Blood Pressure Responses To Sodium-bicarbonate Ingestion Prior To Prolonged Exercise In The Heat

Sodium-bicarbonate (NaHCO3) ingestion during prolonged exercise in the heat may mitigate metabolic acidosis and reduce the risk of acute kidney injury. However, NaHCO₃ ingestion may potentially elevate blood pressure, yet its effects on blood pressure responses during prolonged exercise in hot conditions have not been studied. PURPOSE: To examine blood pressure responses to NaHCO3 ingestion prior to prolonged exercise in the heat. METHOD: In a double-blinded, randomized, cross-over design, eight healthy and active men (n = 5) and women (n = 3) (age = 28.8 ± 5.8 years; body fat percentage = 20.7 ± 8.9%) participated in this study. NaHCO3 (0.2 g/kg body weight) or placebo (PLA) was ingested prior to 120 minutes of moderate exercise (walking at ~65% of maximal heart rate) in the heat (40 °C/~20% relative humidity). Seated auscultatory blood pressure measurements were performed pre and immediately post ingestion, immediately post exercise, and one-hour post exercise. Two-way repeated measures analysis of variance examined main effects of time, condition, and their interaction on systolic (SBP) and diastolic (DBP) blood pressure, mean arterial pressure (MAP), and pulse pressure (PP) while adjusting for baseline values. RESULTS: A main effect of time on SBP was observed (p = 0.02) where SBP decreased over time for both sessions (PLA session: baseline = 117 ± 3.0 mmHg, immediately post ingestion = 120.5 ± 6.4 mmHg, immediately post exercise = 120.0 ± 2.1 mmHg, one-hour post exercise = 118.0 ± 1.0 mmHg; NaHCO3 session: baseline = 118 ± 2.2 mmHg, immediately post ingestion = 119.2 ± 4.8 mmHg, immediately post exercise = 117.2 ± 3.0 mmHg, one-hour post exercise = 114.2 ± 2.7 mmHg). No other significant main effects of time, condition, or their interaction on these blood pressure measures were detected (p > 0.05). CONCLUSION: These findings suggest that an acute ingestion of NaHCO3 prior to prolonged exercise in the heat does not increase blood pressure in active adults with normal blood pressure. Future research is needed to investigate the influence of chronic NaHCO3 ingestion on blood pressure and cardiovascular adaptions to prolonged exercise in the heat and on those with elevated resting blood pressure. Supported by: The authors gratefully acknowledge the funding of the Deanship of Graduate Studies and Scientific Research, Jazan University, Saudi Arabia, through Project Number: GSSRD-24