Running just five minutes a day can increase your life expectancy. That's what a group of exercise researchers concluded after 15-year-long study.

Published a few years ago in The Journal of the American College of Cardiology, the results made runners rejoice -- and raised many questions among the scientific community, runners and non-runners alike. People wanted to know if running was truly the holy grail of exercise. Everyone wanted more conclusive scientific evidence, as New York Times Well columnist Gretchen Reynolds writes.

After digging into the results of a new study about running and longevity, Reynolds concludes the original study's results are on point.

Published last month in Progress in Cardiovascular Disease, this study has a fitting title: Running as a Key Lifestyle Medicine for Longevity. The researchers found that in general, runners had a 25-40 percent reduced risk of premature mortality and lived about three years longer than non-runners. They even calculated life expectancy of runners vs. non-runner to the hour. Every hour of running translates to an increased life expectancy by seven hours.

You don't have to be fast, skinny or in perfect health

What's more, the study found it didn't matter how slowly people ran. Whether you shuffle, jog or sprint, you're running. You just need to put one foot in front of the other to increase your life expectancy.

Even more surprising, the study found the same life expectancy-boosting results for runners who were overweight or occasionally smoke and drank. Though it is worth mentioning that most people who run consistently generally have healthier lifestyles. So lifestyle choices also play a role in how long you life. Another important takeaway from the study: Most participants in the studies were white and middle class.

What about other exercise like walking and biking? Not as effective as running, the study found. By comparison, non-running exercise like biking or walking only dropped the risk of premature death to around 12 percent.

Interested in learning more about how running can increase your life expectancy? Read more from Gretchen Reynolds in New York Times.