PROFESSIONAL TENNIS PLAYERS

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1 INFLUENCE OF PHYSICAL TRAINING ON CORE MUSCLES IN PROFESSIONAL TENNIS PLAYERS Mara Estevez, PT, Cert. MDT 1 Alejandro R. Greco, PT 2 Santiago Gómez Argüello, PT, Cert. MDT 3 ABSTRACT Objective: To evaluate changes of the core muscles endurance professional tennis players after a non-specific physical training program. Material and Methods: We performed the muscular endurance test protocol developed by Stuart McGill 11 (Appendix 1) to 17 professional tennis players in January and July 2011 who developed a non-specific physical training program. Results: 50% of the ratios worsened in the total number of tennis players who were under the core stabilization program. Even though, the players who most increased endurance times were the ones who most worsened the ratios. Conclusion: n: The tennis players who do not practice a specific and individualized physical training program could produce an imbalance in the ratios of the core muscles increasing the injury risk. 1 Physical Therapist and coordinator of the tennis academy "Tenis Planet", El Clú, Saavedra, CABA, Argentina. 2 Physical Therapist of the Argentine Davis Cup Team. 3 Physical Therapist at the hospital of the Maimonides University, CABA, Argentina. 1 Influence of core muscles physical training in professional tennis players

2 INTRODUCTION AND OBJECTIVE CTIVES Tennis is a game of repetition. With such a great amount of repetition it is easy to see how a tennis player could develop strength and flexibility imbalances throughout their body, which could lead to injury or limit performance if not corrected 1. Tennis demands the spine to repeat movements of flexion, extension, lateral bending and rotation, and has been shown that intense matches are generally a risk factor for developing low back pain 2. The function of the spine is to be the fixed point from which the extremities are anchored to produce the correct mechanical movement. Therefore it is necessary that the muscles that provide support have the endurance and strength needed to control, coordinate and optimize function. If trunk muscles fatigue, as occurs during intense training or matches, it produces a loss in synchrony between upper and lower extremities, which may cause a reduction in muscle strength. This may in turn prevent a proper transfer of force resulting in inappropriate compensation by the body while performing a particular function 3. When applied to sports performance, the stability of the core provides foundation upon which the upper and lower extremities may contract to accelerate or decelerate body segments 4. For example, athletes that perform throwing type joint actions may benefit from greater core stability as ground reaction forces are transferred up through the lower extremities, across the trunk, and out to the throwing arm 5. During throwing type joint actions, the kinetic energy of the ball or implement gradually increases, which allows for maximal velocity at the point of impact or release. However, deconditioned core muscles may not effectively transfer kinetic energy, with greater compensatory stress being placed on the muscles, joints, and connective tissues of the arm in order to maintain high throwing velocity. Under such conditions, the athlete is more prone to injury 5. By strengthening the core, one enhances the ability to better utilize the musculature of upper and lower body to perform a task. This means to produce more efficient, accurate, and powerful movements. Furthermore, a strong trunk is critical because force is transferred most efficiently through the body in a straight line. When the trunk is poorly developed, the result is poor posture, which can lead to less efficient movements 6. 2 Influence of core muscles physical training in professional tennis players

3 Therefore, without adequate core strength and stability, the athlete will not be able to apply extremity strength. This coupling action, created by a strong core, connects movements of the lower body to those of the upper body and vice versa. A well-developed core allows for improved output, increase in neuromuscular efficiency and a decrease incidence of overuse injuries 7. If you select a normal person from the street and test their core strength you will find that the muscles of the lower back are slightly stronger than those of the abdominal 8, 9. In tennis players, however, this is not the case. Roetert et. al. 9 found that the abdominal muscles that flex the trunk are actually stronger than the back muscles in elite junior tennis players. It is likely that this is due to the fact that these players use the abdominal muscles to generate the trunk flexion that occurs with every serve that is hit. It is important to address this strength imbalance because weak musculature in the lower back may contribute to low back injury which is the number one injury sustained in tennis. Ellenbecker and Roetert 10 tested elite junior tennis players and found a symmetrical rotational strength of the trunk using an isokinetic dynamometer, indicating that healthy players and uninjured players should have a symmetrical strength development in both rotation directions, left and right. This provides more useful information on the core training strategy of tennis players. Emphasis should be placed in both flexors and extensors to ensure that a balanced muscle development is produced, as well as an emphasis on rotation exercises due to the predominance of trunk rotation inherent in all tennis strokes. This paper aims to measure the performance of the core muscles after six months of training in professional tennis players. 3 Influence of core muscles physical training in professional tennis players

