Évolution de la puissance maximale anaérobie au cours de la croissance chez le footballeur

Purpose – The aim of the study was to assess the improvement in Maximal Anaerobic Power (PMAna) from two tests in soccer players during growth.Methods – The experiment was carried out in 328 players, 11–18 years old, during their stay at the Clairefontaine National Soccer Center. PMAna was measured from the last 10 meters of the a 40 m-sprint test (ST) and a jump test (JT). The skeletal age (AO) is used as reference, and not the chronological one.Results – The results of the two tests are highly correlated (r= 0.8–0.9), PMAna values being always higher in the ST than in the JT.The most significant increase in PMAna occurs between 13 and 14 years AO (+47% for the ST, +27% for the JT), remains still significant up to 16 AO (respectively +38% and +24% between 14 and 16 AO), but the maximum value is reached at 17 AO. Between 12 and 16 AO, the PMAna value is multiplied by 2.29 for the ST and 1.81 for the JT.Conclusions – Sprint and jump tests seem well adapted to estimate PMAna in soccer players. The measure of the skeletal age during growth is needed for a better interpretation of the results. In addition, results obtained during growth allow a reliable estimation of PMAna in adulthood.     

Estimation de la contribution énergétique d'origine aérobie et anaérobie et de sa répartition au cours d'un 800 m couru sur le mode compétition

Aim – Determine the part of each energetic system at different times of 800m competition. Oxygen uptake and speed were recorded continuously.Materials and methods – Five athletes performed on an outdoor track a test to determine the maximal oxygen uptake and the maximal aerobic speed and a supramaximal exercise of 800m.Results – The overall energetic expenditure as well as the oxygen deficit assessed at 31.9% were almost identical at those obtained during an 800m race running on a treadmill. Only the repartition of the oxygen deficit notably differed during the race. This suggered that the kinetic of the speed had a determining incidence on the anaerobic contribution as well as aerobic contribution when there were changes in running velocity.     

Extension du modèle puissance–temps limite pour estimer la production d’énergie aérobie et anaérobie lors de l’exercice intense

Aim

Examine how the modelling of the relation between power and time to exhaustion can provide an estimation of the production of aerobic and anaerobic energy during intense exercise.

Current knowledge

The hyperbolic model made it possible to define the critical power corresponding to the maximal rate of energy renewed by aerobic metabolism. A new model distinguishing the critical power from the maximal aerobic power has been built to estimate more precisely the anaerobic contribution. Data from middle distance runners and subjects tested on cycle ergometer showed a relative contribution of anaerobic metabolism arising from critical power and increasing until around 10 % of total power when aerobic energy production reaches its maximum.

Prospects

Considering the slow component of oxygen uptake would provide a more precise analysis of energy production and transformation during exercise at high intensity.     

Étude optoélectronique du mouvement de pédalage chez des cyclistes lors d'un exercice à 250 Watts. Comparaison entre une selle standard et une selle ergonomique

Purpose – The aim of this experiment was to evaluate and to compare the motor behaviour of cyclists who rode a bicycle equipped with a standard saddle and an ergonomic saddle that has no perineum support.Methods – Six trained cyclists (Mean ± SD: age, 37 ± 9 yr.; body mass, 74 ± 1 kg; height, 178 ± 5 cm) rode a bicycle equipped with a standard saddle or an ergonomic saddle, mounted on Gymrol velodyne. The trial began at 100 Watts, the workload increased 50 Watts per three minutes until 250 Watts. At the end of the last level a video data collection was realised with a Vicon system at 50 frames per second. Only the cyclist's right side movements were collected.Conclusion – At the workload of 250 Watts the motor behaviour of the cyclists was not different when they used the standard saddle or the ergonomic saddle except the maximal extension of the knee (p < 0.05), the amplitude of the flexion extension movement of the knee (p < 0.05) and the localisation of the maximal adduction on the crank angle (p < 0.05) which was significantly different between the two saddles. The ergonomic saddle doesn't dramatically modify the cyclist's motor behaviour during a mean power exercise and it has an advantage, it removes the perineum support.     

Infections ORL,immunodépression et stress liés à la pratique des activités physiques et sportives

Objectives – Understand the pathophysiology of upper respiratory tract infections (URTI), the most common ailment of elite athletes.Actualities – URTI likely develop as a consequence of local or systemic immunosuppression. Such a lowered protection may result both from training and from the stress associated to competitive sports. This literature review summarises the physiology of the immune system associated to the upper respiratory tract, then presents evidence supporting the impact of stress and training respectively on the immune system.Perspective – Better knowledge of the impact of high-level sport on the immune system may allow to adapt training and competition in order to avoid or limit the immunosuppression leading to an increased susceptibility to infections.     

Effets de l'entraı&#x0302;nement sur les potentiels aérobie et anaérobie de jeunes nageurs. Exercice réalisé avec les bras

Aims – Investigate the influence of exercise training on the aerobic and anaerobic capacities of young swimmers.Methods – Ten male swimmers aged 15.2 ± 3.8 years participated: five sprint specialists and five middle-distance specialists. Each subject performed, an arm ergocycle, two laboratory tests, a maximal incremental exercise test and a force–velocity test, once in February (T1) and then again in June (T2).Results – For all subjects combined (n=10), the results showed a significant increase in maximal anaerobic power (p < 0.01) between T1 and T2. Aerobic capacity did not change significantly between the two tests in either group.Conclusion – This study demonstrates the interest of evaluating aerobic and anaerobic capacity in young swimmers during arm exercise. The change in results over the 5-month period between the two tests indicates the importance of scheduling exercise tests during the course of athletic training programs.     

Influence du statut hydrique sur la variation des paramètres physiologiques et biomécaniques lors d'un exercice de pédalage de longue durée

Purpose. – Study was to investigate the influence of hydration status on maximal and sub-maximal muscular performances during prolonged cycling exercise.Methods. – Eight well-trained subjects exercised for 180 min in a moderate environment at a workload requiring ∼60% maximal oxygen uptake. Two conditions, with fluid (F) and no fluid ingestion (SF), were investigated. During all the tests oxygen uptake was collected, cadence and applied force on the cranks were recorded. Furthermore maximal voluntary contraction performance (MVC) was recorded before and immediately after exercise.Results. – A significant increase in energy cost of cycling was observed during the no fluid condition only. After exercise a significant reduction in MVC was recorded whatever the condition. No significant change in cycling mechanics was observed.Conclusion. – This study indicate that cycling during 3 h leads to a significant impairment of maximal muscular performance but has no effect in cycling mechanics in well trained cyclists. Furthermore this effect seems independent from hydration status.