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Effect of voluntary vs. artificial activation on the relationship of muscle torque to speedThe suggestion by Phillips and Petrofsky (1980) and Wickiewicz et al. (1984) that artificial activation of the knee extensor muscles should result in greater relative changes in torque than those evident with maximal voluntary activation is examined by investigating the speed-torque relationship of the right knee extensor muscle group in eight human subjects in whom activation was achieved by 'maximal' voluntary effort or by electrical stimulation. Torque was measured at a specific knee angle during isokinetic concentric or eccentric actions at velocities between 0.17 and 3.66 rad/s and during isometric actions. It is shown that, with artificial activation, the relative changes in both eccentric and concentric torque were greater as the speed increased; the speed-torque relationship was independed of the extent of activation and was similar to that of an isolated muscle. On the other hand, activation by the central nervous system during maximal effort depended on the speed and the type of muscle action performed.
Document ID
19910035937
Document Type
Reprint (Version printed in journal)
Authors
Dudley, Gary A. (NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Harris, Robert T. (NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Duvoisin, Marc R. (NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Hather, Bruce M. (NASA John F. Kennedy Space Center Cocoa Beach, FL, United States)
Buchanan, Paul (NASA Kennedy Space Center; Bionetics Corp., Cocoa Beach, FL; Ohio University Athens, United States)
Date Acquired
August 15, 2013
Publication Date
December 1, 1990
Publication Information
Publication: Journal of Applied Physiology
Volume: 69
ISSN: 0161-7567
Subject Category
AEROSPACE MEDICINE
Funding Number(s)
CONTRACT_GRANT: NAS10-10285
Distribution Limits
Public
Copyright
Other