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.