Ok, the study is a few years old, from 2014 actually, but there’s no reason the findings shouldn’t hold up. As reported in the New York Times, the findings of Duck-chul Lee, a professor of physical activity epidemiology at Iowa State University, show that regular runners — including those jogging slower than 6 miles per hour — were 30 percent fitter than walkers and sedentary people and had a 30 percent lower risk of dying over the next 15 years.
So yes, in general, the faster you go the bigger the benefit, at least in terms of risk of death. But its also true that the faster you go, the greater the risk of injury, and there is, of course, another study showing a significantly greater risk of short-term injury for runners, when compared to the risk for walkers. What to do? Cautious readers might start by reading this piece in the New York Times.