VO₂ Max - Factors Affecting VO₂ Max

Factors Affecting VO₂ Max

The factors affecting VO₂ are often divided into supply and demand factors. Supply is the transport of oxygen from the lungs to the mitochondria (including lung diffusion, stroke volume, blood volume, and capillary density of the skeletal muscle) while demand is the rate at which the mitochondria can reduce oxygen in the process of oxidative phosphorylation. Of these, the supply factor is often considered to be the limiting one. However, it has also been argued that while trained subjects probably are supply limited, untrained subjects can indeed have a demand limitation.

Tim Noakes, a professor of exercise and sports science at the University of Cape Town, describes a number of variables that may affect VO₂ max: age, gender, fitness and training, changes in altitude, and action of the ventilatory muscles. Noakes also asserts that VO₂ max is a relatively poor predictor of performance in runners due to variations in running economy and fatigue resistance during prolonged exercise.

Cardiac output, pulmonary diffusion capacity, oxygen carrying capacity, and other peripheral limitations like muscle diffusion capacity, mitochondrial enzymes, and capillary density are all examples of VO₂ max determinants. The body works as a system. If one of these factor is sub-par, then the whole system loses its normal capacity to function properly.

In theory, the drug Erythropoietin (EPO) can boost VO₂ by a significant amount. This makes it attractive to dopers in endurance sports like professional cycling. By 1998 it had become widespread in cycling and led to the Festina affair as well as being mentioned ubiquitously in the USADA 2012 report on the US Postal team. Greg LeMond has suggested establishing a baseline for riders' VO₂ (and other attributes) to detect abnormal performance increases.