For decades, we've been told that the more exercise you get, the better off you'll be. The Centers for Disease Control and Prevention, for example, recommends at least two and a half hours of moderate-intensity exercise or 75 minutes of vigorous activity, making it clear that "more time equals more health benefits."
But less may be more, according to a study just published in the Journal of the American College of Cardiology. In fact, those who engage in light exercise may actually live longer than those who run longest, hardest, and most often.
So says Peter Schnohr at the Copenhagen City Heart Study, a long-running survey of the habits and health of residents of the Danish capital city. Since the 1970s, the study has reported time and again on the health benefits of jogging and other sorts of exercise. In a recent analysis, however, Schnohr and his team found that athletes who ran more than four hours a week, more than three times a week, or at a fast pace "appeared to lose many of the longevity benefits noted with [a] less strenuous dose of jogging," Schnohr writes.
There was no discernible benefit from either moderate or strenuous jogging, but there might have been a downside. While they couldn't be statistically distinguished from sedentary people, moderate joggers died at about two-thirds the rate of non-joggers.
Finding that conclusion "somewhat surprising," Schnohr and his fellow researchers decided to dig a bit deeper into the data. From 2001 to 2013, Schnohr's team asked a total of 1,511 study participants how many minutes they ran per week, how often they went for a run, and to measure the intensity of the run.
The research team next combined those numbers into a single measure to determine how strenuously people exercised. For instance, those who ran at a slow or average pace for fewer than 150 minutes a week were light joggers, while those who ran at a fast pace more than three times a week and for more than 150 minutes total were strenuous joggers.
Consistent with earlier results, light joggers were the least likely to die during the 12-year course of the study. After adjusting for age, sex, smoking, drinking, education, and diabetes, the team found that group crossed life's finish line at little bit more than a fifth the rate of sedentary non-joggers.
Meanwhile, there was no discernible benefit from either moderate or strenuous jogging, but there might have been a downside. While they couldn't be statistically distinguished from sedentary people, moderate joggers died at about two-thirds the rate of non-joggers, and—again after adjusting for health factors such as age and smoking—strenuous joggers died at twice the rate of those who sat around doing nothing.
The reason may be quite simple: "[Strenuous] jogging corresponds to very heavy vigorous exercise ... which when performed for decades could pose health risks," especially to the cardiovascular system, the authors write. They argue that while that sort of jogging might help reach peak physical fitness in the short term, high-intensity, high-volume training isn't ideal for long-term health.