Many health organizations, such as the World Health Organization, recognize the benefits of physical activity and recommend 150 minutes of moderate-intensity exercise a week. However, whether or not less exercise than this recommendation can benefit life span had been unclear.
Chi-Pang Wen, MD, MPH, DrPH, of National Health Research Institutes in Taiwan and China Medical University Hospital, and Jackson Pui Man Wai, PhD, of National Taiwan Sport University, and their colleagues assessed the health benefits of a range of physical activity levels. The study included more than 400,000 people participating in a medical screening program in Taiwan between 1996 and 2008, with an average follow-up of eight years. On the basis of self-reported weekly exercise, participants were placed into one of five categories of exercise levels: inactive, low, medium, high, or very high. The authors calculated hazard ratios (HR) for mortality risks for every group compared with the inactive group, and they 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 minutes per week (about 15 minutes a day), had a 14% reduced risk of death, a 10% reduced risk of dying of cancer, and on average a three year longer life expectancy. Every additional 15 minutes of daily exercise beyond the minimum amount of 15 minutes a day further reduced the risk of death by 4% and cancer death by 1%. These benefits were applicable to all age groups and both sexes, and to those with heart disease risks. Individuals who were inactive had a 17% increased risk of death compared with individuals in the low-volume group.
The authors write in the study, "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 commentary, Anil Nigam, MD, and Martin Juneau, MD, of the Montreal Heart Institute and the Université de Montréal, Quebec, Canada, conclude, "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."