Effects of Same-day Strength Training on Serve Performance in Female Collegiate Tennis Players

Transcription

1 Brigham Young University BYU ScholarsArchive All Theses and Dissertations Effects of Same-day Strength Training on Serve Performance in Female Collegiate Tennis Players Staci Kayleen Reynolds Brigham Young University - Provo Follow this and additional works at: Part of the Exercise Science Commons BYU ScholarsArchive Citation Reynolds, Staci Kayleen, "Effects of Same-day Strength Training on Serve Performance in Female Collegiate Tennis Players" (2005). All Theses and Dissertations This Thesis is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in All Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact scholarsarchive@byu.edu.

2 EFFECTS OF SAME-DAY STRENGTH TRAINING ON SERVE PERFORMANCE IN FEMALE COLLEGIATE TENNIS PLAYERS by Staci Kayleen Reynolds A thesis submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Master of Science Department of Exercise Sciences Brigham Young University April 2005

3 Copyright 2005 Staci K. Reynolds All Rights Reserved

4 BRIGHAM YOUNG UNIVERSITY GRADUATE COMMITTEE APPROVAL of a thesis submitted by Staci Kayleen Reynolds This thesis has been read by each member of the following graduate committee and by majority vote has been found to be satisfactory. Date Shane S. Schulthies, Chair Date Philip E. Allsen Date Pat Vehrs Date Iain Hunter

5 BRIGHAM YOUNG UNIVERSITY As chair of the candidate s graduate committee, I have read the thesis of Staci Kayleen Reynolds in its final form and have found that (1) its format, citations, and bibliographical style are consistent and acceptable and fulfill university and department style requirements; (2) its illustrative materials including figures, tables, and charts are in place; and (3) the final manuscript is satisfactory to the graduate committee and is ready for submission to the university library. Date Shane S. Schulthies Chair, Graduate Committee Accepted for the Department Ruel Barker Chair, Department of Exercise Sciences Accepted for the College Gordon B. Lindsay, Associate Dean College of Health and Human Performance

6 ABSTRACT EFFECTS OF SAME-DAY STRENGTH TRAINING ON SERVE PERFORMANCE IN FEMALE COLLEGIATE TENNIS PLAYERS Staci Kayleen Reynolds Department of Exercise Sciences Master of Science The purpose of this study was to evaluate the effects of same-day strength training on velocity and accuracy of a tennis serve among five female Division I intercollegiate athletes at the second and sixth week of a strength training program. Velocity and accuracy of 20 tennis serves were measured approximately four hours after a morning split-body (lower legs and trunk) strength training session termed the lift-day (LD) and were compared to measures taken on days that no lifting took place, termed the non-lift day (NLD). For each test day, velocity was multiplied by accuracy to provide an overall serve performance score for each NLD and LD. An ANOVA revealed that there was no significant difference in any of the measured variables between the NLD and the LD at any time period throughout the study. A mean serve performance score difference

7 between NLD (77.56) and LD (78.05) of 0.49 was not statistically different [p = 0.84]. The results of this study suggest that female collegiate tennis players may strength-train with no significant effect on same-day serve performance following adequate recovery. Key Words: Fatigue, Weight Lifting, Serve Velocity

8 ACKNOWLEDGMENTS I would like to thank Coach Manning and the women s tennis team for allowing me to take time from their busy practice schedules in order to collect my research. I would also like to thank my committee Dr. Allsen, Dr. Hunter, and especially Dr. Vehrs and my Chair Dr. Schulthies for helping me work through all the trials of completing this research project. I owe much gratitude to them for all their patience and assistance. I would also like to express my deepest appreciation to the Athletic Training staff at Brigham Young University, who not only have taught me so much about being an athletic trainer but also about being a better person. Thanks especially to Carolyn Billings who gave me the continued support as a student, a trainer, and a friend throughout my college days. Thanks for being my north star, constant and guiding. Most of all I would like to thank my parents and family for their love and support in everything I have been and have accomplished in my life. I love them with all my heart and could not have made it to this point without them. With them I share this wonderful moment.

9 Table of Contents List of Tables...ix List of Figures...x Effects of Same-Day Strength Training on Serve Performance in Female Collegiate Tennis Players Abstract...2 Introduction...3 Methods...4 Results...7 Discussion...8 Practical Application...13 References...14 Appendix A Prospectus...19 Introduction...20 Review of Literature...24 Methods...35 References...40 Appendix B Raw Data...45 viii

10 List of Tables Table Page 1 Comparison of Serve Performance Scores on Lift and Non-lift Days...17 ix

11 List of Figures Figures Page 1 Court Setup With Accuracy Lines...18 x

12 xi

13 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 1 Effects of Same-day Strength Training on Serve Performance in Female Collegiate Tennis Players by Staci K. Reynolds, MS, ATC Shane S. Schulthies, PhD, PT, ATC Philip E. Allsen, EdD Pat Vehrs, PhD Iain Hunter, PhD Department of Exercise Sciences Brigham Young University, Provo, Utah Direct Correspondence to: Staci K. Reynolds, MS, ATC 151 S W. #50 Provo, UT Phone: (801) skr23@ .byu.edu

