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18-08-2011 | Internal medicine | Article

15 minutes daily exercise may lengthen life


Free abstract

MedWire News: Spending 15 minutes a day participating in moderate activity, such as brisk walking, may reduce a person's risk for death by 14% and increase their life expectancy by 3 years, shows research published in The Lancet.

Chi Pang Wen (National Health Research Institutes, Zhunan, Taiwan) and colleagues explain that current guidelines recommend adults spend 150 minutes per week exercising, but personal time constraints mean this can be difficult to attain.

"Identification of a minimum amount of exercise - or minimum dose - sufficient to reduce mortality is desirable because a small amount of exercise can be easier to achieve," say the researchers, who assessed the health benefits of different amounts of physical activity in 416,175 individuals (48% men) from Taiwan.

Study participants completed a self-administered questionnaire about their medical history and lifestyle. They were asked to classify the types and intensities of weekly leisure-time physical activity that they did during the previous month.

On the basis of their responses, the participants were placed into one of five categories of exercise volumes: inactive, or low, medium, high, or very high activity and followed-up for 8.1 years, on average.

The researchers report that, compared with individuals in the inactive group, those in the low-volume activity group, who exercised for an average of 92 minutes per week or 15 minutes a day, had a 14% reduced risk for all-cause mortality, a 10% reduced risk for cancer mortality, and a 20% reduced risk for cardiovascular mortality.

Furthermore, every additional 15 minutes of daily exercise beyond the minimum amount of 15 minutes per day further (up to 100 minutes a day, after which there was no additional health benefit) reduced all-cause mortality by 4% and all-cancer mortality by 1%.

Indeed, all-cause mortality risk was 20% lower among participants reporting medium volume activity (222 min/week), 29% lower among those reporting high volume activity (362 min/week), and 35% lower among those with very high volume activity (524 min/week), compared with inactive participants.

Wen and team note that the risk reductions were applicable regardless of a person's gender, age, or health status, or whether or not they smoked, drank alcohol, or were at risk for cardiovascular disease.

Individuals who were inactive had a 17% increased risk for mortality compared with individuals in the low-volume group.

When the researchers measured participants' life expectancy at age 30 years, they found that men and women in the low-volume activity group were expected to live 2.6 and 3.1 years longer than those in the inactive group, respectively. For individuals who met the recommended amount of daily exercise (150 min/week), life expectancy was 3.7-4.2 years longer.

"The minimum amount of exercise reported in this study is half of that recommended worldwide, but individuals are more likely to do 15 minutes of daily exercise than they are 30 minutes of daily exercise," Wen and co-authors remark.

Editorialists Anil Nigam and Martin Juneau, from Université de Montréal in Quebec, Canada, agree. "The knowledge that as little as 15 minutes 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," they write.

By Laura Dean

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