The Effect of Scapular-Retractor Fatigue on External and Internal Rotation in Patients with Internal Impingement

Abstract

CONTEXT: Scapular strengthening is thought to be an important component of the rehabilitation of patients with internal impingement. OBJECTIVE: To determine the effect of scapular-retractor-muscle fatigue on internal- and external-rotation-torque production in patients with internal impingement. DESIGN: Case control study. SETTING: Outpatient clinic. PARTICIPANTS: 15 patients and 18 healthy subjects. INTERVENTION: A scapular-retractor-fatigue protocol. MAIN OUTCOME MEASURE: Shoulder-rotation-torque production. RESULTS: After the scapular-retractor-fatigue protocol external-rotation strength was reduced in patients (involved 25%, noninvolved 19%; P < .001). CONCLUSION: Fatigue in the scapular retractors resulted in lower shoulder-rotation-torque production. These findings emphasize the importance of the scapular retractors for proper function of the shoulder rotators with the arm in an abducted position in patients with internal impingement.