Differences in the angle of the medial longitudinal arch and muscle activity of the abductor hallucis and tibialis anterior during sitting short-foot exercises between subjects with pes planus and subjects with neutral foot.

BACKGROUND AND

OBJECTIVES

Excessive activity of the tibialis anterior muscle may be a causal mechanism in overuse injuries such as stress fracture in pes planus patients. However, information about this relationship is limited. In this study, we compared the angle of the medial longitudinal arch, the activities of the abductor hallucis and tibialis anterior muscles, and the activity ratio of tibialis anterior/abductor hallucis in individuals with pes planus and those with a neutral foot position during short-foot exercises conducted while sitting.

METHODS

Differences between the groups were analyzed using an independent t-test. In all, 28 university students participated in this study (14 subjects in each group).

RESULTS

The activity of the abductor hallucis muscle was significantly lower (p < 0.001), and the activity ratio of tibialis anterior/abductor hallucis was significantly greater (p = 0.012) in the pes planus group than in the neutral foot group during the exercise.

CONCLUSIONS

Clinicians should recognize that pes planus patients may compensate for reduced activation of the abductor hallucis to maintain the angle of the medial longitudinal arch during the sitting short-foot exercise.