Gait speed and multi-segment foot joint kinematics throughout the entire stance phase using statistical parametric mapping

The foot is a multi-segment structure whose segments function together. Due to its ongoing connection with the support surface, the foot must be capable of managing loads that vary with gait speed. Previous studies have provided considerable insight into the relationship between foot joint kinematics and gait speed. However, their primary reliance on discrete measures, such as peak joint angles, has limited understanding of how these relationships evolve throughout the stance phase. The aim of this study was to investigate the effects of gait speed on full time-series trajectories of multiplanar foot joint kinematics using statistical parametric mapping. According to our findings, faster walking primarily increased ankle eversion and midfoot dorsiflexion during weight acceptance (∼17–29% of the stance phase). In contrast, during propulsion, faster walking increased ankle plantar flexion (∼80–100% of the stance phase) and inversion (∼82–90%), as well as midfoot plantar flexion (∼82–100%) and adduction (∼90–98%), together with greater dorsiflexion of the first metatarsophalangeal joint after heel-off (∼43–98% of the stance phase). These multiplanar joint kinematic alterations across the ankle–foot joints throughout the stance phase reflect greater foot-arch collapse in early stance and foot-arch recoil in late stance, which may facilitate appropriate energy absorption and generation in response to increasing gait speed. Importantly, these adaptive foot motions were not captured by previous discrete analyses, which may obscure phase-dependent changes during gait. The present continuous time-series approach revealed detailed temporal adaptations in foot kinematics across the stance phase, providing a more comprehensive characterization of gait mechanics.