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Maximal Oxygen Consumption (VO2Max) |
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Maximal Oxygen Consumption, or VO2max, is
the maximum amount of oxygen you can consume in a minute. VO2,
without the "max" designation, simply refers to oxygen consumption. |
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The following equation allows us to
calculate VO2: VO2= Q x AVO2Diff
Let's talk about the different parts of this equation. |
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Q represents Cardiac Output. Cardiac
output is the amount of blood ejected by the heart per minute. The
equation for cardiac output is: Heart Rate x Stroke Volume, stroke
volume being the volume of blood ejected by the left ventricle with
each beat of the heart. Since blood carries oxygen, cardiac output
is important for determining the maximal oxygen consumption. |
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AVO2diff is the arterial-venous oxygen
difference. While cardiac output was the "delivery" component of
oxygen consumption, AVO2diff is the "extraction" component. AVO2diff
is a representation in the difference of blood oxygen content in the
arteries and the veins, and gives us information about how much oxygen
was absorbed by the tissues. For example, if blood in the arteries
contains 20 ml of oxygen and blood in the veins contains 5 ml of
oxygen, the AVO2diff is 15 ml. This means that the tissues absorbed
15 ml of oxygen (absorption occurs in the capillaries). AVO2diff is
important because oxygen delivered to the tissues (via Q) is not
effective if it cannot be absorbed. |
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Together, the two components comprise
maximal oxygen consumption. |
