Affiliations: [a] The Physical Therapy Department, The University of
Montana, Missoula, MT 59812, USA Tel. +1 406 243-4753/5183; Fax: +1 406
243-2795; E-mail: [email protected]
Note: [] This study was conducted within The Motor Control Research
Laboratory, The Physical Therapy Department
Abstract: The purpose of this study was to examine the contribution of the
passive resistive torque to the total peak concentric isokinetic torque of the
calf muscle-tendon unit. Thirty healthy, active women (age: 32 [SD 8] years)
were tested using a KIN-COM 500H force dynamometer. The right calf
muscle-tendon unit was first stretched passively at 5 dg from relaxed plantar
flexion to the maximal angle of available dorsiflexion to measure the passive
resistive torque. Subjects then performed maximal concentric plantar flexion
from the maximal dorsiflexion angle at randomized test velocities of 30, 60,
120 and 180 dg. The passive resistive torque was subtracted from the total
concentric peak torque to determine the active concentric peak torque. The
angular delay from the onset of movement to the angle of total peak and active
peak torques, and the percent contribution of the passive resistive torque to
the total peak torque were calculated. One-way ANOVA procedures showed that the
total and active peak torques decreased, and their respective angular delays
increased, with increasing test velocities (P < 0.001). The active peak
torque was less than the total peak torque (P < 0.001), and the angular
delay for the active peak torque was greater than for the total peak torque
among all test velocities (P < 0.001). The percent contribution of the
passive resistive torque to the total peak torque ranged from 10.5% but this
did not differ among the four concentric test velocities. The passive resistive
torque contributed significantly to the total peak concentric torque and
shifted the angular delay toward the onset of movement. The passive resistive
torque contribution was essentially constant among the four test velocities,
probably influenced by the decrease in concentric peak torques and the increase
in the angular delay that resulted from the increasing test velocities.
