BL Cross


Brett L. Cross. Florida State University, Tallahassee, FL.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death worldwide. In America, Black adults have a greater number of CVD risk factors and are more likely to develop and die from CVD than any other race. Lifestyle factors, such as physical activity (PA) and sleep, critically influence CVD risk. However, the role of lifestyle in mediating racial disparities in CVD risk factors in young adults is unclear. Therefore, we assessed known cardiovascular risk factors, blood pressure (BP) and arterial stiffness, as well as objective physical activity and sleep habits, in young Black and White adults. METHODS: We measured central BP and carotid-femoral pulse wave velocity (cf-PWV; an index of arterial stiffness) in 15 Black (8F/7M; 21±3 years, BMI: 24±5 kg/m2) and 20 White (10F/10M; 21±4 yrs, BMI: 23±3 kg/m2) participants via pulse waveform analysis and applanation tonometry, respectively. Additionally, we used wrist-worn actigraphy to quantify seven-day PA (sedentary time, low intensity PA, moderate-vigorous PA, and total steps) and sleep (total sleep time [TST] and sleep irregularity, defined as the standard deviation of nightly sleep duration) habits. Cardiovascular measures and lifestyle factors were compared between races using independent t-tests. Analysis of covariance was then used to inspect for race differences in cardiovascular health after adjusting for lifestyle factors that differed by race. RESULTS: Compared to White participants, Black participants demonstrated greater systolic (100±8 vs. 107±11 mmHg; p=0.02) and diastolic (67±6 vs. 72±7 mmHg; p=0.02) BP. Meanwhile, cf-PWV differences in Black (6.2±0.8 m/s) vs. White (5.7±0.8 m/s) participants were inconclusive (p=0.06). PA metrics did not differ between races (all p>0.05). Likewise, TST was not different between the races (p=0.53), but sleep irregularity was greater (p=0.02) in Black (81±24 min) vs. White (59±26 min) participants. After adjusting for sleep irregularity, no race differences in central systolic (p=0.94), diastolic (p=0.15), or cf-PWV (p=0.85) were seen. CONCLUSIONS: We observed higher blood pressure and potentially greater arterial stiffness in young Black vs White individuals. Detected differences in central BP were no longer significant once we adjusted for sleep irregularity. These findings suggest that irregular sleep duration may contribute to the preclinical development of CVD in young Black individuals.

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