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.

Health benefits of physical activity are well known, yet available physical activity data is limited from children living in African and Asian countries. The purpose of the cross-sectional study was to evaluate and compare physical activity and sedentary behavior patterns, particularly hourly variations, among children in Kenya and Japan. Participants included 298 primary school students (122 Kenyan, 176 Japanese) aged 9–12 years. Physical activity and sedentary behavior were measured with accelerometers. Domain-specific physical activity, screen time, and proportion of children using active transport to school were measured by questionnaire. A two-way ANOVA (countries × time) was used to examine the differences in the activity patterns between Kenyan and Japanese children. The results from the present study demonstrated that Kenyan children spent more time in moderate-to-vigorous physical activity compared to Japanese children (p < 0.05) with the greatest differences found for weekday evenings (for boys and girls) and weekend afternoons (for girls). This suggests that these were ‘critical periods’ to differentiate the physical activity levels between Kenyan and Japanese children. However, a higher proportion of the children from Japan used active transport to school and spent less time in television viewing and computer gaming. The results suggest that both countries have successes and challenges that can aid in developing effective and country-specific intervention strategies for promoting physical activity.

The present study aimed to clarify the effect of the foot strike pattern on muscle–tendon behavior and kinetics of the gastrocnemius medialis during treadmill running. Seven male participants ran with 2 different foot strike patterns (forefoot strike [FFS] and rearfoot strike [RFS]), with a step frequency of 2.50 Hz and at a speed of 2.38 m/s for 45 seconds on a treadmill with an instrumented force platform. The fascicle behavior of gastrocnemius medialis was captured using a B-mode ultrasound system with a sampling rate of 75 Hz, and the mechanical work done and power exerted by the fascicle and tendon were calculated. At the initial contact, the fascicle length was significantly shorter in the FFS than in the RFS (P = .001). However, the fascicular velocity did not differ between strike patterns. Higher tendon stretch and recoil were observed in the FFS (P < .001 and P = .017, respectively) compared with the RFS. The fascicle in the positive phase performed the same mechanical work in both the FFS and RFS; however, the fascicle in the negative phase performed significantly greater work in the FFS than in the RFS (P = .001). RFS may be advantageous for requiring less muscular work and elastic energy in the series elastic element compared with the FFS.

[Purpose] We aimed to determine the cause of floating toe syndrome, along with methods for correction and prevention. [Participants and Methods] We recruited 93 Japanese male students. Participants were grouped, according to primary sport, as Sprinters (SPR), Swimmers (SWM), Gymnasts (GYM), Kendoists (KND) and Controls (CON). Degree of floating toe syndrome was measured according to whether any toe was not in full contact with the ground in a static standing posture—the Floating Toe Point (FTP). Two points were given for each toe that was not at the FTP. The sum of the FTP was defined as the Floating Toes Score (FTS), and was classified as follows: Normalcy (over 18 points), Incomplete Contact (between 10 and 17 points), and Floating Toes (Under 9 points). [Results] The mean FTS for all participants (10.40 ± 5.803) met the criteria for Floating Toes. Scores were highest for SWMs (13.46 ± 5.710), followed by GYMs (13.26 ± 4.505), and SPRs (12.00 ± 4.870), who all met the criteria for Incomplete Contact. Both KNDs (6.55 ± 5.409) and CONs (9.45 ± 4.824) met the criteria for Floating Toes. [Conclusion] SWMs had the highest FTSs, followed by GYMs, and SPRs. KNDs had the lowest FTS. However, no group was classified as Normal. We suggest that athletes who practice or train with bare feet do not necessarily have higher FTSs, if evaluated in the standing posture.

Introduction: We aimed to investigate the effect of Sorbothane insole insertion and foot strike patterns on shock attenuation during running. Methods: Nine male students participated in the study. Running was performed on a 15 m runway at a constant speed of 3.33 m/s. Two types of insoles (EVA and Sorbothane) and two-foot strike patterns (forefoot and rearfoot) were used, creating four experimental conditions. The tibial acceleration and vertical ground reaction force (GRF) were measured, and their peak and loading rate were calculated. A two-way ANOVA (insole × foot strike pattern) was performed. Results: Tibial acceleration showed no significant interaction. However, the peak and loading rate of vertical GRF were significantly higher in the rearfoot strike pattern. The Sorbothane insole significantly reduced the loading rate only in the rearfoot strike condition. Ankle joint angles showed differences depending on foot strike and insole type. Conclusion: These findings suggest that the foot strike pattern may has a greater influence on impact characteristics than the difference in insole material under the present conditions. While Sorbothane insoles may offer some benefits in reducing impact loading during rearfoot strike, further studies with larger sample sizes are required to confirm these effects.