How Much Exercise Do You Need?

We know exercise reduces the incidence of cancer, diabetes and cardiovascular disease, but how much is needed? The WHO answer to this question is at least 600 on a standardised measure of total (work-related plus leisure) exercise called Metabolic Equivalent Tasks, or METs. This is the ratio of energy expenditure while performing an activity to expenditure at rest. Running for 75 minutes per week, atop of an otherwise sedentary life, yields the WHO standard of 600 METs. Better than nothing, but not enough according to a massive and sophisticated meta-analysis [1] – 2,000 to 4,000 METs are necessary to achieve material benefit (250 – 500 minutes of running). After this threshold, further gains with yet more exercise are nugatory. So lots of exercise is ideal, but excessive exercise is a fetish that wastes time. I aim to do two hours of ‘spinning’ and 90 minutes of doubles tennis each week. Let’s say spinning has an MET of 10, then I spend 1200 MET minutes spinning. If doubles tennis consumes 3 METs, then I spend 270 MET minutes. So my total METs is 1470 – not quite optimal. This study does not shed light on whether 2,000 METs spent in short bursts is better or worse than the same energy expenditure doing something really tedious, like lengths in a swimming pool. For that we need a study comparing “weekend warriors” with people who take similar amounts of exercise, but spread more evenly over the week.[2] The study was based on answers to questionnaires sent to participants in two huge cohort studies – the Health Survey for England and the Scottish Health Survey. The study replicates a link between exercise and overall mortality, cardiovascular mortality, and cancer mortality. However, the pattern of exercise does not seem to make much difference to the risk reduction.

— Richard Lilford, CLAHRC WM Director

References:

  1. Kyu HH, Bachman VG, Alexander LT, et al. Physical activity and risk of breast cancer, colon cancer, diabetes, ischemic heart disease, and ischemic stroke events: systematic review and dose-response meta-analysis for the Global Burden of Disease Study 2013. BMJ. 2016; 354: i3857.
  2. O’Donovan G, Lee I-M, Hamer M, et al. Association of “Weekend Warrior” and Other Leisure Time Physical Activity Patterns With Risks for All-Cause, Cardiovascular Disease, and Cancer Mortality. JAMA Intern Med. 2017.
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2 thoughts on “How Much Exercise Do You Need?”

  1. Dear Richard,
    you explicitly put as an indication of NEED the incidences of the somatic diseases. But are they just reciprocates for the length of life? And wasnt it shown about 20 y ago that the time spent in regular exercise is much more than the time of life possible to earn? In this case, doesnt it reasonable to believe that the main argument if not the incidence, but the gay of exercise? And if it is true, isnt the question of how much you need is of no sense?

  2. Interesting piece Richard. Especially about the plateau. My old exercise physiology professor always said that professional sport (i.e., lots of exercise) is bad for the human body. So similar to the Table Mountain in Cape Town, there is a plateau but too much exercise is bad for your health.

    Regarding to your own METs, you have sold yourself short because you omitted the cycling that one might do during your commute to work and the walking at work going between meetings.

    Max Feltham

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