Effects of Repeated Stretching on Muscle Size and the Strength of Human Skeletal Muscle

Abstract

The muscle enlargement and strengthening effects of repeated stretching of skeletal muscle of human subjects were investigated. [Subjects] The subjects were 20 healthy males. [Methods] An isokinetic dynamometer was used for repeated stretching of the triceps surae muscle. The intervention group which received repeated stretching through passive dorsiflexion movement of the ankle joint was compared with a control group. The muscle architectural index (gastrocnemius muscle thickness and pennation angle), the triceps surae muscle strength, and the range of motion of active dorsiflexion at the ankle joint as the dependent variable were measured, were weasured. [Results] The intervention group showed significantly increased gastrocnemius muscle thickness and pennation angle. No significant difference was seen between the groups in the muscle strength or the range of motion. [Conclusion] Repeated stretching has beneficial effects on the muscle enlargement of the triceps surae muscle in healthy males. This suggests that muscle strengthening involves mechanisms other than those causing muscle enlargement.