Influence of midsole thickness on vertical loading rates, footstrike pattern and temporal spatial parameters in runners

![CDATA[Rationale/Objectives: Midsole thickness is a key component in the running shoe design. Increased (e.g. maximalists) or decreased (e.g. minimalists) midsole thickness have been proposed to lower impact loading and prevent running injury. Previous studies tested different shoe models on the market, which may differ in the shoe constructs other than midsole. Therefore, we used identical shoe models with a range of midsole thicknesses (1, 5, 9, 21, 25 and 29 mm) to examine the effect on the loading rates and running kinematics. Methods: Fifteen male habitual rearfoot strikers were asked to run on an instrumented treadmill with six shod conditions in a randomized test sequence. Average and instantaneous loading rates (VALR and VILR), footstrike angle (FSA) and temporal spatial parameters (i.e., contact time, cadence, and stride length) were compared between six shod conditions. Results: Repeated measures ANOVA indicated significant effect on VALR (p<0.001), VILR (p<0.001), footstrike angle (p=0.013), contact time (p<0.001), cadence (p=0.003) and stride length (p=0.004) between the six shod conditions. Pairwise comparisons showed that shoes with thinner midsole (1 and 5 mm) increased vertical loading rates and shortened the contact time, when compared with thicker midsole shoes (25 and 29 mm). Conclusions: Shoes with thinner midsole thickness (< 5 mm) may increase vertical loading rates and reduce contact time. Yet, midsole thickness may not pose a direct influence on footstrike pattern, cadence and stride length.]]