Peer Review #1 of "The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments (v0.1)"

Abstract

Background: Normative foot kinematic and kinetic data with different walking speed will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects. Methods: Ten healthy male subjects participated in this study, who were asked to carry out walk at a self-selected speed. After measuring and averaging the results of normal walking, the subjects were asked to perform 25% slower and 25% faster walk respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX) and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01m/s (SW), 1.34m/s (NW) and 1.68m/s (FW). Results: Hindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion increased in FW, while hallux relative to forefoot (HX/FF) dorsiflexion decreased. Increased peak eversion and peak external rotation in HF/TB were observed in FW with decreased peak supination in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW. Discussion: Limited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF dorsiflexion. Although small angle variation in HF/TB eversion and FF/HF supination during FW may have profound effects for foot kinetics. Higher HF/TB external rotation contributed to the forefoot push-off the ground while the center of mass progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical center of mass (COM) height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response.