14 2 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE ABSTRACT The purpose of this study was to evaluate the effects of same-day strength training on velocity and accuracy of a tennis serve among five female Division I intercollegiate athletes at the second and sixth week of a strength training program. Velocity and accuracy of 20 tennis serves were measured approximately four hours after a morning split-body (lower legs and trunk) strength training session termed the lift-day (LD) and were compared to measures taken on days that no lifting took place, termed the non-lift day (NLD). For each test day, velocity was multiplied by accuracy to provide an overall serve performance score for each NLD and LD. An ANOVA revealed that there was no significant difference in any of the measured variables between the NLD and the LD at any time period throughout the study. A mean serve performance score difference between NLD (77.56) and LD (78.05) of 0.49 was not statistically different [p = 0.84]. The results of this study suggest that female collegiate tennis players may strength-train with no significant effect on same-day serve performance following adequate recovery. Key Words: Fatigue, Weight Lifting, Serve Velocity

15 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 3 INTRODUCTION Tennis has become a highly competitive sport requiring a tremendous amount of power and accuracy in order to be successful. One of the most important strokes each player must learn is the tennis serve. The serve is the start of each point and is the only aspect in which a player has total control over its outcome (2). However, it is the most difficult stroke to learn because of the complex and coordinated movements involving the trunk and upper and lower extremities (2). The coordination of body parts has been termed the kinetic chain (8, 15), and allows generation, summation, transfer, and regulation of forces from the legs to the hand (12). It is well known that in order to increase serve performance, muscle strength of the entire kinetic chain must be increased without affecting serve accuracy. Proper strength training has, therefore, become a vital aspect of tennis training. Due to the multiple competition seasons that occur in tennis, it is inevitable that players may be scheduled to strength train on the same day as a match. Many athletes and coaches choose to forgo such strength training sessions on the premise that strength training the same day as competition will decrease performance (17). Previous research evaluating the effects of same-day strength training on sport performance (10, 13, 17) have shown that same-day strength training among female athletes did not have any effect on various aspects of performance. Results from previous studies suggest that strength training is not as detrimental to performance as once thought, warranting further research in other sports. Therefore, the purpose of this study was to evaluate the effects of same-day strength training on velocity and accuracy

16 4 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE of the tennis serve, compared to serve performance without an earlier strength training stimulus. METHODS Subjects Ten members of the women s intercollegiate Division I tennis team at Brigham Young University were invited to participate in this study. Subjects followed a specified strength training program throughout the duration of this study. The strength training program was designed by the coaches and strength training staff. None of the participants had been involved in a periodized strength training program that consisted of lifting two or more times a week within the last 3 months. All participants had been involved in a regular strength training program in the last year which consisted of lifting two or more times a week for at least six weeks. All participants completed and signed an informed consent form prior to participation in the study. This study was approved by the Institutional Review Board (IRB) at Brigham Young University. Experimental Design A 2x2x2 repeated measures design guided this study. Serve performance of each participant was measured four times for each of the two variables over the course of this study. Testing occurred twice each week in conjunction with the strength training program, termed the lift-day (LD), and twice without the strength training stimulus, termed the non lift day (NLD). This occurred at the second week and sixth week of the strength training program. Strength training sessions started the second

17 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 5 week of September on Monday, Tuesday, Thursday, and Friday, with lifting taking place at 6:45 a.m. the day of testing. Testing was performed four times each week at 11:30 a.m., approximately a half hour prior to the start of practice. This allowed an average of four hours rest from the end of the strength training session to the start of serve testing. There was at least a 24 hour span between each of the serve testing days. Upper and lower body strength training sessions were each performed twice a week for a total of four strength training sessions per week. Serve performance was tested on the same day that the lower body and core was strength trained. The decision was made to serve test the same day as the lower body strength training was performed because 54% of the total force generated during serve performance comes from the leg/hip/trunk link, with only 21% of total force coming from the shoulder (12). Strength Training Program The strength training program was designed as a split-body routine. Each strength training session included a warm-up followed by a variety of either upper or lower body lifts using two to six sets of three to ten repetitions with each exercise. Training intensity varied between 60% and 90% of a one repetition maximum (1 RM), depending on the number of sets and reps that were performed. Lifts performed on the lower-body strength training day included squats, hang cleans, lunges, stiff leg deadlifts, and calf raises. Serve Performance Both velocity and accuracy were measured during all serve testing sessions and each participant completed 20 NCAA Division I match rule serves per session.

