Force-time measurements of knee muscle functions of subjects with multiple sclerosis.

The purpose of this study was to determine whether the time-rate of muscle tension development, the muscle tension-maintaining capacity, and the reciprocal inhibition time of muscles in subjects with multiple sclerosis were significantly different from those of healthy subjects. An isokinetic dynamometer was used to evaluate the quadriceps femoris and hamstring muscles of 15 Experimental Group subjects with multiple sclerosis and 17 healthy Control Group subjects. The muscles were tested isometrically at 45 degrees of knee flexion and isokinetically at speeds of 30 degrees/sec and 90 degrees/sec. The subjects with multiple sclerosis demonstrated a significant (p less than .001) slowing of the time-rate of muscle tension development and a significant (p less than .005) decrease in muscle tension-maintaining capacity when compared with healthy subjects. The difference in the reciprocal inhibition time of muscles of the Experimental and Control Groups was not significant. When the reciprocal inhibition time of muscles was expressed as a percentage of the total torque curve, however, a significant prolongation (p less than .001) was observed in the subjects with multiple sclerosis.