A Comparative Study of the Torque Generated by the Shoulder Internal and External Rotator Muscles in Different Positions and at Varying Speeds

Abstract

The torque generated by the shoulder internal and external rotator muscles duringconcentric isokinetic contractions has been investigated. Recordings were made in three positions: neutral, 90 degrees of flexion, and 90 degrees of abduction; and at three speeds of contraction (60, 120, and 180 /sec) in each of these positions. Twelve healthy female university students were randomly selected from a 100 female volunteer population. Testing was accomplished using an isokinetic dynamometer. A two-way analysis of variance for position and speed was conducted. The greatest torque values for the internal rotator muscles were achieved in the neutral position, while maximum values for the external rotators were developed in 90 of shoulder flexion. The test speed of 60 degrees /sec was shown to produce the highest torque values for the external rotator muscles. However, no difference in test speeds of contraction was found when analyzing the torque values generated by the internal rotator muscles. Implications for strength training are discussed.J Orthop Sports Phys Ther 1987;9(6):217-222.