18 6 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE Subjects were given a second attempt if the first serve was fault, and if both serves were fault, zero points were awarded for that serve. If a serve hit the net and landed in the service court, also known as a let, subjects were given a re-serve which did not count against the two attempts given for each one serve. Ball velocity (mph) was measured using a Sports Radar gun (Sports Radar Company; Homosassa, FL). The radar gun was placed inside the serve court, set back 8 inches from the net, and 18 inches from the midline stripe, in the opposite serve court so that it was in line with the individual. This allowed for velocity to be recorded as the ball came off the racquet, even if the net was hit, or a let occurred. Accuracy was measured by the ability to serve into a marked area of the deuce court. There were three arcs drawn on the court, the first measuring 18 inches from the midline corner and each subsequent line 18 inches from the previous one (Figure 1). The highest value of 1.75 points was rewarded for serving within the arced area closest to the corner, 1.5 points for serving within the second arc, 1.25 points for serving within the third arc, one point for any other part of the serve court, and zero points were awarded for a double fault serve. Velocity (mph) of each serve was multiplied by the accuracy point value to create an overall serve performance score for each serve. Overall serve performance scores for all 20 scores were averaged to create one score for each day. Statistical Analysis A 2X2X2 repeated measures ANOVA was used to compare the serve testing scores between 1) lift day (LD) verses non-lift day (NLD), 2) following two and six

19 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 7 weeks of training, and 3) the first day verses the second day of testing each week. Because initial results between the two weeks of testing showed no significant difference in any of the variables (velocity, accuracy, and velocity x accuracy), the data were pooled so only serve performance scores on LD and NLD were compared. A oneway repeated measures ANOVA was then computed to compare velocity, accuracy, and velocity x accuracy between the NLD and LD (alpha = 0.05). The pooled data allowed for an increase in power in the statistical analysis. RESULTS Of the ten tennis team members who were invited to participate in this study, five completed the study. All five players which discontinued participation in the study did so due to non-research related injuries or issues. A summary of the serve performance scores (velocity, accuracy, and velocity x accuracy) on the LD and NLD are shown in Table 1. The repeated measures ANOVA revealed no significant difference between serve performance variables between the LD and NLD following two and six weeks of training. The average serve velocity on the NLD and the LD was ± 2.3 mph and ± 2.9 mph, respectively. The difference between serve velocity on the NLD and LD (1.22 ± 0.6 mph) was not significant (p = 0.15). The overall serve accuracy on the NLD and the LD was 0.95 ± 1.01 and 0.98 ± 0.89, respectively. The difference between the serve accuracy on the NLD and LD (0.06 ± 0.12) was not significant (p = 0.48).

20 8 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE The overall serve performance score (velocity x accuracy) on the NLD and LD was ± 8.54 and ± 7.39, respectively. The individual combined difference between the overall serve performance scores on the NLD and LD (3.67 ± 1.15) was not significant (p = 0.84). DISCUSSION The results of this study suggest that same-day lower body strength training followed by adequate recovery does not have a detrimental effect on serve performance following two or six weeks of strength training. These findings agree with those of Woolstenhulme et al. (17) who reported that strength training had no effect on either anaerobic power or shooting accuracy when both were performed on the same day by female collegiate basketball players. The underlying reason for why coaches and players often forego strength training on the same day as a performance is the potential for muscle fatigue and soreness to alter performance. Bloomer and Ives (4) reported that in order for a muscle fiber to be trained, it must first be recruited and then fatigued. Furthermore, Rooney et al. (16) stated that skeletal muscle fatigue contributes to strength training induced gains in strength. Fatigue as defined by Kent-Braun (11) and Allman (1) is the reduction in the maximum force generating capacity of a muscle. Evidence of muscle fatigue, such as alterations to excitation-contraction coupling has been shown to still be present one day post isometric resistance training, and also muscle damage was present 3-5 days post training (3). It has also been shown that proprioception altered by fatigue could lead to disruption in efferent neuromuscular responses (14) causing a decrease in

21 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 9 control over the speed of movement, and decrease the accuracy of position sense (9) affecting serve performance. We speculate that the strength training program used in this study did not have an effect on serve performance because it did not induce fatigue or soreness of significant magnitude or duration. It is unlikely that an athlete would engage in strength training to the extent of intentionally causing lasting fatigue and soreness that would influence performance. The intent of the strength training program used in this study was not necessarily to induce fatigue or soreness but to represent an in season strength training session that an athlete would typically perform. There are several reasons why the strength training program used in this study did not induce muscle fatigue or soreness of the magnitude or duration necessary to affect performance. The strength training program used in this study was a split body routine and serve performance was measured only following the lower body lifting session. It was shown by Kibler (12) that 51% of the kinetic energy and 54% of total force generated during the tennis serve originated from the leg/hip/trunk link, with only 13% of total energy and 21% of total force coming from the shoulder. Therefore, it was assumed that serve performance would be most affected following a lower body strength training session. The fact that service performance was not affected by sameday strength training suggests that fatigue was not severe enough to alter performance. We also believe that the split-body strength training was not a factor because the results of this study agreed with results of previous studies done at Brigham Young University which used a full-body strength training routine while researching the effects of same

