We investigated how midfoot stiffness of running shoes influences foot segment kinematics and ground reaction force (GRF) during heel-toe running. Nineteen male rearfoot strike runners performed overground heel-toe running at 3.3 m/s when wearing shoes with different midfoot bending stiffnesses (low, medium, and high) in a randomized order. A synchronized motion capture system (200 Hz) and force plate (1000 Hz) were used to collect the foot-marker trajectories and GRF data. Foot kinematics, including rearfoot-lab, midfoot-rearfoot, forefoot-rearfoot, and forefoot-midfoot interactions, and kinetics, including GRF characteristics, were analyzed. Our results indicated that high midfoot stiffness shoes reduced the forefoot-rearfoot range of motion (mean ± SD; high stiffness, 7.8 ± 2.0°, low stiffness, 8.7 ± 2.1°; p < 0.05) and forefoot-midfoot range of motion (mean ± SD; high stiffness, 4.2 ± 1.1°, medium stiffness, 4.6 ± 0.9°; p < 0.05) in the frontal plane. No differences were found in the GRF characteristics among the shoe conditions. These findings suggest that an increase in midsole stiffness only in the midfoot region can reduce intersegmental foot medial-lateral movements during the stance phase of running. This may further decrease the tension of the foot muscles and tendons during prolonged exercises.

Background:Anterior cruciate ligament injuries commonly occur during sports that involve sudden stops or direction changes. Although athletes often use arch-support insoles in competition and training, little is known about the effect of foot insoles on knee biomechanics and jump take-off performances.Objective:This study aimed to investigate the effects of arch-support insoles on knee kinematics and kinetics during the stop-braking phase and the subsequent jump take-off performances.Study design:That is a quasi-experimental study, repeated-measures design.Methods:Twenty male healthy recreational university basketball athletes performed stop-jump with maximum effort in both arch-support and flat insole conditions. Paired t-tests were performed on knee kinetics and kinematics and jump performance variables to determine whether there were significant differences between insole conditions.Results:Wearing arch-support insoles experienced larger ground reaction forces (GRFs), loading rates of peak vertical and posterior GRFs, peak knee adduction and rotation moments, and knee flexion angular velocity than the flat insoles (P < 0.05).Conclusions:The increased GRFs and knee loading in arch-support insoles are indicative of a higher risk of anterior cruciate ligament injuries. The findings could be insightful to the knee mechanics that are related to performance and injury potential during stop-jump maneuvers.