Even 15 minutes of exercise a day is good: study

HONG KONG (Reuters) - Doing just 15 minutes of moderate exercise a day could be enough to make a difference, a large study in Taiwan suggests.

Most people struggle to stick to the standard guideline of 30 minutes a day of exercise, five days a week. The researchers hope the lower, but still helpful, "dose" of exercise they identified will motivate more people to get off the couch.

Lead researcher Chi Pang Wen of Taiwan's National Health Research Institutes said dedicating 15 minutes a day to a moderate form of exercise, like brisk walking, would benefit anyone.

"It's for men, women, the young and old, smokers, healthy and unhealthy people. Doctors, when they see any type of patient, this is a one-size-fits-all type of advice," Wen told Reuters in a telephone interview.

Wen and colleagues, who published their findings in the medical journal The Lancet on Tuesday, tracked over 416,000 participants for 13 years, analyzing their health records and reported levels of physical activity each year.

After taking into account differences in age, weight, sex and a range of health-related indicators, they found that life expectancy for the group that performed just 15 minutes of moderate exercise a day was three years longer than for the group that remained inactive.

Studies like this one -- called "observational studies" -- can't prove conclusively that exercise was the cause of longer life expectancy, because participants were allowed to choose whatever options appealed to them. This can lead to biased results.

Wen and colleagues tried to make the results as reliable as possibly by adjusting for personal factors that might affect participants' choices or outcomes

They also found that daily exercise was linked to a lower incidence of cancer and appeared to reduce cancer-related deaths in one person in ten.

"Sooner or later, you are going to die. But compared to the inactive group, the low exercise group (had) a reduction of 10 percent in cancer mortality," Wen said.

Wen said the Taiwan findings were consistent with similar studies in the past using Caucasian participants, but his team was the first to come up with the minimum level of exercise necessary.

"None of the other papers were able to conclude ... what specific amount of exercise would be enough. Ours is the first one to say that 15 minutes would be enough," he said.

"We hope this will make it more attractive for inactive people, that they can allocate 15 minutes a day, rather than 30, which is more difficult."

SOURCE: http://bit.ly/orG4QR The Lancet, online August 15, 2011.