Modulation of lower limb joint stiffness during a Half-Marathon in male runners with Varying Degrees of arch support

This study aimed to determine the effect of arch support on joint stiffness and dynamic joint stiffness during a half-marathon run. Twenty-one highly trained male distance runners completed two sessions with identical Advanced Footwear Technology marathon shoes of high or low arch support. Joint angles and moments were calculated during PRE and POST sessions to determine the joint stiffness and dynamic joint stiffness (DJS). A two-way repeated-measures ANOVA was conducted to analyze the fatigue (PRE versus POST) and arch support (High versus Low), with a significance level set at 0.05. Stiffness showed an arch support effect at the knee POST half-marathon, with greater frontal-plane stiffness in Low (0.367 ± 0.039) than High (0.224 ± 0.019) arch support (p = 0.002) and greater transverse-plane stiffness in PRE session (0.037 ± 0.005) than POST session (0.017 ± 0.003) under the high support (p = 0.002). For DJS, the hip was higher with high support in the frontal plane (0.166 ± 0.019 versus 0.093 ± 0.014, p = 0.009) during the PRE session and in the transverse plane (0.104 ± 0.016 versus 0.050 ± 0.003, p = 0.016) during the POST session. Knee showed a significant decrease (p = 0.001 and p = 0.012) in sagittal DJS from PRE to POST under both arch support conditions, and a PRE transverse support effect (low > high). Ankle showed a significantly (p = 0.044) increased sagittal DJS from PRE (0.107 ± 0.011) to POST (0.149 ± 0.010) only with high arch support. Distance run induced fatigue and arch support modulate lower-limb stiffness in a joint- and plane-specific manner, with DJS more responsive than static measures. Findings highlight the demand for individualized arch support strategies. Changes of knee stiffness and ankle DJS during the POST session may serve as key biomechanical markers for injury risk and footwear design.