Immediate and long-term effects of anti-pronation insoles on spatiotemporal gait parameters in individuals with flat feet

Purpose of the study: This study examined the immediate and long-term effects of anti-pronation insoles on gait characteristics in young adults with flexible flatfoot compared with healthy controls. Methods: Twenty-four participants (12 flatfoot, 12 controls) underwent gait analysis under barefoot and shod conditions using a 3D motion system. The flatfoot group wore custom anti-pronation insoles during testing and continued daily use for six weeks. Spatiotemporal gait parameters were analyzed using repeated measures ANOVA and MANOVA. Results: At baseline, the flatfoot group showed significant temporal differences, including prolonged opposite foot off and reduced single support duration ( p < 0.05). Short-term insole use led to partial improvements, while post-intervention assessments demonstrated significant increases in step and stride length and normalization of stance-phase timing ( p < 0.05). Cadence, walking speed, and step time remained unchanged. Conclusion: Anti-pronation insoles produced both immediate and sustained improvements in gait timing and spatial characteristics in individuals with flexible flatfoot. Importantly, these benefits emerged not only after a single session but also following six weeks of use, underscoring the adaptive potential of long-term intervention. While gait velocity and cadence were unaffected, improvements in step and stride length and stance-phase dynamics suggest enhanced stability and efficiency. These findings support anti-pronation insoles as a conservative and clinically relevant strategy for restoring gait mechanics in individuals with flatfoot.