【論文摘要】Serve Kinematics Following an Isokinetic Fatigue Protocol in Recreational Tennis Players

【論文摘要】肩旋轉肌群疲勞活動對於業餘網球選手肩關節與肩胛骨運動學和發球時序上的影響

詹禹慈(Yu-Tzu Chan) ； 林吟亮(Yin-Liang Lin)

《物理治療》 47卷4期 (2022/12) Pp. 281-282

https://doi.org/10.6215/FJPT.202212.O04

摘要

Background and Purpose: Fatigue is one of the risk factors contributing to shoulder injury in tennis players. Tennis serve has been reported to be a traumatic skill, especially in the late cocking stage and acceleration phase of a serve. Only one study observed the serve kinematics after lower trapezius was fatigued by electrical stimulation. However, no study has investigated the effects of a fatigue protocol for shoulder rotators on serve kinematics and serve sequence patterns. Thus, we aimed to investigate whether fatigue of shoulder rotators affected serve kinematics in healthy recreational tennis players. Methods: This was an exploratory study, and 26 healthy recreational tennis players were included. The subjects performed a fatigue protocol of shoulder internal and external rotation with an isokinetic dynamometer. Torque and median power frequency (MDF) of the shoulder rotators were measured to confirm fatigue. Kinematics of shoulder, scapula, and racket during serves without a ball were recorded by the motion capture system. The paired t-test was used to compare the changes of torque, MDF, serve kinematics and serve sequence pattern before and after fatigue. Results: After the fatigue protocol, the rotator torques decreased 35.3-38.78%. Except latissimus dorsi, anterior deltoid, pectoralis major and infraspinatus showed a significant decrease in MDF (Cohen's d = 0.45-0.99, p ＜ 0.05). Players served with an early shoulder horizontal adduction pattern (d = 0.49, p = 0.029). In the late cocking stage, shoulder external rotation was decreased (d = 0.83, p ＜ 0.05) and at the end of acceleration phase, there was a decrease in shoulder elevation, horizontal adduction, scapula internal rotation and anterior tilt (d = 0.42- 0.75, p ＜ 0.05). Conclusions: The isokinetic fatigue protocol fatigued shoulder rotators and also affected serve kinematics. The early shoulder horizontal adduction may be a strategy to avoid shoulder internal impingement. Moreover, the alternations of scapular kinematics at the end of acceleration phase may be also a compensatory strategy to maintain sufficient subacromial space. Clinical Relevance: The results may indicate that players may adopt a compensatory strategy during serve after fatigue. Future studies may need to investigate the changes in kinematics following a long duration of competition or practice.