VO2Max – What is it and Does it Matter?
[Article by James Mortimer of Sweat Elite]
VO2max, VO2peak, physical work capacity; just some of the terms you may have heard being thrown around, but what do they really mean? Firstly, they all refer to broadly the same concept and are only differentiated by differences in testing procedure, as such, we shall use “VO2max” to refer to this concept for the rest of this article.
Is it a measure of intensity? Fitness? Is it useful? Can I measure it?
VO2max refers to the maximum rate at which an individual can use oxygen during exercise. It is determined by both cardiovascular and respiratory parameters, more specifically it is cardiac output times the arteriovenous oxygen difference. This all sounds a little complicated however the concept becomes easier to understand if we consider the path of oxygen from the outside air through to our working muscles.
To state the obvious; when we breathe in, we fill our lungs with air (~21% of this is oxygen at sea level), this oxygen then transfers from our lungs across an extremely thin barrier into our blood. This now oxygen-rich blood is then pumped around our body until it reaches an area of working muscle where some of it is pulled out of our bloodstream as it is required for metabolic processes. However we do not use all the oxygen that was transferred into our blood and some is left behind. This gap between when our blood is most and least full of oxygen is the arteriovenous difference mentioned earlier.
The other parameter determining VO2max is cardiac output. This is the volume of blood our heart pumps in one minute and is defined by heart rate (bpm) and stroke volume (the amount of blood squeezed out of the heart per beat).
So why does all this science matter and what does it mean for you? First of all, VO2max is the strongest independent predictor of future life expectancy so everyone out there should be at the very least slightly interested in their own value, athlete or not. Additionally VO2max becomes especially useful once we consider its impact on athletic performance.
In order to walk, run or move at all, our body needs to produce energy; we can either produce this energy without oxygen (anaerobic) or with oxygen (aerobic). Any exercise will require energy production from both aerobic and anaerobic systems however their relative contribution is determined by the duration and intensity of the effort. As anaerobic energy production is only possible for a very short period of time, our bodies will always try to meet the energy demands aerobically. In trained individuals it has been shown that during a maximal effort the switch to predominantly aerobic energy systems occurs somewhere between 15 and 30 seconds into exercise as by this point we have “run out” of anaerobic fuel. The rate of work, power output or running pace that an individual can maintain aerobically is determined largely by their VO2max.
Direct measurement of VO2max requires some expensive laboratory equipment however if it is a number that you are particularly interested in knowing then it is likely that a private provider in your area may offer testing services. Additionally, universities are frequently looking for study participants and may include VO2max testing in certain studies. If you are looking for a rough estimate, and something you can do regularly to track changes, then there are a number of tests available as predictors of VO2max.
If you so desire, a 20-metre progressive shuttle run test (beep test) is probably the best estimator. This has been the focus of a number of scientific studies in different populations and subsequently many tables showing max test level and corresponding VO2max are available online; one such table has been included below. Alternatively, once you know your maximum beep test level you can times this number by 3.48 then add 14.4 (y=3.48x + 14.4) and this will also give a fairly good approximation. For reference, an average sedentary male will have a VO2max of around 35-40 ml.kg.min-1 and Michael Joyner’s famous paper determining optimal marathon performance used a value of 84 ml.kg.min-1 (although scores higher than this have been reported many times).
For an athlete, it is likely that a 3000m event will be run at close to VO2max. Anything shorter than this will be run at a higher intensity, with anaerobic energy systems making up the difference and for 5k, 10k and greater, exercise intensity will be <90% VO2max. Despite being in the range of VO2max, 3000m pace is not maintainable for much longer than this due to lactate accumulation (intensity can be below VO2max but above lactate threshold, this will be discussed in a future article).