4 MATERIAL AND METHODS We performed an observational, descriptive, prospective, longitudinal study. Seventeen professional tennis players, aged between 16 and 20 years old (mean 17,86) of the tennis academy "Tenis Planet", Saavedra, Bs. As., Argentina, were included in this study. All male players and without injuries at the moment of the test. Nine were eliminated. One by presenting an injury at the time of the second test; two for not attending on the day of the second test; and six because they left the academy before the second test. Therefore, there were eight players in the study. We performed the muscular endurance test protocol developed by Stuart McGill 11 (Appendix 1) to the players on January and July The maximum time (in seconds) that they could maintain certain postures for the different muscles groups in the zone (flexors, extensors and laterals) was measured with a stopwatch. After obtaining the maximum times, we compared the two records with the times and mean ratios found in healthy individuals in a study done by McGill and Col (2007) (Appendix 2). The players were practicing general core stabilization exercises prior to the tests, which were not modified during the time between the two tests. 4 Influence of core muscles physical training in professional tennis players

5 RESULTS The results of the eight players that were analyzed are in the charts below: In July only 3 players (37,5%) increased flexion endurance time (ES, FR y WE); 2 (25%) were closer to the mean (FR y WE); and only 4 (50%) were within the range defined by ±1 SD (JPO, AS, FR y WE). 5 Influence of core muscles physical training in professional tennis players

6 In the extension, in July, 3 players (37,5%) increased (CW, ES y WE) endurance time; 5 (62,5%) were closer to the mean (JPO, CW, ES, TL y WE); y 6 (75%) were within the range defined by ± 1 SD (JPO, CW, ES, FR, JA y TL). In the right side bridge, in July, 4 players (50%) increased endurance time (CW, ES, TL y WE); 4 (50%) were closer to the mean (JPO, ES, TL y WE); y 6 (75%) were within the range defined by ± 1 SD (JPO, CW, FR, JA, TL y WE). 6 Influence of core muscles physical training in professional tennis players

7 In the left side bridge, in July, 3 players (37,5%) increased endurance time (ES, TL y WE); 3 (37,5%) were closer to the mean (ES, TL y WE); y 4 (50%) were within the range defined by ± 1 SD (ES, FR, JA y TL). In the flexion over extension ratio in July, 4 players (50%) were within the range (AS, ES, FR y WE) y 2 (25%) were closer to the mean (CW y ES). In the right side bridge over the left side bridge ratio in July, 3 players (37,5%) were within the range (AS, JA y TL) and 2 (25%) were closer to the mean (JPO y TL). 7 Influence of core muscles physical training in professional tennis players

8 In the right side bridge over the extension ratio in July, 7 players (87,5%) were within the range (JPO, AS, CW, ES, FR, JA y TL) y 4 (50%) were closer to the mean (AS, CW, FR y TL). In the left side bridge over extension ratio in July, 7 players (87,5%) were within the range (JPO, AS, CW, ES, JA, TL y WE) y 6 (75%) were closer to the mean (JPO, AS, CW, ES, JA y TL). 8 Influence of core muscles physical training in professional tennis players

9 At the endurance times we can see that a greater number of players decreased the maximum endurance time in all postures, except in the right side bridge. With respect to the mean, we can see that in both flexion over extension and right over left side bridge ratios, a greater number of players worsened them. Meanwhile, in both side bridges over extension the ratios improved in a greater number of players. 9 Influence of core muscles physical training in professional tennis players

10 In July, flexion, left side bridge and the flexion over extension ratio showed fewer players within acceptable ranges than in January. By contrast, extension, and both side bridges over extension ratios showed a greater number of players. Finally, right side bridge and right over left side bridge ratio showed the same number of players within the range in both tests. This analyze has been done previously on each specific chart. 10 Influence of core muscles physical training in professional tennis players

11 Of the total of all ratios taken from the 8 players, both in January as in July, 50% worsen, 6% remained the same and 44% improved them. 11 Influence of core muscles physical training in professional tennis players

12 DISCUSSIO ION Several studies have shown 12,13,14,15,16,17,18,19,20, that one of the greatest injury risks is the presence of body asymmetries, either in strength, flexibility, alignment, or range of motion. As described above, for the spine to be able to transfer forces efficiently from the lower to the upper extremities, it should be properly stabilized by the trunk muscles. If the force ratios between the different core muscles groups present imbalances, the transfer will be affected and the load increases, both in the spine and in other peripheral joints, increasing injury risk 1, 2, 3, 4, 5, 6, 7. Based on the results presented above, the 8 players doing the exact same stabilization program did not show a consistent pattern of improvement, as some have increased their endurance times, others decreased them, some improved their ratios and others worsened them. It is likely that factors such as playing technique, weekly attendance, illness, injuries, tours, nutrition, hydration, or rest have influenced the results. However, it was clear that 50% of the ratios worsened in the total of all players who were under this core stabilization program. As relevant data we can remark that the ones that most improved their endurance times, which were WE (improved 4 postures) and ES (improved 3 postures), were the ones that had the worst ratios (WE worsened in all and ES just improved in one). By contrast, AS, who worsened at all his endurance times, is one of the players who most improved the ratios (3 ratios and the remaining stayed the same) and is the most balanced player. CONCLUSION The McGill trunk muscular endurance tests taken to these professional tennis players showed that athletes who do not practice a specific and individualized physical training program based on improving ratios imbalances (and not at the maximum endurance times), evidenced in the test, could not improve or even worsen them, increasing in this way the risk of suffering injuries. Further studies will be needed to confirm these results and determine if a specific training program can balance the ratios. 12 Influence of core muscles physical training in professional tennis players

