Dr. Joann Elisabeth Manson

When I was in medical school in the late 1970s, it was very common to use the male model for teaching. For instance, there was the classical "70 kilogram man," and you know, the doses of drugs that would be used for a male of that body size, and also the risk factors for diseases, and the treatment of various diseases in males. The Nurses' Health Study was started in 1976, with 121 thousand female registered nurses. It was really the first large-scale observational study of women, looking at risk factors for many chronic diseases— breast cancer, colon cancer, heart disease, diabetes, and previously, most of these studies had been in men. I feel very strongly that there needs to be more of an emphasis on prevention and health promotion than there's been in the past. The paradigm has been treatment of disease, more so than prevention. And there is increasing evidence that lifestyle factors play an enormous role in prevention of disease. I've often said that regular physical activity is as close to a magic bullet for good health as we've come in modern medicine, despite all the technological advances. The list of conditions that can be prevented or at least improved through regular exercise is really an expansive one. You're talking about reduced risk of diabetes, heart disease, stroke, obesity, several forms of cancer— particular colon cancer and breast cancer, osteoporosis, and many others. And the portfolio is enormous. Our understanding of the benefits of exercise also has evolved over the years. We used to believe that vigorous and prolonged exercise was necessary in order to improve health. That you needed to get your heart rate at least 70 to 80 percent maximum, you needed to do the exercise continuously, at least 20 minutes, 3 times a week, and it had to be quite vigorous. We now know that even moderate intensity exercise, such as brisk walking— and it can be broken up into maybe 15 minutes or even 10 minutes at a time—can have important health benefits including the prevention of heart disease, and stroke, and diabetes, and various forms of cancer, and osteoporotic fractures. So I think we're learning more and more about the benefits of moderate exercise—which is good news from a public health standpoint. Because many people will not engage in vigorous exercise. And setting the bar too high, can serve as a deterrent of getting started.