Reliability of torque measurements during passive isokinetic knee movements in healthy subjects

In the literature, few data are available about the reliability of torque m easured during passive isokinetic knee movements. This study investigated t he consistency of torque measurements during passive knee movements at 60, 180 and 300 degrees/second in 30 healthy subjects. Intraclass correlation v alues ranged between 0.78 and 0.92 when the results of two consecutive test s were compared. When retests were performed after repositioning the subjec ts, intraclass correlation values ranged between 0.43 and 0.87. These findi ngs indicate the necessity for meticulous standardization of the test situa tion. Series of 10 consecutive movements, specifically repetitions of knee flexion at 180 and 300 degrees/second, indicated that torque measurements d uring the first two movements were less stable than those following. A conc urrent change in electromyographic activity in the rectus femoris muscle su ggested that these torque variations resulted from habituation of the stret ch reflex.