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Abstract: Introduction: Carbon plates have been used to increase running shoes' longitudinal bending stiffness (LBS), but their effect during a long duration run remains unknown. Our study aimed to identify the effect of LBS on energy cost of running (Cr), biomechanics, and fatigue during a half-marathon.Methods: Thirteen well-trained male runners (half-marathon time < 1 h40) performed two half-marathons at 95% of the running speed associated with their second ventilatory threshold on two separate visits, with either high-LBS shoes (HLBS, with carbon-plates) or standard-LBS (SLBS) shoes. Before and after the half-marathon, Cr at 12 km/h with both shoes (two 6-min bouts: Cr12) and ankle plantarflexors (PF) force were measured. During the half-marathon, running kinematics, shoe perceived comfort, and Cr were assessed.Results: During Cr12 measurements before and after the half-marathon, HLBS was 1.0 ± 2.1% more economical than SLBS (p < 0.001). During the half-marathon, Cr increased with running duration (p = 0.048) but there was no distance × condition effect. HLBS increased contact time (+3%, p = 0.01), decreased metatarsophalangeal joint dorsiflexion (-9%, p = 0.01), and was perceived less comfortable than SLBS, independently from running duration. At the end of the half-marathon, HLBS shoes led to higher PF force loss (-20.0 ± 9.8% vs -13.3 ± 11.0%, p = 0.048).Conclusions: Adding curved carbon plates in the running shoes slightly improved Cr during short running bouts at low intensity but not during a half-marathon. This discrepancy may be explained by day-to-day Cr variability and variation in shoe comfort. PF fatigue was higher with HLBS shoes but the accentuated fatigue did not further impact the biomechanical perturbations induced by the plates. Our results suggest that carbon plates alone do not provide a significant advantage for half-marathon performance., Competing Interests: Conflict of Interest and Funding Source: The authors did not receive funding from any organization or company in order to perform the study., (Copyright © 2024 by the American College of Sports Medicine.)

This study investigated the effects of marker placement (skin- vs shoe-mounted) on metatarsophalangeal joint (MTP) kinematics and kinetics during running. Fifteen trained men ran on a 15-m track at 10 and 13 km/h with three (low, standard and high stiffness) shoe longitudinal bending stiffnesses (LBS). Reflective markers were fixed on the shoe upper, and on the skin using holes cut in the shoe. Three-dimensional marker positions and ground reaction forces were recorded at 200 and 2000 Hz, respectively. Kinematic and kinetic parameters were analyzed using one-dimensional metrics (statistical parametric mapping). MTP joint was less dorsiflexed at midstance ([57% to 100%] of braking phase and [0% to 48%] of pushing phase), and the MTP joint plantarflexion moment was higher ([22% to 55%] of pushing phase) with the shoe markerset in comparison with the skin markerset. The effect of LBS on MTP angle was found to be significant for a larger percentage of each stride using the shoe markerset compared to the skin markerset. However, the effect of LBS on plantarflexion moment was significant with the shoe markerset only. The effect of running speed on MTP angle was significant for a larger percentage of each stride with the skin markerset. This study demonstrates that the placement of markers influences the measurement of MTP kinematics and kinetics and that these effects are mediated by other variables such as LBS or running speed. It is concluded that the shoe markerset does not fully reflect the movement of the MTP joint., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

In recent years, there has been a significant expansion in female participation in endurance (road and trail) running. The often reported sex differences in maximal oxygen uptake (VO 2max ) are not the only differences between sexes during prolonged running. The aim of this narrative review was thus to discuss sex differences in running biomechanics, economy (both in fatigue and non-fatigue conditions), substrate utilization, muscle tissue characteristics (including ultrastructural muscle damage), neuromuscular fatigue, thermoregulation and pacing strategies. Although males and females do not differ in terms of running economy or endurance (i.e. percentage VO 2max sustained), sex-specificities exist in running biomechanics (e.g. females have greater non-sagittal hip and knee joint motion compared to males) that can be partly explained by anatomical (e.g. wider pelvis, larger femur-tibia angle, shorter lower limb length relative to total height in females) differences. Compared to males, females also show greater proportional area of type I fibres, are more able to use fatty acids and preserve carbohydrates during prolonged exercise, demonstrate a more even pacing strategy and less fatigue following endurance running exercise. These differences confer an advantage to females in ultra-endurance performance, but other factors (e.g. lower O 2 carrying capacity, greater body fat percentage) counterbalance these potential advantages, making females outperforming males a rare exception. The present literature review also highlights the lack of sex comparison in studies investigating running biomechanics in fatigue conditions and during the recovery process., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Although shoe friction has been widely studied in occupational ergonomics, information was lacking about friction in sport shoes. The purpose of the study was to examine the neuromechanical adaptations to different shoe-surface interface in an aerobic-gym specific movement. Sixteen females performed 10 change of direction movements in two shoe conditions differing by their outsoles (ethyl-vinyl-acetate: EVA and rubber: RB) to ensure significant differences in mechanical coefficients of friction (EVA = 0.73 ± 0.07 and RB = 1.46 ± 0.15). The kinematics, kinetics and muscle activities of the right lower-limb were analysed. Statistical parametric mapping was used to investigate the kinematics and kinetics adaptation to the different shoe-surface coefficients of friction. The participants had a longer stance duration in the EVA compared to the RB condition (526 ± 160 ms vs. 430 ± 151 ms, p < .001). The ankle and knee joints powers and works were lower during both the braking and the push-off phases in the EVA as compared to the RB condition. Preactivation of the agonist muscles (soleus, gastrocnemius medialis and vastus medialis) decreased in the EVA compared to the RB condition (-28.5%, -26.5% and -49.0%, respectively). Performing a change of direction movement with slippery shoes reduced the ankle and knee joints loadings, but impaired the stretch-shortening cycle performance. Participants demonstrated thus a different neuromechanical strategy to control their movement which was associated with a reduced performance., (Copyright © 2018 Elsevier B.V. All rights reserved.)