Isokinetic Peak Torque Ratios and Shoulder Injury History in Adolescent Female Volleyball Athletes

Abstract

Few researchers have examined shoulder strength in adolescent volleyball athletes despite increasing levels of participation in this age group. To compare medial and lateral isokinetic peak torque of the rotator cuff among skill levels and between athletes with and without a history of shoulder injury. Cross-sectional design. The Human Performance Lab and Athletic Training Lab. Thirty-eight female adolescent club volleyball athletes from 10 to 15 years of age (mean = 13.02 +/- 1.60 years). We measured concentric and eccentric peak torque of the medial and lateral rotators of the shoulder and calculated resultant cocking and spiking ratios based on peak torque values. Athletes at higher skill levels had higher peak torque measurements in concentric and eccentric medial and lateral rotation compared with the athletes at lower skill levels. No differences in peak torque existed between participants with or without an injury history 6 months before the study. Strength ratios did not differ across skill levels, but previously injured participants produced lower eccentric medial rotation to concentric lateral rotation ratios compared with participants without a history of injury (P = .02). At the highest skill level, previously injured participants produced lower eccentric lateral rotation to concentric medial rotation ratios compared with participants without an injury history (P = .04). Differences in medial and lateral shoulder rotator strength ratios appear to be related more to injury prevalence than to absolute strength. Shoulder dysfunction related to strength ratio deficits also may exist in adolescent female volleyball athletes. Preventive shoulder strengthening programs focused on improving eccentric strength and correcting imbalances between medial and lateral rotators may be warranted for all female adolescent volleyball athletes.