IS THE KINETIC COMMUNICATOR TRULY ISOKINETIC?

Abstract

217 The function of an isokinetic dynamometer is to measure dynamic muscle characteristics throughout a range of motion at a constant velocity. This study examined the capability of a Kin-Com 500H to maintain the requisite constant velocity. The Kin-Com was set in passive mode for knee extension/flexion at velocities of 30, 60, 90, 150, 210 and 250 degrees per second. Five trials at each of these velocities were recorded with a JC Labs high-speed video system at 60 Hz and 200 Hz. Data were reduced with a PEAK5 motion analysis system. The raw and conditioned data were compared with the velocity settings of the Kin-Com and revealed differing magnitudes of lever arm rotational velocity over the range of motion. In every case, the Kin-Com's output reported a constant and stable velocity. Generally, the Kin-Com did not maintain a constant rotational velocity at any of the isokinetic settings as measured with the Peak 5 system. Less data smoothing resulted in less accurate velocities when compared to the settings on the device. However, with greater data conditioning, the PEAK5 data revealed a more stable velocity which more closely matched that of the Kin-Com. These results suggest the isokinetic velocities reported by the Kin-Com 500H dynamometer may be highly conditioned and therefore, may not accurately reflect lever arm accelerations and decelerations which occur over the range of motion.