW and the women at 0% BW.

Maximum jump heights were reached at 0% BW and were 35.2 ± 3.4 cm for the men and 27.5 ±

3.1 cm for the women. Respective mean % Jump values at 50 and 100% BW were 70.0 ± 6.4 and

47.7 ± 5.4% for men and 67.5 ± 8.5 and 43.1 ± 6.5% for women. Figure 10 is an example of an individual test for a male athlete who performed SJ up to 125% BW.

Figure 5 Mean and SD for the relative average power achieved during unloaded and loaded squat jumps. *Significant (p ≤ 0.05) difference between men and women.

Figure 6 Mean and SD for the relative average power achieved in the first 100 ms during unloaded and loaded squat jumps. 34

Figure 7 Mean and SD for the relative average power achieved in the first 200 ms during unloaded and loaded squat jumps. *Significant (p ≤ 0.05) difference between men and women.

Figure 8 Mean and SD for the jump height achieved during unloaded and loaded squat jumps. *Significant (p ≤ 0.05) difference between men and women. 35

Figure 9 Mean and SD for the percentage of best jump height achieved during unloaded and loaded squat jumps. *Significant (p ≤ 0.05) difference between men and women.

Figure 10 Mean and SD for the maximal force difference between dominant and nondominant leg expressed as a percentage of the nondominant leg during unloaded and loaded squat jumps. 36

Figure 11 Power-load curves from an individual athlete in one testing session. The data used is from the squat jump that achieved the highest relative average power at each load

3.2 The anaerobic power and capacity of elite Austrian male alpine ski racers

3.2.1 The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity in alpine ski racers with loaded countermovement jumps (Paper II)

Study 1: Loaded Repeated Jump Test Test-Retest Reliability

In the test-retest reliability study, a high degree of reliability was found between the P measurements. PREF had the highest ICC (0.987) with a 95% confidence interval from 0.959 to

0.996. The lowest ICC of the variables was 0.881 for the 150 seconds P with a 95% confidence interval from 0.610 to 0.964 (Table 8).

Table 8 Power (W.kg-1) for 2 LRJTs and interclass correlation coefficients

LRJT 1 LRJT 2 Interclass Correlations Variable n SEM Mean±SE Mean±SE (95% Lower Bound, Upper Bound)

PREF 13 35.8±1.2 35.4±1.2 0.987 (0.959, 0.996) 0.471

P30 13 33.0±1.1 33.1±1.1 0.931 (0.774, 0.979) 1.027

P60 13 31.7±1.0 31.4±3.8 0.958 (0.863, 0.987) 0.747

P90 13 30.0±1.1 30.1±1.0 0.960 (0.869, 0.988) 0.730

P120 13 28.8±1.1 29.0±0.9 0.900 (0.673, 0.970) 1.113

P150 13 27.3±0.8 27.4±0.9 0.881 (0.610, 0.964) 0.949

Mean P 13 30.2±1.0 30.2±1.0 0.955 (0.852, 0.986) 1.186

Study 2: Evaluation of General Preparation Period Training on Anaerobic Power and Capacity

The number of valid jumps was 51.3 ± 1.7 (mean 6 SE) in June and 51.6 ± 1.5 in October. Each athlete completed the test duration of 2.5 minutes. The ANOVA showed that the P of the 30-second intervals was significantly affected by the factor of test session (p = 0.001), or the P for the 30- seconds intervals was higher in October. The P intervals were significantly affected by the factor of fatigue (p = 0.04), as P of the 30-second intervals decreased as the test progressed. There was no significant interaction between test session and fatigue (p = 0.15), therefore the relative effect of fatigue did not change from June to October. The post hoc observed power for the factor of test session was 0.97 and 0.79 for fatigue, and 0.11 for the interaction of test session and fatigue.

Table 9 and Figure 12 show that PREF, Pmean, P30, P60, P120, and P150 were significantly higher in

October than in June. P90 showed no significant change (p = 0.07). Figures 12–15 illustrate the group and individual P variable changes after the GPP phase. Figure 12 illustrates that the drop-off

38 in P over time was similar in the June and October testing sessions, but P was higher in October.

The percentage of the first LCMJ P relative to PREF did not significantly change from June to

October, nor did P relative to PREF for any of the 5 intervals (P30rel, P60rel, P90rel, P120rel, and P150rel), therefore the relative intensity and the effect of fatigue for the 2 tests was similar (Table 10). Due to the small sample size, statistical power for the paired t-tests was not consistently high, as shown in Table 9.

Table 9 Power (W.kg-1) for June and October (mean ± SE), *October > June, p < 0.05

Variable PREF Pmean P30 P60 P90 P120 P150

June 37.0±1.2 33.6±1.2 35.5±1.3 35.0±1.4 34.2±1.2 32.4±1.2 30.6±1.2

October 39.0±1.4* 35.8±1.3* 37.7±1.4* 37.1±1.4* 35.8±1.2 34.6±1.4* 33.6±1.3*

Figure 12 Means and standard error for the relative average power achieved in the 30 s intervals. * Significant (p < 0.05) difference between June and October.

Table 10 Power as percent PREF for first LCMJ and each 30 s interval of LRJT (mean ± SE)

Variable First LCMJ P30rel P60rel P90rel P120rel P150rel

June 96 ± 1.7 96 ± 1.2 94±1.2 92 ± 1.5 88 ± 1.7 83 ± 2.4

October 97 ± 1.2 97 ± 1. 95 ± 2.3 92 ± 3.0 89 ± 2.4 86 ± 2.8

Figure 13 Individual relative average powers achieved in the 30 s intervals.

Figure 14 Individual relative average powers achieved for the reference countermovement jump in June and October. The thicker line represents the group means.

Figure 15 Individual relative average powers achieved for the total test mean power in June and October. The thicker line represents the group means. 41

Table 11 Statistical power of paired t tests comparing June and October power variables ______

Variable PREF Pmean P30 P60 P90 P120 P150

G Power 0.63 0.96 0.95 0.46 0.37 0.98 0.94 ______

3.3 The longitudinal anaerobic power and capacity of elite Austrian female alpine ski racers

3.3.1 The 2 minute loaded repeated jump test: longitudinal anaerobic testing in elite alpine ski racers. (Paper III)

Each athlete completed the test duration of 2 minutes and at least 48 LCMJ in every testing session.

LCMJrel remained stable from year to year (between 96% and 98% PMAX), ensuring consistent test intensity. FI remained stable over the four years. The FI for seasons 1, 2, 3 and 4 were 14.8 ± 5.8,

17.3 ± 7.6, 15.9 ± 7.8 and 16.3 ± 5.2 respectively.

PMAX improved significantly from season 1 to season 4 [F (3, 27) = 7.923, p < 0.05], with season

1 being significantly less than all other seasons. Pairwise comparisons between the other 3 seasons

. -1 . -1 showed no differences [season 1: PMAX = 30.5 ± 2.3 W kg ; season 2 PMAX = 32.3 ± 2.3 W kg ;

. -1 . -1 season 3 PMAX = 33.5 ± 3.4 W kg ; season 4 PMAX = 33.6 ± 3.0 W kg ] (see Figures 12 and 13).

The pairwise comparisons revealed that the PMAX change between season 1 and all other seasons was significant.

. - P0-120 [F (3, 27) = 4.019, p < 0.05] increased by 9.2% up to season 3 (27.1 ± 2.8 to 29.7 ± 3.4 W kg

1 . -1 ) and was unchanged from season 3 to 4. P0-120 in season 4 (29.6 ± 2.4 W kg ) was significantly higher than seasons 1 and 2.

FIS points decreased significantly (racing performance improved) [F (3, 27) = 11.020, p < 0.05], from 18.1 ± 8.2 in season 1 to 8.4 ± 4.8 in season 4. Pairwise comparisons revealed that FIS points

42 in seasons 2, 3 and 4 were significantly lower than in season 1 (see Table 12).

