Objective: To investigate the effects of a foot-muscle training program on plantar pressure distribution, foot muscle strength,
and foot function in persons with flexible flatfoot.
Material and Method: Participants received foot-muscle training 3 times weekly, over 8 weeks. Training consisted of
gastrosolues muscle stretching and strengthening the muscles around the ankle and the intrinsic muscles. The contact area
and peak pressure under the hallux, first metatarsal, and medial midfoot were assessed by the Force Distribution Measurement
Platform while walking. Strength of the tibialis posterior and peroneus longus muscles were assessed by handheld dynamometer. Foot function regarding difficulty in activities of daily living was assessed. All measures were assessed at pre-training, intermediate-training, and post-training. Friedman ANOVA was used for testing mean differences among the variables.
Results: Five participants with flexible flatfoot were recruited in the study. Results demonstrated significant increases in tibialis posterior (p = 0.018) and peroneus longus muscles strength (p = 0.007), and significant decrease in foot function score (p = 0.021). In addition, no significant difference in contact area and peak pressure was observed among testing periods.
Conclusion: Foot-muscle strength and foot function in persons with flexible flatfoot can be improved significantly after receiving foot-muscle training.

Keywords: Flexible flatfoot, Plantar pressure distribution, Foot-muscle training