END RANGE ECCENTRIC ANTAGONIST CONCENTRIC AGONIST STRENGTH RATIOS - ANEW PERSPECTIVE IN SHOULDER STRENGTH ASSESSMENT

The dynamic muscle stabilizers of the shoulder are critical to high pe rformance in the overhead athlete. Previous evaluations of shoulder st rength have focused on the concentric strength of the rotator cuff. Fu nctionally, the rotator cuff muscles interact in an eccentric/concentr ic fashion. This is the first study to evaluate the end range eccentri c antagonist/concentric agonist ratios of the shoulder rotators. Seven ty-live asymptomatic college-level males were tested through a range o f 20 degrees of lateral rotation to 90 degrees of medial relation usin g the Kin-Com computer-assisted, hydraulic-resisted, isokinetic dynamo meter at a speed of 90 degrees/sec. The end range (60-90 degrees) rati os for the medial rotators functioning eccentrically and lateral rotat ors functioning concentrically were 2.39:1 and 2.15:1 for the dominant and nondominant shoulders, respectively. End range (10 degrees of lat eral rotation-20 degrees of medial rotation) ratios for lateral rotato rs functioning eccentrically and medial rotators functioning concentri cally were 1.08:1 and 1.05:1 for the dominant and nondominant shoulder s, respectively. The application of this functional assessment of stre ngth testing results may provide important information in the evaluati on of the injured shoulder in the overhead athlete, for prescreening, and to gauge return to sports after injury or surgery.