Table 12 FIS points for the ski racers for the best individual discipline (mean ± SD), n = 10. ______Season FIS points FIS points range 2010* 15.2 ± 5.6 5.1 – 20.4 2011 10.9 ± 6.3 4.1 – 23.1 2012 8.8 ± 4.2 1.2 – 15.5 2013 8.4 ± 4.8 2.5 – 16.1 ______* 2010 > 2011, 2012, 2013

Figure 16 Individual reference LCMJ (PMAX) over four seasons for all subjects. The thick broken line shows group mean PMAX over 4 seasons.

Figure 17A Group PMAX means with 95% confidence intervals for seasons 1 - 4. * p < 0.05 Figure 17B Group P0-120 means with 95% confidence intervals for seasons 1 - 4. * p < 0.05

Figure 18 Group mean longitudinal progression of P0-120 and FIS points over 4 seasons. P0-120 development is represented with the solid line; FIS points changes with the dotted line.

Figure 19 Individual longitudinal progression of P0-120 and FIS points over 4 seasons for all subjects. P0-120 development is represented with the solid line; FIS points changes with the dotted line.

Figure 20 Scatter plots of PMAX and FIS points for each of 4 seasons for each subject. * p < 0.05

Figure 21 Scatter plots of P0-120 and FIS points for each of 4 seasons for each subject. * p < 0.05

Figure 22 Scatter plots of the comparisons of season-to-season changes in PMAX and FIS points for each of 4 seasons for each subject. * p < 0.05 46

Figure 23 Scatter plots of the comparisons of season-to-season changes in P0-120 and FIS points for each of 4 seasons for each subject.

3.4 Summary of the results of the 3 papers.

The first paper showed that men produced higher values at all loads for all power variables (except

P01) and jump height (p < 0.05). No significant gender differences were found in power reached at

100ms. Maximum power was reached at light loads (men at 25% BW and women at 0% BW), and power decreased uniformly thereafter.

The second paper proved that the 2.5 minute LRJT is reliable, and that the GPP training improved all power variables except P90. The effect of fatigue was unchanged, but the increase in almost power variables indicated improved anaerobic fitness.

The third paper showed that anaerobic power and capacity improved over the 4 seasons, but improvement was not statistically significant from year to year. The fatigue effect did not change.

Racing performance (FIS points) improved significantly, but did not correlate with the LRJT results.

4 DISCUSSION

Gender differences in anaerobic power in elite alpine ski racers

The male ski racers had higher results in all anaerobic power variables with the exception of P01 and P02 at 75% BW. It has been demonstrated that trained men are more powerful than trained women (Ikeda et al., 2007, Yanagiya et al., 2003), so it was expected in this study that the men would have higher values in the power variables.

If it can be assumed that men produce more power than women do, it would be expected that the male skiers would have higher power outputs also in the first 100 ms of the SJ. Minimal gender differences in P01 indicate that the men did not generate high power in the first 100 ms when compared with the other power variables. One hundred milliseconds in skiing is a relatively short period of time in the context of a complete ski turn. A technical analysis of GS turns performed by a world class ski racer showed that typical GS turn to be approximately 1.4 seconds in duration

(Raschner et al., 2001). Thus, 100 ms may simply not be enough time to generate high levels of force for both male and female ski racers.

These SJ tests are very useful in detecting leg dominance in athletes because the 2 force plates allow comparisons of the forces produced by the right and left legs. ACL injuries are more common in female ski racers (Tecklenburg, et al., 2006), but there were no significant differences between men and women in Fmaxdiff over the tested loads.

Effect of increasing load on the power-load relationship

The athletes reached maximum P at 25% BW (men) or 0% BW (women), and then P decreased with increasing load. Ski racers must contend with high centrifugal forces when carving (Raschner et al., 2001), and external forces on a SL racer can be as high as 5 times bodyweight (Supej and

Holmberg, 2019). Therefore, training with 0 or 25% BW may be too light when specifically training power for skiing. It is proposed that the load at which the power-load curve deflection

49 occurs should be the training load for improving anaerobic power. P is the variable most used in assessing or expressing a skier’s power, but P01 and P02 aid in identifying the power deflection point. In some cases, a deflection in the power-load curve is not easily defined, but is easily detected when P01 and P02 curves are examined. The variables P01 and P02 are more sensitive as an athlete attempts to overcome the heavier load over a short fixed period. The athlete’s curves in Figure 10 show that maximum P was reached at 0% BW and that there was a deflection point at 50% BW in

P. This particular ski racer should train at 50% BW when training to improve average power, which is skiing specific.

Reliability of the LRJT

The LRJT has been used in Austria to evaluate anaerobic fitness in elite ski racers for over 10 years, and the reproducibility of the test has now been demonstrated. The high ICCs should encourage coaches and scientists to use the LRJT to detect training changes in anaerobic fitness. The test is appropriate for technical skiers because the 60 jumps simulate the number of gates in a race. It is also suitable for speed specialists because the short breaks between LCMJs eliminates the conservation of energy in repeated reactive jumps, which seldom occurs in SG or DH and the duration of 2.5 minutes mimics the longest WC DH, the Lauberhorn in Wengen.

Effect of GPP training on anaerobic power and capacity

The GPP training program improved the ski racers’ anaerobic fitness. PREF was significantly higher in October; therefore, the athletes were able to produce more power at the start of the test. The P values remained elevated throughout the LRJT (Pmean increased) with no change in the relative effect of fatigue, indicating improved aerobic capacity.

Bosco and his group used jump tests to evaluate anaerobic fitness and prescribe training with 12 members of the Italian alpine ski team (Bosco, 1997, Bosco et al., 1994). They also found that the anaerobic power and capacity increased from June to October; but the Bosco tests were very

50 different from the tests used here. The Austrians completed 60 LCMJ in 2.5 minutes with 40% BW additional load, and the Italians had the same number of jumps in 1 minute with 50% BW additional load. Notwithstanding the different test protocols used here and by Bosco (1994), the evidence shows that a well-planned preseason training program can improve anaerobic fitness.

The longitudinal development of anaerobic power and capacity in elite ski racers

In the Austrian women studied here over 4 years, the increase in anaerobic power from season 1 to

2 was evident during testing. PMAX increased from season 1 to 4 by 10% (statistically significant) and P0-120 increased by 9% from season 1 to 3. Nine of the athletes had their best anaerobic capacity results in season 3 or 4 but only season 4 was statistically greater than seasons 1 and 2. In a study of female Olympic medal winners, women peaked in their mid-twenties (Elmenshawy et al., 2015).

The Austrian athletes investigated here had an average age of 20 in season 1, so enhanced LRJT results with each season were expected, but positive anaerobic power and capacity development was evident mainly when comparing season 1 to the other three seasons.

Bosco and his group compared jump test results in 1994 with those in 1989 for 7 male and 8 female

Italian ski racers (Bosco, 1997). On the men’s side, they found 7–8% improvements in 15-second mean jump heights for the first 2 intervals (15 seconds and 30 seconds) but no changes for 45 seconds or 60 seconds. In contrast, they showed that Alberto Tomba (multiple Olympic and world champion) improved over 25% in the first 3 15-second periods and by about 13% for the last period.

On the women’s team, jump test results were not significantly different over five years (1989 to

1994) for seven women. The only woman with increased anaerobic capacity was Deborah

Compagnoni (also multiple Olympic and world champion). Over the 45-second test, she improved about 20% in the first 15s, 12% in the second, and 10% for the third 15s period.

The correlation of anaerobic power and capacity to alpine ski racing performance

The relationship between LRJT results and ski racing performance indicated a weak relationship.

FIS points from season 1 to 4 decreased significantly (54% for the group mean, indicating more racing success), anaerobic power (10%) and anaerobic capacity (9%) both increased over the 4 seasons. However, LRJT results statistically correlated with performance only in season 4. The anaerobic power increase from season 1 to 2 did not correlate with the decrease in FIS points.

