Load, but Not Speed and Surface Impact Foot Strike Angle

Foot strike angle may play an important role in lower limb musculoskeletal injuries that are common for military personnel, and as such we decided to investigate the possible correlation between foot strike angle and the vertical ground reaction forces (GRFs) while traversing over varying terrain textures to simulate military conditions. This study aimed to determine the effect of speed, body borne load, and surface on foot strike angle.18 participants had lower limb biomechanics quantified during a walk (1.5 m/s) and run (4.5 m/s) with and without a 15 kg load over a flat and uneven surface. The flat surface consisted of the “normal” laboratory floor. The uneven surface was a 3D printed imitation of local running terrain which was then secured over the force platform with a metal frame for testing. Results showed that participants exhibited a prominent heel strike with load, which may increase injury risk and exasperate the large increases in vertical GRFs observed with walking and running with load. Unexpectedly, the uneven surface did not impact foot strike angle and led to a small decrease in vertical GRF measures.