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VO2max the promises of the present: the latest discoveries.
Our recent works show that VO2max can be maintained at 100% for a very long time and even during a Marathon. The difference in performance at the highest level is done on VO2max and even on the anaerobic capacity, both metabolisms being dependant of each other. To be hard-wearing at VO2max requires a large anaerobic capacity which will allow you to be successful during a Marathon by being able to vary your running speed.
Here we give you the bases of the knowledge of the physiological meaning of VO2max.
We will give you the continuation of these bases and the novelties at the rate of your attendance of the section and your questions and participation.
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VO2max : The basics
1 °) First criterion of the evaluation of the aerobic metabolism: The aerobic maximal power corresponding to the intensity of an exercise in the maximal consumption of oxygen (VO2max).
The aerobic metabolism brings in the oxygen for the resynthèse of ATP from the complete degradation of carbohydrates and lipids in water and carbon dioxide. To estimate until which power or speed of exercise this metabolism can again satisfy the energy needs by unit of time, we measure the sportsman’s consumption of oxygen by calculating the difference between the concentration of oxygen which it took in the inspired ambient air and that of the air which the subject expired.
This concept of measuring the consumption of oxygen dates from the beginning of century, as shown on ancient photos, the measure (already very precise) was made by the analysis of the air expired in big rubber bags (called " bags of Douglas ", name of a physiologist of the beginning of century). Indeed, to consume 4 litres of oxygen per minute in the intense exercise (0, 3 l / min at rest), a man has to ventilate approximately 140 litres of air. At the present moment, the automatic analyzers measure at almost real time the consumption of oxygen (VO2) and the volume of ventilated air. The modern devices are more and more miniaturized and already allow going on the ground. The sportsman carries the broadcasting analyzer on his back and the doctor or the scientist reads the remote values on his receiver (by telemetry). Thus, the effects of a session of training can be estimated in a live situation.
The consumption of oxygen (VO2) increases in a proportional way in the power or the speed of the exercise, as well as the cardiac frequency on which it depends (figure 1 and 2). However, at a certain speed which serves as mark of training, we notice an upper limit of the consumption of oxygen (we reach the maximum debit or VO2) beyond which all the additional energy will be supplied by the anaerobic metabolisms, especially lactic, conditioning an early stop of the exercise.
That is why this speed corresponding to the beginning of an upper limit plateau of the consumption of oxygen at its maximum is called the speed to VO2 (v VO2) or still maximal aerobic speed (VAM).
Figure 1 Is the relation between the consumption of oxygen, the heart rate and the running speed, for the determination of the maximal consumption of oxygen and its associated speed v VO2 (still called: maximal aerobic speed, VAM).
Figure 2 is the protocol of exercise allowing bringing to light the relation between the consumption of oxygen in answer to the increase of the running speed by stages of 3 minutes. VAM is the maximal aerobic speed i.e. the smallest speed seeking VO2 (named also v VO2).
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The importance of the aerobic process and the quantity of energy which it transforms can be estimated from the gaseous exchanges of the lungs. During an exercise of increasing intensity, made on a tread mill (for a runner), the consumption of oxygen increases linearly with the developed power (the speed) until a borderline value which remains constant, even if the compulsory power is still increased (figure 1). This borderline value corresponds to the maximal consumption of oxygen (VO2), and the power from which this one is reached corresponds to the aerobic maximal power (really produced external work).
In a young male adult of medium size and weight (174 cm and 66,8 kg), the value of VO2 is about three litres per minute (coefficient STPD: "Standard Temperature Pressure and Dry " that is to say dry, temperature 0°c, barometric pressure averages 760 mmHg). His aerobic maximal power is about 250 watts on an ergo metric bicycle. On a tread mill, three litres of VO2 correspond, for a standard energy cost of 3,5 ml of O2 consumed per minute, per kilogram and by km h-1 of increase of the speed between 10 and 20 km h-1 (or 210 ml / kg / km), for a man of 66 kg:
VO2 (ml / min / kg) = 3000 (ml / min) / 66 kg = 45, 5 (ml / min / kg),
This allows us to calculate for a standard energy cost of 210 ml / kg / km, an aerobic maximal speed (VMA) of:
VMA (kph) = VO2 (ml / min / kg) / 3, 5*
(*ml / min / kg of O2 consumed by kph of increase of the running speed between 10 and 20 kph *); the basic relation linking VO2MAX and the running speed is the one given by Léger and Haberdasher (1984):
VO2 (ml/min/kg) = 3, 5 (ml/min/kg) speed (km/h).
Because the maximal consumption of oxygen depends on the quantity of muscular mass involvement, it is obvious that to compare the aerobic capacity of a 50 kg woman with that of an 80 kg man, we use the relative value of VO2 ml of consumed O2 per minute and per kilogram of physical weight.
For this, we simply divide the absolute value of VO2 obtained in 1.min-1 (STPD) by the weight of the sportsman in kilograms, so 3 litres of absolute VO2 "become": 45ml.min-1.kg-1 for our standard woman of 66 kg. This value represents more than 10 times the expense of energy at rest. In the sedentary woman this value is about 35 ml.min-1.kg-1. Moreover, at whatever level of capacity there is, we always note a difference of 10 ml/min-1.kg-1. This would mean noticing that the difference decreases in relative value (percentage of VO2) when the level increases: indeed 10 ml.min-1.kg-1 of the distance represents 22 % between 35 and 45 mlO2 kg-1.min-1. Perhaps this is due to the fact that the high-level sportswomen have a fat percentage of mass much less important than said "home-bodies".
Now the fat mass unlike the “active” muscle does not consume oxygen. On the other hand, it intervenes in the expression of the VO2 relative as it is included in the total body weight. This is why the difference connected to the gender disappears largely when we report VO2 to the active mass (by taking into account only the thin mass for the calculation of relative VO2 for men and women). The extreme values in VO2 are situated between 25 and 95 ml.min-1.kg-1 or between 1, 5 and 6, 5 l.min-1 of the absolute value.
VO2 varies with age, being at its maximum in the 20th year, stabilizing at 30 years to decrease gradually and representing only70% of this value at 60 years. This regression, independent of gender, can be delayed by a regular training in stamina. We notice that our national marathon runners, men and women have the respective mean values of 80 and 68, 9 ml.min-1.kg-1.
In the next section we shall envisage:
The evaluation of the maximal oxygen consumption (VO2MAX).
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