Influence des caractéristiques de la natation sur la performance lors d’un enchaînement natation–cyclisme

Purpose. – Investigate the influence of previous swimming on energy expenditure during the subsequent cycling exercise of a triathlon.Methods. – Ten well trained triathletes underwent 3 swim-to-cycle transitions and 1 isolated cycling trial (C trial). The cycling exercises consisted in 15 min on a bicycle ergometer at a power output corresponding to the ventilatory threshold +5 %. During the transitions, this exercise was preceded by swimming bouts soliciting different muscles, undertaken at a 750 m competition pace for the same duration (swimming with arms and legs: Sal trial, with arms only: SA trial, or with legs only: SL trial).Résultats. – The swimming bouts of SA and Sal trials involved a significant increase in energy expenditure during subsequent cycling in comparison with isolated cycling (P < 0.05). Moreover, cycling efficiency was not significantly different between SA and SAL trials (P > 0.05).Conclusion. – A short intense swimming leads to an increase in energy expenditure during subsequent cycling, because of the thermoregulatory adjustments and the additional oxygen cost of respiratory work involved during swimming. It also shows that physiological adaptation during cycling does not depend on the lower limb work during prior swimming.     

Estimation de la dépense énergétique lors d'une régate en dériveur

Introduction. – Assess the energetic cost during small craft competition.Methods. – Height healthy sailors have been tested during three regattas. Heart rate, vertical jump, glycemia, cortisol and testosterone have been recorded.Results and discussion. – Regattas did not show significant difference for hormones. However, a significant 10% decrease of glycemia was presented. Heart rate increased during competition, but it was different according to the wind velocity and wind direction. The oxygen cost of sailing is relatively light. However, this cost could be increase with bad conditions of sailing. It seems that aerobic capacity is important regarding performance.     

Mise en évidence de la sollicitation du cycle des purines nucléotides lors d’un combat de judo

Objective. – Energy solicitation during a judo match and the kinetics of recovery were assessed by measuring the metabolites of oxypurine cascade level and the glycolytic pathway.Methods. – Venous blood samples were taken from sixteen national judo athletes (aged 18.4 ± 1.6 years), before (T1) and at 3 minutes (T2), 1 hour (T3) and 24 hours (T4) post-match. A 7-day diet record was used to evaluate the values for nutrient intakes.Results. – Nutrient analysis indicated that these athletes followed a low carbohydrate diet. Plasma lactate concentration rose to 12.3 ± 1.8 mmol l^–1 at the end of the match. An increase in extracellular markers of muscle adenine nucleotide catabolism, urea and creatinine levels was observed at T2 while uric acid levels remained unchanged. Persistent high concentrations of urea were observed during the post-training recovery period for 24 h. Ammonia, hypoxanthine, xanthine and creatinine values returned to their control levels within 12 h of recovery. Uric acid concentrations rose from T3 and did not return to baseline 24 h after the match.Conclusions. – These results showed that a judo match induces mobilisation of protein metabolism.     

Électromyostimulation et récupération fonctionnelle d’un muscle dénervé

Aim. – The purpose of this revue is to focus on research concerning the effect of chronic muscle electrical stimulation after denervation and reinnervation.Actuality. – The therapeutic use of electricity date back to ancient times, when the greeks used electric eels to treat physical ailment. Today electrotherapy is very commonly applied by certified athletic trainers. Alpha motor neurons conduct impulses from the spinal cord to the muscle. When the conduction of impulses to muscle is disrupted, the individual loses control of the affected muscle. When the nerve to the muscle is not functioning, the muscle is denervated, or without innervation. Unlike nerve fibers in the central nervous system, peripheral nerve fibers can regenerate and active control of the muscle can be restored.Perspectives and projects. – The efficacy of electrical stimulation of denervated muscle has not been established in human. Electrical stimulation does not bring about reinnervation; however a regularly stimulated muscle may recover force-generating capacity sooner if reinnervation occurs. In mammals, it has been show since several years that the regular stimulation of a denervated and reinnervated muscle promoted the motor function return. Recently, it has also been observed in animals, that muscle stimulation with a biphasic current was responsible to a more rapid return of the muscle sensibility. However, these preliminary works realized in the young mammals need to be improved.     

Intention de changement de comportement lors de la campagne de santé publique Vas-Y au Québec

PurposeThe present study examined associations between intention of youth to change their health behaviours and the messages of a media campaign held in Québec from 2004 to 2008, designed to increase awareness on active living and healthy eating's health benefits.MethodsSix hundred and three parent-youth dyads from primary and secondary schools participated to this cross-sectional survey by questionnaire at the end of the campaign. The intention to behaviour change in youth aged 10–16 years and their parents, their respective perceptions of the campaign's messages and their exposition to the campaign according to their school level were analyzed.ResultsSeventy-eight percent of youth heard about the campaign. One third of those having indicated that they knew the messages aimed at changing one or two behaviours. Youth from primary school vs. high school (P = 0.008) and those with a positive perception of messages (P < 0.001) were youths with the highest intention to change their behaviour.ConclusionThe high level of awareness reached in such a short period suggests that campaigns with motivating messages can be used to influence attitudes and intentions to adopt healthy eating and active living.