In this study, we examined the relationship between changes in the height of medial longitudinal arch (MLA) of the foot after 5 km running and changes in toe flexor strength and running-induced changes in MLA height in healthy male university students. As a result, the navicular height and the arch height ratio decreased after 5 km running, and a significant positive correlation (r＝0.48) was found between the strength of the toe flexor strength and the amount of change in the arch height ratio before and after running. This suggests that it is important to prevent a decrease in MLA even for relatively short running distances of 5 km in order to prevent running-related injury. In the future, it will be necessary to investigate the effects of training aimed at improving foot function on the decrease in MLA caused by running.