Anaerobic capacity was higher in season 4 when compared to seasons 1 and 2, but these P0-120 changes had no relationship to FIS points differences. P0-120 increases between season 1 and season

3 negatively correlated with the change in skiing performance for the same period. Results of a 30 s variation of Bosco’s test correlated with racing performance in Spanish male adolescent ski racers

(Emeterio and González-Badillo, 2010), but the predictive power of anaerobic tests for ski racing success was not corroborated by the current study. The hypothesis that anaerobic power and capacity as measured with the LRJT would correlate with ski racing performance was rejected.

This supports the premise of Turnbull et al. (2009) that no singular factor can predict ski racing success.

The younger athletes in the study may have influenced the positive correlation between both anaerobic measures and performance in season 4. After four seasons in the national program, the younger athletes had progressed in their ski racing and had started to stabilize their performance.

Perhaps racers need a threshold level of technical competence and racing experience before they are able to capitalize on enhanced anaerobic power and capacity.

A single case example in this study (with no statistical support) revealed that one participant achieved the best racing performance concurrently with the highest recorded anaerobic capacity

(P0-120) in season 3. This athlete went on to win a gold and a silver medal at the 2014 Olympic

Games. This finding agrees with other case examples in the scientific literature where two top ski racers (the aforementioned Tomba and Compagnoni) possessed the highest anaerobic capacity levels (Bosco, 1997). Bosco stated, “speed-endurance capacity is likely to be the most important

52 capacity for alpine skiers”. Although the most successful racers in Bosco’s work had the highest anaerobic power and capacity, there were no reported statistical tests with all athletes to test for correlations between racing performance and anaerobic test results. Singular examples do not represent evidence of a causal relationship between anaerobic capacity assessed with vertical jumps and alpine ski racing performance. Results of a 30 s variation of Bosco’s test correlated with racing performance in Spanish male adolescent ski racers (Emeterio and González-Badillo, 2010), but the predictive power of anaerobic tests for ski racing success was not corroborated by the current study.

This supports the premise of Turnbull et al. (2009) that no singular factor can predict ski racing success.

Jumps as testing mode for ski racing

The mode of testing for ski racers may a problem. Skiing is not an “explosive” sport and is dominated by slow eccentric contractions (Berg and Eiken, 1999, Berg et al., 1995, Hydren et al.,

2013). In order to get the best power output during jumps, an athlete must be explosive and focus on extension of the ankles, knees and hips. This “triple extension” does not exist in ski racing, as the ankles are always in a flexed position in ski boots. Explosive leg extension at the end of a turn can lead to loss of contact with the snow, which is disadvantageous in ski racing (Supej et al.,

2011). Jumping utilizes the same muscle groups active in ski racing, but does not simulate what happens during a ski turn. Kröll et al (2015) measured maximal knee angles in SL and GS of 132

± 6° and 138 ± 8 respectively during an on-snow kinematic study, implying that the knees are always flexed to some extent.

The CMJs performed in the LRJT are vertical, and a ski racer utilizes vertical actions to weight and unweight his or her skis. This allows the racer “… to regulate and adjust the magnitude of the snow reaction force to control the degree and timing of the snow’s influence on the skier’s trajectory”

(Reid, 2011). By controlling the interaction between snow and ski, the ski racer can turn and

53 navigate a racecourse. These vertical actions almost never involve full extension of the hips and knees, so jumping does not replicate carving.

Physical capabilities and ski racing

Turnbull (2009) stated that technical ability has the greatest influence on performance, but all physiological systems must have high capabilities. Gilgien et al. (2018) maintained that ski racers with different physical characteristics can compete at high levels.

A ski racer’s leg strength impacts the ability to control the ski racer’s vertical actions, which is a very important technical aspect of skiing. In conversations with the then conditioning coach of the

Norwegian alpine ski team in 1998, it was learned that Kjetil Andre Aamodt could perform a back squat with 220 kg, at a bodyweight of 85 kg. This is almost 260% bodyweight. Refnes (1999) claimed that all male WC and European Cup athletes in the Norwegian program could squat at least 2.5 times their body weight. The external forces that a ski racer absorbs on snow have been estimated to be up to 3.2 times bodyweight in GS (Gilgien et al., 2018) and as high as 5 times bodyweight in SL (Supej and Holmberg, 2019), so strength is a factor in ski racing. But an athlete must also have the “feeling” and timing to weight and unweight the skis just enough to produce the optimal trajectory of the skis when carving. So ski racing cannot be reduced to physical capabilities.

. -1. -1 ̇ Aerobic fitness is also important. Ingemar Stenmark’s reported 71 ml kg min VO2max may or may not have played a role in his record of 86 World Cup victories. Hermann Maier was reputed to have trained large volumes of low intensity cycling and that this was one of the keys to his success.

Anaerobic fitness plays a role in ski racing as well. Tomba, Compagnoni and the Austrian woman had the highest anaerobic fitness and the most ski racing success in their training groups. These singular examples are not scientific or statistically based, and do not imply cause and effect.

Norway’s Aamodt, the most successful Olympic ski racer in history (4 golds, 2 silver and 2 bronze 54 medals) was perhaps the fittest racer that Norway has ever produced. Aamodt’s fitness cannot be referenced; the author has had personal communications with the Norwegian conditioning coach.

But they do lead one to speculate on the importance of fitness in alpine ski racing. Perhaps these athletes were simply so motivated and driven to succeed and worked very hard on their fitness, as well as the other factors that influence racing success.

Gilgien et al (2018) wrote that the physical training of alpine skiers is complex, with multiple capacities such as strength and endurance trained in the same training phase. They also called for a better understanding of the effects of training on the various components of fitness, maintaining that more research is definitely needed to examine the interplay of physical conditioning with on- snow training.

Future directions for testing ski racers

Koller and Schobersberger (2019), who are involved in testing the Austrian ski team, suggest that the present preseason aerobic and anaerobic tests are of limited use for prediction of alpine skiing performance. They claim that a valid and reliable test battery that can predict performance in alpine skiing seems to be lacking, and that future research should screen for valid components of athletic performance.

Turnbull (2009, p. 146) concluded in his review of the physiology of alpine skiing:

There remains a need to establish accurate profiles of current, world-leading

athletes that do not show bias from a nation-specific training methodology. There

is also a need to identify the specific physiological costs of ski racing and the

usefulness of aerobic vs anaerobic training methodologies, given advances in both

ski technique and technology, and physiological measurement technology.

French researchers (Bottollier, 2019) have investigated the metabolic similarities of slideboard sliding, as used by speedskaters, to GS and SL skiing. They found that sliding was more similar to

55 skiing than cycling, running or trampoline bouncing. This work is still in the early stages but may prove interesting.

Testing anaerobic power and capacity in ski racers could include the use of eccentric movements and/or devices, such as the Intelligent Motion GmbH Lifter. More work should focus on developing a test that employs eccentric muscle actions and mimics the rhythm and duration of ski racing.

Coaches and scientists need a valid and reliable anaerobic fitness test for alpine ski racers to monitor and evaluate preseason training. On snow training during the GPP does not allow anaerobic capacity testing because the courses are too short. Coaches and athletes should not rely on races to test the ability to maintain muscular power in alpine ski racing. If this ability is not adequate, the athlete and coach have no time to change training strategies, not to mention the injury risk the athlete may face.

5 CONCLUSION

Anaerobic power and capacity in alpine ski racers can be reliably measured with the LRJT and the

MLD testing system. Male racers produce more power than females except when power is averaged over the first 100 ms of a SJ. The 100 ms period may be too short to test power in skiers. There are no bilateral force imbalance differences between genders. The power-load relationship indicates that women were less explosive than their male counterparts were and that maximum power is reached at light loads for both men and women. Power training loads should not be the load at which maximum power is produced, but at the load where the deflection in the power curve occurs.

The loads should be described as % BW.

Effective GPP training will improve anaerobic power and capacity of ski racers. Higher anaerobic power with the same relative effect of fatigue will increase the mean power over the LRJT, which will equate to increased anaerobic capacity.

Anaerobic power and capacity improves to a limited degree longitudinally, as evidenced by results of the LRJT. Anaerobic power and capacity measures derived from the LRJT do not correlate with ski racing performance.

