What is the optimal amount of exercise needed to live a long life? It’s slightly more than you may think, but not as much as you might expect, according to two studies published April 6, 2015 in JAMA Internal Medicine.

Dr. I-Min Lee, professor in the Harvard T.H. Chan School of Public Health department of epidemiology and professor of medicine at Harvard Medical School, and Dr. Hans-Olov Adami, adjunct professor of epidemiology at Harvard Chan, were co-authors of one study, conducted with the National Cancer Institute and other institutions. After pooling data on exercise habits of over 661,000 adults, they found non-exercisers to be at highest risk of early death, while those who did any leisure-time physical activity, even if less than currently recommended, had a 20 percent lower mortality rate than did non-exercisers during an average follow-up of 14 years. Those who followed the currently recommended 150 minutes of moderate-intensity exercise each week had 31 percent less risk of dying during follow-up compared with non-exercisers.

The authors found those who tripled the recommended level of exercise — working out moderately, mostly by walking, for 450 minutes weekly, or about an hour each day — were 39 percent less likely to die prematurely than those who never exercised, according to a story in the New York Times. And, the benefit flattened out at this level — those who did even more exercise did not experience additional reductions in mortality rate. Read more