Effects of different acceleration and deceleration rates on isokinetic performance of the knee extensors

The Kinetic Communicator provides three acceleration/deceleration rates (low, medium, and high) to control the limb and, thus, prevent impact forces and torque overshoot found with free acceleration. The purpose of this study was to examine the effect of three acceleration/deceleration rates on isokinetic performance of the knee extensors on the Kinetic Communicator. Thirty-one healthy females with no history of knee pathology performed three concentric/eccentric contractions of the knee extensors at each acceleration/deceleration rate at a velocity of 90 degrees /sec. A one-way repeated measures analysis of variance (ANOVA) and Scheffé post hoc tests were used to compare between each acceleration/deceleration rate: 1) the average velocity, peak torque, and average torque of the whole curve; and 2) the average velocity, average torque, and range of motion of the acceleration and deceleration phases. The acceleration/deceleration rate significantly affected the average velocity of the whole curve, acceleration phase, and deceleration phase. Although acceleration/deceleration rate had some effect on average torque in the acceleration and deceleration phases, peak torque and average torque of the whole curve were not significantly affected. Thus, in this study, the choice of acceleration/deceleration rate at 90 degrees /sec did not appear to have a clinically significant effect on average torque and peak torque for the whole curve. J Orthop Sports Phys Ther 1991;14(4):161-168.