National Runners' Health Study: Fleetest Are Healthiest
By Jeffery Kahn, jbkahn@lbl.gov November 12, 1996

BERKELEY, CA -- Current government guidelines state that the health benefits of exercise depend principally on the total amount of physical activity rather than on how hard you exercise. However, a new report from the National Runners' Health Study explicitly disputes this conclusion.

The study of over 8,000 runners finds that prolonged, vigorous exercise provides a range of benefits beyond that provided by the recommended daily brisk walk. Importantly, the study suggests that intense exercise appears to confer one set of benefits whereas lengthy exercise provides another.

The study finds that faster runners have lower blood pressure. In contrast, distance may be more important than quickness for increasing "good" cholesterol (HDL).

Dr. Paul Williams, the study's author, presented his findings Tuesday, November 12 at the 69th Scientific Sessions of the American Heart Association in New Orleans. "Our results suggest that different exercise prescriptions may target specific heart disease risk factors," said Williams, a life scientist at Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab).

The study involved 8,290 male and 1,837 female recreational runners. Williams had access to medical data provided by the runners' own physicians along with recent ten-kilometer race times and weekly running mileage for each runner. Race times provide a good measure of how fast individuals run when training. That's because runners who finish races quickly also tend to run faster during regular training runs.

Williams reports that men and women who ran faster had lower blood pressure, triglycerides, body mass index, and narrower hips. That's when adjusted for weekly training distances, age, alcohol intake, and diet.

For men, relative to the benefits of running longer weekly distances, running faster is estimated to have 13.3 times greater impact on lowering systolic blood pressure, 2.8 times greater impact on lowering diastolic blood pressure, and 4.7 times greater impact on narrowing waistlines. For women, running faster as versus running longer is estimated to have 5.7 times greater impact on lowering systolic blood pressure.

Running longer distances, on the other hand, had a more pronounced effect on another coronary heart disease risk factor. Running more miles had an over six-fold stronger effect on raising HDL-cholesterol than did running faster. That was the case for both men and women. Numerous studies show that higher HDL cholesterol levels protect against heart disease.

Should men and women exercise harder or longer, run faster or farther, to get the maximum health benefit? These questions are at the heart of the newly emerging medical field of exercise prescription.

"In terms of reducing heart disease risk," says Williams, "diet prescription has been an active area for over four decades. But now, prescribing different exercise regimens for specific heart disease risk factors faced by an individual is an idea whose time has arrived."

WIlliams cautions that genetics is partly responsible for why some runners are faster. Each individual's race times, however, can be increased by running more quickly when training and by increasing intervals of fast running during workouts.

"Exercise prescription makes a lot of sense," says Williams. "Clinical trials still must be conducted but our data suggests that longer runs may be best for raising HDL and faster runs best for lowering blood pressure."

Berkeley Lab conducts unclassified scientific research for the U.S. Department of Energy. It is located in Berkeley, California and is managed by the University of California.

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