Consistency of hemodynamic and autonomic mechanisms underlying post-exercise hypotension

Post-exercise hypotension (PEH) is a clinically relevant phenomenon, but its mechanisms vary between different studies and between the participants within each study. Additionally, it is possible that PEH mechanisms are not consistent in each individual (i.e. within-individual variation), which has not been investigated yet. Thus, the aim of the current study was to assess the within-individual consistency of PEH hemodynamic and autonomic mechanisms. For that, 30 subjects performed 4 sessions divided in 2 blocks (test and retest). In each block, an exercise (cycling, 45 min, 50%VO₂peak) and a control (seated rest, 45 min) session was randomly conducted. Blood pressure (BP) and its mechanisms were evaluated pre- and post-interventions. In each block, individual responses were calculated as post-exercise minus post-control, and a response was considered present when its magnitude reached the typical error of the measurement. Consistencies were evaluated by comparing test and retest responses through kappa coefficient (k). PEH consistency was calculated using role sample, while mechanisms consistency was evaluated in those with consistent PEH. Twenty-one (70%) participants showed consistent PEH, 5 (17%) presented PEH in only test or retest and 4 (13%) had absent PEH response, characterising a good consistency (k = 0.510). Regarding mechanisms' responses, good consistency was found for heart rate (k = 0.456), sympathovagal balance (k = 0.438), and baroreflex sensitivity (k = 0.458); while systemic vascular resistance (k = 0.152), cardiac output (k = -0.400), stroke volume (k = -0.055), and sympathetic vasomotor modulation (k = -0.096) presented marginal consistencies. Thus, PEH is a highly consistent physiological phenomenon, although its mechanisms present variable consistencies.