The rotator-cuff in the shoulder has both stabilization and force production roles during the tennis serve. Excessive rotator-cuff strength ratios have been identified as a predisposition for overuse injury. Current strength training methods prevent utilization and training of the glenohumeral joint and the rotator-cuff in both the stabilization and force production roles. It was expected that the novel sport-specific air-resistance strength training tool would increase performance of tennis first-serve ball velocity without adversely affecting the first-serve accuracy, not significantly alter the isometric strength ratio between the internal and external rotators of the shoulder, and the isometric strength of both the internal and external rotation of the shoulder would be increased equally. Ten subjects ranged in age from 16 to 23 years, were elite tennis athletes and asymptomatic of shoulder pathology. Isometric shoulder strength was measured for external and internal rotation. First-serve ball velocity data were collected. All subjects served as their own controls, participating in two five-week training periods, with pre and post data collections taken to measure the change in shoulder strength, service velocity, and accuracy across the control and experimental periods. The experimental training period included a novel air-resistance strength-training tool. Although statistically insignificant, there were improvements in ball velocity, serve accuracy, increases in both internal rotator and external rotator shoulder strength, and an alteration in the ER:IR shoulder strength ratio. The practical applications of the novel air-resistance strength-training apparatus cannot be confirmed under the conditions of the present study. Further research should examine the long-term effects of the air-resistance strength training apparatus.
Key Words:
Shoulder strength, functional testing, tennis serve.