DOCTOR'S VIEW ARCHIVE
Berkeley--According to public health recommendations by the Center for Disease Control and Prevention (CDC), the majority of health benefits gained from physical exercise activity are achieved by walking 2 miles (3.2 km) briskly most of the days of the week. They also assert that the benefits of increased exercise is 12 times greater in sedentary people than in those that are active.
Data from a study published in 1996 called the National Runners' Health Study contradicts the implications of the CDC guidelines by suggesting a substantial benefit in reduction of risk factors for heart disease in men whose exercise activity exceeded the recommended levels.
In a study, published in the New England Journal of Medicine (NEJM, 1998), Paul T. Williams, Ph.D. reported data of 1837 female runners throughout the United States. The data suggests that women who exercised at levels exceeding the current CDC guidelines had substantial increases in blood HDL cholesterol ("good" cholesterol). This effect was noted whether the women were pre- or postmenopausal, or were taking estrogen replacement.
HDL cholesterol is recognized as a form of cholesterol that reduces heart disease risk. High HDL cholesterol levels are desirable, while low HDL cholesterol increases the risk of coronary heart disease. Dr. Williams points out that higher blood HDL cholesterol concentrations in the women who exercised at higher levels could provide these women with the added health benefits of decreased heart risk.
The findings of this study suggest additional benefits to women who increase their exercise beyond the levels recommended by the current CDC guidelines. The editors of NEJM in an accompanying editorial, while not discounting these additional benefits, warn that vigorous exercise leading to complications of loss of the menstrual period, reproductive disorder, or repeated musculoskeletal injuries is excessive.
For more information, please visit the MedicineNet.com Cholesterol Center.