Whether you do a little or a lot, exercise is always healthy
If you can't stand exercising, American epidemiologists have good news for you. You only need to do a little to drastically reduce your chances of developing fatal forms of cancer or cardiovascular disease. The same researchers also have good news for sports addicts who do much more than experts advise. A lifestyle that includes inordinate amounts of exercise hardly decreases mortality as well.
Walking briskly for half an hour five times a week is the amount of physical exercise that health scientists recommend for everyone. Expressed in calorie expenditure that amounts to 7.5 metabolic-equivalent hours per week [MET h/wk]. And if you already do this amount of exercise? Then you should double it.
Stacks of studies have shown that following this advice reduces your mortality risks. But what happens if you get more exercise than the recommended 7.5-15 MET h/wk? This is the question that researchers at the American National Cancer Institute Shady Grove set out to answer with the epidemiological study that they published in June 2015 in JAMA.
The researchers gathered data from previously published studies and collated them. This amounted to 661,137 people who had been followed for 14.2 years.
The participants who exercised more than the recommended daily hour of walking [LPTA] turned out to be better protected against dying from cancer or cardiovascular disease than those who just did the recommended amount of exercise. 5-10 times the recommended amount of 7.5-15 MET h/wk provided the most protection. The participants who exceeded the recommended amount by more than 10 times had a slightly higher mortality risk than the participants with the optimal amount of exercise, but this increase was of negligible significance.
The figure below shows the effect for the two different forms of mortality. Physical exercise reduces the chance of dying from cardiovascular disease [blue line] most at 22.5-40 MET h/week. In other words: doing a good hour of walking each day. The effect of physical exercise on the risk of dying from cancer increases the more physical exercise you do. In this case: the more the better.
"These findings are informative for individuals at both ends of the physical activity spectrum", the researchers wrote. "They provide important evidence to inactive individuals by showing that modest amounts of activity provide substantial benefit for postponing mortality, while reassuring very active individuals of no exercise-associated increase in mortality risk."
JAMA Intern Med. 2015 Jun;175(6):959-67.
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