Saturday, 25th April 2020


In previous Blogs I have given an idea of the recommendations of governments and health organisations for the amount of exercise we need to take for the good of our health. Today I will look at how much exercise we actually take.

Surveys of How Much?

A number of surveys examine this question on a more or less regular basis. They include the Health Survey for England (HSE), Active People Survey, National Travel Survey and The General Household Survey. The HSE compares current population activity with the Department of Health recommendations. The HSE uses “validated questionnaires” completed by wide sections of the population to assess the level of compliance with these guidelines.  Different types of activity are assessed to take into account the time spent participating in physical activities and the number of active days in the last week. By this measure the proportion of adults meeting the recommendation has increased steadily since 1997 for men and 1998 for women. In 1997, 32 per cent of men met the recommendation, increasing to 43 per cent in 2012. Among women, 21 per cent met the recommendation in 1997 and 1998, increasing to 32 per cent in 2012.

After 2012 the recommendations changed to include shorter bursts of activity so the figures in the past few years cannot be compared with the earlier figures. Currently the estimates are that 66% of men and 58% of women meet the guidelines. These are based on responses to questionnaires about levels of activity.

Are we getting more active?

Yes. The surveys may be dependent on the inaccurate self reporting of questionnaires, but there is no reason to believe that the level of inaccuracy is changing. The most recent survey of activity indicates that the over 55 age group was the most likely to show an increase which is heartening since the figures fall off sharply with increasing age. This is illustrated by the graph which heads this Blog. As I repeat often, it is the older generations who have most to gain from taking enough exercise.

But how accurate are the surveys?

Not very – because they depend upon the accuracy of the self-assessment of the individuals completing the questionnaires and are likely to be substantial overestimates. When activity is actually measured it is a lot less than when estimated (self-reported) by those being surveyed.

For instance the 2008 HSE survey not only used questionnaires but also measured the activity levels of the participants. They used accelerometers (a sort of sophisticated pedometer) to record information on the actual frequency, intensity and duration of physical activity in one minute “epochs” – showing accurately the  daily activity of their subjects over a period of one week.   On these measures, 6 per cent of men and 4 per cent of women achieved the government’s recommended physical activity level – just 15% of the level of compliance indicated by individuals’ own questionnaire responses – revealing a staggering level of either self-deception or just downright lying!

Social desirability bias is the term used for this form of self-deception and applies particularly to diet and exercise. We eat about 50% more than we think we do and take about half to two thirds the amount of exercise.

How much does this matter?

Perhaps not as much as you may think. The beneficial effects of physical activity are mostly measured by comparing health outcomes with questionnaire responses, not measured activity levels. However it does mean that stated physical activity may not be the best measure of exercise levels to use. When the effects of physical fitness are compared with stated activity levels, it is physical fitness which is a far better predictor of future heart disease and mortality, particularly in younger subjects. Hardly surprising is it? Our fitness level may be a better reflection of how much exercise we actually take as compared with what we might like to think we take.

So just how fit are we? I will try to tell you next time.

 PS Covid-19 again.

This is not exercise related but I thought that you might be interested to hear what the British Medical Journal thinks about the way the pandemic is being handled in this country from the point of view of health professionals. Here are some quotes from the Editorial in this week’s issue:

Around the world, health and social care workers are dying because of occupational exposure to covid-19. Many hundreds have died, including more than 100 in the UK. Are these deaths, and others yet to come, an inevitable cost of this pandemic? Not if some (or all) of them could have been avoided with better planning and provision. It is impossible not to feel let down by political and healthcare leaders who, while sloganning and clapping for the NHS, have so evidently failed to protect those working within it.

The UK government’s response to this crisis has been characterised from the beginning by complacency, arrogance, and delay, worsened in subsequent weeks by broken promises about the supply of personal protective equipment, apparent ignorance of the situation on the frontline, and poorly explained and shifting guidance.”

 ….. damning about the UK government’s attempts to shift the blame for staff deaths onto community infection and have no faith in its proposed investigation. “Without referring each death to the coroner, can we be confident that the circumstances of their employment have not resulted in these individuals paying the ultimate price through their daily work?”

Should the public wear face masks? …………. conclude that, while good evidence is lacking, policy makers should apply the precautionary principle. Concern that masks should be kept for use by health workers is “an argument for manufacturing more masks, not for denying them to the populations who could potentially benefit.”



  1. Mike Hayward says:

    Thanks Hugh, excellent as ever. I thought Fiona Godlee’s leader in the BMJ was absolutely right and should be absolute dynamite, but I suspect that the current bunch of rather low grade fakers will brush it off as usual.

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