Context: Most patients on an index concentric isokinetic test of the shoulder internal and external rotators have significant torque-acceleration-energy (TAE) deficits. Objective: To assess the effectiveness of rehabilitation on muscle power in patients with shoulder dysfunctions. Design: Prospective, pretest-posttest. Setting: Physical therapy clinic. Participants: 67, mean age 28.7 +/- 12.89 years. Main Outcome Measures: Concentric shoulder internal and external rotators measured with arm at 90 degrees of abduction, 90 degrees of elbow flexion. Isokinetic velocities tested: 60 degrees, 180 degrees, and 300 degrees/s. Results: A paired t test (P < .05) compared the differences from index to discharge test for involved and uninvolved internal and external shoulder rotators. Percentages of TAE deficits involved vs uninvolved on discharge and change in TAE from index to discharge were also analyzed. Significant improvement of the involved shoulder for all velocities for both internal and external rotators was seen. The uninvolved extremity saw statistically significant improvements at all velocities for external rotators yet only at 300 degrees/s for internal rotators. Involved-extremity TAE deficits returned to within 10% on discharge. Conclusions: The study demonstrated improved muscle power as measured by TAE in shoulder internal and external rotators in a sample of patients treated in an outpatient clinic.