22 10 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE day strength training on performance among female collegiate soccer and basketball players (13, 17). Carpenter et al. (6) suggested that the alterations in shoulder proprioception that could lead to changes affecting serve performance may be reduced with proper training. Therefore, serve performance of athletes with greater strength training experience is less likely to be affected by changes in shoulder proprioception related to strength training. Same-day strength training may not have affected serve performance of athletes in this study because they had been involved in strength training prior to the beginning of the study. Therefore, the participants were accustomed to strength training and were already somewhat conditioned despite the two month lag in the strength training program. Bompa (5) suggested that recovery following activity is largely associated with fitness level. The higher the fitness level, the faster the recovery of skeletal muscles following a fatiguing bout of exercise. This infers that the four-hour rest period between strength training and serve performance in this study was sufficient enough to provide the participants of this study time to recover. Woolstenhulme (17) and Murakami (13) made similar conclusions. Woolstenhulme (17) reported that six hours was enough recovery time between strength training and anaerobic power testing, and eight hours was enough recovery time before speed spot shooting among female basketball players. Clarkson et al. (7) demonstrated that exercise induced injury to the anatomy of the muscle depends on an individuals training level, with a more trained individual

23 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 11 experiencing less damage. The subjects in this study were members of a Division I intercollegiate tennis team, who had been engaged in a routine strength training program for at least two weeks prior to assessing serve performance and had been involved in similar strength program in the year prior to testing. Serve performance was tested following the second week of strength training in this study to avoid the effects of delayed onset muscle soreness often experienced at the commencement of a strength training program. The findings of this study also support the suggestions made by Carpenter et al. (6) and Bompa (5) that the higher the training level, the less likely that the expected effects of fatigue that are seen in untrained populations would occur. Our findings may also support those of Behm et al. (3) who reported trained individuals had less of a chance of losing velocity if muscle damage occurs. Most strength training programs are periodized so that less strain is put on the muscle during in-season competition times, and more strain during the off season. Because tennis has multiple competition seasons, athletes or coaches may decrease the lifting load to prevent unwanted muscle soreness that is thought to affect performance. This raises the question of whether or not the lifting load would be sufficient to elicit the desired fatigue (i.e., training) response. Because testing was not done immediately following the strength training stimulus, it is unknown if the stimulus received was enough to cause muscle fatigue that would alter serve performance, or if the subjects had enough recovery time. Due to the fact the lifting program was a split body routine, even if the stimulus was enough to elicit change, results may have not been as significant if compared to a same-day total-body strength training routine evaluated in a

24 12 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE similar manner, despite the fact that over half the total energy and force come from the lower half of the body (12). The sample size for this study was small leading to a question of power, but results of a power analysis showed that with an alpha of 0.05, power was However, the mean difference between the LD and the NLD was only one-tenth of the standard deviation between subjects, suggesting a low effect size. We also computed an effect size analysis that assumed a stronger power of 0.8 and found that the mean detectible difference that would be statistically significant was This was over two times the amount of the mean difference found in our study (0.49), suggesting that even if we had more subjects, and greater power in this study, the results would still be in favor for strength training on the same day as serve performance. In addition, the accuracy and overall scores were slightly better in the LD group, suggesting that there would still be no detrimental effect of weight training seen, even if more subjects had been included. There was a slight trend toward decreased velocity on the LD when evaluated alone, however this decrease was not statistically significant. This information might be useful for future research, in that training might affect speed, but not accuracy, and when taken performance into account on same-day strength training days, subjects may decrease speed and increase accuracy as a compensation. One aspect that is crucial to sport performance is how the athlete feels and the psychological ramifications that may accompany same-day strength training and performance testing. This study did not evaluate the psychological effects of strength

25 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 13 training and performance on the same day, we therefore cannot rule out the possible psychological impact of same-day strength training on competitive performance. Even though there was no significant difference between the LD and the NLD, an athlete or coach who has the mindset that same-day strength training affects performance, may not be able to accept such results. Future studies can begin to evaluate any psychological changes that might result from a similar same-day strength training study, and they can also begin to look at the effects that same-day strength training has on performance within four hours of strength training, since this study and other studies (13, 17) showed that fatigue was not an issue after then. PRACTICAL APPLICATIONS The results of this study suggest that when routine strength-training sessions and tennis matches fall on the same day, athletes do not need to forego their regularly scheduled strength-training session if adequate recovery time is permitted. Serve performance was not effected by same day lower body strength training followed with adequate recovery.

26 14 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE References 1. ALLMAN, B.L., and C.L. RICE. Neuromuscular fatigue and aging: Central and peripheral factors. Muscle and Nerve. 25: BAHAMONDE, R.E. Changes in angular momentum during the tennis serve. J. Sports Sci. 18(8): BEHM, D.G., K.M. BAKER, R. KELLAND, and J. LOMOND. The effect of muscle damage on strength and fatigue deficits. J. Strength Cond. Res. 15(2): BLOOMER, R.J., and J.C. IVES. Varying neural and hypertrophic influences in a strength program. NSCA J. 22(2): BOMPA, T. Periodization of Strength: The New Wave in Strength Training. Toronto, ON, Canada: Veritas, CARPENTER, J.E., R.B. BLASIER, G.G. PELLIZZON. The effects of muscle fatigue on shoulder joint position sense. Am. J. Sports Med. 26(2): CLARKSON, P.M., K. NOSAKA, and B. BRUAN. Muscle function after exercise-induced muscle damage and rapid adaptation. Med. Sci. Sports Exerc. 24(5): COHEN, D.B., and M.A. MONT. Upper extremity physical factors affecting tennis serve velocity. Am. J. Sports Med. 22(6):

