Difference in isokinetic strength of the muscles around dominant and nondominant shoulders

Muscle training usually plays an important role in the treatment of shoulder disorders. Clinicians traditionally predict the pre-injury strength of an injured shoulder by using the contralateral uninjured side as the baseline data.

The primary purpose of the present study was to determine the difference in isokinetic peak torque of dominant and nondominant shoulders.

Both shoulders of 39 healthy subjects (24 men, 15 women) were tested isokinetically by using the CON-TREX MJ dynamometer at two angular velocities (60 and 180 degrees/sec) during abduction, adduction, flexion, extension, internal rotation and external rotation.

There were statistical differences of contralateral peak torque in almost all directions of shoulder muscle contractions except in shoulder flexion at both speeds. Peak torque of shoulder adduction, extension, and internal rotation were greater in the dominant side. Shoulder abduction and external rotation peak torque were greater in the nondominant side.

Therefore, clinicians should not directly use the isokinetic strength of the contralateral shoulder as normal baseline data for an injured side without consideration.