Kintetic Chain Linking in Tennis
Tennis is a great illustration of the concept of kinetic linking and the kinetic chain. Kinetic linking is the coordinated activation of the segments of the body to produce the most efficient movement pattern. Sports that involve striking an object, require coordinated joint rotations occurring in a specific sequence, where power is generated from the core musculature and is transferred quickly to the appendages (Spaniol, 2012) In the case of a tennis groundstroke power is generated from push off and rotation from the foot and ankle complex, and hips is transferred through trunk, to the arm, to the racquet (Papageorgiou, 2016). Optimal timing of a leg drive, trunk rotation, upper arm elevation, forearm extension, arm internal rotation, forearm pronation, and wrist flexion will allow a tennis player to generate powerful groundstrokes.
In an inefficient kinetic chain there are often energy leaks caused by a breakdown in form. An energy leak originates from muscle imbalance, poor stability or weakness, leading to inefficient muscle recruitment. This compromises the speed of movement as other muscle groups compensate, which leads to muscular fatigue, excess stress on joints, and potential overuse injuries (Joyce & Lewindon, 2016). Common kinetic chain breakdowns in a tennis groundstroke can be caused by weak hip musculature, causing a an inadequate production of force from the push-though of the leg leading to compensations in trunk rotation, shoulder rotation, forearm pronation, and wrist flexion, or poor trunk rotation and shoulder posterior musculature causing the wrist and elbow to drive acceleration (Roetert, Kovacs, Knudson, & Groppel, 2009). These kinetic chain leakages increase strain on the elbow in the case of ground strokes. The elbow functions as the transfer site of the kinetic energy of the body and the racquet. Ground strokes that do not maximize the kinetic link increase stresses at the elbow and can be a factor in tendinopathy of the elbow, specifically tennis elbow (lateral epicondylitis).
A good assessment of kinetic chain linkage for tennis groundstrokes would be a side medicine ball throw. This assessment should be included in a full screening of tennis players participating in a strength and conditioning program. Ikeda, Kijima, Kawabata, Fuchimoto, and Ito (2006) found the side medicine ball throw test to be a reliable indicator of explosive power. In the assessment the athlete starts with a light medicine ball (2-5 kg) in a standing position, with the feet slightly apart and facing the direction the ball is to be thrown. The hands grip the ball, and the ball is extended in front of the athlete by the arms. To begin the athlete swings the ball behind them by rotating the trunk and hips back, and then swung back quickly while extending the arms and shoulder and releasing the ball near the top of the shoulders. The athlete should be encouraged to use their back, arms, and legs to generate the most force. This test should be performed on both the right and left side to measure any significant power differences in the sides. The distance should be measured from the athlete from where the ball lands and be used as a benchmark for progress. During the test the coach should look for adequate trunk rotation, drive through the hip, letting the ball go at the right point, and sequencing of the legs, torso and arms (Team SKLZ, 2012). The test is especially good for tennis because a well executed side medicine ball throw follows the same kinetic linking pattern as a ground stroke.
To fix an energy leak in the kinetic chain caused by weak hip musculature causing inadequate push though in the ground stroke the athlete can perform glute bridges. The glute bridge strengthens the posterior hip musculature, specifically the gluteals, hamstrings, and lower back (Verstegen & Williams, 2005). The athlete lies down to with knees bent, and drives up through the heels lifting the hips off the ground until the knees, hips, and shoulders form a straight line. To address an energy leak caused by poor trunk rotation, the athlete should adopt a rotational training method. Incorporating side medicine ball throws would transfer to tennis and teach the athlete how to transfer energy efficiently from the legs, trunk, and arms (Team SKLZ,2012). Lastly to address a leakage caused by weak posterior shoulders, the athlete can perform physio ball ys. This exercise strengthens the rotator cuffs, upper back, and by performing it on physio ball challenges core stability (Verstegen & Williams, 2005). To perform the exercise the athlete lies supine on a physio-ball, with their arms in front in a “y” position, and raises the arms. The athlete should start with no weight, and gradually increase the resistance to a light load.
References
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keda, Y., Kijima, K., Kawabata, K., Fuchimoto, T., & Ito, A. (2006). Relationship between side medicine-ball throw performance and physical ability for male and female athletes. European Journal of Applied Physiology, 99(1), 47-55.
Joyce, D., & Lewindon, D. (2016). Sports Injury Prevention and Rehabilitation: Integrating medicine and science for performance solutions. Londres: Routledge.
Papageorgiou, K. G. (2016). An analysis of the kinetic chain model in forehand drive.Medicine and Science in Tennis, 21(2), 22-27.
Roetert, E. P., Kovacs, M., Knudson, D., & Groppel, J. L. (2009). Biomechanics of the tennis groundstrokes: Implications for strength training. Strength and Conditioning Journal, 31(4), 41-49.
Spaniol, F. J. (2012). Striking skills. Strength and Conditioning Journal, 34(6), 57-60.
Team SKLZ. (2012, July 18). Medicine ball perpendicular throw [Video file]. Retrieved from https://www.youtube.com/watch?v=qi2_4KDmn-E
Verstegen, M., & Williams, P. (2005). Core performance: The revolutionary workout program to transform your body and your life. Emmaus, PA: Rodale.