Effects of the number of sit-stand maneuver repetitions on baroreflex sensitivity and cardiovascular risk assessments.

Sit-stand maneuvers (SSMs) have increasingly been used for baroreflex sensitivity (BRS) measurement in physiological research, but it remains unknown as to how many SSMs need to be performed to measure BRS and assess its relationship with cardiovascular disease (CVD) risk. Therefore, this study aimed to determine 1 ) the effect of the number of SSM repetitions on BRS, and 2 ) the association between BRS and CVD risk factors. Data were collected from 174 individuals during 5 min of spontaneous rest and 5 min of repeated SSMs at 0.05 Hz (i.e., 15 cycles of 10-s sit and 10-s stand). During SSMs, BRS was calculated from the incremental cycles of 3, 6, 9, 12, and 15 SSMs using transfer function analysis of heart rate (HR) and systolic blood pressure (SBP). General CVD risk factors, carotid arterial stiffness, and cardiorespiratory fitness were measured. In result, HR and SBP increased during SSMs ( P < 0.05). The BRS remained at a similar level during the resting and SSM conditions, whereas the coherence function reached its peak after 3 cycles of SSMs. BRS with ≥6 cycles of SSMs was strongly correlated with age ( r = -0.721 to -0.740), carotid distensibility ( r = 0.625-0.629), and cardiorespiratory fitness ( r = 0.333-0.351) (all P < 0.001). Multiple regression analysis demonstrated that BRS with ≥6 cycles of SSMs explained >60% of the variance in CVD risk factors. Therefore, our findings suggest that repeated SSMs significantly strengthens the association between BRS and CVD risk factors. Particularly, BRS with ≥6 cycles of SSMs is strongly associated with CVD risk.