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David Perrier and Karine Monteil

The aim of this study was to determine the effect of wearing a triathlon wet suit on the technical parameters of the front crawl stroke. Eight highly trained male triathletes were filmed with underwater camcorders during two 1500-m swim tests: one with a wet suit (WS) and the other with a standard suit (SS). Two conditions were considered: Condition I (CI) and Condition XV (CXV), representing the 1st and the 15th 100-m, respectively. Views were synchronized and digitized using kinematic analysis software (Schleihauf, 1994) to obtain 3-D coordinates of the anatomical landmarks of the body. Results showed that the wet suit and duration of the exercise significantly influenced stroke parameters. The swim with WS was characterized by greater stroke length and a progressive increase in stroke frequency, resulting from a more extended elbow position during the stroke and from a decrease in the absolute and relative times of the propulsive phase. These changes indicated more efficient upper limb action. The duration of exercise modified the swim with WS and SS. The loss of velocity observed in CXV was related to a decrease in stroke length, or more precisely a reduction in lever arm length during the aquatic phase, insufficiently offset by a slight increase in stroke frequency. These two motor responses, a less extended elbow position and a stroke frequency increase, emerged as an easier motor solution for coping with the effect of fatigue. This solution could be regarded as an adaptation to the duration of the exercise.

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Marianne Haguenauer, Pierre Legreneur and Karine M. Monteil

To our knowledge jumping kinematics have never been studied in elderly persons. This study was aimed at examining the influence of aging on vertical jump performance and on interjoint coordination. Two groups of adults, 11 young men ages 18–25 years and 11 older men ages 79–100 years, were filmed while performing a maximal squat jump. Compared to young adults, jump height was significantly decreased by 28 cm in the elderly. Older adults spontaneously jumped from a more extended position of the hip. Results showed a decrease in hip, knee, and ankle linear velocity and angular amplitude with aging. The decrease in jump height was attributed to a decrease in explosive force and in the range of shortening of extensor muscles. In agreement with the literature, a proximo-distal coordination pattern was observed in young adults. Older adults used a simultaneous pattern. This may indicate that adults adjust their pattern of joint coordination as they age.

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Isabelle Rogowski, Karine Monteil, Pierre Legreneur and Pierre Lanteri

This study investigated the influence of the covering swimsuit and the fabric surface properties on the butterfly stroke kinematics. Surface properties were evaluated by wetting measurements of two fabric samples: one for training suits and one for competition suits. The surface of the second one was coated by mechanochemical treatment in order to modify its surface properties. Nine national level swimmers performed a 50-m butterfly at submaximal velocity in three swimsuit conditions: conventional, long, and coated long swimsuits. From video recording, the hip was digitized at the entry and exit of the swimmer's hand in order to calculate the duration, hip displacement, and hip linear velocity during underwater and recovery phases and during stroke. The results for wetting show that competition fabric was more water-repellent than training fabric, but both were isotropic. Moreover, the mechanochemical treatment increased water repellency and anisotropy. The swimming results indicated that, when compared to a conventional swimsuit, wearing a coated long swimsuit increased hip linear velocity during stroke, and particularly during the recovery phase which had a shorter duration. These results suggest that the covering swimsuit should be coupled with the water repellent and anisotropic properties of the fabric surface in order to improve swimming performance.

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Yoann Blache, Maarten Bobbert, Sebastien Argaud, Benoit Pairot de Fontenay and Karine M. Monteil

In experiments investigating vertical squat jumping, the HAT segment is typically defined as a line drawn from the hip to some point proximally on the upper body (eg, the neck, the acromion), and the hip joint as the angle between this line and the upper legs (θUL-HAT). In reality, the hip joint is the angle between the pelvis and the upper legs (θUL-pelvis). This study aimed to estimate to what extent hip joint definition affects hip joint work in maximal squat jumping. Moreover, the initial pelvic tilt was manipulated to maximize the difference in hip joint work as a function of hip joint definition. Twenty-two male athletes performed maximum effort squat jumps in three different initial pelvic tilt conditions: backward (pelvisB), neutral (pelvisN), and forward (pelvisF). Hip joint work was calculated by integrating the hip net joint torque with respect to θUL-HAT (WUL-HAT) or with respect to θUL-pelvis (WUL-pelvis). θUL-HAT was greater than θUL-pelvis in all conditions. WUL-HAT overestimated WUL-pelvis by 33%, 39%, and 49% in conditions pelvisF, pelvisN, and pelvisB, respectively. It was concluded that θUL-pelvis should be measured when the mechanical output of hip extensor muscles is estimated.