Arch support insoles reduce fatigue of the lower extremity muscles in people with flatfoot during a walking task.

People with flatfoot encounter challenges while walking. This study investigated whether arch support insoles (ASIs) can reduce fatigue of the lower extremity muscles during a walking task in people with flatfoot compared with flat insoles (FIs). A total of fifteen female college students with flatfoot were recruited and considered eligible for the study, with each subject fulfilling the inclusion criteria of Chippaux-Smirak index > 45%. A paired sample t test was used to compare the difference in power spectral area (PSA) of the subdivided frequency band interval of 20-140 Hz between ASIs and FIs. A Wilcoxon test was used for assessing nonnormal data. Effect size (ES) was calculated as a measure of the practical relevance of the significance by using Cohen's d. The results showed that the PSA of the RF muscles (P < 0.05; ES = 0.90) during uphill walking and of the RF (P < 0.05; ES = 1.21) and TA muscles (P < 0.05; ES = 0.61) during downhill walking was significantly smaller for ASIs than for FIs. The current evidence suggests that ASIs alleviates RF muscle fatigue during uphill walking and relieves RF and TA muscle fatigue during downhill walking.