The Basic Study of Shoulder Internal and External Muscle Strength

The First Report: Muscle Strength Characteristic of Normal Subjects and Comparison of Muscle Strength in Normal Subjects with the Patients with Shoulder Instability

Abstract

The purpose of this investigation was to evaluate the muscle strengths of shoulder rotators in the patients with shoulder instability. Subjects were 15 normal males and 10 patients with shoulder instability. Torques of internal and external shoulder rotators were measured using an isokinetic torque machine (KIN-COM 500 H). Peak torques and external/internal peak torque ratio were compared between two groups.
During both concentric and eccentric contractions, peak torques of both internal and external rotators was significantly lower in the patients than in the normal subjects. External/internal peak torque ratio of concentric contraction was also higher in the patients than in the normal subjects.
Those results may imply that the muscle exercise training for shoulder instability requires not only appropriate quantity levels such as exercise intensity but also appropriate quality ones such as the concentric and eccentric contraction mode.