Ethnic differences in the cardiac responses to aerobic exercise.

Cardiovascular disease disproportionately affects North American Indigenous populations. Ethnic differences in cardiac responses to exercise are known, though Indigenous populations response is unknown. To evaluate cardiac responses to aerobic exercise among Canadian Indigenous and European adults. Indigenous ( = 12, 4 females, 1 male incomplete) and European ( = 12, all completed) Canadian age and sex-matched adults 19-40 years and free of cardiovascular disease or diabetes completed a cycle ergometer maximal aerobic power test and 30 min at 60% maximal aerobic capacity on two separate days. Echocardiographic assessments preceded and immediately followed exercise. Responses to maximal exercise were similar among ethnicities including decreases in stroke volume index, cardiac output index and ejection fraction, and increases in arterial-ventricular coupling. However, following submaximal exercise, only Indigenous adults demonstrated reductions in end systolic volume, end diastolic volume (154.8 ± 40.6 mL to 136.5 ± 33.0 mL,  = 0.01, vs. 149.4 ± 22.4 mL to 147.1 ± 27.0 mL;  = 0.81), stroke volume index (44.9 ± 8.7 mL m to 38.0 ± 6.5 mL m,  = 0.002, vs. 46.4 ± 7.1 mL m to 44.0 ± 6.5 mL m;  = 0.28) and arterial compliance. Indigenous and European adults demonstrated similar cardiac responses to maximal exercise, though only Indigenous adults demonstrated cardiac responses to submaximal exercise.