Latest revision as of 05:04, 16 April 2013

A graph showing that O₂ consumption increases with exercise intensity until a maximum is reached, which is V̇O₂max.

V̇O₂max is the maximum (max) volume (V) of oxygen (O₂) you can use during exercise. Measuring V̇O₂max requires specialist equipment, but there are many locations with the facilities and the cost is usually under $100. The procedure involves running on a treadmill while wearing a mask to capture your breath. There is a warm up period, and then you run at a reasonably stressful pace while the treadmill gradient is steadily increased until you can't keep going. For most of the test, as the workload increases so does the O₂ you use. However, there will come a point where the increased workload does not have a corresponding increase in O₂ usage. This is the point where you are using as much O₂ as you are capable of and the increased workload is coming from anaerobic systems. While V̇O₂max is interesting, it does not include details of Running Economy, so it does not give a complete picture of a runner's capabilities. Arguably, VDOT is a more useful measure of fitness.

1 Estimating VO2max

V̇O₂max can be estimated from a race performance, and this is implemented in the VDOT Calculator. Another approach is the Cooper test developed in 1968 found that the distance that could be covered in 12 minutes was strongly correlated with VO2max^[1]. However, the Cooper test requires a lot of motivation and a good sense of pacing, as 12 minutes is a relatively long period for this type of test^[2]. A similar technique is to increase running speed every two minutes until exhaustion, then VO2max can be estimated from the maximum speed that was achieved using Léger & Mercier formula:^[3]:

V̇O2max = speed * 3.5

Where V̇O₂max is in ml/Kg/min and vV̇O₂max is in km/hr.

2 V̇O₂max and V̇O₂peak

This graph shows that V̇O₂peak, which is the highest O₂ observed, without the plateau that defines V̇O₂max.

Some research uses the term V̇O₂peak rather than V̇O₂max, and while the two are similar, there is an important difference. Where V̇O₂max is the highest O₂ uptake seen, even though exercise intensity has continued to increase, V̇O₂peak is simply the highest O₂ seen^[4]. It's possible for V̇O₂peak to be the same as V̇O₂max, but only if the test is terminated at just the right point. The biggest problem with V̇O₂peak is that a training program might result in a subject getting better at the test, which would result in a higher V̇O₂peak value, without actually changing their V̇O₂max. For instance, I might have a V̇O₂max of 60, but find the testing protocol so hard that I give up when my V̇O₂ reaches 50 which would only give a V̇O₂peak value. If I do some high intensity training, I'd be more comfortable at these high workloads and I might reach a V̇O₂peak of 55, which would look like a 10% improvement, but is actually not a change in physical fitness.

3 V̇O₂max and vV̇O₂max

The velocity that is reached at V̇O₂max is called vV̇O₂max, and the time that vV̇O₂max can be sustained for is called T_lim or T_max.

4 References

1. ↑ Kenneth H. Cooper, A Means of Assessing Maximal Oxygen Intake<subtitle>Correlation Between Field and Treadmill Testing</subtitle>, JAMA: The Journal of the American Medical Association, volume 203, issue 3, 1968, pages 201, ISSN 0098-7484, doi 10.1001/jama.1968.03140030033008
2. ↑ LV. Billat, JP. Koralsztein, Significance of the velocity at VO2max and time to exhaustion at this velocity., Sports Med, volume 22, issue 2, pages 90-108, Aug 1996, PMID 8857705
3. ↑ L. Léger, D. Mercier, Gross energy cost of horizontal treadmill and track running., Sports Med, volume 1, issue 4, pages 270-7, PMID 6390604
4. ↑ THE PEAK VERSUS MAXIMUM OXYGEN UPTAKE ISSUE, Brian J. Whipp, Ph.D., D.Sc., Institute of Membrane and Systems Biology, University of Leeds,Leeds, UK