Relationships of heart disease risk factors to exercise quantity and intensity.

OBJECTIVE To assess the relationships of exercise amount and exercise intensity to coronary heart disease risk factors measured cross-sectionally in runners. METHODS Physician-supplied medical data were compared with subjects' reported average running amount (kilometers run per week) and running intensity during their best recent 10-km race (kilometers per hour) in 7059 male and 1837 female recreational runners. Ten-kilometer race velocity (kilometers per hour) is known to be related to exercise intensity during training. RESULTS Men and women who ran faster (ie, at greater intensity) had lower blood pressures; triglyceride levels; ratios of total cholesterol to high-density lipoprotein cholesterol; body mass indexes (calculated as the weight in kilograms divided by the square of the height in meters); and circumferences of the waist, hips, and chest when adjusted for weekly running distance, age, consumption of alcohol, and diet. Relative to the effect of running distance, running velocity had a 13.3 times greater calculated effect on systolic blood pressure, a 2.8 times greater calculated effect on diastolic blood pressure, and a 4.7 times greater calculated effect on waist circumference in men, and a 5.7 times greater calculated effect on systolic blood pressure in women when adjusted. In contrast, running distance had a more than 6-fold greater calculated effect on adjusted plasma high-density lipoprotein cholesterol levels than running velocity in both sexes. CONCLUSIONS Exercising more intensely could improve coronary heart disease risk factor level beyond that achieved by exercise amount alone; however, proof of causality remains to be determined from clinical trials. Exercise intensity and amounts may target specific coronary heart disease risk factors.