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R Flandrois

Publications and source records attributed to R Flandrois.

66 records · Page 4Linked to original sources
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[Control of pulmonary ventilation during muscular exercise (author's transl)].

The ventilatory changes as function of time or power depend on the type of exercise. However, in any case, two kinds of factors are involved in these changes : fast, neurogenic, factors and other factors, slower, which are thought to be humoral. Neurogenic stimuli arise from the periphery and from the central nervous system. Peripheral stimuli are induced by the repetitive changes of muscle length and by the motion of articulations. Ventilatory output is also increased by stimuli coming from motor centers. These two kinds of factors induce a ventilatory increase at the start of exercise ("accrochage ventilatoire"). Both chemical and physical stimuli act as humoral factors. The arterial PO2 is scarcely reduced even during maximal exercise, but the increased blood level of norepinephrine may account for the enhanced sensitivity of the centers to the oxygen drive. The sensitivity of the respiratory centers to PaCO2 is not increased. The pH is lowered and can reach 7.15 during very intense exercise. tthis acidity may account for the increased ventillatoy output under these circumstances. The increased body temperature may partly explain the progressive increase of ventilatory output during long lasting exercise, but it does not change the alveolar ventilation. It thus appears that the exercise ventilatory behaviour meets the metabolic, acid-base balance and thermolytic requirements.

Acid-Base Equilibrium↗
PubMedDate not supplied

[Metabolic and respiratory parameters during muscular exercise in man (author's transl)].

Muscle can use ATP exclusively as the direct source of energy for contraction. The muscle ATP stores cannot provide more than 1 or 2 kcal of muscular work. tthe energy for resynthetizing ATP is supplied by three processes : the breakdown of creatine phosphate, anaerobic glycolysis and aerobic processes. These three mechanisms are characterized by different inertia, maximal output and capacity. Taking into account the part of aerobic processes in energy production, the physical fitness of an individual is usually expressed by its maximal oxygen uptake (VO2 max.). When the energy requirements cannot be met by aerobic reactions, the subject contracts an oxygen deficit which is compensated for during the recovery period by an oxygen uptake exceeding the rest requirements. During exercise tidal volume and ventilatory frequency are increased. The increase in ventilatory output is directly related to the workload until 75% of the maximal aerobic power is reached. For higher relative workloads the increase in ventilatory output is steeper. This increased ventilation allows the organism to limit the decreases in PaO2 and pH during exercises of high intensity.

Adenosine Triphosphate↗