Among the many parameters used to determine fitness, VO2 max is among the least understood by the non-scientific community. This may be because it’s not a readily available value like heart rate, for example. Expensive equipment in a controlled environment is necessary to obtain an accurate measurement. An aura of performance lab mystery shrouds this quantifiable dimension of aerobic ability.

Simply stated, VO2 max is the volume of oxygen used during maximum exertion. The value assigned equates to the cubic milliliters of oxygen consumed in one minute per kilogram of body weight. The higher the value is, the more capacity the individual has to metabolize oxygen. High end scores for fit males tend to lie between 44 and 55 depending upon age. Females fall in the 31 to 42 range. For perspective, consider that Steve Prefontaine was measured at 84,  Grete Waitz at 73, and Lance Armstrong at 83.  A thoroughbred horse reaches about 150.

Our gene pool determines lung capacity, heart size, and chemical ability of the muscle cells, but virtually all of us can affect our unique oxygen uptakes with a specifically designed exercise regimen. It has been shown that increased intensity has greater positive impact on VO2 max for fit individuals, and increased volume produces better initial results on sedentary persons.

There is scientific debate as to whether the delivery system (heart and lungs) or the utilization process (cells creating ATP for muscle contraction) is the limiting factor, but we all have unique maximal levels, which is one reason why everyone can’t train to be an elite athlete. Further, a lower VO2 max level can be offset by superior bio-mechanics in a given sport, a higher pain tolerance, or an increased lactate threshold.

There are VO2 max calculators, tables, and equations that can give a crude approximation of one’s level. The only way to obtain a true value is to pony up $200 bucks and go to an exercise physiology lab knowing you’re going to hurt.

The test entails being hooked up to an ECG machine that monitors cardiac activity. Respiration is done into a mouthpiece with sensors that measure both volume and oxygen concentration of exhaled air. In most cases a treadmill is used and the subject is given steadily higher levels of stress until the heart rate planes.

So what do we do with the data? If you are a world class performer, it’s one more number to analyze on your way to the gold, but all of this may be informational overkill for the recreational sports enthusiast and indeed for most competitive athletes. As we continue to apply science to sports, newer and better means of measuring potential and performance will evolve. For most of us, a heart rate monitor and stop watch continue to be the tools of choice for assessing fitness. Sometimes simpler is better.