When considering the application of VO2max, it is important to keep a number of principles in mind. Firstly, VO2max is a good predictor of potential endurance performance in a heterogenous group of individuals but does not always forecast performance among a group of homogenous athletes. That is to say, if you compared the VO2max scores of everyone sitting at your local cafe, or on your train in the morning then it would be a good bet that the person with the highest relative VO2max would be the best 5k runner. However, if you compared the VO2max scores of the athletes in the 5000m final at the World Championships it is much less likely that VO2max would predict finishing order for this group. This is the case as these athletes will all have very high VO2max scores and sit within a tight range of each other, subsequently other physiological and tactical factors make the difference. It’s a good thing this is the case, otherwise all endurance sport events would be guaranteed to be won by the highest VO2max athlete and be very boring to watch.
Secondly we must consider trainability; the ability to improve VO2max with training is a highly individual scenario. A number of longer term studies (interventions of 4-6 months) have demonstrated increases in VO2max in the range of 10-17%, but these numbers do not present the full picture. For example, an untrained individual with a VO2max of 35 ml.kg.min-1 will very likely be able to do some aerobic training and increase their score to at least 40 fairly easily, whilst a training athlete with a VO2max of 70 will potentially never be able to reach 80, or at the very least will have to work extremely hard to do so. To further complicate things, in adults we typically see a decrease in VO2max of around 4 ml.kg.min-1 over the course of a decade however training has been shown to have a very helpful impact on reducing the rate of this decline; even if your training isn’t increasing your score, it might be stopping a downfall.
Physiological adaptations from training that result in increased VO2max can be put into three main categories. 1. Rapid improvements (in days-weeks) come about through increases in blood volume. 2. In a number of weeks there will be adaptation in skeletal muscle that may lead to VO2max improvements. 3. Over the course of many months (>6) structural changes in the heart will occur and increase VO2max by increasing stroke volume.
Thankfully for those of us who are interested, there are plenty of studies out there that have recorded and tracked VO2max for a number of high performing athletes. One study tested Lance Armstrong (controversy aside) from 1992-1999 and noticeably there was no obvious increase or trend in his VO2max. The performance improvements observed in this time period were attributed to changes in other relevant variables. Another study tested Paula Radcliffe 6 times between 1992 and 2003 and also found her average yearly VO2max did not obviously change over this time period (it sat at around 70 ml.kg.min-1). These results are not unexpected as both of these individuals were already high performance athletes prior to the commencement of these studies and had probably already come very close to their aerobic peak.
Whether it’s for athletic or personal health reasons, VO2max is a hugely relevant physiological measure. This article is really just the tip of the iceberg and below are a number of links to scientific articles used in the writing of this piece that may be of interest for further reading.
References and Further Reading;
Bouchard, C., Blair, S. N., Church, T. S., Earnest, C. P., Hagberg, J. M., Häkkinen, K., … & Rao, D. C. (2012). Adverse metabolic response to regular exercise: is it a rare or common occurrence?. PloS one, 7(5), e37887.
Coyle, E. F. (2005). Improved muscular efficiency displayed as Tour de France champion matures. Journal of Applied Physiology, 98(6), 2191-2196.
Jones, A. M. (2006). The physiology of the world record holder for the women’s marathon. International Journal of Sports Science & Coaching, 1(2), 101-116.
Joyner, M. J. (1991). Modeling: optimal marathon performance on the basis of physiological factors. Journal of Applied Physiology, 70(2), 683-687.
Leger, L., & Gadoury, C. (1989). Validity of the 20 m shuttle run test with 1 min stages to predict VO2max in adults. Canadian journal of sport sciences= Journal canadien des sciences du sport, 14(1), 21-26.
Leger, L. A., & Lambert, J. (1982). A maximal multistage 20-m shuttle run test to predict $$\dot V $$ O2 max. European journal of applied physiology and occupational physiology, 49(1), 1-12.
Ramsbottom, R., Brewer, J., & Williams, C. (1988). A progressive shuttle run test to estimate maximal oxygen uptake. British journal of sports medicine, 22(4), 141-144.
Strasser, B., & Burtscher, M. (2018). Survival of the fittest: VO2max, a key predictor of longevity. Front Biosci (Landmark Ed), 23, 1505-1516.
Spencer, M. R., & Gastin, P. B. (2001). Energy system contribution during 200-to 1500-m running in highly trained athletes. Medicine & Science in Sports & Exercise, 33(1), 157-162.
