Force responses to constant velocity shortening of electrically
stimulated human muscle-tendon complex.
Cook, C. S., M. J. N. Mc Donagh.
School of Sport and Exercise Sciences and Department of Physiology,
University of Birmingham, Birmingham B15 2TT, England
APStracts 3:0124A, 1996.
Force-velocity curves in human muscle often have unexpectedly high
forces at high velocities . If series elasticity is the cause it
should have less effect at lower activation levels and larger
shortening amplitudes. The first dorsal interosseus muscle-tendon
complex was shortened at different levels of activation and by
different amplitudes. Force-velocity curves had high force well
maintained at high velocities. With an actuator release of 4.21 mm at
80% of maximal activation, force was > 45% of isometric force
(Po) for all actuator velocities above 200mm/s (1.49 muscle lengths
/s). At 30% activation the force was > 25% of Po at these`
velocities. The smaller 2.46mm releases produced higher forces than
the 4.21mm releases at these velocities. At 80 % activation force was
> 65% Po and at 30% activation it was > 50% Po at these
velocities. . Corrections of these data for elasticity produced
classic Hill type force-velocity curves. A model incorporating the
Hill force-velocity equation and a spring in series accounts for the
results .
Received 28 March 1995; accepted in final form 4 January 1996.
APS Manuscript Number A339-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 13 March 96