Researchers identify amount of exercise needed to lower risk of 5 diseases

Shot of young couple running on hillside road outside the city. Young man and woman jogging in morning with bright sunlight. (iStock)

Doctors often tout how exercise can help ward off disease, but previous research hasn’t concluded just how much physical activity is needed to reap those benefits.

To find out, researchers in the United States and Australia conducted a meta-analysis of 174 studies published between 1980 and 2016 that examined the effect of exercise on five chronic diseases: breast cancer, colon cancer, diabetes, heart disease and stroke.

Study authors observed that, to a certain point, the more a person exercised, the lower his or her risk of all five conditions. But the sweet spot for health gains occurred when individuals had a total activity level of 3000-4000 metabolic equivalent (MET) minutes a week, according to a news release. Benefits halted beyond an activity level of 4000 MET minutes a week.

MET measures express the energy cost of physical activity, which is calculated by the number of calories an activity can burn multiplied by the number of minutes a person is engaged in said activity. On its website, the Centers for Disease Control and Prevention outlines the MET value of various activities, from walking the dog or biking, to mountain climbing or aerobic dancing.

Researchers’ results, which were published Tuesday in The BMJ, suggest current World Health Organization recommendations for a minimum total physical activity level of 600 MET minutes a week across different domains of life may be insufficient.

They noted that people can achieve 3000 MET minutes a week by incorporating physical activity in everyday tasks, such as climbing stairs for 10 minutes, vacuuming for 15 minutes, gardening for 20 minutes, running for 20 minutes, and walking or cycling for 25 minutes, according to the release.

Although the meta-analysis consisted of observational studies that didn’t necessarily draw causal relationships, researchers said their results suggested global recommendations may need to be revised.

"With population aging, and an increasing number of cardiovascular and diabetes deaths since 1990, greater attention and investments in interventions to promote physical activity in the general public is required," they wrote in the study. "More studies using the detailed quantification of total physical activity will help to find a more precise estimate for different levels of physical activity.”