27 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE FORESTIER, N., N. TEASDALE, and V. NOUGIER. Alteration of the position sense at the ankle induced by muscular fatigue humans. Med. Sci. Sports Exerc. 34(1): KAURANEN, K.L., T.S. PERTTI, and H.V. VANHARANTA. Strength training for 1h in humans: effect on the motor performance of normal upper extremities. Eur. J. Appl. Physiol. 79(5): KENT-BRAUN, J.A. Central and peripheral contributions to muscle fatigue in humans during sustained maximal effort. Eur. J. Appl. Physiol. 80: KIBLER, W.B. Biomechanical analysis of the shoulder during tennis activities. Clin. Sports Med. 14(1): MURAKAMI, Y. The effect of same-day strength training on ball velocity of division I female soccer players. Masters Thesis, Brigham Young University, Provo, MYERS, J.B., and S.M. LEPHART. The role of the sensorimotor system in the athletic shoulder. J. Athl. Train. 35(3): ROETERT, E.P., T.S. ELLENBECKER, D.A. CHU, and B.S. BUGG. Tennisspecific shoulder and trunk strength training. Strength Cond. 19(3): ROONEY, K.J., R.D. HERBERT, and R.J. BALNAVE. Fatigue contributes to the strength training stimulus. Med. Sci. Sports Exerc. 26(9):

28 16 SAME-DAY STRENGTH TRAINING AND SERVE PERFORMANCE 17. WOOLSTENHULME, M.T., B.K. BAILEY, and P.E. ALLSEN. Vertical jump, anaerobic power, and shooting accuracy are not altered 6 hours after strength training in collegiate women basketball players. J. Strength Cond. Res. 18(3):

29 17 Table 1. Comparison of serve performance scores on lift and non-lift days Non Lift Day Lift Day p Value Velocity ± ± Accuracy ± ± Combined ± ± All values are mean ± standard deviation for all 5 subjects and both weeks of serve testing. Combined value represents velocity x accuracy.

30 18 NET Figure 1. Court setup with accuracy lines.

31 19 Appendix A Prospectus

32 20 Chapter 1 Introduction Tennis is an age-old sport that has over the years become a highly competitive sport that requires a tremendous amount of power and accuracy. One of the most important strokes is the tennis serve. The serve is the start of each point and is the only aspect in which a player has total control over its outcome (Bahoamonde, 2000). However, it is the most difficult stroke to learn, because of the complex movements involving the trunk, upper and lower extremities, all working in coordination with each other (Bahoamonde, 2000). This coordination of body parts is termed the kinetic chain (Cohen and Mont, 1994; Roetert, Ellenbecker, Chu, and Bugg, 1997), and allows generation, summation, transfer, and regulation of forces from the legs to the hand (Kibler, 1995). It is well known that in order to increase power, muscle strength of the entire kinetic chain must also be increased. Strength training has, therefore, become a vital aspect of tennis training. Because of the long tennis season, strength training is often performed during the competitive season. Due to the multiple competition seasons, it is inevitable that some of the scheduled strength training sessions fall on the same day as a match. Due to the popular opinion that strength training the same day as competition will decrease performance, many athletes and coaches choose to forgo such strength training sessions (Kerbs, 2000; Woolstenhulme, 2000). Little research has been completed evaluating the effects of same-day strength training on sport performance (Kauranen, Pertti, and Vanharanta, 1999; Kerbs, 2000;

33 21 Murakami, 2002; Woolstenhulme, 2000). However, it is still unclear whether strength training the day of competition is beneficial, detrimental, or has no effect at all (Kerbs, 2000; Woolstenhulme, 2000). No research has been done on evaluating the effects of strength training on the tennis serve, and no research was found reviewing same-day strength training effects on elite tennis players in moderately or highly strength trained conditions. Statement of Problem The main purpose of this study will be to evaluate the effects of same-day strength training on velocity and accuracy of the tennis serve. It will also evaluate whether the effects of same-day strength training are different between elite tennis players in a moderately trained and a highly strength trained state. Null Hypothesis 1. Same-day strength training will have no significant effect on service performance (velocity and accuracy). 2. The effects of same-day strength training will be no different between moderately and highly strength trained players. Alternate Hypothesis 1. Strength training will have an effect on performance of a tennis serve when both strength training and service performance are performed the same day. 2. There will be a difference in the effects on serve performance after same-day strength training between moderate and highly trained states.

34 22 Operational Definitions Kinetic chain - the link of legs, hips, trunk, and upper limbs that generates force for certain motions, such as the tennis serve. Elite tennis player - an individual who has played competitive tennis and is a member of a Division I NCAA collegiate tennis team. Moderately trained state - An individual who is currently involved in a highly regular total body strength program, strength training at least twice a week for no more than two weeks, but prior to the two weeks has had no regular total body strength training program, strength training less that once every week for the prior two months. However, in the prior year the individual has at some time been involved in a regular strength training program. Highly trained state - An individual who is involved in a highly regular, total body strength training program, strength training two or more times a week for at least six weeks. Service accuracy - The ability to serve into a specified area marked on the tennis court. Assumptions 1. The subjects will give maximal effort throughout this study. 2. A player is considered elite by being on a NCAA Division I college tennis team. Delimitations 1. The tennis serve is an accurate measure of competition performance. 2. The subjects tested will be collegiate age.

