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Maximal Oxygen Consumption
(VO2Max, Maximal Aerobic Capacity) |
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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. |
