Exercise and mortality

5797534694_a36e9d8b0dExercising helps you to live longer, whatever the amount you are doing. If you exercise a little, your risk of an early death drops and if you exercise a lot, it drops even more. This is the conclusion of a study published on April 6th in the JAMA.

If you plot “benefits” against “dose” on a graph, most biological systems will show an inverted “U”. Take food for example: if you eat too little, you might die, but if you eat too much, you might also die. If you take a medicine, you have to take the right amount, as taking not enough will have no effect and taking too much is toxic.

Is the same true for exercise? Everybody agrees that you need a minimum of exercise to stay healthy, but some people believe that too much is bad for you. The recent cases of sudden deaths during competitions and the findings of heart rhythm disturbances in older endurance athletes have fuelled the debate.

To answer this question, Hannah Arem and her colleagues have looked at the mortality rates and physical activity levels of 661 137 men and women over 14.2 years.

Sure enough, they showed that having the recommended amount of exercise (a minimum of 150 min of moderate intensity, or 75 min of vigorous intensity endurance exercise per week) resulted in a 30% lower mortality risk compared to not exercising at all. However, any exercise is much better than none, as people who did less than the recommended amount already reduced their mortality risk by about 20%.

Working out more is even better, and exercising 2 to 3 times the recommended amount reduces your risk by 37%, while doing 3 to 5 times more leads to a 39% reduction.

The researchers noticed that those who exercise 10 times or more the recommended amount did not reduce their risk any further, but they could not observe any evidence of harm either.

Can I believe this?

This is very large study, which makes it trustworthy. Moreover, the results are the same for both genders and all BMI ranges.

On the other hand, it is based on questionnaires, and participants can easily over- or underestimate what they are doing or change their habits. However, most population studies about exercise and mortality suffer from these same limitations.

If Hannah Arem is right, concerning exercise, there cannot be too much of a good thing. Even though I have never met anybody running marathons or participating in triathlons for health reasons only, it is good to know we are not harming our bodies.

Keep going, but make sure that you avoid overtraining and injuries!

References

Arem H, Moore SC, Patel A et al. Leisure time physical activity and mortality: a detailed pooled analysis of the dose-response relationship. JAMA Intern Med 2015; DOI:10.1001/jamainternmed.2015.0533. (Abstract)

Photo

photo credit: <a href=”http://www.flickr.com/photos/57389319@N00/5797534694″>IMG_3934 -1</a> via <a href=”http://photopin.com”>photopin</a&gt; <a href=”https://creativecommons.org/licenses/by/2.0/”>(license)</a&gt;

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4 thoughts on “Exercise and mortality

  1. Wear and tear of our bodies should also be factored in. Enough exercise will make joints stronger for example, but too much can surely lead to premature wear.

  2. You are right that overuse injuries can make you stop exercising, which is bad for you. You can only do as much as your body allows you to do, and we all learn by experience…

    However, I haven’t found any study suggesting that too much exercise is bad for your joints or muscles -as long as they are healthy to start with.

    Thank you for commenting!

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