The purposes of this study were to clarify the electromyography (EMG) of plantar flexors and to analyze the fascicle and tendon behaviors of the gastrocnemius medialis (GM) during running in the carbon-fiber plate embedded in thicker midsole racing shoes, such as the Nike ZoomX Vaporfly (VF) and traditional racing shoes (TRAD). We compared the fascicle and series elastic element behavior of the GM and EMG of the lower limb muscles during running (14 km/h, 45 s) in athletes wearing VF or TRAD. GM EMGs in the push-off phase were approximately 50% lower in athletes wearing VF than in TRAD. Although the series elastic element behavior and/or mean fascicle-shortening velocity during the entire stance phase were not significantly different between VF and TRAD, a significant difference was found in both the mean EMG and integral EMG of the GM during the push-off phase. EMG of the gastrocnemius lateralis (GL) during the first half of the push-off phase was significantly different between VF and TRAD. Present results suggest that VF facilitates running propulsion, resulting in a decrease in GM and GL EMGs at a given running velocity during the push-off phase, leading to a reduction in metabolic cost.

Understanding the foot strike pattern (FSP) and impact force of running-related injuries is crucial for athletes and researchers. This study investigated a novel method for detecting FSP using the loadsol^® sensor insole during treadmill running. Twelve collegiate athletes ran at three different speeds (12, 15, and 20 km/h), with their FSP determined using both the kinematic method based on the foot strike angle and the loadsol^® method based on the plantar force applied to the rear-, mid-, and forefoot sensor areas. This study provides significant insights into FSP detection. Comparing the kinematic method to the loadsol^® method, the rearfoot, midfoot, and forefoot strike detection rates were 94.7%, 37.1%, and 81.8%, respectively. Moreover, the FSP was not uniform, even during treadmill running at a constant speed, with most participants exhibiting mixed patterns across different speeds. The loadsol^® sensor insole could offer a promising device for in-field measurement of FSP and impact forces, potentially helping researchers and athletes better understand and predict the potential running-related injury risks by monitoring step-to-step variations in running biomechanics.

This study explored the relationship between floating toes and athletic performance among collegiate track and field athletes. A total of 422 athletes (sprinters, jumpers, and distance runners) and 136 controls participated in this study. Plantar surface images were captured using a specially designed foot scanner during standing to calculate the floating toe score. The score, which sums the floating toe points of all toes, categorizes them into ‘floating toe’, ‘incomplete contact’, or ‘normal toe’. The World Athletics score served as a measure of athletic performance. Overall, collegiate track and field athletes had a significantly higher mean floating toe score (14.22 ± 4.87 points) than controls (11.06 ± 6.05 points) (p < 0.05), suggesting that fewer floating toes may confer a performance advantage. Within the track and field events, sprinters and jumpers showed significantly higher floating toe scores than distance runners (p < 0.05), emphasizing the variations in floating toes across different events. Although no significant correlation between floating toe score and World Athletics score was observed overall, a significantly negative correlation was found among distance runners (r = -0.25, p = 0.006), indicating that distance runners with higher athletic performance tend to have more pronounced floating toes. These findings suggest a nuanced relationship between floating toes and various aspects of track and field performance, particularly in distance running.