Difference in Isokinetic Strength of the Muscles around Dominant and Nondominant Shoulders
Pisit Lertwanich MD*, Chanin Lamsam MD*, Teerawat Kulthanan MD*
Affiliation : * Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University
Background : Muscle training usually plays an important role in the treatment of shoulder disorders. Clini-
cians traditionally predict the pre-injury strength of an injured shoulder by using the contralateral uninjured
side as the baseline data.
Objective : The primary purpose of the present study was to determine the difference in isokinetic peak torque
of dominant and nondominant shoulders.
Materials and Methods : 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 o/sec) during abduction, adduc-
tion, flexion, extension, internal rotation and external rotation.
Result: 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.
Conclusion : Therefore, clinicians should not directly use the isokinetic strength of the contralateral shoulder
as normal baseline data for an injured side without consideration.
Keywords : Isokinetic, Muscle strength, Shoulder