Further investigations are necessary to create testing protocols that simulate the physiological demands on alpine ski racers.

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■ universität ■ innsbruck

Eidesstattliche Erklärung

Ich erkläre hiermit an Eides statt durch meine eigenhändige Unterschrift, dass ich die vorliegende Arbeit selbständig verfasst und keine anderen als die angegebenen Quellen und Hilfsmittel verwendet habe. Alle Stellen, die wörtlich oder inhaltlich den angegebenen Quellen entnommen wurden, sind als solche kenntlich gemacht.

Die vorliegende Arbeit wurde bisher in gleicher oder ähnlicher Form noch nicht als Magister /Master-/Diplomarbeit/Dissertation eingereicht.

Datum

72 8. PAPERS I-III

Paper I:

Patterson, C., Raschner, C. and Platzer, H.-P. (2009) Power variables and bilateral force differences during unloaded and loaded squat jumps in high performance alpine ski racers. Journal of Strength and Conditioning Research, 23 (3), 779-787.

Paper II:

Patterson, C., Raschner, C. and Platzer, H.-P. (2014) The 2.5-minute loaded repeated jump test: evaluating anaerobic capacity in alpine ski racers with loaded countermovement jumps. Journal of

Strength and Conditioning Research, 28 (9), 2611-2620.

Paper III:

Patterson, C., Platzer, H.-P and .Raschner, C. (2019) The 2 minute loaded repeated jump test: longitudinal anaerobic testing in elite alpine ski racers. Journal of Sports Science and Medicine 18,

128-136.

73 Original Research Power Variables and Bilateral Force Differences During Unloaded and Loaded Squat Jumps in High Performance Alpine Ski Racers

Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter

Department of Sport Science, University of Innsbruck, Innsbruck, Austria

Address correspondence to Carson Patterson, [email protected]. Journal of Strength and Conditioning Research: May 2009 - Volume 23 - Issue 3 - p 779-787 doi: 10.1519/JSC.0b013e3181a2d7b3

Abstract

Patterson, C, Raschner, C, and Platzer, H-P. Power variables and bilateral force differences during unloaded and loaded squat jumps in high performance alpine ski racers. J Strength Cond Res 23(3): 779-787, 2009-The purpose of this paper was to investigate the power-load relationship and to compare power variables and bilateral force imbalances between sexes with squat jumps. Twenty men and 17 women, all members of the Austrian alpine ski team (junior and European Cup), performed unloaded and loaded (barbell loads equal to 25, 50, 75, and 100% body weight [BW]) squat jumps with free weights using a specially designed spotting system. Ground reaction force records from 2 force platforms were used to calculate relative average power (P), relative average power in the first 100 ms of the jump (P01), relative average power in the first 200 ms of the jump (P02), jump height, percentage of best jump height (%Jump), and maximal force difference between dominant and nondominant leg (Fmaxdiff). The men displayed significantly higher values at all loads for P and jump height (p < 0.05). No significant differences were found in P01. The men had significantly higher P02 at all loads except 75% BW). Maximum P was reached at light loads (men at 25% BW and women at 0% BW), and P decreased uniformly thereafter. Individual power-load curves show a deflection point. It is proposed that the load where the power-load deflection point occurs be used as the power training load and not the load at which maximum P is reached. It is also proposed that loads not be described in %1-repetition maximum (RM), but as %BW. This system can be used to safely assess and train power with loaded jumps and free weights.

Key Words: power training, ski-specific testing, ACL injury prevention

Due to copyright reasons the whole article had to be removed. The final published article is available at https://doi.org/10.1519/JSC.0b013e3181a2d7b3 Original Research The 2.5-Minute Loaded Repeated Jump Test: Evaluating Anaerobic Capacity in Alpine SKI Racers With Loaded Countermovement Jumps

Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter

Department of Sport Science, University of Innsbruck, Innsbruck, Austria

Address correspondence to Carson Patterson, [email protected]. Journal of Strength and Conditioning Research: September 2014 - Volume 28 - Issue 9 - p 2611-2620 doi: 10.1519/JSC.0000000000000436

Abstract

Patterson, C, Raschner, C, and Platzer, H-P. The 2.5-minute loaded repeated jump test: Evaluating anaerobic capacity in alpine ski racers with loaded countermovement jumps. J Strength Cond Res 28(9): 2611–2620, 2014—The purposes of this study were to test the reproducibility of the 2.5-minute loaded repeated jump test (LRJT) and to test the effectiveness of general preparation period (GPP) training on anaerobic fitness of elite alpine ski racers with the LRJT. Thirteen male volunteers completed 2 LRJTs to examine reliability. Nine male Austrian elite junior racers were tested in June and October 2009. The LRJT consisted of 60 loaded countermovement jumps (LCMJs) with a loaded barbell equivalent to 40% bodyweight. Before the LRJT, the power (P) of a single LCMJ was determined. Power was calculated from ground reaction forces. The mean P was calculated for the complete test and for each 30-second interval. The interclass correlation coefficients (between 0.88 and 0.99) for main variables of the LRJT demonstrated a high reliability. A repeated-measures analysis of variance indicated that anaerobic capacity was significantly higher in October (p ≤ 0.05). The ski racers' single LCMJ P increased from 37.0 ± 1.2 W·kg−1 to 39.0 ± 1.4 W·kg−1. The mean P of the total test improved from 33.6 ± 1.2 W·kg−1 to 35.8 ± 1.3 W·kg−1, but relative effect of fatigue did not change. The GPP training improved the athletes' ability to produce and maintain muscular power. The LRJT is a reliable anaerobic test suitable for all alpine ski racing events because the 60 jumps simulate the approximate number of gates in slalom and giant slalom races and the 2.5 minutes is equivalent to the duration of the longest downhill race.

Key Words: ski-specific testing, power training, strength endurance

Due to copyright reasons the whole article had to be removed. The final published article is available at https://doi.org/10.1519/JSC.0000000000000436 ©Journal of Sports Science and Medicine (2019) 18, 128-136 http://www.jssm.org

` Research article

The 2 Minute Loaded Repeated Jump Test: Longitudinal Anaerobic Testing in Elite Alpine Ski Racers

Carson Patterson , Hans-Peter Platzer and Christian Raschner Department of Sport Science, University of Innsbruck, Austria