13 REFERENCES 1 Riewald, S. & Ellenbecker, T. El Desequilibrio en el Jugador de Tenis. ITF Coaching and Sport Science Review Dic 2005; 37: Hainline B. Low back injury. Clin Sports Med 1995; 14: Cholewicki, J. and McGill, S.M. Lumbar Posterior Ligament Involvement During Extremely Heavy Lifts Estimated from Fluoroscopic Measurement. Journal of Biomechanics 1992; 25: Hodges, P. W. & Richardson, C. A. Relationship between limb movement speed and associated contraction of the trunk muscles. Ergonomics 1997; 40(11), Willardson, J. Core stability for athletes. 6 Brittenham, D., and G. Brittenham. Stronger Abs and Back. Human Kinetics, Champaign, Illinois Hedrick, A. Training the Trunk for Improved Athletic Performance. Strength and Conditioning Journal 2000; 22(3), McGill, S. M., Childs, A., and Liebenson, C. Endurance times for stabilization exercises: Clinical targets for testing and training from a normal database. Arch. Phys. Med. Rehab. 1999; 80: Roetert, E. P., McKormick, T. J., Brown, S. B., & Ellenbecker, T. S. Relationship between isokinetic and functional trunk strength in elite junior tennis players. Isok Exercise Science 1996; 6: Ellenbecker, T. S. and Roetert EP. An Isokinetic profile of trunk rotation strength in élite tennis players. Med Sci Sports Exerc 2004; 36: McGill, S. M., Low Back Disorders - Evidence Based Prevention and Rehabilitation, Second Edition, Human Kinetics Publishers, Champaign, Illinois, 2007, Nadler, S. F., Malanga GA, Feinberg JH, Prybicien M, Stitik TP, DePrince M. Relationship between hip muscle imbalance and occurrence of low back pain in collegiate athletes: a prospective study. Am J Phys Med Rehabil 2001; 80: Myer, G. D., Brent, J. L., Ford, K. R., Hewett, T. E. A pilot study to determine the effect of trunk and hip focused neuromuscular training on hip and knee isokinetic strength. Br J Sports Med 2008;42: Söderman, K., Alfredson, H., Pietilä, T., Werner, S. Risk factors for leg injuries in female soccer players: a prospective investigation during one out-door season. Knee Surgery, Sports Traumatology, Arthroscopy 2001; 9(5): Baumhauer, J. F., Alosa, D. M., Renstrom Per A. F. H., Trevino, S., Beynnon, B. A Prospective Study of Ankle Injury Risk Factors. Am J Sports Med September 1995 vol. 23 no Rauh, M. J., Koepsell, T. D., Rivara, F. P., Rice, S.G., Margherita, A. J. Quadriceps Angle and Risk of Injury Among High School Cross-Country Runners. JOSP 2007, 37(12): Ekstrand, J. and Gillquist, J. Soccer injuries and their mechanisms. Medicine and Science in Sports and Exercise 1983, 15: Influence of core muscles physical training in professional tennis players

14 18 Knapik, J. J., Bauman, C. L., Jones, B. H., Harris, J., Vaughan, L. Preseason strength and flexibility imbalances associated with athletic injuries in female collegiate athletes. Am J Sports Med January 1991; 19(1): Plisky, P. J., Rauh, M. J., Kaminski, T.W., Underwood, F.B. Star Excursion Balance Test as a predictor of lower extremity injury in high school basketball players. JOSP 2006 Dec; 36(12): Yeung, S. S., Suen, A. M. Y., Yeung, E. W. A prospective cohort study of hamstring injuries in competitive sprinters: preseason muscle imbalance as a possible risk factor. Br J Sports Med 2009;43: Influence of core muscles physical training in professional tennis players

15 APPENDIX PENDIX 1 15 Influence of core muscles physical training in professional tennis players

16 APPENDIX 2 16 Influence of core muscles physical training in professional tennis players

MEASURING BILATERAL ASYMMETRY IN A LONG TERM ATHLETE MONITORING

MEASURING BILATERAL ASYMMETRY IN A LONG TERM ATHLETE MONITORING Kimitake Sato Department of Exercise and Sport Science, Center of Excellence for Sport Science and Coach Education, East Tennessee State