Isokinetic dynamometry applied to shoulder rotators - velocity limitations in eccentric evaluations

Area of Science:

• Sports Medicine
• Biomechanics
• Orthopedics

Background:

• Isokinetic testing is crucial for evaluating shoulder function in athletes.
• Understanding the relationship between torque and velocity is vital for accurate assessment.
• Overhead athletes are susceptible to shoulder injuries, necessitating reliable testing methods.

Purpose of the Study:

• To determine if collegiate overhead athletes (with and without shoulder pain) and non-athletes can achieve preset velocities during shoulder rotation isokinetic evaluations.
• To assess the correlation between torque and velocity in these isokinetic tests.
• To evaluate the validity of specific testing parameters for shoulder rotator muscles.

Main Methods:

• A cross-sectional, controlled laboratory study involving collegiate overhead athletes and non-athletes.
• Isokinetic dynamometry (Biodex System 3) was used to assess shoulder internal and external rotation.
• Participants performed maximal concentric and eccentric contractions at 90°/s, 180°/s, and 240°/s with the arm abducted at 90°.

Main Results:

• Most participants did not reach the isokinetic phase during eccentric tests at 180°/s and 240°/s, especially for external rotation.
• Strong correlations between torque and velocity were observed during eccentric testing.
• No significant differences in maximal velocity were found between groups when the preset velocity was not achieved.

Conclusions:

• The use of reactive eccentric tests at velocities exceeding 180°/s may be questionable for evaluating shoulder external rotators in collegiate overhead athletes and non-athletes in the tested position.
• Clinicians should carefully assess whether the isokinetic phase was reached when using higher velocities in eccentric shoulder rotation tests.
• Further research may be needed to refine isokinetic testing protocols for overhead athletes.