Cardiac autonomic regulation following a 246-km mountain ultra-marathon: An observational study.

Physical exercise requires integrated autonomic and cardiovascular adjustments to maintain homeostasis. We aimed to observe acute posture-related changes in blood pressure, and apply a portable noninvasive monitor to measure the heart index for detecting arrhythmia among elite participants of a 246-km mountain ultra-marathon. Nine experienced ultra-marathoners (8 males and 1 female) participating in the Run Across Taiwan Ultra-marathon in 2018 were enrolled. The runners' Heart Spectrum Blood Pressure Monitor measurements were obtained in the standing and supine positions before and immediately after the race. Their high-sensitivity troponin T and N-terminal proB-type natriuretic peptide levels were analyzed 1 week before and immediately after the event. Heart rate was differed significantly in the immediate postrace assessment compared to the prerace assessment, in both the standing (P = .011; d = 1.19) and supine positions (P = .008; d = 1.35). Postural hypotension occurred in 4 (44.4%) individuals immediately postrace. In 3 out of 9 (33.3%) recruited finishers, the occurrence of premature ventricular complex signals in the standing position was detected; premature ventricular complex signal effect was observed in the supine position postrace in only 1 participant (11.1%). Premature ventricular complex signal was positively correlated with running speed (P = .037). Of the 6 individuals who completed the biochemical tests postrace, 2 (33.3%) had high-sensitivity troponin T and 6 (100%) had N-terminal proB-type natriuretic peptide values above the reference interval. A statistically significant increase was observed in both the high-sensitivity troponin T (P = .028; d = 1.97), and N-terminal proB-type natriuretic peptide (P = .028; d = 2.91) levels postrace compared to prerace. In conclusion, significant alterations in blood pressure and heart rate were observed in the standing position, and postexercise (postural) hypotension occurred among ultra-marathoners. The incidence of premature ventricular complexes was higher after the race than before.