The effect of knee position on torque output during inversion and eversion movements at the ankle

The purpose of this study was to compare the effect of knee position on the magnitude of torque generated during the isokinetic movements of inversion and eversion at the ankle. Mean peak torque values at 30 and 120 degrees /sec were collected from 12 subjects, ages 21-31, from two test positions. The knee was stabilized in 10 degrees of flexion for the first test position and 70 degrees for the second. Additionally, mean peak amplitude of hamstring motor unit action potentials was compared between the two test positions to demonstrate differences in hamstring activity. At both speeds, mean peak torque values of the inversion-eversion movements, as well as mean peak amplitude of hamstring motor unit action potentials, was significantly lower in 10 degrees compared to 70 degrees of knee flexion (p < 0.01). It was concluded that isokinetic testing at the ankle with the knee in a close packed position, near full extension, provides a more valid representation of isolated muscular performance than testing with the knee in a loose packed position of midrange flexion.J Orthop Sports Phys Ther 1988;10(5):177-183.