Accession Number : ADP001619

Title :   Changes in Human Joint Compliance during Peripheral Ischemia,

Corporate Author : ILLINOIS UNIV AT CHICAGO CIRCLE DEPT OF INDUSTRIAL AND SYSTEMS ENGINEERING

Personal Author(s) : Jaeger,Robert J. ; Agarwal,Gyan C. ; Gottlieb,Gerald L.

Report Date : JAN 1983

Pagination or Media Count : 21

Abstract : Joint compliance was measured at both the wrist and ankle by applying various torque waveforms (step, sinusoidal, and random) about the joint while measuring the resulting joint angle. Stretch-evoked electromyographic activity (EMG) was recorded from agonist-antagonist muscle pairs at the joint being tested. Measurements were made on normal human subjects before and after the development of peripheral ischemia in the limb. Ischemia is thought to preferentially block conduction in large diameter nerve fibers. Before ischemia developed, feedback from primary muscle spindles was intact. As ischemia developed, this feedback was reduced or eliminated. Under normal conditions, the compliance measured by sinusoidal techniques is dependent on input amplitude and the resting level of contraction in the muscle. However, for any given mean level of contraction and RMS level of perturbation, the compliance is often well fitted by a second order linear seen at low frequencies. In terms of a second order mechanical system model, these changes were observed in the stiffness and viscosity parameters, and not in the moment of inertia. The observations are strongly dependent on the level of muscle fatigue during the development of ischemia.

Descriptors :   *Joints(Anatomy), *Ischemia, Wrist, Electromyography, Angles, Reflexes, Humans, Muscles, Fatigue(Physiology), Response(Biology), Neuromuscular transmission, Biofeedback, Operators(Personnel), Motor reactions, Stiffness, Mathematical models, Man machine systems

Distribution Statement : APPROVED FOR PUBLIC RELEASE