Background: Official guidelines from the Centers for Disease Control and Prevention assert that the majority of health benefits from physical activity are obtained by walking 2 miles (3.2 km) briskly most days of the week (the energy equivalent of running 8 to 12 km per week). The objective of our study was to examine the dose-response relation in women between risk factors for coronary heart disease, particularly the concentration of high-density lipoprotein (HDL) cholesterol, and vigorous exercise at levels that exceed the official guidelines.
Methods: The number of kilometers run per week reported by 1837 female recreational runners in a national cross-sectional survey was compared with medical data provided by the women's physicians.
Results: In these cross-sectional data, plasma HDL cholesterol concentrations were higher by an average (+/- SE) of 0.133 +/- 0.020 mg per deciliter (0.003 +/- 0.0005 mmol per liter) for every additional kilometer run per week, an amount nearly identical with that previously reported for men (0.136 +/- 0.006 mg per deciliter [0.004 +/- 0.0002 mmol per liter] per kilometer per week). Among women who ran less than 48 km per week, mean plasma HDL concentrations were significantly higher with each 16-km increment in distance. Women who ran more than 64 km per week had significantly higher mean concentrations of HDL cholesterol than did women who ran less than 48 km per week. They were also significantly more likely to have HDL cholesterol concentrations greater than 100, 90, or 80 mg per deciliter (2.6, 2.3, or 2.1 mmol per liter) than were women running less than 64 km per week. HDL cholesterol concentrations increased significantly in relation to the number of kilometers run per week in premenopausal women who were not using oral contraceptives and in postmenopausal women, whether they were receiving estrogen-replacement therapy or not.
Conclusions: Substantial increases in HDL cholesterol concentrations were found in women who exercised at levels exceeding current guidelines; higher HDL cholesterol concentrations could provide added health benefits to these women.