The meaning of your VO2max

Your VO2max

Last week I explained how you could measure your own fitness level as your VO2max. Since you are not actually measuring the amount of oxygen you are absorbing from breathing, the figure is your “predicted VO2max” – but it is reasonably accurate.

Variations in fitness

There is a number of factors which may effect your VO2max:

1. Your inheritance – your genetic code influences your fitness level
2. Your gender – men have approximately 15% higher VO2max than women. At any age women are significantly less fit than men, mostly because they have a different body composition with a greater fat content. When this is allowed for by adjusting the figure for fat-free mass, there is little difference between the sexes.
3. Your age – VO2max increases through childhood and adolescence to reach a maximum in the early to mid twenties. After that it decreases gradually – by between 1 and 2% each year until you are about 70 after which the decline is more rapid.
4. Your exercise habit. The more and harder you exercise the greater your VO2max and the more slowly it declines with age.

Normal levels of VO2max

Here are the approximate ranges of VO2max for different ages and gender.

Range of VO_2max for men

Age	Poor	Below average	Average	Good	Very good
20–29	<35	35–38	38–45	45–50	>50
30–39	<31	31–35	35–41	41–49	>49
40–49	<30	30–33	33–39	39–48	>48
50–59	<26	26–31	31–36	36–45	>45
60–69	<21	21–29	29–33	33–41	>41
70–79	<15	15–25	25–29	29–36	>36

 

Range of VO_2max for women

Age	Poor	Below average	Average	Good	Very good
20–29	<23	23–33	29–33	33–41	>41
30–39	<23	23–27	27–31	31–40	>40
40–49	<21	21–24	24–29	29–37	>37
50–59	<20	20–23	23–27	27–35	>35
60–69	<18	18–21.5	21–25	25–31	>31
70–79	<12	12–19	19–21	21–28	>28

 

How accurate are the figures?

These figures  must be taken with more than a pinch of salt. The average fitness level and the variation in fitness differ from one group to another. There have been many studies to try to determine the average fitness of the population as a whole, with variations from very unfit to very fit – but the results which such surveys have produced show wide discrepancies because of the way in which the subjects have been selected and the nature of the testing systems used.

So the figures have been compiled from a number of sources to give the best guesses for each age and sex. They are only a guide, but should give you an idea of where you fit into the scheme of things.

In some cases the figures are derived from people who have volunteered to be tested; in other cases the sample is drawn from a particular set, such as those seeking routine health checks; and in a few cases the individuals being tested have been chosen randomly. Even for the most representative group tested, the average level of fitness will exceed reality because there will be a proportion of the subjects who have physical problems that prevent them completing the test. Their results are therefore discounted, thus raising the average. Given that population measurements apply only to those members of the population who can complete the test and the proportion who are unable to do this increases with age, the overestimate of population fitness levels is much greater for older age groups.

The difficulty in giving the normal range of physical fitness in the general population is illustrated by the two best and most representative investigations carried out in England over the past 30 years:

• The Allied Dunbar Fitness Survey in 1990 tested a sample of 1,741 adults aged 16–74 chosen at random in 30 locations around the UK. They used a treadmill in a central mobile laboratory. For men, the average VO_2max fell from 55.5 in the 16–34 age group to 32 in the 65–74 age group.
• The Health Survey for England in 2008 also tested a random sample –1,969 people – using a step test in the individuals’ homes. For men, the average VO_2max fell from 40.9 in the 16–34 age group to 29.9 in the 65–74 group.

It might be expected that both studies would produce comparable results, but in practice the earlier study suggested that in 1990 the population of England was significantly fitter than it was in 2008. There are several explanations for such a disparity: perhaps the samples were in some way biased differently; the testing methods were not comparable; it was easier to get the subjects to exercise harder in a laboratory than in their own homes where emergency help was less available; or maybe we really are getting steadily less fit, the victims of our increasingly sedentary lifestyles.

All this explains why any table of normal fitness levels must be flawed. However, I do believe that it can be helpful to know roughly where you fit into the range of possible fitness levels, so I have constructed the tables above for this purpose.

Age related decline in VO2max

Taking moderate exercise does not greatly change the rate of decline with age – at about 1 to 2% per annum –  but it does of course still give a better fitness level at any age than being less active. More vigorous training, however, as in older athletes, does decrease the rate of decline – to about 0.5 per cent each year even in old age.