Mean data (SD) of the vertical ground reaction force (a) impact peak (IP) and (b) loading rate (LR) for the CON and MAX shoes at slow (10 km/h) and fast (14.5 km/h) running speeds. Univariate difference between shoe conditions (t-test): *p < 0.05 and ***p < 0.001. Shoe by speed interaction effects (two-way repeated measures ANOVA): ^#p < 0.05. The main effect for shoe conditions (two-way repeated measures ANOVA): ⁺p < 0.05 and ⁺⁺⁺p < 0.001.