Running A 161-km Ultra-marathon Acutely Reduces Central Blood Pressure And Improves Pulse-wave Characteristics

BACKGROUND: Completing an ultra-marathon running event (>42.2 km) is a tremendous physiological stressor. There is concern that these events could harm cardiovascular health acutely and over time. However, central blood pressure (cBP) and pulse wave characteristics have not been characterized after running an ultra-marathon. Therefore, the purpose of this study was to test the hypothesis that central BP would decrease while augmentation pressure (AP) and augmentation index (AIx) would increase after finishing an ultra-marathon. METHODS: We estimated supine cBP and performed central pulse wave analysis via automated cuff (SphygmoCor XCEL, AtCor Medical) at the brachial artery among 37 finishers (9F/28M; BMI: 22.9 ± 1.8 kg/m2, age: 45 ± 10 years) of the 2023 161-km Western States Endurance Run. Measures were taken 1-3 days before (pre) and ≤ 1 hour after race completion (post). We compared pre versus post heart rate, systolic cBP, diastolic cBP, central pulse pressure (PP), AP, subendocardial viability ratio (SEVR), and AIx adjusted to a heart rate of 75 bpm (AIx75). We present normally distributed data (Shapiro-Wilk; P ≥ 0.05) as mean ± SD, compared time points with paired t-tests (α < 0.05), and quantified changes with Cohen’s d effect sizes. We present non-normal data as median [IQR], compare time points with Wilcoxon sign rank tests, and quantify differences with rank biserial correlation (r) effect sizes. RESULTS: We present outcomes as pre vs. post. After the race, there was a significant increase in heart rate (57 [11] vs. 71 [15] bpm, P < 0.001, r = 0.89). There was a significant decrease in systolic cBP (115 ± 9 vs. 107 ± 9 mmHg, P < 0.001, d = 0.89), diastolic cBP (78 ± 7 vs. 75 ± 8 mmHg, P = 0.01, d = 0.40), PP (37 ± 6 vs. 31 ± 5 mmHg, P < 0.001, d = 1.10), AP (6 [4] vs. 2 [6] mmHg, P < 0.001, r = 0.83), and SEVR (172 [29] vs. post: 128 [29] %, P < 0.001, r = 0.94) but not AIx75 (10.0 [11.0] vs. 6.0 [21.0] %, P = 0.09 r = 0.32). CONCLUSIONS: CBP was lower after the race, which confirmed part of our hypothesis. Contrary to our hypothesis, AP was lower and AIx75 was unchanged. The reduction in SEVR suggests a lower myocardial oxygen supply:demand ratio after completing the race. These data suggest that running an ultra-endurance race acutely reduces central BP, improves pulse wave characteristics, and reduces subendocardial blood flow. Western States Endurance Run Medical Research Program