OBJECTIVE: We studied whether the quantity and quality of walking necessary to decrease the risk of cardiovascular disease among women differed substantially from that required to improve cardiorespiratory fitness. DESIGN: A randomized, controlled, dose-response clinical trial with a follow-up of 24 weeks. SETTING: A private, nonprofit biomedical research facility. PARTICIPANTS: One hundred two sedentary premenopausal women, 20 to 40 years of age, were randomized to one of four treatment groups; 59 completed the study (16 aerobic walkers (8.0 km/h group), 12 brisk walkers (6.4-km/h group), 18 strollers (4.8-km/h group), and 13 sedentary controls). Eighty-one percent were white, 17% black, and 2% Hispanic. INTERVENTION: Intervention groups walked 4.8 km per day, 5 days per week at 8.0 km/h, 6.4 km/h, or 4.8 km/h on a tartan-surfaced, 1.6-km track for 24 weeks. MAIN OUTCOME MEASURES: Fitness (determined by maximal oxygen uptake) and cardiovascular risk factors (determined by resting blood pressure and serum lipid and lipoprotein levels). RESULTS: As compared with controls, maximal oxygen uptake increased significantly (p < 0.0001) and in a dose-response manner (aerobic walkers greater than brisk walkers greater than strollers). In contrast, high-density lipoprotein cholesterol concentrations were not dose related and increased significantly (p < 0.05) and to the same extent among women who experienced considerable improvements in their physical fitness (8.0 km/h group, +0.08 mmol/L) and those who had only minimal improvements in fitness (4.8-km/h group, +0.08 mmol/L). High-density lipoprotein cholesterol also increased among the 6.4-km/h group, but did not attain statistical significance (+0.06 mmol/L; p = 0.06). Dietary patterns revealed no significant differences among groups. CONCLUSION: Thus, we conclude that vigorous exercise is not necessary for women to obtain meaningful improvements in their lipoprotein profile. Walking at intensities that do not have a major impact on cardiorespiratory fitness may nonetheless produce equally favorable changes in the cardiovascular risk profile.

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