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The Journals of Gerontology Series A: Biological Sciences and Medical Sciences 56:B524-B532 (2001)
© 2001 The Gerontological Society of America

Old Adults Exhibit Greater Motor Output Variability Than Young Adults Only During Rapid Discrete Isometric Contractions

Evangelos A. Christoua and Les G. Carltona

a University of Illinois at Urbana-Champaign

Evangelos A. Christou, Neural Control of Movement Lab, Department of Kinesiology and Applied Physiology, University of Colorado at Boulder, Boulder, CO 80309-0354 E-mail: echristo{at}colorado.edu.

Decision Editor: John A. Faulkner, PhD

The purpose of this study was to examine the ability of young and elderly individuals to control submaximum levels of force (5–90%) during continuous and rapid discrete isometric contractions of the quadriceps femoris. Participants were 24 young (25.3 ± 2.8 years) and 24 elderly individuals (73.3 ± 5.5 years) that were healthy and active. The strength of elderly participants was approximately 40% lower than young participants. The standard deviation and coefficient of variation (CV) of force were greater during discrete contractions than during continuous isometric contractions. During continuous isometric contractions, young and elderly participants exhibited similar CVs of force. During discrete contractions, however, elderly participants exhibited greater CVs for peak force and impulse and greater standard deviations and CVs for temporal characteristics than young participants. Results suggest that the control of force in active elderly people declines only during rapid discrete contractions and that this decline may be associated with declines in temporal characteristics of the force production.




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