Reliability of autonomic and vascular components of baroreflex sensitivity in adolescents

Summary Improvements in the autonomic and vascular systems are implicated in cardiovascular disease risk reduction. Baroreflex sensitivity ( BRS ) is composed of vascular and autonomic components. This study aimed to investigate between‐ and within‐day reliability of BRS and its autonomic and vascular determinants in adolescents. Thirteen male adolescents (14·1 ± 0·5 y) participated in this study. For between‐day reliability, participants completed four experimental visits separated by a minimum of 48‐h. For within‐day reliability, participants repeated BRS assessments three times in the morning with one hour between the measures. BRS was evaluated using the cross‐spectral gain ( LF gain) between blood pressure and heart rate interval. BRS was further divided into: 1) vascular component using arterial compliance ( AC ); and 2) autonomic component measured as LF gain divided by AC ( LF gain/ AC ). LF gain, AC and LF gain/ AC presented between‐day coefficient of variation ( CV ) of 20%, 17%, and 20%, respectively. Similarly, variables associated with blood pressure control, such as cardiac output, mean arterial pressure, heart rate and total peripheral resistance, presented CV s ranging from 6% to 15%. Within‐day reliability was poorer compared to between‐day for LF gain (25%), AC (25%), and LF gain/ AC (31%), as well as all hemodynamic variables ( CV s from 11% to 22%, except heart rate with presented CV of 6%). This study indicates suitable between‐ and within‐reliability of BRS and its autonomic and vascular determinants, as well as hemodynamic variables associated with BRS , in adolescents.