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Muscles et l'apport d'oxygène

  • Notes d'étude
  • Révisions du sujet
    Phomolo P.
    BW
    Phomolo P.

    The muscles say, 'If you deliver it, we will use it' Several experiments of different types support the concept that it is oxygen delivery, not oxygen utilisation, that limits VO2 max. By performing an exercise with one leg and directly measuring muscle oxygen consumption of a small mass of muscle (using arterial catheterisation), it has been shown that the muscle's capacity to use oxygen exceeds the heart's capacity for delivery. Thus, although the average male has about 30 to 35kg of muscle, only a portion of this muscle can be well perfused with blood at any one time. The heart cannot deliver a high volume to all skeletal muscle and still maintain adequate blood pressure. As further evidence for a delivery limitation, long-term endurance training can result in a 300% increase in muscle oxidative capacity, but only about a 15 to 25% increase in VO2 max. VO2 max. can be altered artificially by changing the oxygen concentration in the air. VO2 max. also increases in previously untrained subjects before a change in skeletal muscle aerobic capacity occurs. All of these observations demonstrate that VO2 max. can be dissociated from skeletal muscle characteristics. Stroke volume, in contrast, is linearly related to VO2 max. Training results in an increase in stroke volume and therefore an increase in maximal cardiac output. Greater capacity for oxygen delivery is the result. More muscle can be supplied with oxygen simultaneously while still maintaining necessary blood pressure levels.

    Zachary B.
    US
    Zachary B.

    What are different muscles and oxygen delivery rates?

    Rk S.
    IN
    Rk S.

    The muscles say, 'If you deliver it, we will use it' Several experiments of different types support the concept that it is oxygen delivery, not oxygen utilisation, that limits VO2 max. By performing an exercise with one leg and directly measuring muscle oxygen consumption of a small mass of muscle (using arterial catheterisation), it has been shown that the muscle's capacity to use oxygen exceeds the heart's capacity for delivery. Thus, although the average male has about 30 to 35kg of muscle, only a portion of this muscle can be well perfused with blood at any one time. The heart cannot deliver a high volume to all skeletal muscle and still maintain adequate blood pressure. As further evidence for a delivery limitation, long-term endurance training can result in a 300% increase in muscle oxidative capacity, but only about a 15 to 25% increase in VO2 max. VO2 max. can be altered artificially by changing the oxygen concentration in the air. VO2 max. also increases in previously untrained subjects before a change in skeletal muscle aerobic capacity occurs. All of these observations demonstrate that VO2 max. can be dissociated from skeletal muscle characteristics. Stroke volume, in contrast, is linearly related to VO2 max. Training results in an increase in stroke volume and therefore an increase in maximal cardiac output. Greater capacity for oxygen delivery is the result. More muscle can be supplied with oxygen simultaneously while still maintaining necessary blood pressure levels.

    Muhammad S.
    PK
    Muhammad S.

    What is the delivery rates of oxygen in contraction of Muscles.

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