body mass index (BMI) and weekly walking distance

An interesting study was published in Medicine & Science and Sports & Exercise, the official journal of the American College of Sports Medicine, in November 2005. In a study of over 27,000 women, body mass index (BMI) and weekly walking distance were compared. The findings showed that the highest levels of obesity were found in women who are sedentary or walked the least, and that the most dramatic decrease in body mass index occurred between 0 and about 12 miles per week, with relatively little change in BMI levels associated with greater distances. The deepest declines in BMI occurred when comparing sedentary individuals to those who walked even short distances regularly. This concurs with previous studies, showing that the most important and dramatic improvements in health occur when one goes from being sedentary to doing almost any amount of exercise. Relatively little further improvement in health occurs beyond 12-15 miles per week. Other studies have shown that above 20 miles per week, the rate of overuse injuries increases. I counsel my patients that walking or running farther than about 20 miles per week provides little additional health benefits, and that time spent running beyond that distance might be better spent doing some resistance exercise, which helps stimulate and build muscle and bone mass.

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