Influence de l'hydratation sur la sécrétion d'hormone de croissance induite par l'exercice

Aim – Study was then to investigate hydration influence on exercise-induced GHh secretion.Methods and results – Seven healthy men underwent a submaximal rectangular cycling exercise for 30 minutes to 150 watts during two sessions. A first one without any water intake and a second one with ingestion of spring water corresponding to the volume of water lost during the first session. Plasma volume decrease was significantly higher during the first session (p < 0.05). Total GH secretion was significantly lower during this session (p < 0.05).Conclusion – A moderate dehydration decreases exercise-induced GH response. Thus, hypovolemia may exert a negative feed back on GH secretion, during exercise.     

Effet de l’intensité de course sur la force de poussée en rugby

Introduction. – The rugby is a discipline requiring, in the same time, strength qualities and a high aerobic capacity for repeating intense exercises over 2 × 40 min.Synthesis of the facts. – Fourteen rugby players performed a maximal progressive test of journey (running) then two sequences of 40 min, respectively, to 60% and 80% of HR_max, interrupted with pushes on a yoke with constraint gauges. At 80% HR_max, the mean scrummaging force (1466 ± 244 N) was lower (P < 0.05) than at 60% HR_max (1523 ± 266 N).Conclusion. – The qualities of specific force are directly affected by the intensity of running. Therefore, there is a need to optimize the aerobic potential notably for the players of the first line directly concerned by the fight.     

Effet de la castration sur le développement des muscles squelettiques

Introduction – Study the effects of the castration on skeletal muscle.Synthesis of facts – Physical and chemical muscle characteristics of 90 males, females and males rabbits castrated at three days were studied after slaughter when 14 weeks old. Longissimus dorsi muscle was analysed. LD chemical characteristics were insignificantly modified by castration. LD muscle was significantly more tender for females and castrated males than for entire males.Conclusion – The castration affects internal structure of skeletal muscle of rabbits slaughtered at 14 weeks of age.     

Dynamique de la locomotion en fauteuil roulant manuel : influences de la masse totale et de sa répartition antéropostérieure sur la résultante des forces de freinage

Purpose. – This study presents a new method for determining the resultant braking force during wheelchair displacement and investigates the respective effects of the level and the distribution of the system’s mass.Method and results. – A three-dimensional accelerometer was fixed directly under the seat of wheelchair and was used to measure the deceleration of the mass-and-wheelchair’s system. Three masses (50, 70 and 90 kg) were laid on a support in 3 positions corresponding to three distributions (10, 40 and 70%) of the system’s total mass upon the front casters. A series of 15 deceleration trials was performed for each of the 9 combinations. Statistical results showed that the system’s deceleration was mainly explained by the mass distribution upon the front casters (92%) and in the least by the system’s total mass (8%).Conclusion. – Considering the fore-and-aft movements of the subject’s centre of mass during wheelchair locomotion, the results of this study let us assume that the resultant braking force does not remain constant along the propulsion cycle. Moreover, the present method could be used to investigate the influence of wheelchair’s adjustments and floor’s characteristics on the resultant braking force.     

Répercussion de l’asthme induit par l’exercice sur la performance aérobie de l’enfant

Introduction. – Exercise-induced asthma is a clinical syndrome leading to a transient narrowing of the airways after the end of the exercise.Synthesis of results. – In order to observe its effect on aerobic performance 60 prepubescent children including 36 asthmatics have achieved a maximal increased exercise and a 8min constant exercise. The maximal expiratory flow-volume significantly decreased after the 2nd exercise in the exercise-induced asthma children. This means that airways were narrowing with exercise intensity. These narrowing did not seem to have any effect on the aerobic parameters measured in our study.Conclusion. – We conclude that controlled asthma does not limit the aerobic performance in prepubescent children.     

Effet de l'intensité de l'entraînement sur les réponses en catécholamines à l'exercice supramaximal chez des endurants de sexe masculin

Introduction – In this study we compared catecholamine responses to the Wingate-test in 2 male endurance trained groups: 6 middle distance runners (DFC) (800m and 1500m) and 6 long distance runners (DFL) (5000 m and 10,000 m).Results – As expected DFL exibited higher maximal oxygen consumption (72 ± 2,5 vs 79 ± 4,5 ml min^–1kg ^–1 fat free mass respectively for DFC and DFL) and DFC exibited higher performances during the Wingate-test (15,8 ± 0,3 vs 14,7 ± 0,4 W kg^–1 fat free mass respectively for DFC and DFL). In opposite differences between maximal catecholamine responses (Adrénaline: 3,8 ± 0,7 vs 3,5 ± 0,3 nmol l^–1. Noradrénaline: 20,4 ± 1,5 vs 16 ± 2,1 nmol l^–1 respectively for DFC and DFL) and maximal plasma lactate were not significant.Conclusion – This results suggests that endurance specificity may not induce different catecholamines responses to sprint exercise.     

Influence de la distance de course sur les paramètres cinématiques de nage chez les nageurs avec palmes de haut niveau

Introduction – Finswimming is a new sport activity. The optimization of the leg’s propulsive action is fundamental to improve the performance. The aim of this work is to quantify finswimmer’s movements per race distances, using a kinematic analysis.Fact synthesis – Five elite finswimmers were video recorded during underwater races. The connections between the average velocity of stroke, frequency and range of finswimmers undulation are observed as a fonction of race distance.Conclusion – Finswimmers are shown to adjust and to stabilize instantaneously their movements in terms of race distance.