35 23 3. Only females will be evaluated. 4. The study will evaluate only the serve, which is one aspect of tennis play. Limitations 1. Overall performance is limited in a controlled setting. Any detriment that may have been seen in the controlled setting could be overcome in an actual competition setting due to the motivation, adrenaline, influence of coaches, and fans. 2. Subjects will be volunteer members of Brigham Young University women s collegiate tennis team. Significance Most coaches and players understand that strength training will help improve performance. It is important that both coaches and players understand the effects of sameday strength training on tennis performance. If strength training were detrimental to serve velocity or accuracy at any time in the season, then it would be understood that it should be avoided. On the other hand, if there is no detriment to performance, there may be potential benefits of not missing a strength training session and allowing better compliance with the strength training regimen. It is also important to know if a player in the moderate level of training will elicit detriments to serve performance that are not seen when the player becomes highly trained.

36 24 Chapter 2 Review of Literature Search Contents In order to find research to aid in writing this literature review, the following internet indexes were searched: Medline (EBSCO), CINHAL, SportDISCUS (WEBSPIRS). The following grid below outlines the main key terms that were used and how they were combined. References of three unpublished studies done by previous master students (Kerbs, 2000; Woolstenhulme, 2000; Murakami, 2002) on the effects of strength training and same-day performance were also thoroughly searched. Effects of Fatigue and Tennis and Author Search Strength training Strength training Strength training Lephart-S* (Scott) Biomechanics and Biomechanics Biomechanics fatigue Fatigue and muscle Proprioception Biomechanics and shoulder Proprioception and fatigue Tennis has become one of the most highly competitive sports over the years. In earlier years the tennis serve was merely the means to put the ball into play, and now the tennis serve has become one of the key elements of play, and is the single most devastating stroke that can provide an advantage over the opponent (Talbert and Fishman, 1977). A serve requires a tremendous amount of velocity, along with faultless accuracy in order to be a threat. There are three main serves in tennis, termed according to the spin of the ball. A kick serve, also known as the American twist serve, has topspin that when serving from the right side will cause the ball to hit the serve court and take an

37 25 abrupt jump up and towards the left, or opposite side of the person serving (Talbert and Fishman, 1977). A slice or spin serve has side spin that will cause the ball to bounce and spin toward the same side of the person serving (Talbert and Fishman, 1977). Whereas, a flat serve has little to (or) no spin and tends to go strait at the opponent leaving little margin for error (Talbert and Fishman, 1977). Each serve requires the highly coordinated movement of various body parts known as the kinetic chain. Reaction forces are transferred from the ground through the body segments of the kinetic chain and finally to the racket (Bahamonde, 2000). In order to generate the greatest hand or racquet speed at ball impact, the shoulder must be able to generate force, but also function as a link in the kinetic chain, transferring forces from the legs, hips, and trunk to the racquet. A study done by Kibler (1995) on world class tennis players showed that rotational velocities of 1500 deg/sec are achieved in the service motion. Hand speed at ball impact as a result of these velocities is approximately 47 miles per hour. It has been shown that 51% of the total kinetic energy and 54% of the total force originates from the leg/hip/trunk link, with only 21% of total force coming from the shoulder (Kibler, 1995). In order to increase velocity, strength training needs to include the entire kinetic chain. Cohen and Mont (1994) showed that there is a positive correlation between increased muscle strength and increases in the velocity of a tennis serve. Strength Training It is important to maintain a routine strength training schedule. With the popular belief by coaches and players that strength training should be avoided on game days,

38 26 because of the long standing idea that it will cause detriments to performance, constant adjustments are being made to the strength training schedule. Because matches do not always fall on the same day of the week, many strength training sessions are missed or not taken seriously, causing the athlete to miss the potential benefits that accompany each strength training session. In order to maintain optimal training levels and take advantage of the potential benefits, it is suggested that strength training sessions not be missed. Strength training has been proven to increase muscle force, strength, agility, coordination, and power, all of which are essential to tennis (Kraemer, Ratamess, Fry, et al., 2000). Hendrick (1993) showed that strength training one time per week will slow the rate of decline, but will not maintain strength and power. There are three modes of strength training: isokinetic (concentric-concentric, concentric-eccentric), isometric, and isotonic resistance. The three modes are classified according to the difference between how the resistance is applied to the muscle. With isokinetic training, a computer is used to assure that resistance to the muscle is accommodated as the joint moves through normal range of motion. The computer can be programmed to allow for concentric-eccentric contractions, but is commonly a concentric-concentric contraction. Isometric training applies resistance to the muscle without any change to joint angle, whereas isotonic training is a constant resistance as the joint moves through the full range of motion and is almost always concentric-eccentric contractions. All methods have shown to increase muscular strength in healthy individuals; however, strength gains may be compromised in isokinetic training, because of the omission of eccentric contractions most of the time (Marks, 1996).

