Motor unit discharge behavior in older adults during maximal effort
contractions.
Kamen, Gary, Steven V. Sison, C. C. Duke Du, and Carolynn Patten.
Motor Control Laboratory, Department of Exercise Science,
University of Massachusetts, Amherst, MA
APStracts 2:0369A, 1995.
A reduction in maximal force production is a common observation in
older individuals. In an effort to determine whether aging is
accompanied by reductions in central motoneuron drive limiting motor
performance, motor unit discharge records were obtained from seven
young (ages 21-33) and seven older ( > 67 yrs of age) adults.
Informed consent was obtained from all subjects. The task required
the subject to perform a maximal abduction of the second digit under
isometric conditions. Motor unit potentials in the first dorsal
interosseous were monitored using a selective four-wire needle
electrode and identified off-line with the aid of a Dantec
electromyograph. The maximal discharge rate in the older adults (31.1
imp/s) was significantly smaller (p < .05) than that in the
younger subjects (50.9 imp/s). These findings suggest that reductions
in maximal force capability in older adults is partially due to an
impaired ability to fully drive the surviving motor units.
Received 3 January 1995; accepted in final form 24 July 1995.
APS Manuscript Number A1-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 August 1995.