Source
Journal of Applied Physiology. 72(3):1205-11, 1992 Mar.
Abstract
We developed an apparatus to quantify the biomechanical behavior of
the dorsi- and plantarflexor muscles of the ankle
of an anesthetized mouse. When the dorsi- or plantarflexor muscle
group is activated by electrical stimulation of either
the peroneal or tibial nerve, the apparatus measures the moment
developed about the ankle during isometric, isovelocity
shortening, or isovelocity lengthening contractions. Displacements
may be performed over the full 105 degrees range of
ankle motion with an angular resolution of 0.09 degrees.
Bidirectional isovelocity ramps in ankle angle up to 1,100
degrees/s are possible and are equivalent to maximum velocities of
2.3 fiber lengths/s (Lf/s) for the fibers in tibialis
anterior muscle and 11.9 Lf/s for those in gastrocnemius muscle.
During single contractions of the dorsi- and
plantarflexor muscle groups at 37 degrees C and with both knee and
ankle joint at 90 degrees neutral position, the
isometric tetanic force developed was 1.4 and 3.3 N, power output at
2.2 Lf/s was 3.1 and 5.9 mW, and power
absorption at 0.5 Lf/s was 4.9 and 9.0 mW, respectively. These values
are in reasonable agreement with data from the
same muscle groups tested in situ. We conclude that the apparatus
provides valid measurements of force and power of
the dorsi- and plantarflexor muscle groups.