Isokinetic dynamometry applied to shoulder rotators – Velocity limitations in eccentric evaluations

The objectives of this study were to evaluate if collegiate overhead athletes, with and without shoulder pain, and non-athletes could reach a preset velocity in internal and external shoulder rotation isokinetic evaluations; and to evaluate the correlation between torque and velocity. Controlled laboratory study, cross-sectional. Evaluations were performed using the isokinetic dynamometer Biodex System 3. Participants were assessed seated, with the arm at 90° of shoulder abduction and 90° of elbow flexion, from neutral rotation to 90° of external rotation. Five maximal contractions of isokinetic concentric and reactive eccentric internal and external rotation were performed at the velocities 90°/s, 180°/s and 240°/s. Data were processed with using MatLab. Most participants did not reach the isokinetic phase during eccentric tests at 180°/s and 240°/s, particularly in the external rotators evaluation. High correlations between torque and velocity of eccentric tests were found. The groups presented no differences in maximal velocity attained in trials which preset velocity was not reached. These results call into question the use of reactive eccentric tests at velocities higher than 180°/s for the isokinetic evaluation of shoulder external rotators in collegiate overhead athletes and non-athletes in this specific position. In such cases, careful evaluation of the velocity is recommended to determine if the isokinetic phase was reached.