Running shoe crash-pad design alters shoe touchdown angles and ankle stability parameters during heel–toe running

Abstract

Purpose: Running shoe crash-pads are commonly used to improve cushioning during heel–toe running. However, guidelines regarding shape and positioning of crash-pads are rare. This research examined the effect of systematically modified running shoe crash-pads on vertical ground reaction force characteristics and lower extremity kinematics during heel–toe running.Methods: Four custom-made running shoes featured crash-pad variations regarding horizontal extent and vertical position embedded within ethylene-vinyl acetate (EVA) midsoles. Crash-pads were located at the posterior-lateral midsole and had two sizes (narrow and wide) and two positions (top and bottom). Twenty-four runners performed five valid laboratory running trials per shoe while capturing ground reaction forces and lower extremity kinematics. Perception of cushioning, stability, and overall preference was assessed during outdoor loop running. Shoe variable means were compared for main (p < .05) and interaction (simple) effects (p < .05) by two within participants’ factors (size and position) repeated measures analyses of variance (ANOVA) and effect size estimation (pη2).Results: Rearfoot motion variables indicated biomechanical effects on running shoe stability induced by crash-pad size and position. Shock attenuation was marginally affected by shoe modifications and was not perceived by runners. Runners also did not perceive rearfoot stability alterations among shoes.Conclusion: Crash-pad modifications at the posterior-lateral region of EVA midsoles do not necessarily change substantially biomechanical and perceived running shoe cushioning properties. However, crash-pads applied in this research influenced rearfoot stability characteristics during running. In addition to dual density use at the medial shoe border, dual density use at the posterior-lateral midsole can provide opportunities to control rearfoot stability during heel–toe running.