[The morphological adaptation of the fibers of the human m. triceps surae during local endurance training]

Abstract

Under investigation were effects of local endurance training of triceps of the calf in physically active volunteers who performed plantar bending in the talocrural articulation 3-4 times a week for 8 weeks with 30% of the maximum arbitrary effort for 40 minutes with 60 movements a minute. The exercise was fulfilled by one foot only. The local training resulted in a 19% greater density of capillaries in the triceps of the calf and in 30% greater amount of capillaries per a fiber. No significant changes were found during training in the ratio of the I and II types of fibers and in their area of cross section, although a tendency for hypertrophy of the Ist type fibers was noticed. Changes in the cross section area of the Ist type fibers and capillary density during training had a considerable negative interrelation. These findings show that the character of the muscle response to training is determined by a correlation of the parameters characterizing its initial state and the parameters of the morphological optimum, corresponding to the given level of functional activity.