The effect of knee position on concentric isokinetic parameters

Abstract

Advances in isokinetic technology have allowed clinicians to objectively test the muscles of the knee joint in a variety of positions. It is well known that muscular force is influenced by joint position and muscle length, and the knee is no exception. The purpose of this study was to examine the effects of seated and prone position on isokinetic strength. Fourteen male university rugby players (n=14) volunteered to participate in the study. Isokinetic seated knee flexion and extension testing was done on a Biodex System 3, followed by the prone test after a 7-10 day rest period. This study demonstrated position dependence for peak torque (PT), for both quadriceps and hamstring, with the seated position producing greater values than the prone test at both velocities. The optimum angle for torque development in the quadriceps was greater in the prone position, whilst for the hamstrings the angle of PT was greater in the seated position. The prone position appears to consistently produce lower levels of strength, despite the augmented range of movement (ROM). The data suggest that the seated position is superior for PT values, and that optimum joint angle for force production is position specific.

Keywords: Knee, isokinetic, position, joint angle, peak torque.