Ys. Hang et al., FAILURE OF STIMULATED SKELETAL-MUSCLE MAINLY CONTRIBUTED BY PASSIVE FORCE - AN IN-VIVO RABBIT MODEL, Clinical biomechanics, 11(6), 1996, pp. 343-347
Objective. To evaluate the role mechanism of stimulated muscle. Design
. An in vivo rabbit model. Background. Eccentric contractions can resu
lt in a greater incidence of muscle injury. However, the relative role
of the active and passive muscle force in the failure mechanism of th
e activated muscle is not well elucidated. Methods. After anaesthesia,
New Zealand white rabbits were fixed in a frame on a materials testin
g machine, The triceps surae muscle-tendon units were passively stretc
hed to rupture with our without continuous nerve stimulation. The forc
e and muscle length were simultaneously recorded. Active muscle force,
passive muscle force, and ratio of the active to passive muscle were
calculated and depicted against strain. Results. The results showed th
at the mean maximal passive force of triceps surae muscle was 293.1 N
at a strain of 38%. The mean peak active muscle force was 21.5 N at a
strain of 21%. The ratio of active to passive muscle force reached its
peak first, followed by the active muscle force, and then the passive
muscle force, The ratio of active to passive muscle force at the peak
total force was only 3.3%. Conclusions. The stimulated muscle can exe
rt its maximal response at extreme physiological extension. Injury of
the stimulated muscle is caused mainly by passive muscle force.