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The prevailing hypothesis about grasping in primates stipulates an evolution from power towards precision grips in hominids. The evolution of grasping is far more complex, as shown by analysis of new morphometric and behavioural data. The latter concern the modes of food grasping in 11 species (one platyrrhine, nine catarrhines and humans). We show that precision grip and thumb‐lateral behaviours are linked to carpus and thumb length, whereas power grasping is linked to second and third digit length. No phylogenetic signal was found in the behavioural characters when using squared‐change parsimony and phylogenetic eigenvector regression, but such a signal was found in morphometric characters. Our findings shed new light on previously proposed models of the evolution of grasping. Inference models suggest that Australopithecus, Oreopithecus and Proconsul used a precision grip.

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The aim of this study was to assess technical changes during constrained swimming in time-to-exhaustion tests. Ten swimmers of national standard performed a maximal 400-m front crawl and two sets of exhaustion tests at 95%, 100%, and 110% of mean 400-m speed. In the first set (free), swimmers had to maintain their speeds until exhaustion and mean stroke rate was recorded for each test. In the second set (controlled), the same speed and individual corresponding stroke rate were imposed. The durations of the exhaustion tests, relative durations of the stroke phases, and arm coordination were analysed. For each speed in the "controlled" set, the exhaustion tests were shorter. Moreover, variables were consistent, suggesting a stabilization of stroke technique. Under the free condition, stroke rate increased to compensate for the decrease in stroke length. At the same time, swimmers reduced the relative duration of their non-propulsive phases in favour of the propulsive phases. Thus, swimmers changed their arm coordination, which came close to an opposition mode. These two constraints enable swimmers both to maintain their stroking characteristics and develop compensatory mechanisms to maintain speed. Moreover, stroke rate can be seen as a useful tool for controlling arm technique during paced exercise.

The wheel camber of a wheelchair is a significant parameter that must be taken into account in the search for optimal regulation of a wheelchair. This study examined the effects of different rear-wheel camber (9°, 12° and 15°)today used mainly in the handibasket championship-on the various kinetic and kinematic parameters of the propulsion cycle. Eight males, all players in the French handibasket championship, were asked to participate in this study. They performed three 8 s maximal sprints as measured by a wheelchair ergometer, 9°, 12°, and 15° of rear-wheel camber. The results of our study show that residual torque increases in proportion to the increase in wheel camber. This could explain other study results, which show a decrease in mean velocity and an increase in both power output and time of the propelling phase, in relation to the wheel camber. These results should provide the information necessary for optimal wheelchair regulation.

Des progrès considérables des technologies mobiles ont été constatés sur les quinze dernières années, notamment avec le développement des écrans tactiles. Depuis que le vieillissement est un phénomène démographique mondial, plusieurs études ont été menées pour étudier et améliorer l'interaction des personnes âgées avec ces nouvelles technologies. Ces études sont importantes car les dispositifs mobiles, souvent équipés d'un écran tactile,peuvent aider à améliorer la qualité de vie des personnes âgées (soins de santé, maintien du lien social, jeux sérieux). Comprendre l'interaction de ce groupe d'utilisateurs avec des écrans tactiles peut ainsi faciliter l'adoption des technologies interactives et leur future utilisation. Cette revue de la littérature analyse trente-six études qui ont évalué des techniques d'interaction pour des sujets âgés utilisant des dispositifs avec écran tactile. Cette revue vise 1) à analyser la situation de ces trente-six études (population, équipements, tâches et techniques d'interaction) et 2) à identifier les situations d'utilisation des écrans tactiles et des techniques d'interaction qui doivent encore être étudiées. Les résultatssont l'analyse descriptive des populations incluses, des dispositifs choisis, des tâches effectuées et des techniques d'interaction, ainsi qu'unesynthèse des paramètres pertinents à prendre en compte pour des études sur les techniques d'interaction tactile. Sur chaque point, nous présentons une discussion sur les résultats, les recommandations des auteurs et des repères pour des travaux futurs. Mots clés :Ecran tactile, techniques d'interaction, personnes âgées.