Ethnic-specific determinants of exercise capacity in a healthy high-risk population

African Americans (AA) have been shown to have lower exercise capacities and a higher prevalence of related risk for cardiovascular disease (CVD) compared to European Americans (EA). Broad biopsychosocial models that may inform the design of ethnic-specific exercise programs have not been well examined. We thus examined exercise capacity and its biopsychosocial correlates in a healthy population of AA and EA at increased risk of CVD.

Subjects underwent maximal graded treadmill testing with gated single-photon emission computed tomography (SPECT); exercise capacity was expressed in MET-minutes. Medical history, psychosocial variables, general well-being, physical activity, and anthropometrics were assessed. Peak filling rate, a measure of left ventricular function, and ejection fraction were obtained from SPECT imaging, and the presence of silent ischemia was determined from the treadmill and SPECT imaging.

The sample (N = 1054) was 47% AA and 60% female. Mean age was 52.1 ± 9 yr for AA and 49.9 ± 10 yr for EA. Body mass index (BMI) was 32.5 ± 6.7 kg·m(-2) for AA and 29 ± 5.3 kg·m(-2) for EA. AA achieved a mean maximal exercise level of 31 MET·min less than EA did. In separate regression models by race, BMI (r(2) = 0 .30), age (r(2) = 0 .07), and sex (r(2) = 0 .03) explained 40% of the variance in MET-minutes in AA and 36% in EA, with a similar hierarchy of associated variables. The remaining variables had minimal effect on exercise capacity in either group.

BMI, older age, and female sex together contribute most to exercise capacity in both ethnicities. Hypothetically important biopsychosocial variables that may help shape ethnic-specific exercise programs add little to the prediction of exercise capacity. Thus, programs designed to reduce disparities in exercise capacity still need to first and foremost be geared to the age and sex demographics and address obesity.