The effect of limitation of movement on longitudinal muscle growth

Abstract

One hind foot of each member of a group of young rabbits was immobilized in dorsi-flexion during a period varying from 4 to 25 weeks. This prevention of movement resulted in a considerable diminution in the longitudinal growth of the muscle belly of tibialis anterior, and isometric tetanic tensions equivalent in degree to those of the control muscle of the normal leg were exerted at shorter belly lengths and through a reduced range of movement of the foot. Resting tension developed as soon as the muscle was stretched beyond its maximum length in vivo under the experimental conditions. In a second group of young rabbits a length of chain joining the tibia to the foot enabled the latter to be fully dorsi-flexed, but prevented plantar-flexion beyond an angle of 90° with the leg. The consequent diminution in excursion of the belly of tibialis anterior, which was maintained for a period extending up to 42 weeks, had an effect essentially similar to that in the first group, but the decrease in longitudinal growth of the muscle belly was less pronounced.