Association Between Eccentric and Isometric Shoulder Rotation Strength, Shoulder Range of Motion and Injury Incidence...

For competitive adolescent athletes, injury avoidance is a challenge, and causes of injury are complex and multifactorial. Despite an incidence of 8.2 shoulder injuries per 1,000 hours of tennis played, few studies have investigated the association between shoulder strength, range of motion (ROM), and injury.

Eccentric and isometric shoulder muscle strength and/or shoulder ROM are associated with new shoulder complaints and/or injuries.

Cohort study.

Level 3.

At baseline 301 adolescent competitive tennis players aged 13 to 19 years completed a questionnaire, were assessed with a shoulder protocol for strength and ROM and followed weekly (for shoulder complaint/injury) for 52 consecutive weeks. Outcomes were a first incidence of a tennis-related shoulder complaint or injury in the dominant arm, defined as a sum score of ≥20 or ≥40, respectively, on the Oslo Overuse Injury Questionnaire. Two cohorts were created for Cox regression analyses, adjusted for age, sex, and playing level: (1) shoulder complaints (n = 204), and (2) shoulder injuries (n = 252).

The most definitive adjusted associations were a hazard rate ratio (HRR) of 1.3 (95% CI 1.0-1.8) for a shoulder complaint in eccentric external rotation (eccER) strength, and a HRR for shoulder injuries of 1.4 (95% CI 1.0-1.9) in isometric internal rotation (IIR) strength in the 90-90 position, and 1.5 (95% CI 1.1-2.0) in eccER normalized to body mass.

Higher values of eccER shoulder strength, IIR strength at the 90-90 position, and eccER shoulder strength normalized to body mass, were associated with shoulder complaints/injuries in adolescent competitive tennis players.

Incorporating a training program that takes volume and intensity into account in the daily oncourt sessions, to build resilience through a well-planned, long-term training and competition plan to minimize shoulder injury risk may be of importance.