Adaptive Changes in Longitudinal Arch During Long-distance Running

This study investigates the biomechanical adaptations of the longitudinal arch (LA) in long-distance runners, focusing on changes in stiffness, angle, and moment during a 60-minute run. Twenty runners participated in this experiment, and were asked to run at a speed of 2.7 m·s^-1 for 60 minutes. The kinematic and kinetic data collected at five-minute intervals during running were calculated, including the stiffness of LA in the loading phase (k_load) and the stiffness of LA in the unloading phase (k_unload), the maximum LA moment (M_max), the range of LA angle change (∆θ_range), and the maximum LA angle change (∆θ_max). Foot morphology was also scanned before and after running. Variations of kinematic and kinetic data were analyzed throughout the running activity, as well as variations of foot morphology pre- and post-run. Results showed that there was a significant decrease in k_load (p < 0.001), coupled with increases in ∆θ_range (p = 0.002) and ∆θ_max (p < 0.001), during the first 15 minutes of running, which was followed by a period of mechanical stability. No differences were found in k_unload and M_max throughout the running process and the foot morphology remained unchanged after running. These results highlight a critical adaptation phase that may be pivotal for improving running economy and performance.