Racial patterns of heart rate in an employed adult population

This study explored racial patterns of heart rate in a large population of employed Chicagoans: 39,665 adults screened in Chicago firms between late 1967 and early 1973. Of these, 30,876 were white or black adults age 18--64 with complete data, and not on drug therapy for hypertension. Mean heart rates of young black men and women were significantly lower than mean heart rates of young white men and women. This difference was not present for the age groups 35 and older. The difference was present in both smokers and non-smokers; in normotensives and in persons with elevated blood pressure; and could not be explained by differences in relative body weight. The difference persisted after simultaneous adjustment for differences in the mean values of systolic blood pressure, relative weight, serum cholesterol, post-loaded plasma glucose, and number of cigarettes smoked per day.