A study published Online First by The Lancet shows that just 15 minutes of physical activity per day reduces a person's risk of death by 14% and increases life expectancy by 3 years compared with inactive people. The Article is by Dr Chi-Pang Wen, National Health Research Institutes, Taiwan, and China Medical University Hospital, and Dr Jackson Pui Man Wai, National Taiwan Sport University, and colleagues.

The health benefits of leisure-time physical activity are well known, but whether less exercise than the generally recommended 150 min a week can have life expectancy benefits is unclear. Thus the authors assessed the health benefits of a range of volumes of physical activity in a Taiwanese population.

The study included over 400 000 Taiwanese people who participated in a standard medical screening programme in Taiwan between 1996 and 2008, with an average follow-up of 8 years. On the basis of self-reported weekly exercise, participants were placed into one of five categories of exercise volumes: inactive, or low, medium, high, or very high activity. The authors calculated hazard ratios (HR) for mortality risks for every group compared with the inactive group, and calculated life expectancy for every group.

Compared with individuals in the inactive group, those in the low-volume activity group, who exercised for an average of 92 min per week (about 15 min a day) had a 14% reduced risk of all-cause mortality, a 10% reduced risk of all-cancer mortality, and on average a 3 year longer life expectancy. Every additional 15 min of daily exercise beyond the minimum amount of 15 min a day further reduced all-cause mortality by 4% and all-cancer mortality by 1%. These benefits were applicable to all age groups and both sexes, and to those with cardiovascular disease risks. Individuals who were inactive had a 17% increased risk of mortality compared with individuals in the low-volume group.

The authors say: "In Taiwan, if inactive individuals engage in low-volume daily exercise, one in six all-cause deaths could be postponedmortality reductions of similar magnitude have been estimated for a successful tobacco control programme in the general population."

They conclude: "If the minimum amount of exercise we suggest is adhered to, mortality from heart disease, diabetes, and cancer could be reduced. This low volume of physical activity could play a central part in the global war against non-communicable diseases, reducing medical costs and health disparities."

In a linked Comment, Dr Anil Nigam and Dr Martin Juneau, Montreal Heart Institute and Université de Montréal, Quebec, Canada, conclude: "The knowledge that as little as 15 min per day of exercise on most days of the week can substantially reduce an individual's risk of dying could encourage many more individuals to incorporate a small amount of physical activity into their busy lives. Governments and health professionals both have major roles to play to spread this good news story and convince people of the importance of being at least minimally active."

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Provided by Lancet