39 27 Despite the type of training, there are neural and muscular adaptations that contribute to the increased development of muscle force. Several authors have described the neural adaptation observed in the muscle, with training (Enoka, 1988; Marks, 1996; Moritani and Devries, 1979; Sale, 1988). Marks (1996) and Kauranen, Pertti, and Vanharanta (1998) have suggested that increased neural density of signal generation is responsible for the improvement in neuromuscular performance. An increase in firing rate and recruitment will lead to increases in coordination and specificity of movement (Kauranen et al., 1998). Evaluating this idea, Hoff and Almasbakk (1995) conducted a study on a team of female handball players using heavy resistance strength training exercises and specificity of movement training. Results showed that throwing velocity increased with strength training, and when combined with specificity of movement training of the throwing motion, it increased the speed of muscle unloading. This suggests that the increase in motor unit recruitment carried over from strength training to the specificity of movement. Sale (1988) suggested that improved coordination or increased learning was associated mainly with neural adaptation. Neural gains in strength are accomplished by additional motor units being activated through increased motor unit firing rate, increased absolute number of active motor units in a synergistic fashion, or the relative motor unit net increases between agonist activation and antagonist inhibition (Bloomer and Ives, 2000). These increases in neuromuscular properties are followed by hypertrophy gains and other myogenic responses (Marks, 1996).

40 28 Such myogenic responses include: increases in the size of muscle fibers, increase in contractile protein concentration, conversion of fiber types, increases in the crosssectional area, and changes in calcium uptake and release (Marks, 1996). These responses help to increase strength and performance. Effects of Strength Training In order to evaluate any potential detriment to performance, the effects of strength training need to be understood. It has been suggested that in order for a muscle fiber to be trained, it must first be recruited and then fatigued (Bloomer and Ives, 2000). It is this fatigue that brings about strength gains (Rooney, Herbert, and Balnave, 1994). However, fatigue may be one of the possible causes of decreased performance following strength training. Muscle and fiber damage, as well as psychological factors may also contribute to decrements in performance following strength training. Fatigue Fatigue, defined as an acute reduction in the ability to exert maximum forcegenerating capacity of a muscle regardless of whether or not the task itself can still be performed successfully (Allman and Rice, 2002; Kent-Braun, 1999), has been shown to decrease muscle strength, proprioception, position sense, and alter biomechanics. It can occur in the central or peripheral regions and has been reported to be multi causal, with fatigue to specific fiber type, and recruitment of motor units being the major factors (McLaughlin, 2001). Many factors will contribute to local fatigue. Skeletal muscle fiber type is related to fatigue in that the type I fibers are slow twitch (ST), highly oxidative, highly resistant to fatigue. Fast twitch (FT) type II fibers have a low oxidative capacity

41 29 and are less resistant to fatigue. As the load of training increases, FT fibers are activated in order to perform the fast, high-power contraction (Bompa, 1993). Training has been reported to significantly increase power and maximum strength (Bompa, 1993), but because type II fibers are less resistant to fatigue, there will be greater chance that fatigue will affect performance later the same day. It is unknown how long fatigue inhibits performance but has been shown to vary depending on the causes of fatigue (Behm et al., 2001). Behm et al. examined whether an acute bout of resistance training had prolonged detrimental effects on muscle activation and excitation-contraction coupling. The study showed that decreases in eccentric and isometric force were still present one day post exercise, muscle damage was still present 3-5 days post, and muscle inactivation was a contributor to strength deficit one day post exercise. Despite the fact that certain changes are still present one day post exercise it is not known whether this will affect same-day performance. No research was found showing immediate increases to performance following a strength training bout. Decreases in the recruitment of motor units due to fatigue are seen in the peripheral nervous system (PNS), and within the central nervous system (CNS). Central nervous system fatigue can be neurobiological or psychological, but despite the origin, central drive is reduced and this will lead to a decrease in motor unit recruitment. Central nervous system has been linked to neurochemical changes that may have time courses lasting longer than that of muscle metabolic fatigue (Bloomer and Ives, 2000). Even if a muscle is recovered metabolically, the nervous system may not be capable of recruiting high-threshold fibers later on to perform maximum level tasks, such as serving. This

