The researchers' prospective observational study involved 416,175 Taiwanese who participated in a standard medical screening program from 1996 to 2008.
Study participants completed a questionnaire on their medical history, lifestyle information and weekly physical activity for the previous month by intensity -- light (walking), moderate (brisk walking), vigorous (jogging) or high vigorous (running).
To account for occupational effects, participants also characterized their physical activity at work -- ranging from sedentary to hard physical labor.
The study, published in the journal The Lancet, reported those who reported less than 1 hour a week of leisure time physical activity were classified as inactive -- 54 percent of all participants. However, those exercising for 30 minutes daily added about four years to life expectancy, the study says.
Dr. Xifeng Wu of The University of Texas MD Anderson Cancer Center, the senior author, Dr. Chi-Pang Wen of the National Health Research Institutes of Taiwan, the lead author, and colleagues also found that a person's risk of death from any cause decreased by 4 percent for every additional 15 minutes of exercise up to 100 minutes a day over the course of the study.
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