power and capacity of ski racers should be regularly monitored (Patterson et al., 2014). Abstract This study investigated the 4-year development of anaerobic Tests assessing anaerobic power and capacity are power and capacity in Austrian elite female alpine ski racers and not measuring metabolism, but power output (Chamari et examined the relationship between the 2-minute loaded repeated al., 2010). Anaerobic power is the maximal power devel- jump test (LRJT) results and ski racing performance (Interna- oped during all-out, short-term effort and reflects the en- tional Ski Federation (FIS) points). Ten Austrian elite female ski ergy-output capacity of intramuscular high-energy adeno- racers were tested prior to four racing seasons. The LRJT con- sine triphosphate and phosphocreatine (ATP and PCr) sisted of 48 loaded countermovement jumps (LCMJs) with bar- and/or anaerobic glycolysis. Anaerobic capacity is the bell load equivalent to 20% bodyweight. Before the LRJT, maxi- maximum amount of ATP resynthesized via anaerobic me- mal body mass normalized average power of a single LCMJ tabolism during a specific mode of short-duration maximal (PMAX) was determined. The mean jump power was calculated exercise (Green and Dawson, 1993). across all jumps in the test (P0-120). Anaerobic power (PMAX) in season 2 (32.3 ± 2.3 W.kg-1) significantly improved over season Jump tests have been used by a number of investi- 1 (30.5 ± 2.3 W.kg-1) (p < 0.05) but there were no further differ- gators to determine anaerobic power and capacity in alpine ences between seasons, with season 3 at 33.5 ± 3.4 W.kg-1 and skiers (Bosco, 1997; Bosco et al., 1994; Breil et al., 2010; . -1 season 4 at 33.6 ± 3.0 W kg . Anaerobic capacity (P0-120) in- Emeterio and González-Badillo, 2010; Karlsson et al., creased up to season 3 by 9.2% (27.1 ± 2.8 to 29.6 ± 2.4 W.kg-1), 1978; Nikolopoulos et al., 2009; Patterson et al., 2009; Pat- but was significantly higher only when comparing season 4 to terson et al., 2014; White and Johnson, 1991). Bosco seasons 1 and 2 (p < 0.05). FIS points changed significantly (p < (1997) evaluated the anaerobic capacity (measured with re- 0.05), from 18.1 ± 8.2 in season 1 to 8.4 ± 4.8 in season 4 (lower peated jumps) of alpine ski racers. He showed that the most FIS points indicates better racing results). FIS points had a posi- successful individual male and female slalom and giant sla- tive relationship with PMAX (r = -0.73, p < 0.05) and P0-120 (r = - 0.64, p < 0.05) only in season 4. Improvements in FIS points from lom racers at that time (both Olympic champions) had the year to year did not correlate with seasonal increases in LRJT re- highest anaerobic capacity and that seven of eight interna- sults. In conclusion, anaerobic power improved only after season tional female ski racers did not increase their anaerobic ca- 1, and anaerobic capacity changes were evident only in season 4. pacity over 5 years. Bosco proposed that anaerobic capac- Ski racing performance (FIS points) correlated with LRJT test re- ity correlated with ski racing performance but did not sta- sults in only season 4. The LRJT can monitor a ski racer’s anaer- tistically prove this. The results of a 30 s version of Bosco’s obic power and capacity, but does not correlate with ski racing test did correlate with racing performance in Spanish male performance. adolescent ski racers (Emeterio and González-Badillo, Key words: Alpine skiing, female, anaerobic power and capacity, 2010). jump test. Patterson and coworkers (2014) introduced the 2.5 . minute loaded repeated jump test (LRJT) as an evaluation tool of anaerobic power and capacity in male ski racers. Introduction This test was standardized, repeatable and portable, allowing for testing at training camps as well as in a laboratory. The regular monitoring of physical fitness and sport-spe- The test was 2.5 minutes long and the athletes performed cific performance is important in elite sports to increase the 60 loaded countermovement jumps (LCMJs). The test mir- likelihood of success in competition (Chaabene et al., rors the duration of the longest International Ski Federation 2018). There is no consensus regarding the influence of (FIS) World Cup (WC) men’s downhill, and the number of physiological parameters on alpine ski racing performance gates in the technical events of slalom and giant slalom. (Maffiuletti et al., 2006; Neumayr et al., 2003, Turnbull et The 2.5 minute LRJT was modified for women, and al., 2009). Therefore, sport scientists have difficulty pre- has been used to test the Austrian women’s alpine ski team dicting ski racing performance. since 2006. The longest women’s WC race in the Anaerobic metabolism plays a large role in alpine 2012/2013 season was the Lake Louise downhill at almost ski racing, as it is a high intensity sport (Gross et al., 2014; 2 minutes (winning time 1:52.61). Women’s FIS WC sla- Polat, 2016; Veicsteinas et al., 1984; Vogt et al., 2003). lom races normally have about 60 turning gates, and giant Skeletal muscle fatigue is a limiting factor in skiing perfor- slalom races about 50 gates. The women’s LRJT requires mance (Ferguson, 2010) and can be a risk factor in ski rac- 48 LCMJs with a barbell loaded with a weight equivalent ing injuries (Spörri et al., 2012). Therefore, anaerobic to 20% of the athlete’s bodyweight and is 2 minutes long.

Received: 02 March 2018 / Accepted: 08 January 2019 / Published (online): 11 February 2019 Patterson et al. 129

The original version of the test is reliable, and sen- collect data. The vertical ground reaction forces were sitive enough to detect adaptations in anaerobic power and measured with two separate force platforms. The sampling capacity during a preseason-training phase (Patterson, et rate was 1000 Hz. The transducer signal was directly am- al., 2014). It has not been explored if and to what extent plified in the platforms to reduce interference. The reliabil- anaerobic power and capacity measures made with the ity of the single LCMJ analysis (ICC: r = 0.944 - 0.981) LRJT improve in world class ski racers from season to sea- (Patterson et al., 2009) and the 2.5-minute LRJT parame- son or over several seasons, or if these measures are related ters (ICC: r = 0.881 - 0.987) of the MLD system has been to ski racing performance. reported elsewhere (Patterson et al., 2014). Thus, a multi-season standardized and repeatable evaluation of anaerobic power and capacity assessed with Calculation of power output and countermovement the LRJT in elite alpine ski racers would provide insights depth into the longitudinal physical development of alpine ski The ground reaction force record obtained from the force racers and also determine if the test has predictive value for platforms was used to calculate power output. The ground racing performance. reaction force impulse was determined by calculating the Therefore, this study has two aims: first, to deter- area under the force–time curve by numerical integration, mine if anaerobic power and capacity would improve in fe- as described by Linthorne (2001). At the bottom of the male world class ski racers over 4 seasons; and secondly, countermovement, the subject’s velocity of body center of to investigate the relationship between LRJT results and ski mass (�) was zero (� 0). This point was defined as time racing performance. zero (�). The impulse–momentum theorem was applied to The hypotheses were that LRJT results measuring the concentric phase of the jump, from � through to the anaerobic power and capacity would improve over 4 sea- time point where maximum velocity of body center of mass sons; and that the results of the LRJT would correlate with was reached (�) which was assumed to be the takeoff ve- ski racing performance. locity � ). The impulse on the subject was:

Methods � �� Participants Where � was the ground reaction force, � was the total mass of the The same ten female Austrian national alpine ski team ath- subject and the loaded barbell, and � was the gravitational acceleration. letes were tested prior (August – October) to each of the 2010, 2011, 2012 and 2013 FIS alpine ski racing seasons. Pmean was the average power over the concentric Seven had achieved at least a top 10 placing in a FIS WC phase of the countermovement jump, or from � to � . race prior to or during the seasons examined, and collec- Power was be derived from: tively this group had won 60 FIS WC, 5 FIS world cham- �� ∙� pionship and 3 Olympic medals. The mean age, height, Where � was power and � was force. So Pmean was calculated with the weight and Body Mass Index for the athletes are presented following formula: ∙ in Table 1. Pmean = All skiers tested were experienced with weight training, particularly in squatting. A physician medically screened each athlete before each season to ensure that To calculate the depth of the countermovement, the there were no contraindications to participation in ski rac- displacement–time record was obtained by numerically in- ing or any physical activity with the team. The athletes tegrating the velocity–time record (Linthorne, 2001). The gave informed consent before the testing. The parents of velocity–time record was obtained by dividing the resultant athletes who were minors at the beginning of the study force–time record by the combined mass of the subject and gave informed signed consent. An institutional review the barbell to give the acceleration–time record, and then committee (Department of Sport Science, University of numerically integrating with respect to time using the trap- Innsbruck) and the Sport Science Committee of the Aus- ezoid rule. The displacement–time record was obtained by trian Ski Federation gave prior approval for the testing and numerically integrating the velocity–time record, again us- testing was performed according to the Declaration of Hel- ing the trapezoid rule. sinki. � � �� Data collection equipment The hardware (MLD-Station Evo2) and software (MLD Where � was the position of the center of mass at time of takeoff (�) and 3.2—Muskel-Leistungs-Diagnose 3.2) from SPSport (SP � was the position of the center of mass at time point at the bottom of the Sportdiagnosegeräte GmbH, Trins, Austria) were used to countermovement (�.

