MECHANICAL CHARACTERISTICS OF KNEE EXTENSION EXERCISES PERFORMED ON AN ISOKINETIC DYNAMOMETER

The purpose of this study was to evaluate selected mechanical characte ristics of knee extension exercises performed on a LIDO Active Isokine tic System. A female subject performed two repetitions of maximal effo rt knee extension at 16 different preset angular velocities (PAVs). Th e gravitational and inertial effects were included in the computation of the resultant knee torque. For each repetition, the knee flexion an gle, the angular velocity and acceleration of the shank, and the knee torque throughout the range of motion were computed. The shank angular acceleration values indicated that if the inertial effect is not cons idered the knee torque will be underestimated in the initial phase and errors in knee torque up to about 6 N . m can be expected for the res t of the repetition. The durations when the shank angular velocity was within +/- 5% and +/- 10% of PAV (expressed as percent ages of the re petition time) were found to decrease with increasing PAV. The differe nce between PAV and shank angular velocity at the instant of peak torq ue also increased with increasing PAV. The results demonstrate the lim itations that may exist in an isokinetic dynamometers.