The blood pressure variability and baroreflex sensitivity in healthy participants are not determined by sex or cardiorespiratory fitness

BackgroundHeart rate (HR) and blood pressure (BP) autonomic modulation and baroreflex sensitivity (BRS) are important indexes of cardiovascular homeostasis. However, methodological errors are often observed, such as joint analysis of men and women. Another important aspect is that we still do not know whether cardiorespiratory fitness influences these autonomic parameters in healthy individuals.ObjectivesThis study aimed to investigate whether sex can affect BRS, autonomic modulation of HR and BP variabilities (HRV and BPV, respectively), as well as the influence of cardiorespiratory fitness on these autonomic parameters.MethodsHealthy men and women (N=120) were assigned to groups according to the peak oxygen consumption (VO2peak) obtained in the cardiorespiratory test: low cardiorespiratory fitness (VO2peak: 22-38ml/kg/min), moderate cardiorespiratory fitness (VO2peak: 38-48ml/kg/min), and high cardiorespiratory fitness (VO2peak>48ml/kg/min). HRV and BPV evaluations were performed for all groups in the frequency domain by spectral analysis. Spontaneous BRS was assessed using the sequence method.ResultsWomen presented lower BP values compared with men. HR did not differ between sexes, but showed an inverse relationship with cardiorespiratory performance. The HRV analysis showed greater sympathetic modulation for men and greater vagal modulation for women. Men and women presented similar results for systolic BPV and BRS, and cardiorespiratory performance did not influence any of the autonomic parameters evaluated.ConclusionCardiorespiratory fitness does not interfere with HRV and BPV autonomic modulation or BRS. However, the cardiac modulatory balance differs between sexes, with a greater influence of the autonomic vagal component in women and the sympathetic component in men.