Table 1. Physical characteristics of the ski racers (mean ± SD), n = 10. Season Age (yr) Height (cm) Body mass (kg) Body Mass Index (kg.m2) 2010 20.0 ± 2.7 167.3 ± 3.5 66.3 ± 4.0 23.7 ± 2.2 2011 21.1 ± 2.7 167.3 ± 3.5 67.0 ± 4.6 24.1 ± 2.2 2012 22.0 ± 2.6 167.3 ± 3.5 66.5 ± 4.6 23.9 ± 1.8 2013 23.1 ± 2.7 167.3 ± 3.5 65.4 ± 5.3 23.6 ± 2.3

130 Jump test female ski racers

Procedures fit to the jump data so that missing data points could be The testing conditions for the Austrian Ski Federation were interpolated. Each athlete then had power values for 48 controlled and remained very similar for each testing ses- CMJs. A mean power for the complete test (P0-120) was also sion. Coaches instructed athletes regarding activity and calculated from the 48 values. diet before the tests so that testing conditions were stand- The first valid LCMJ (LCMJrel) of the LRJT was ardized. The LRJT was part of a battery of tests used to compared to PMAX (percentage of PMAX) as a control that evaluate the Austrian Ski Federation alpine ski teams the test was performed with maximal effort. (Raschner et al., 2013), and was the last test in the battery. PMAX was defined as the measurement of anaerobic Before the LRJT, the subjects completed 1–2 series of power, P0-120 as the measurement of anaerobic capacity, squats with a weight of their choice. and fatigue index (FI) as the indicator of anaerobic fatigue. The subjects performed single LCMJs with a loaded FI as a control parameter was determined by taking barbell (20% bodyweight). In order to allow comparisons the percentage difference between PMAX and the average of between jumps, a consistent countermovement depth was the relative power of the last 12 jumps (30 seconds dura- necessary. The subjects were instructed to perform a fast tion) of the LRJT (P120.). downward movement (to approximately 90° knee flexion) FI = � 100 immediately followed by a fast upward movement, jump- The seasons 2010, 2011, 2012 and 2013 were des- ing as high as possible. The athlete was instructed to in- ignated as season 1, season 2, season 3 and season 4. crease or decrease the depth of the countermovement until The changes between seasons in the measures of a satisfactory depth was found. The countermovement P , P and FIS points were also assessed, eliciting six depth from the reference jump was used to standardize the MAX 0-120 season differences (1 and 2, 1 and 3, 1 and 4, 2 and 3, 2 and countermovement depth for the LRJT. Every jump was 4, and 3 and 4). controlled for countermovement depth and jumps with a countermovement depth of less than 90% of the reference Statistical analysis jump depth were not used in the data. Differences between seasons were calculated for all out- Subjects were given feedback regarding their tech- come measures. The linear relationship between the out- nique, power, and the countermovement depth of the come measures and the seasonal differences in the outcome LCMJ. When the subject’s technique was satisfactory, 3-5 measures were assessed using Pearson correlation coeffi- individual LCMJs were performed (single jumps with rests cients for each season and each season-to-season compari- between) to determine the reference LCMJ to compare son. Analysis of variance (ANOVA) with repeated with the LRJT jumps. The single 20% LCMJ that produced measures (SPSS 18.0 for Windows) was performed to de- the highest average power relative to body mass with an tect differences. Pairwise comparisons were made using appropriate depth was used as the reference power (P ) MAX student t-tests. Scatter plots were made for each season to for the LRJT. After establishing the P , the athlete then MAX compare the following: P with FIS points, P with took a rest of at least 3 minutes. MAX 0-120 FIS points, changes in P with changes in FIS points and The LRJT was again described and explained, and MAX changes in P with changes in FIS points. Statistical sig- when the subject was ready, the LRJT was performed. The 0-120 nificance was set at α = 0.05. test was 2 minutes long and the load was 20% body mass. The subject jumped every 2.5 s, (48 LCMJ) pausing briefly between jumps to avoid reactive jumps. A computer mon- Results itor in front of the athlete assisted in LCMJ timing with a visual countdown for each jump. Each athlete completed the test duration of 2 minutes and at least 48 LCMJ in every testing session. LCMJrel re- Ski racing performance analysis mained stable from year to year (between 96% and 98% Ski-racing performance was based on FIS points. FIS PMAX), ensuring consistent test intensity. FI remained stable points were organized so that the best in the world in each over the four years. The FI for seasons 1, 2, 3 and 4 were discipline had 0 points and the 31st in the world had 6 14.8 ± 5.8, 17.3 ± 7.6, 15.9 ± 7.8 and 16.3 ± 5.2 respec- points. Occasionally everyone’s FIS points were adjusted tively. to ensure that this was the case. Thus, a racer’s FIS points PMAX improved significantly from season 1 to sea- were a measure of how he / she compared with the rest of son 4 [F (3,27) = 7.923, p < 0.05], with season 1 being sig- the world. A racer’s FIS points were the average of the nificantly less than all other seasons. Pairwise comparisons racer’s best 2 races in that discipline in the last 13 months. between the other 3 seasons showed no differences [season . -1 Lower FIS points indicated better performance. For each 1: PMAX = 30.5 ± 2.3 Wkg ; season 2 PMAX = 32.3 ± 2.3 . -1 . -1 season, the discipline with the lowest FIS points was used W kg ; season 3 PMAX = 33.5 ± 3.4 W kg ; season 4 PMAX for each athlete. = 33.6 ± 3.0 W.kg-1](see Figures 1 and 2). The pairwise comparisons revealed that the PMAX change between season Data treatment 1 and all other seasons was significant. The software calculated the power of all jumps for each P0-120 [F (3,27) = 4.019, p < 0.05] increased by 9.2% athlete. Each jump was numbered, and the power values up to season 3 (27.1 ± 2.8 to 29.7 ± 3.4 W.kg-1) and was for all valid jumps were recorded. Data sets were created unchanged from season 3 to 4. P0-120 in season 4 (29.6 ± 2.4 for each athlete with missing values in the cases of invalid W.kg-1) was significantly higher than seasons 1 and 2. jumps. In the event of missing jumps, a regression line was FIS points decreased significantly (racing perfor-

Patterson et al. 131

mance improved) [F (3,27) = 11.020, P < 0.05], from 18.1 p < 0.05), indicating that as anaerobic capacity increased, ± 8.2 in season 1 to 8.4 ± 4.8 in season 4. Pairwise compar- racing performance decreased. isons revealed that FIS points in seasons 2, 3 and 4 were significantly lower than in season 1 (see Table 2).

Table 2. FIS points for the ski racers for the best individual discipline (mean ± SD), n = 10. Season FIS points Range 2010* 15.2 ± 5.6 5.1 – 20.4 2011 10.9 ± 6.3 4.1 – 23.1 2012 8.8 ± 4.2 1.2 – 15.5 2013 8.4 ± 4.8 2.5 – 16.1 * 2010 > 2011, 2012, 2013

Figure 3. Group mean longitudinal progression of P0-120 and FIS points over 4 seasons. P0-120 development is represented with the solid line; FIS points changes with the dotted line.

Discussion

The first aim of this study to determine if anaerobic power

and capacity would improve over 4 seasons produced in-

conclusive results. Anaerobic power improved from season Figure 1. Individual reference LCMJ (PMAX) over four sea- 1 to season 2 but subsequently plateaued. Anaerobic capac- sons for all subjects. The thick broken line shows group mean ity enhancements were only evident when comparing sea- PMAX over 4 seasons. son 4 to seasons 1 and 2. There was no continuous im-

provement in either anaerobic power or capacity so the hypothesis that anaerobic power and capacity would improve in female world class ski racers over the four seasons was only partially confirmed. The increase in PMAX results from season 1 to 2 was evident during testing. Training in the preseason leading up to season 2 may have influenced the test results, but training was not controlled in this study so training effects cannot be ascertained. Nine of the athletes had their best an-

