PURPOSE This study examined the biomechanical differences in running shoes with two midsole materials, ethylene-vinyl acetate (EVA) and polyether block amide (PEBA), and carbon fiber plate insertion. METHODS Ten recreational runners participated in the study and performed running trials on a 12m runway at a controlled speed of 3.89 m/s ± 5%. Biomechanical data were obtained for time-continuous variables of the metatarsophalangeal (MTP) joint (angle, moment, and power), as well as for discrete variables (push-off time, peak vertical impact force, peak anterior propulsion force, and timing of joint power transition). Data were analyzed using statistical parametric mapping for continuous data and the Wilcoxon signed-rank test for discrete variables (α = .05). RESULTS Compared with no-plate conditions, the EVA sole with plate significantly reduced push-off time, MTP joint range of motion, positive joint power, and peak anterior propulsion force, with an earlier timing of joint power transition (p < .05). In contrast, the PEBA sole with plate decreased MTP joint range of motion but increased plantar flexion moment, negative joint power, and push-off time (p < .05). Furthermore, under plate-inserted conditions, PEBA significantly increased plantar flexion moment, negative joint power, and push-off time, as well as exhibited a delayed timing of joint power transition compared with EVA (p < .05). CONCLUSIONS The interaction between midsole material and plate insertion causes complex variations in MTP joint energy management. Specifically, EVA shoes with a plate may facilitate rapid roll-off and promote swift turnover, thereby enhancing acceleration. In contrast, PEBA shoes with a plate may promote prolonged energy absorption, which could potentially reduce joint fatigue during long-distance running.
Purpose The purpose of this study was to investigate the effect of midsole hardness on gait mechanisms by wearing a backpack. Methods Ten healthy adult males(age:23.20±1.33yrs, heights: 1.72±0.03cm, weights: 67.60±5.95kg) participated in this study. Subjects walked at a speed of 1.5m/s in an 8m section wearing randomly selected midsole hardness (Soft, Medium, Hard) shoes and backpack (30% of body weight). For measurement of body movement, 10 infrared cameras (Vicon motion capture system, UK) and force plate (AMTI, ORG-6, US) were used. Results First, in the shock phenomenon change, the ground contact time was longer when wearing a backpack. Second, in the shock absorption strategy, the pack plantarflexion velocity at the ankle joint was faster in Hard than Soft, and the pack dorsiflexion moment decreased when wearing a backpack (p<.05). Also, the pack extension moment of the knee increased significantly when wearing a backpack. Fourth, in the mechanical negative work, the ankle joint performed less work than the medium soft, and the knee joint increased as the backpack was worn (p<.05). Conclusion As a result of this study, the difference in the hardness of the midsole used in this study does not seem to affect the biomechanical movement of gait even when wearing a backpack. In future studies, it is necessary to investigate the effect of the midsole through the presence or absence of shoes or inducing muscle fatigue.
