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.