L'excès de consommation d'oxygène post-exercice supramaximal individualisé : influence du niveau d'aptitude physique

Objective. – Determine the influence of physical fitness level on excess post-exercise oxygen consumption after supramaximal-intermittent exercise.Method. – Fourteen subjects (seven trained and seven sedentary subjects) performed three repetitions of an exercise corresponding to 60% of time to exhaustion at 120% of the maximum aerobic power, with two recovery periods of 5 min each. The third exercise was followed by 20 min of recovery. The oxygen uptake was measured continuously using a breath-by-breath device. Blood samples were taken from fingers during recoveries for lactate analyses.Results. – The excess post-exercise oxygen consumption increased gradually during recovery in trained subjects (P < 0.01). However, values were practically similar in sedentary subjects. In addition, we found a linear relationship between excess post-exercise oxygen consumption and decrease lactate during the 20 min recovery. Whatever the level of subject physical fitness, these two parameters were significantly correlated (r = 0.94; P < 0.01). Trained subjects have significantly higher excess post-exercise oxygen consumption than sedentary subjects (P < 0.05) and greater lactate decrease during recovery (P < 0.01).Conclusion. – Between and after repetition of supramaximal individualized exercise, the excess post-exercise oxygen consumption vary according to the level of physical fitness.     

Influence d'un programme de marche sur la consommation maximale d'oxygène (V̇O2 max) et les aptitudes psychomotrices de sujets âgés sains et actifs

Introduction – The aim of this study was to determine the effects of a fast walking training program on maximal oxigen uptake and perceptive motor skills in healthy active elderly subjects.Methods – Nine subjects, 63 to 69 years old, had a twelve week walking training (one-day bouts of exercice, five times a week), with an average intensity at the anaerobic thresehold level. Direct measurements of oxigen uptake on treadmill and perceptive motors skills (reaction time, postural regulation, motor dexterity) were performed before and immediately after the training program. Before training program, we found a good level of aerobic physical fitness in this elderly population for their age. After the training period, we found a significant increase in maximal oxigen consumption (p<0.01), but there were no significant change for motor skills.Conclusion – So, even if motor skills seemed not to be influenced by aerobic training program, however this program remains of interest on a metabolic point of view.     

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.     

Le chémoréflexe des membres inférieurs élève le débit sanguin et la consommation d'oxygène musculaire au début d'un exercice modéré des membres supérieurs

Aim – Test the hypothesis that increases in forearm blood flow (FBF) during the adaptive phase at the onset of moderate exercise would allow a more rapid increase in muscle oxygen uptake (VO_2mus).Materials and methods– Nine subjects completed forearm exercise in control (Ref) and leg occlusion (Occ) conditions. In Occ, exercise of ischemic calf muscles was performed prior to the onset of forearm exercise to activate the muscle chemoreflex evoking a 25 mmHg increase in mean arterial pressure that was sustained during forearm exercise.Results – A higher VO_2mus accompanied the higher FBF during the adaptive phase of the Occ tests, yet there was no difference in the baseline or steady state VO_2mus between Occ and Ref. Supplying more blood flow at the onset of exercise allowed a more rapid increase in oxidative phosphorylation supporting our hypothesis that, at least for this type of exercise, O₂ supply is rate limiting.     

Approche biomécanique du cyclisme moderne,données de la littérature

Aims – To carry out a review of the literature in connection with optimisation of the body position in cycling.Current knowledge – Well-studied subject in the field of biomechanics of sport, it seems important in to draw up a bibliographic assessment in order to realise a physiological, ergonomic and mechanical interpretation of body position in cycling. This interpretation will be mainly based on a pedalling analysis, a definition of postural references which can influence energetic cost in cycling and the choice of parameters which allow repeatable measurements or which are easily found.Points of views and plans – This article opens the prospect for research dealing with multivariable and multidisciplinary postural optimization.