aerobic capacity results in season 3 or 4 but only season 4

was greater than seasons 1 and 2. In a study of female Figure 2. (A) Group PMAX means with 95% confidence inter- Olympic medal winners, women peaked in their mid-twen- vals for seasons 1 - 4. (B) Group P0-120 means with 95% confidence intervals for seasons 1 - 4. * p < 0.05 ties (Elmenshawy et al., 2015). The athletes investigated in this paper had an average age of 20 in season 1, so en- A statistically significant correlation between jump hanced LRJT results with each season were expected, but power variables and FIS points occurred only in season 4. positive anaerobic power and capacity development was evident mainly when comparing season 1 to the other three PMAX [r = -0.73)] and P0-120 [r = -0.64]. Jump power variables were negatively related to FIS points, meaning higher seasons. anaerobic power and capacity both correlated positively to Bosco (1997) conducted a 45 s jump test with eight ski racing performance (see Figures 3, 4, 5, 6, 7 and 8). female international alpine ski racers and found that jump Figures 7 and 8 illustrate the relationships between test results were not altered over five years (1989 to 1994) changes in anaerobic measures and the changes in perfor- with seven women. This is a similar time span as the four mance. Values below the horizontal axis (negative) indi- years presented here, but reasons for little or no changes in cate that FIS points decreased (enhanced performance), anaerobic power and capacity in both groups cannot be de- and values to the right of the vertical axis (positive) indi- termined without knowledge of the training programs. cate that the anaerobic measure increased. There were no Bosco’s (1997) subjects were described as national team athletes, but it is not known what level of competition they significant positive correlations between increases in PMAX and performance progression from season to season. The raced at during the study. The Austrian women in this study were not all skiing WC races over the entire study period, relationship between P0-120 development and the FIS points progress from season 1 to season 3 was positive (r = 0.64, so as the lower level racers advanced in their ski careers

132 Jump test female ski racers

better anaerobic power and capacity coupled with more required 60 consecutive jumps, at the rate of about 1 Hz, racing success would be expected. Comparisons of anaer- so the 60 jumps were reactive and faster, creating a higher obic test results between Bosco’s study and this investiga- intensity and requiring more coordination, causing an ear- tion are tenuous, as the methodologies were different. In lier onset of fatigue. Bosco measured jump height with a the LRJT, the athletes jumped 48 times every 2.5 s (two contact pad and the LRJT measured ground reaction forces minutes test duration) to avoid reactive jumps. Bosco’s test to calculate power.

Figure 4. Individual longitudinal progression of P0-120 and FIS points over 4 seasons for all subjects. P0-120 development is represented with the solid line; FIS points changes with the dotted line.

Figure 5. Scatter plots of PMAX and FIS points for each of 4 seasons for each subject. * p < 0.05

Patterson et al. 133

Figure 6. Scatter plots of P0-120 and FIS points for each of 4 seasons for each subject. * p < 0.05

Figure 7. Scatter plots of the comparisons of season-to-season changes in PMAX and FIS points for each of 4 seasons for each subject. * p < 0.05

134 Jump test female ski racers

Figure 8. Scatter plots of the comparisons of season-to-season changes in P0-120 and FIS points for each of 4 seasons for each subject.

Karlsson and coauthors (1978) stated that fatigue in where two top ski racers (one male and one female Olym- alpine skiing is not fully understood and more research is pic champion) possessed the highest anaerobic capacity needed to examine the potential mechanisms of fatigue and levels (Bosco, 1997). However, case examples do not rep- thus develop better training techniques. Coaches and sport resent evidence of a causal relationship between anaerobic scientists agree that superior fitness is a factor that can re- capacity assessed with vertical jumps and alpine ski racing duce risk of injury (Spörri et al., 2012), but the relationship performance. Results of a 30 s variation of Bosco’s test between anaerobic measures and performance is not clear. correlated with racing performance in Spanish male ado- The second aim of the study, to investigate the rela- lescent ski racers (Emeterio and González-Badillo, 2010), tionship between LRJT results and ski racing performance but the predictive power of anaerobic tests for ski racing indicated a weak relationship. LRJT results correlated with success was not corroborated by the current study. This performance only in season 4. The anaerobic power in- supports the premise of Turnbull et al. (2009) that no sin- crease from season 1 to 2 did not correlate with the de- gular factor can predict ski racing success. crease in FIS points. Anaerobic capacity was higher in sea- A more specific physiological measurement of WC son 4 when compared to seasons 1 and 2, but these P0-120 skiers is needed (Turnbull et al., 2009). Jump tests have at- changes had no relationship to FIS points differences. P0- tempted to simulate the physical demands of ski racing 120 increases between season 1 and season 3 negatively cor- (Bosco, 1997; Bosco et al., 1994; Breil et al., 2010; Eme- related with the change in skiing performance for the same terio and González-Badillo, 2010; Karlsson et al., 1978; period. Therefore, the hypothesis that anaerobic power and Nikolopoulos et al., 2009; Patterson et al., 2009; 2014; capacity would correlate with ski racing performance was White and Johnson, 1991). Blood lactate after ski races and rejected. training runs has been reported to have been 7 to 13 The younger athletes in the study may have influ- mmol.L-1 (Vogt et al., 2000; White and Johnson, 1991). enced the positive correlation between both anaerobic Unpublished work by the authors has shown that lactate af- measures and performance in season 4. After four seasons ter the LRJT with men has been between 6 and 11 mmol.L- in the national program, the younger athletes had pro- 1. The LRJT may simulate the metabolic demands of the gressed in their ski racing and had started to stabilize their sport, but jumping is not specific to skiing. performance. Perhaps racers need a threshold level of tech- An athlete should fully extend at the hips, knees and nical competence and racing experience before they are ankles to maximize power in a jump, but explosive leg ex- able to capitalize on enhanced anaerobic power and capac- tension at the end of a turn can lead to skis losing contact ity. with the snow. Loss of snow contact is disadvantageous in A single case example in this study (with no statis- ski racing (Supej et al., 2011). Kröll et al (2015) measured tical support) revealed that one participant achieved the maximal knee angles in slalom and giant slalom of 132 ± best racing performance concurrently with the highest rec- 6° and 138 ± 8° respectively during an on-snow kinematic orded anaerobic capacity (P0-120) in season 3. This finding study. agrees with other case examples in the scientific literature Berg and Eiken (1999) demonstrated that eccentric