42 30 fatigue is task-dependant and may be mediated by intrinsic motoneuronal, spinal, and supraspinal factors (Allman and Rice, 2002). Proprioception is the perception of joint and body movements as well as position of the body, or body segments, in space (Hiemstra et al., 2001). A study by Myers, Guskiewicz, Schneider, and Prentice (1999) compared the ability for a subject to reproduce shoulder position and perform a dynamic stability test before and after fatigue. It was shown that fatigue decreases proprioception of the shoulder (Myers et al., 1999). The suggested causes of decreased proprioception are those that directly relate to central fatigue and peripheral muscle fatigue, such as changes in the metabolic capacity. A decrease in proprioception suggests that there could be a disruption in efferent neuromuscular responses (Myers and Lephart, 2000) causing a decrease in control over the speed of movement, and decrease the accuracy of position sense (Forestier, Teasdale, and Nougier, 2002). Peripheral fatigue is believed to affect joint position sense that is vital to joint stability. A possible cause is desensitization of the muscle spindle, resulting from changes in local metabolism at the muscle (Myers and Lephart, 2000). Such changes include increased concentrations of lactic acid, potassium chloride, bradykinin, arachidonic acid, and serotonin after fatiguing contractions (Myers and Lephart, 2000). Articles reviewed by Allman and Rice (2002) and Kent-Braun (1999) suggested that metabolic inhibition occurs after fatigue, due to accumulation of metabolites altering muscle contractile properties. A study done by Carpenter, Blasier, and Pellizzon (1998) on the effects of muscle fatigue on position sense of the shoulder showed that position

43 31 sense was greatly reduced after fatiguing exercises. Carpenter et al. speculated that if fatigue interferes with position sense, then shoulder function might loose normal muscle coordination, impairing shoulder function (Carpenter et al., 1998). This impaired shoulder function and changes to coordination may alter normal biomechanics. The biomechanics of a tennis serve is a sequential motion, starting from the ground up to the racket (Bahamonde, 2000). Because sequential motion is influenced and ultimately determined by muscular forces distinctive patterns of motion and muscle activation may occur (Rodacki, Fowler, and Bennett, 2001). It could then be assumed that when muscle strength is decreased, following fatigue, reorganization to the coordinated muscle activation of the kinetic chain will occur (Rodacki et al., 2001). If fatigue alters a coordinated pattern, it may be possible that the tennis serve, which is a highly coordinated movement, is subject to adjustments in kinetic chain patterns that will be detrimental to serve performance. Myers et al. (1999) observed the effects of fatigue on proprioception and neuromuscular control, and found decreases in proprioception, but no effect on neuromuscular control, as assessed by sway velocity, or degrees traveled away from one s center of gravity during a ten second trial. However, there was an increase in the number of falls following muscle fatigue, suggesting possible changes to the CNS. The findings of decreased proprioception by Myers et al. (1999) agree with a review by Carpenter et al. (1998) that athletic performance is decreased following muscle fatigue. It has also been shown that muscle fatigue leads to decreases in positions sense at the knee (Hiemstra et al., 2001), and the ankle (Forestier et al., 2002). Sharpe and

44 32 Miles (1993) showed that position sense at the elbow following fatigue leads to a greater number of errors when recreating passive position sense. However, with all of these studies, testing was done immediately after the fatiguing exercise(s). Muscle and Fiber Damage Muscle damage may occur following a strength training session, especially if the session includes eccentric contractions (Friden and Liber, 1992). Strength training induced muscle damage has been well reviewed since Hough (1902) first investigated the phenomenon of delayed onset muscle soreness (DOMS) following exercise (Clarkson, 1992). Muscle damage can result in a loss of muscle force (Behm et al., 2001; Clarkson, Nosaka, and Bruan, 1992), leading to muscle fatigue. The decrease in force may be a result of changes to the sarcomeres as they become stretched during eccentric lengthening actions (Clarkson et al., 1992). Any disruption to the sarcoplasmic reticulum (SR) will result in impaired calcium restoration following activity, leading to a decline of calcium release over time (Behm et al., 2001; Clarkson et al., 1992). Clarkson et al. (1992) suggested that impaired calcium release would contribute to peripheral fatigue. This SR damage can affect an individual s day to day functioning (Behm et al., 2001). Clarkson et al. (1992) reviewed muscle function following exercise induced muscle damage and found muscle soreness and swelling were still present 2-3 days and five days, respectively, following serial repetitions of maximal effort eccentric contractions. However, no studies were found showing this prolonged effect of swelling and soreness on skill performance.

45 33 Performance Effects There have been a few published studies that evaluated the effects of strength training on sport-specific parameters (Kauranen et al., 1999; Shoenfelt, 1991). Shoenfelt (1991) showed that there was no immediate detriment of weight training when compared to aerobic exercise on the performance of free-throw shooting in college players. Two master theses, unpublished to date (Kerbs, 2000; Woolstenhulme, 2000), have also evaluated the effects of strength training on same-day performance in female collegiate basketball players. Woolstenhulme (2000) showed that strength training six hours before testing had no influence on predicted VO 2 max, vertical jump, and anaerobic power, suggesting that strength training weights on game days will not significantly affect physiological performance. Kerbs (2000) showed that there was no detriment after eight hours to free-throw shooting and speed spot shooting, when compared to measurements taken on strength training days, and non-strength training days. Kauranen (1999) showed that after intense strength training of the upper extremity for one hour, there were no negative effects on immediate motor performance functions of the hand. Training Level It has been suggested that with proper training, it may be possible to limit the amount of decreased shoulder proprioception (Carpenter et al., 1998). The higher the level of strength training performance, the more the changes seen in shoulder proprioception following fatigue would be limited. Bompa (1993) also suggested that recovery following activity is largely associated with fitness level, the higher the fitness level, the faster the recovery of muscles following fatigue. Due to the fact that most