Motor imagery of ankle plantar flexion at 50% of maximal voluntary contraction increases the maximal torque of ankle plantar flexion

Abstract

We investigated the influence of motor imagery at 50% of maximal voluntary contraction on maximal ankle plantar flexion torque. Thirty-six healthy volunteers were included in this study. The participants were divided randomly into two groups: a motor imagery group and a control group. Maximal ankle plantar flexion torque was measured before and after intervention using a Biodex System 3 dynamometer. The participants were positioned and secured in the adjustable chair of the dynamometer, with the hip and knee joints in the flexion position and the ankle joint in the neutral position. In the motor imagery group, the participants imagined isometric contraction of the ankle plantar flexor muscle at 50% of maximal voluntary contraction for 1 min. In the control group, the participants maintained a resting state for 1 min without performing motor imagery. Maximal torque was normalized by body mass, and the relative value was obtained by dividing maximal ankle plantar flexion torque after intervention with that before intervention. The relative value of maximal ankle plantar flexion torque/body mass was significantly higher in the motor imagery group than in the control group. These results indicate that motor imagery at 50% of maximal voluntary contraction has a facilitative effect on maximal ankle plantar flexion torque.