Ten thousand steps and more. Do you have eleven minutes a day – 0.76% of your daily time – for your health? So devote them to moderate-intensity physical activity (PA), such as brisk walking, cycling at 15 kilometers per hour or gardening. Such small efforts seven days a week – or fifteen minutes five times a week – are enough to significantly reduce the risk of premature mortality, concludes a study by the team of Leandro Garcia (University of Cambridge) published on February 28 in the British Journal of Sports Medicine.
With seventy-five minutes of moderate-intensity PA per week, which is half the World Health Organization (WHO) recommendations for an adult (one hundred and fifty minutes of moderate-intensity PA per week, or sixty -fifteen if the intensity is sustained), the overall mortality is lowered by 23% compared to inactive individuals, according to their calculations. The reduction is 19% for cardiovascular mortality, and 10% for cancer mortality. For a practice up to the recommendations of the WHO, the reduction is greater, respectively by 31%, 29% and 15%.
However, the relationship between the volume of physical activity and the reduction in mortality is not linear. Beyond three hundred minutes per week of moderate AP, or one hundred and fifty of sustained AP, the additional benefits become marginal. Concerning cancers, the authors analyzed the incidence (occurrence of new cases) according to the level of physical activity for about fifteen tumours. A protective effect of AP is found for tumors of the head and neck, myeloid leukemia, myeloma and stomach cancer. On the other hand, there would be no significant association for other locations, such as the prostate or the kidney.
One in ten preventable deaths
If these new results are hardly surprising on the merits (we now know that, in terms of physical activity, a little is better than not at all), they are to be underlined because of their statistical power. The Cambridge scientists performed a meta-analysis from 196 articles, including data from 94 cohorts, with a total of more than 30 million participants. To reduce the risk of bias, studies with fewer than 10,000 participants were excluded, as were those with follow-up of less than three years.
If all the subjects included in the meta-analysis had had a PA level in line with WHO recommendations, 16% of premature deaths could have been avoided, the researchers estimate. And, at half the level (ie the eleven minutes a day, seven days a week of moderate PA mentioned at the beginning of this article), one in ten premature deaths could have been prevented. Knowing that cardiovascular diseases and cancers are the biggest serial killers worldwide (in 2019, they were responsible for 17.9 million and 9.6 million deaths respectively), the gains in public health terms are potentially colossal.
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