Substrats énergétiques oxydés durant un exercice à faible et haute intensité chez des cyclistes d'âge moyen entraı̂nés comparés à des sujets d'âge moyen sédentaires

Aim – Examine the effect of training on the balance of energetic substrates according to exercise intensities in middle-aged subjects.Methods and results – Seven trained cyclists aged of 52.25 ± 1.7 years and seven sedentary subjects aged of of 52.3±1.6 years performed two exercise periods (1 h) after a fasting night. The first test was performed at an intensity of ventilatory threshold and the second +15% above. Substrate oxidation was determined by indirect calorimetry. Lipid oxidation was higher in trained cyclists than in sedentary subjects during low exercise intensity while during intensity high intensity carbohydrate oxidation was more important in trained cyclists. Plasma catecholamine assays shows a higher epinephrine response in trained cyclists than in sedentary subjects during exrcise at high intensity.Conclusion – The endurance training in middle-aged subjects increases carbohydrate utilization during high exercise intensity, due to a higher adrenergic response while it improves lipid utilization during low exercice intensity.     

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.     

Effets d'un réentraı̂nement à l'effort réalisé au seuil ventilatoire chez l'insuffisant cardiaque

Objectives – Study was to assess the effects of exercise training at the ventilatory threshold on exercise tolerance and quality of life in subjects with chronic heart failure.Methods and results – Nine subjects with moderate chronic heart failureperformed: a maximal exercise test and a six-minute walk test and responded to a quality of life questionnaire, both before and after the training program. The exercise training consisted of 46 minutes of cycling, three times per week, for eight weeks, and the exercise intensity was the heart rate at the ventilatory threshold ±5 beats/min. The results showed that exercise training at the ventilatory threshold improves exercise tolerance (maximal and submaximal) and quality of life in subjects with chronic heart failure. These training benefits were very satisfactory compared with other results in the literature.Conclusion – An individualized exercise intensity set at the ventilatory threshold ensures optimal benefits of exercise training in subjects with chronic heart failure.     

Le test de marche de 6 minutes chez le sujet sain : reproductibilité et intensité relative

Purpose – To assess the reproducibility and the intensity of the 6 min walking test (6 MWT) in healthy subject.Method – Twelve sexagenarian healthy subjects perform, on three days, a maximal exercise test on treadmill and five 6 MWT (two on the morning and three on the afternoon) with cardiorespiratory measurements.Results and conclusion – The distance ambulated and oxygen uptake recorded during the 6 MWT are reproducible from the third test while the heart rate, higher in the afternoon, is influenced by the moment of realisation of this test. The 6 MWT intensity corresponds to 79 ± 4.5% of maximal oxygen uptake. In healthy subject, the 6 MWT, sub-maximal exercise, needs two familiarization tests before being really exploitable.     

L'enfant diabétique à l'exercice : étude multiparamétrique

Methods and results – A multiparametric study was realised on insulinodependant diabetic children (n=11) and on control children (n=24) during linear incremental test on ergocycle, normalised with respect to their own maximal aerobic power. It consist in quantifying electromyographic signal of quadriceps muscle (total energy and mean power frequency of the signal), and cardiorespiratory variables (maximal oxygen consumption, heart rate) and metabolic variables (glycemia, lactatemia). Results showed no significant difference of cardiorespiratory changes and significant difference with metabolic changes between diabetic or control children. Changes in electromyographic variables exhibit different profiles between children but not between groups. A discriminant analysis realised on the set of mean power frequency profiles showed difference between diabetic or control children.Conclusion – Thus, electromyographic changes allowed to characterise exercise aptitude for diabetic children.