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muscle actions were dominant in slalom, giant slalom and capacity improved to a limited degree during the four-sea- super G skiing. Ferguson (2010) concluded that alpine ski- son study duration, as evidenced by results of the LRJT. ing is characterized by isometric and eccentric muscular Anaerobic power and capacity measures derived from the contractions. The LRJT requires both eccentric and con- LRJT did not correlate with ski racing performance. Fur- centric muscle actions during jumping, but currently only ther investigations are necessary to create testing protocols concentric power is used as a test parameter. that simulate the physiological demands on alpine ski rac- Ski racers need high levels of leg strength, as max- ers. imal forces can range between two to four times bodyweight (Gilgien et al., 2013, Reid et al., 2012). However, Acknowledgements The experiments comply with the current laws of the country in which as opposed to many racing sports, athletic strength or they were performed. The authors have no conflicts of interests to declare. power is not the driving force for skiing velocity. In sprint- ing and swimming athletes create the needed forces for References speed, and power tests can predict performance. Jump tests correlated with 100m sprint times (Loturco et al., 2015) Berg, H. E. and Eiken, O. (1999) Muscle control in elite alpine skiing. Medicine and Science in Sports and Exercise 31, 1065-1067. and muscular power assessed in laboratory tests was an im- Bosco, C. (1997) Evaluation and planning of conditioning training for al- portant determinant in swimming (Hawley et al., 1992). pine skiers. In: Science and Skiing. Eds: E. Müller, H. Gravity propels the ski racer down the hill (Stöggl Schwameder, E. Kornexl and C. Raschner. London, England, E et al., 2016, Supej et al., 2011) and the racer must effi- & FN Spon, Chapman and Hall Publishers. 297-308. Bosco, C., Cotelli, F., Bonomi, R., Mognoni, P., and Roi, G. (1994) Sea- ciently use this potential energy. Supej et al. (2011) found sonal fluctuations of selected physiological characteristics of that high-level WC ski racers better controlled the dissipa- elite apline skiers. European Journal of Applied Physiology 69, tion of potential energy, and could more effectively reduce 71-74. ground reaction forces compared to low-level performers. Breil, F. A., Weber, S. N., Koller, S., Hoppeler, H., and Vogt, M. (2010) These aspects involve refined technical skills and are not Block training periodization in alpine skiing: Effects of 11-day HIT on VO2max and performance. European Journal of Applied determined purely by the racer’s strength. There is still “a Physiology (serial online) 109(6), 1077-1086. lack of functional and biomechanical understanding of the Chaabene, H., Negra, Y., Raja Bouguezzi, R., Laura Capranica, L., Em- performance relevant parameters” in ski racing (Spörri et erson Franchini, E., Prieske, O., Hbacha, H. and Urs Granacher, U. (2018) Tests for the assessment of sport-specific performance al., 2012). More work must be done to develop physical in olympic combat sports: a systematic review with practical rec- tests for ski racers. ommendations. Frontiers in Physiology (serial online) 9, 386. The MLD platforms used in this study are portable, Chamari, K., Chaouachi, A. and Racinais, S. (2010) Anaerobic power and allowing for LRJT evaluations at a ski or dryland camp. capacity. In: Exercise Physiology: From a Cellular to an Inte- grative Approach. Volume 75 of Biomedical and Health Re- The 2-minute LRJT presented here simulates the metabolic search. Eds: P. Connes, O. Hue, and S. 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(2013) The small sample size is a problem, but conducting a lon- Determination of external forces in alpine skiing using a differ- gitudinal study with high performance ski racers is difficult ential global navigation satellite system. Sensors 13(8), 9821- 9835. due to the nature of ski racing. It had been noted in other Green, S. and Dawson, B. (1993) Measurement of anaerobic capacities in studies that small sample sizes are often a problem when humans. Definitions, limitations and unsolved problems. Sports working with world-class ski racers (Haaland et al., 2016; Medicine 15(5), 312-327. Kröll et al., 2017). The use of FIS points to evaluate per- Gross, M., Hemand, K., and Vogt, M. (2014) High intensity training and energy production during 90-second box Jump in junior alpine formance may also be a problem. FIS points are based on skiers Journal of Strength and Conditioning Research 28(6), only two results per season, and there is no general rating 1581-1587. for athletes racing well in multiple disciplines (Maisano et Haaland, B., Steenstrup, S. E., Bere, T., Bahr, R., and Nordsletten, L. al., 2015). Also, errors may have been introduced by the (2016) Injury rate and injury patterns in FIS World Cup Alpine skiing (2006-2015): Have the new ski regulations made an im- linear interpolation of missing jumps. Preseason fitness pact? British Journal of Sports Medicine (serial online) 50(1), tests may not reflect in-season fitness, and thus may not be 32-36. an accurate indicator of anaerobic power and capacity dur- Hawley, J. A., Williams, M. M., Vickovic, M. M., and Handcock, P. J. ing racing. (1992) Muscle power predicts freestyle swimming performance. British Journal of Sports Medicine (serial online) 26(3), 151– 155. Conclusion Hydren, J. R., Volek, J. S., Maresh, C. M., Comstock, B. A. and Kraemer, W. J. (2013) Review of strength and conditioning for alpine ski The present investigation showed that anaerobic power and racing. Strength and Conditioning Journal 35(1), 10-28.

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formance in 100-m dash events. Journal of Strength and Condi- tioning Research 29(7), 1966-1971. The 2-minute loaded repeated jump test (LRJT) sim- Maffiuletti, N. A., Impellizzeri, F., Rampinini, E., Bizzini, M., and ulates the duration and number of gates in a World Mognoni, P. (2006) Letter to the editors - Is aerobic power really Cup ski race, and can be used to quantify and compare critical for success in alpine skiing? International Journal of an alpine ski racer’s anaerobic power and capacity. Sports Medicine 27(2), 166-167. Maisano, D., Botta, A. and Franceschini, F. (2015) On the rating system Over the 4-year duration of the study, the Austrian al- in alpine skiing racing: criticism and new proposals. Proceedings pine ski racers in this study improved their ski racing of the Institution of Mechanical Engineers, Part P: Journal of performance as anaerobic fitness increased. Sports Engineering and Technology 230(4), 253-263. Neumayr, G., Hörtnagl, H., Pfister, R., Koller, A., Eibl, G. and Raas, E. Testing anaerobic fitness in ski racers is critical be- (2003) Physical and physiological factors associated with suc- cause it correlates with ski racing performance, and cess in professional alpine skiing. International Journal of the high speeds in racing require maintaining high lev- Sports Medicine 24(8), 571-575. els of strength until a racer has safely arrived in the Nikolopoulos, D., Zafeiridis, A., Manou, V. and Gerodimos, V. (2009) Fitness characteristics of a greek national alpine skiing team: cor- finish area. relation with racing performance. Hellenic Journal of Physical Education and Sport Science 29(4), 329-342. Patterson, C., Raschner, C. and Platzer, H.-P. (2014) The 2.5-minute AUTHOR BIOGRAPHY loaded repeated jump test: evaluating anaerobic capacity in al- Carson PATTERSON pine ski racers with loaded countermovement jumps. Journal of Employment Strength and Conditioning Research 28(9), 2611-2620. Department of Sport Science, University Patterson, C., Raschner, C., and Platzer, H.-P. (2009) Power variables of Innsbruck, Austria and bilateral force differences during unloaded and loaded squat Degree jumps in high performance alpine ski racers. Journal of Strength and Conditioning Research 23(3), 779-787. M.A. Polat, M. (2016) An examination of respiratory and metabolic demands Research interests of alpine skiing. Journal of Exercise Science and Fitness 14(2), Anaerobic power and capacity in alpine 76-81. ski racing, eccentric training Raschner, C., Müller, L., Patterson, C., Platzer, H. P., Ebenbichler, C., E-mail: [email protected] Luchner, R. and Hildebrandt, C. (2013) Current performance Hans-Peter PLATZER testing trends in junior and elite Austrian alpine ski, snowboard Employment and ski cross racers. Sport-Orthopadie - Sport-Traumatologie 29(3), 193-202. Department of Sport Science, University Reid, R., Gilgien, M., Haugen, P., Kipp, R., and Smith, G. (2012) Force of Innsbruck, Austria and energy characteristics in competitive slalom. In: Science and Degree Skiing V. Rds: E. Müller, S. Lindinger, T. Stöggl. Aachen, Ger- Dr. many, Meyer and Meyer Sport Ltd. 373-384. Research interests Spörri, J., Kröll, J., Amesberger, G., Blake, O. M. and Müller, E. (2012) Injuries in alpine skiing, training Perceived key injury risk factors in World Cup alpine ski racing- E-mail: [email protected] an explorative qualitative study with expert stakeholders. British Christian RASCHNER Journal of Sports Medicine 46(15), 1059-1064. Spörri, J., Kröll, J., Schwameder, H. and Müller, E. (2012) Turn charac- Employment teristics of a top world class athlete in giant slalom: a case study Department of Sport Science, University assessing current performance prediction concepts. International of Innsbruck, Austria Journal of Sports Science and Coaching 7(4), 647-659. Degree Stöggl, T., Schwarzl, C., Müller, E. E., Nagasaki, M., Stöggl, J., Scheiber, Ao. Univ.-Prof. Dr. P. and Niebauer, J. (2016) A comparison between alpine skiing, Research interests cross-country skiing and indoor cycling on cardiorespiratory and Talent development in alpine ski racing, metabolic response. Journal of Sports Science and Medicine training 15(1), 184-195. Supej, M., Kipp, R. and Holmberg, H.-C. (2011) Mechanical parameters E-mail: [email protected] as predictors of performance in alpine World Cup slalom skiing. Scandinavian Journal of Medicine and Science in Sports (serial Carson Patterson, M.A. online) 21(6), e72-e81. Olympiazentrum, Institut für Sportwissenschaft, Fürstenweg 185, Turnbull, J. R., Kilding, A. E., and Keogh, J. W. L. (2009) Physiology of 6020 Innsbruck, Austria alpine skiing. Scandinavian Journal of Medicine and Science in Sports 19(2), 146-155.