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Muscle activity (measured by electromyography) and applied load were measured during seven shoulder rehabilitation exercises done with an elastic resistance device. Nineteen men with no shoulder abnormalities performed seven exercises: external and internal rotation, forward punch, shoulder shrug, and seated rowing with a narrow, middle, and wide grip. Qualitative video (60 Hz) was synchronized with the electromyography data from eight muscles (2000 Hz). Fine-wire intramuscular electrodes were inserted into the supraspinatus and subscapularis muscles, and surface electrodes were placed over the anterior deltoid, infraspinatus, pectoralis major, latissimus dorsi, serratus anterior, and trapezius muscles. Ten trials per subject were analyzed for average and peak amplitude, and the results were expressed as a percentage of maximum voluntary contractions. The peak loads for all exercises ranged from 21 to 54 N. The muscle activity patterns suggest that these shoulder rehabilitation exercises incorporating elastic resistance, controlled movements, and low initial loading effectively target the rotator cuff and supporting musculature and are appropriate for postinjury and postoperative patients.

Returning to sports involving dynamic single-legged landings at 4 months after anterior cruciate ligament reconstruction surgery may contribute to accelerated knee joint degeneration.

Context:The overhead throwing motion is complex, and restrictions in range of motion (ROM) at the hip may place additional demands on the shoulder that lead to injury. However, the relationship between hip and shoulder ROM in athletes with and without a history of shoulder injury is unknown.Objective: To (1) determine if differences exist in hip and shoulder ROM between professional baseball players with a history of shoulder injury and those with no history of shoulder injury and (2) assess relationships between hip and shoulder ROM in these players.Design: Cross-sectional study.Patients or Other Participants: Fifty-seven professional baseball players.Main Outcome Measure(s): Outcome measures consisted of hip extension and internal rotation, shoulder internal and external rotation, glenohumeral internal-rotation deficit, and history of shoulder injury. Differences in shoulder and hip ROM were assessed with a 1-way analysis of variance.Associations between hip and shoulder ROM were assessed with linear regression.Results: Nonpitchers with a history of shoulder injury had more external rotation and less internal rotation of the shoulder than nonpitchers with no history of shoulder injury. Glenohumeral internal-rotation deficit was greater in both pitchers and nonpitchers with a history of shoulder injury. The relationship between dominant hip extension and shoulder external rotation was significant for pitchers with a history of shoulder injury and nonpitchers with a history of shoulder injury.Conclusions: Shoulder injury may be associated with specific measures of hip and shoulder ROM, and hip extension and shoulder external rotation may be related in baseball players with a history of shoulder injury. Additional research is necessary to understand the specific mechanisms of shoulder injury in the throwing athlete.Key Words: throwing athletes, injuries, glenohumeral internal-rotation deficit, kinetic chain Key Points N Shoulder internal rotation, nondominant hip internal rotation, and glenohumeral internal-rotation deficit were different in nonpitchers with and without a history of shoulder injury.N Dominant hip extension and shoulder external rotation were associated with a history of shoulder injury in both pitchers and nonpitchers.