620 EP023 – Effects of resistance training on morphology and strength of the peroneus longus and peroneus brevis

Background Resistance training (RT) for the peroneus muscles is important because this muscles undergo morphological and functional changes after lateral ankle sprain. Although we reported the effects of immediate selective intervention on the peroneus longus (PL) and peroneus brevis (PB) (Arima et al., 2022), the effects after long-term RT have not been examined. Aims To investigate whether 8 weeks RT changes PL and PB muscle morphology and strength. Methods Eighteen healthy participants were divided into PL group (Pushed the TheraBand® from the ball of the foot through the ankle eversion: n=9) and PB group (TheraBand® was pulled by the ankle external rotation: n=9). Muscle cross-sectional area (CSA) at 25% and 75% proximal to the line connecting the fibular head and lateral malleolus measured by an ultrasound system, and PL and PB strength measured using a handheld dynamometer were determined at the beginning of week 1 (baseline) and on the first day of the week following each weekly RT. Two-way ANOVA was used to check for differences in the effects of 8 weeks RT. Results There was significant interaction between groups and weeks (p<0.05). The 25% CSA was significantly higher in PL group between weeks 3 and 8 compared to baseline. The 75% CSA was significantly higher in PB group compared to baseline from weeks 4 to 8. PL strength was significantly higher in the PL group between weeks 2 and 8 compared to baseline. PB strength was significantly higher in the PB group from week 3 to 8 compared to baseline (p<0.05 respectively). Conclusions Long-term selective RT of PL and PB was suggested to be possible by the ankle eversion and external rotation. It would be necessary to evaluate the PL and PB separately and intervene selectively when performing RT for improving the morphology and function of the peroneal muscles.