Physical Activity and Fitness in African Americans: Implications for Cardiovascular Health

Abstract

The prevalence of cardiovascular disease (CVD), obesity, diabetes mellitus, hypertension, and physical inactivity is significantly higher in African Americans. The higher prevalence of these important risk factors is thought to be largely responsible for the higher CVD mortality rate in blacks. Limited evidence suggests that the aerobic power of African Americans may be inherently lower than that of whites. This apparent deficiency may be explained, in part, by differences in muscle oxidative capacity but is poorly understood. Studies have shown a lower prevalence of overweight/obesity, the metabolic syndrome, and insulin resistance with higher levels of physical activity/fitness. Training studies have shown that increasing physical activity and/or fitness positively affects metabolic risk factors, body composition, and insulin sensitivity. The few studies of African Americans suggest that they respond to exercise training in a manner similar to whites. Controlling blood pressure of hypertensive blacks at levels comparable with that of whites could result in more than 7000 fewer deaths from CVD. Physical fitness has been shown to be negatively associated with blood pressure in African Americans, but results from interventional studies have been equivocal. Some evidence suggests that increased physical activity and/or fitness may reduce the blood pressure response to submaximal exercise and other stressors in African Americans. Blacks have higher levels of high-density lipoprotein cholesterol (HDL-C) and lower levels of total cholesterol, triglycerides, and small dense low-density lipoprotein particles. Studies suggest that the blood lipid response to exercise training is similar between African Americans and whites. There may be an intensity threshold of 75% of age-predicted maximal heart rate to elicit significant changes in HDL-C. More research is needed to explore the association between physical activity/fitness and CVD risk factors in this population.