Effects of a Shoulder Injury Prevention Strength Training Program on Eccentric External Rotator Muscle Strength and Glenohumeral Joint Imbalance in Female Overhead Activity Athletes

Abstract

Imbalance of the eccentrically-activated external rotator cuff muscles versus the concentrically-activated internal rotator cuff muscles is a primary risk factor for glenohumeral joint injuries in overhead activity athletes. Nonisokinetic dynamometer based strength training studies, however, have focused exclusively on resulting concentric instead of applicable eccentric strength gains of the external rotator cuff muscles. Furthermore, previous strength training studies did not result in a reduction in glenoumeral joint muscle imbalance, thereby suggesting that currently used shoulder strength training programs do not effectively reduce the risk of shoulder injury to the overhead activity athlete. Two collegiate women tennis teams, consisting of 12 women, participated in this study throughout their preseason training. One team (n = 6) participated in a 5-week, 4 times a week, external shoulder rotator muscle strength training program next to their preseason tennis training. The other team (n = 6) participated in a comparable preseason tennis training program, but did not conduct any upper body strength training. Effects of this strength training program were evaluated by comparing pre- and posttraining data of 5 maximal eccentric external immediately followed by concentric internal contractions on a Kin-Com isokinetic dynamometer (Chattecx Corp., Hixson, Tennessee). Overall, the shoulder strength training program significantly increased eccentric external total work without significant effects on concentric internal total work, concentric internal mean peak force, or eccentric external mean peak force. In conclusion, by increasing the eccentric external total exercise capacity without a subsequent increase in the concentric internal total exercise capacity, this strength training program potentially decreases shoulder rotator muscle imbalances and the risk for shoulder injuries to overhead activity athletes.

Measuring Eccentric Strength of the Shoulder External Rotators Using a Handheld Dynamometer: Reliability and Validity

“…22 By strengthening the external rotators in prehabilitation, one could potentially reduce the risk for shoulder injuries. 23 Finally, the HHD has also been used to measure isometric strength for external and internal rotation during preseason screening in adolescent national badminton players. 24 Eccentric testing of rotator cuff strength using the HHD has not been described previously in the literature.…”

Performance Enhancement following a Strength and Injury Prevention Program: A 26-Week Individualized and Supervised Intervention in Adolescent Female Volleyball Players

“…Although the primary reason for resistance training is performance enhancement, it has also been used to prevent sport injuries 5,6 . For example, resistance training has been recommended for treating and reducing the risk of volleyball-related injuries, such as rotator cuff injuries and jumper's knee [7][8][9][10] . In addition, muscle strength appears to have a significant impact on outcome and the ability to return to sport after anterior cruciate ligament surgery 11 .…”

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“…Adolescent athletes of other sports such as handball (Dos Santos Andrade et al, 2014), volleyball (Stickley et al, 2008), and tennis (Ellenbecker & Roetert, 2003) presented values outside normative values. However, the abnormal values cited in these sports occurred due to the presence of overhead and throwing activity, in which there is an increase in the strength of internal rotators without a concomitant gain of strength of external rotators (Ellenbecker & Roetert, 2003;Niederbracht et al, 2008 -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------…”

“…www.efsupit.ro 1111 (Hagemann et al, 2004;Niederbracht et al, 2008;Michael et al, 2009;Tay & Kong, 2016). In the first phase, the leading shoulder is stretched forward and the arm is extended, while the active opposite shoulder is moved backward behind the head in abduction, extension, and external rotation; in the second phase, the traction arm flexes and the opposite shoulder adducts with internal rotation, and the corresponding arm is actively pushed forward (Hagemann et al, 2004).…”