Analysis of the Effects of Static Stretching of the Ankle on Joint Drive Resistance Based on Joint Movement Direction and Exercise Area

The purpose of this study was to examine the effect of static stretching on the plantar flexor muscles of the ankle joint on bilateral resistance to plantar flexion and dorsiflexion. The subjects included 25 healthy men. Ankle dorsiflexion and plantar flexion were passively performed before and after static stretching, and a muscle tonus electromyograph was used to measure the ankle joint’s passive resistance. The spring coefficient was measured as the slope of the angle-torque regression line at the time of passive movement and was compared for the total, proximal, and distal ranges of motion. The dorsiflexion spring coefficient decreased in all angles after stretching, and significant differences were observed in the total and distal ranges of motion. The plantar flexion spring coefficient decreased after stretching in all items, and a significant difference was observed in the total range of motion. The rates of decrease in all excursions were 15.7% and 10.5% for the dorsiflexion and plantar flexion spring coefficients, respectively, with the former showing a higher rate of change. The results suggest that dorsiflexion static stretching for ankle joints may reduce joint drive resistance not only in the dorsiflexion direction but also in the plantar flexion direction.

Keywords: static stretching, ankle joint, dorsiflexion, plantarflexion, spring coefficient.