Isokinetic characteristics of shoulder rotators in patients with adhesive capsulitis

To demonstrate the muscle strength characteristics of shoulder internal and external rotators and the effects of isokinetic exercise on muscle activity in patients with adhesive capsulitis.

Cohort study with control subjects.

Eight patients with adhesive capsulitis and 8 controls.

Maximal isometric and isokinetic strength tests of shoulder internal and external rotators in the scapular plane were carried out. Muscle activities of the rotators were recorded in resting and during maximal isometrics. Muscle strength variables (peak torque, total work and power) and myoelectric variables (resting root-mean-square amplitude pre- and post-tests and the external-internal rotator co-activity in resting and during isometric contractions) were recorded. A mixed repeated-measure analysis of variance test was used to examine the within-group and between-group differences.

For affected shoulders, smaller isometric average torque of internal rotators and high-speed peak torque, total work and power of external rotator were observed. The external/internal rotator ratio of peak torque in high-speed testing also exhibited significant decrease. The myoelectric variables showed no significant changes.

High-speed external rotator strength and isometric internal rotator strength of the affected shoulders were decreased significantly. Isokinetic exercise may not increase the resting muscle activities and co-activity. These results provide a reference in planning muscle strengthening programmes and goals for these patients.