Sports Watches – VO2max

With all the “snazzy” gadgets that recreational and professional athletes are exposed to these days, it is difficult to not encounter certain “scientific” terms, such as VO2max. Although not so long ago, VO2max testing was only something that professional athletes were exposed to, with the new sports watches, all athletes (recreational, weekend warriors) now have exposure to this measurement.

So what is it? What does it mean? What am I supposed to do with it?


Let’s begin by giving a little more information on what VO2max is:

There is an upper limit to the amount of oxygen (O2) that can be consumed during an exercise bout that requires maximal effort. This upper limit is referred to as VO2max, and this is the maximal rate at which an individual can utilize O2 (1). It is determined by the rate at which O2 is transported to the tissues, the O2-carrying capacity of the blood, and the amount of O2 extracted from the blood (2). All of this is measured through indirect calorimetry, in a lab using a metabolic cart or respiratory gas analysers, measuring the pulmonary ventilation and comparing inspired and expired CO2 and O2 concentrations (3).  This measurement has been said to be the single best measurement of cardiorespiratory endurance and aerobic fitness, provided there is no pulmonary disease (1, 2, 4).


So how is it measured?

As mentioned it is measured in a laboratory setting, with a mask strapped to your face, with gas analyser tubes running to a computer system. (see images below).

Depending on your predominant sport (running, cycling, swimming, rowing), the use of treadmill, bike etc would change; thus making it more sport specific (or as specific as one can get for lab-based testing). There are so many different types of protocols that one can use – some are continuous speed (treadmill), some continuous incline (treadmill), continuous wattage (bike) protocols, in that the speed, incline or wattage increases at a set rate until you cannot push anymore (ramp or step protocols are also available within these).

When performing a VO2max test, there are several criteria used to identify if the test was indeed a maximal effort:

  1. A plateau of O2 uptake – exercise intensity relationship (an increase in O2 uptake less than 2 or 3% with an increase in exercise-intensity)
  2. A final respiratory exchange ratio (RER) of 1.15 or above
  3. A final HR within 10 bt.min-1 of predicted age-predicted maximum
  4. A post-exercise (4 – 5 min) blood lactate concentration of 8 mmol.L-1 or more
  5. Subjective fatigue or volitional exhaustion
  6. A rating of perceived exertion (RPE) greater than 19 on the Borg Scale
Graph depicting data of a VO2max test, namely the relationship between O2 and CO2. The AT (Anaerobic Threshold) is the point where CO2 continues to increase while O2 starts to increase at a lower rate and/or starts to decrease – in other words, the cross-over point

What does it mean?

VO2max has been considered to be an indicator of both potential for endurance performance and to a lesser extent, training status; however, although a high VO2max may be considered as a prerequisite for elite performance in endurance sports, it does not guarantee that you will achieve at the highest level (1). It’s important to note that there are several factors that determine overall performance, not just aerobic capabilities, and these include: technique, state of training, and psychological factors that can all positively or negatively impact performance. You may physically be capable of achieving, but if your mind isn’t in the game, it makes it difficult to achieve high/top performance – and visa versa. (Don’t underestimate the power of the mind). Additionally, the higher VO2max values recorded in elite middle- and long-distance athletes is also attributed to a combination of genetic endowment and training – so essentially, if your father/mother are/were very athletic and excelled, likelihood of you excelling may also increase (in endurance sports).


Ok, so you’ve now partially blamed your folks for the lack of genetic excellence with regards to your endurance capabilities, but you’ve got this VO2max value on your watch, and you want to know how to improve it


Your VO2max can improve (increase) with physical activity for 8 – 12 weeks, and then it tends to plateau despite the exercise intensity increasing – just because this happens, doesn’t mean that your endurance performance decreases, it can still increase (remember the other factors I mentioned earlier) (4). So now that we know physical activity can increase VO2max, it’s important to note that this increase is only between 5 and 30% – however, greater increases has been noted in cardiac patients, individuals who started off with minimal initial fitness, and those that have undergone substantial weight-loss (3).


Great! You can improve your VO2max!! But sadly, it does decrease with age (just like most things) – So there’s the age factor.


Are there differences between males and females? Yes. Males tend to have higher VO2max values when compared to females. – remember the definition earlier, where I mention O2 carrying capacity to the tissues? Well, naturally, males (most of them) tend to have greater muscle mass than females, thus needing greater O2 carrying capacity. But don’t let that think that us women aren’t just as capable 😉


Alright, now that we have covered all the essential background information, I suppose I should cover how your watch manages to tell you your VO2max values without you having to run around with a mask on you… There are several calculations that one can use to estimate your VO2max – most of which are based on your age, height, weight, heart rate, and to some degree the speed/power of your training session. When I spoke about training effect, I mentioned the company Firstbeat Technologies Ltd that have developed algorithms and software for some sports watches to enable them to produce all this “science-y” information. This same company has taken one of these calculations, and refined it a little more, instead of just looking at your heart rate, they look at the time between successive HR beats, on/off kinetic information (derived from HR data), and the respiration rate. Important to note that there are limitations to this – it is not a direct estimation, and the watch cannot give you anaerobic energy production. It’s great for those who are just happy to keep going the way they are, but if you are wanting to take your training to the next level, then you should book a VO2max test in a lab. – the benefit of this is that you can find out as to what your exact fat burning zone is, you can find out what fuel source you rely on the most (this coupled with recommendations made by a dietitian can help you out even further), and then there are accurate HR training zones that can be implemented, and the speed at which you should be training to push yourself even more….and there are a few more.

Garmin VO2max Display

If you’re looking to have a VO2max test done, contact your High performance centre, if you are in  KwaZulu Natal, Prime Human Performance Institute can assist your with taking your training to a whole new level. (Fill in a contact form here, and I can assist you)




  1. Eston, R. and Reilly, T. (2009). Kinanthropometry and Exercise Physiology Laboratory Manual: Tests, Procedures and Data. Volume 2: Physiology. Third Edition. Routledge: New York.
  2. Brooks, G.A., Fahey, T.D., and Balwin, K.M. (2005). Exercise Physiology: Bioenergetics and It’s Applications. Fourth Edition. McGraw-Hill Companies, Inc: New York.
  3. Tanner, R.K. and Gore, C.J. (2013). Physiological Tests for Elite Athletes. Second Edition. Human Kinetics: South Australia.
  4. Wilmore, J.H., Costill, D.L., and Kenney, W.L. (2008). Physiology of Sport and Exercise. Human Kinetics: Campaign, IL.

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