Abstract
The isokinetic strength of the internal and external rotator muscles of normal individuals were evaluated in two different test positions.
Ten shoulders of healthy male volunteers were examined. The average peak torque per body weight and average work per body weight at 90 deg/sec. and 180 deg/sec. were measured with a LIDO active system. The test positions were supine with the arm at 0 and 90 deg. abduction and each range of motion was at 45 deg. from the neutral position.
The average peak torque per body weight (N. m /kg) of the external rotator muscles of the dominant arm was the same in both positions, which was 0.36, but that of the internal totator muscles was 0.49 at 90 deg. abduction and 0.42 at 0 deg. abduction, and statistically less at the P>0.05 level of significance. The total work per body weight (J /kg) of the external rotator muscles of the dominant arm was 0.45 in both positions and that of the internal rotator muscles was 0.60 at 0 deg. and 0.55 at 90 deg. abduction, but there were no statistical differences in either position.
The stregth of the internal rotator muscles at 90 deg. abduction was less than at 0 deg. abduction, whereas there was no difference between either of the external rotator muscles. The isokinetic strength of the internal and external rotator muscles produced no definite correlation between each position, which should be discussed separately. However, the 90 deg. abduction position is not ideal for measuring cases with recurrent dislocation of the shoulder due to apprehension of dislocations.
