Significance of fitness test result

Last time I described the Cooper and Rockport tests for measuring your own cardio-respiratory fitness (CRF). For my money these are the most accurate way of assessing your CRF but they will not work for everyone. In the case of those on heart rate slowing drugs, the Rockport test does not apply. For older slower people the Cooper test may be too strenuous. For those with mobility problems like knee or hip arthritis, walking and running tests cannot be used and I know of no easy way of measuring your CRF.

 

Interpretation of CRF

The figures provided for average fitness levels at different ages must be considered cautiously. The average fitness level and the variation in fitness differ considerably from one test 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.

The results of such surveys have produced wide discrepancies, largely because of the way in which the subjects have been selected and the nature of the testing systems used. 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. In a relatively few cases the individuals being tested have been chosen randomly from the population as a whole..

Even for the most representative group tested, the average level of fitness will exceed reality because there will be a proportion of the chosen subjects who have physical problems that prevent them completing the test. Their results are therefore discounted, thus raising the average. Population measurements apply only to those who can complete the test. The proportion who are unable to do this increases with age, which means that 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 32.0 in the 65–74 age group.
• The Health Survey for England in 2008 (2009) 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 would be expected that both studies should 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 of this explains why any table of normal fitness levels must be flawed. It can be helpful to know where an individual is placed in the range of possible fitness levels, so the tables below have been constructed for this purpose. The tables have been compiled from a number of sources to give the best approximations for each age and sex. They are only a guide, but should permit interested parties to establish their position in the various fitness categories.

It is worth noting that after the mid-twenties physical fitness declines throughout life – by about 0.5 per cent per annum in early adult life but getting steeper in middle age at about 1 per cent each year and accelerating in old age to about 2 per cent or more each year.

Undertaking  moderate exercise slows this rate of decline. More vigorous training in older athletes can have a dramatic effect so that runners in their sixties can be as fit as non-exercisers in their twenties and thirties.

At any age women are significantly less fit than men, mostly because they have a different body composition with a greater fat content. When the figures are adjusted so that the comparison is for fat-body weight, there is little difference between the sexes.

Range of VO_2max for men

Age	Poor	Below  Av.	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 Av.	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

 What does this mean for you?

The level of fitness in the UK at all ages is well below ideal and the effect of this increases with age. The result is increased vulnerability to all the degenerative diseases of later life and accounts for the fact that our elderly population is dismally unhealthy. This leads not only to decreased lifespan but, more regrettably, to decreased healthspan and consequently to enormous levels frailty and ill-health in our senior citizens.

So, if you do test your own fitness level, be dissatisfied with anything at or below “average “.

The six minute walk test

For older, less fit people and those with heart or lung diseases, a 6-minute walk is often used but this does not give an accurate measurement of CRF or VO_2max. The procedure is much the same as the Cooper test but for 6 rather than 12 minutes and walking as fast as possible. Below is a table of normative results at different ages over 65. The estimate of fitness given by this method is considerably lower than given by the Cooper 12-minute test. This is because the distance covered is decided by the effort applied – when walking, this seldom reaches a maximum.  However for those able to walk fast enough to get breathless this test does give an idea of functional ability. It is commonly used by cardiac rehabilitation units to assess improvements resulting from the CR programme.

To calculate your own CRF by this method: VO_2max in ml/min/kg = 0.023 multiplied by the 6-minute walk distance in metres plus 4.95

Here are the average distances and  VO_2max at different ages:

6-minute walk test results
Men

Age	Average (metres)	Average VO2max
65	596m	18.6
70	568m	18.0
75	534m	17.2
80	487m	16.3
85	427m	15.5
90	403m	14.2

 

Women

Age	Average (metres)	Average VO2max
65	535m	17.3
70	510m	16.7
75	482m	16.0
80	443m	15.1
85	406m	14.3
90	358m	13.1

 

Next time

Next time I will discuss the effect in later life of low levels of physical activity and thus low fitness levels – that scourge of our times, frailty of old age.