Search

While helmet wearing reduces the severit of injuries in motorcycle crashes, it may also increase the likelihood of getting involved into a traffic accident through a reduction in the rider’s field of view. We thus investigated the perceptual effects of helmet wearing when riding a motorcycle. The task consisted of negotiating curves in a fixed-based motorbike simulator while the helmet visor vertical dimension and need to check the handlebar-mounted speedometer were manipulated. Decreasing the vertical aperture below roughly 30 deg significantly impaired a rider’s ability to maintain their lane position and speed; with the effect of aperture being significantly greater when speedometer checking was required. The present findings help to quantify the tradeoff between physical and perceptual effects in helmet design., Si le port du casque est le moyen le plus efficace pour limiter la gravité des accidents de moto, il pourrait également augmenter le risque d’être impliqué dans un accident puisqu’il limite le champ de vision du motard. Nous avons analysé ici l’effet d’une manipulation du champ de vision sur le comportement de conduite en moto. La tâche consistait à négocier des virages sur un simulateur de moto à base fixe, alors que la hauteur de l’ouverture du casque et la nécessité de contrôler sa vitesse sur un compteur fixé sur le guidon étaient manipulées. Des ouvertures de casque inférieures à 30 deg. environ dégradaient la capacité du conducteur à maintenir sa vitesse et sa position dans la voie; cet effet était d’autant plus marqué dans les conditions impliquant de regarder le compteur de vitesse. Ces résultats ont des implications directes quant à la gestion du compromis entre les contraintes physique et perceptive dans la conception de casques de moto.

International audience

33rd International Conference on Biomechanics in Sports, POITIERS, FRANCE, 29-/07/2015 - 29/07/2015; This study aimed at comparing the glenohumeral (GH) range of motion, and shoulder and scapular muscle strength in elite girl tennis players with (group HoSP; n=15) and without (group H; n=16) history of shoulder pain. The GH joint range of motion in internal (IROM) and external rotation (EROM), as well as the maximal isometric strength of eight shoulder and scapular muscles were bilaterally assessed in 31 girl players. The results showed an increased IROM in HoSP, suggesting a laxity, which may contribute to humeral translation motions in the glenoid cavity at critical tennis positions. The HoSP group also presented a weakness in serratus anterior muscle strength, which may create improper motions of the scapula during the tennis strokes. These findings suggested that stretching and strengthening rehabilitative programs may be specifically developed for the young girl athletes involved in an intensive overhead activity practice.

International audience; While helmet wearing reduces the severity of injuries in motorcycle crashes, it may also increase the likelihood of getting involved into a traffic accident through a reduction in the rider's field of view. We thus investigated the perceptual effects of helmet wearing when riding a motorcycle. The task consisted of negotiating curves in a fixed-based simulator while the helmet visor vertical dimension and need to check the handlebar-mounted speedometer were manipulated. Decreasing the vertical aperture below roughly 30 deg significantly impaired a rider's ability to maintain their lane position and speed; with the effect of aperture being significantly greater when speedometer checking was required. The present findings provide further support for near/far point models of steering and help to quantify the tradeoff between physical and perceptual effects in helmet design.

International audience; Recent improvements in material technology, together with generalization of testing, prototyping, and benchmarking, have impacted on performance in many sports. However, sports equipment properties are often tested through mechanically based standardized protocols. Such protocols would ignore the effects on equipment resulting from mechanically unpredicted manoeuvres performed by athletes aiming for performance, injury protection or comfort. Their use may thus turn out to be of limited use in the evolution of sports equipments towards perfection, as a first-rate equipment is not only the one including high-tech materials but also the one interacting in the best way with the athlete using it.This study aimed at determining, through the example of the backward giant circle on the high bar, whether or not the effects of standardized tests on sports equipment are comparable with the effects caused by real athletic practice. A comparison between the characteristics of the kinematics predicted from a pure mechanical analysis of the giant circle and those observed in real situations during performance of giant circles by seven elite gymnasts’ pointed out differences. According to the mechanical analysis, the gymnasts should be maximally extended at vertical handstand and maximally flexed at the moment of passing through the lower point upwards. Maximal extension in fact occurred when their body center of mass had rotated approximately 120° from the handstand and maximal flexion occurred approximately 100° after having passed through the lower point.This result suggests that manufacturers should realize that standardized test only provide limited information, as differences in kinematics between the predicted and observed solution are associated with differences in the force exerted. Integration of the effect of intentional actions of the athlete using the equipment as a constraint in test procedures would render these more comprehensive thus allowing development of more efficient equipment.