The Biggest U.S. Study on Exercise Just Ran Out of Money

Since 1991, Paul Williams, a scientist at the Lawrence Berkeley National Laboratory, has been studying the same 156,000 people to find out how their running and walking habits affect their health. About every 10 years, he asks them about their medical history and tracks their health outcomes as the years go on. Now that many participants are older, he's also assessing their aging process and life spans. About a third of Williams's participants came to him through a survey that Runner's World published on his behalf; the rest he found by approaching people at road races.

The National Runners' and Walkers' Health Studies, as Williams's project is called, is the country's largest longitudinal exercise study and has led to the publication of 65 papers. Some of the project's results are obvious (running will help you lose weight faster than walking) while others are more revelatory. Williams has linked regular running and walking to a decrease in the risk of breast cancer, Alzheimer's, and even cataracts. He's found that runners are less likely to suffer from joint problems and arthritis than nonrunners, and that heart attack survivors are less likely to die from heart disease if they run a moderate amount each week (run more than that and the protective benefits seem to disappear). "We know exercise is good for us," Williams said, "but I'm trying to find out what the benefits really are."