The Efficacy Of Combining Sodium Bicarbonate And Glycerol Ingestion For The Purposes Of Hyperhydration
Siegler, Jason C. Medicine & Science in Sports & Exercise: August 2021 - Volume 53 - Issue 8S - p 350
PURPOSE: To characterize the fluid retention characteristics and gastrointestinal discomfort when combining sodium bicarbonate (NaHCO3) and glycerol to determine the efficacy of this combination as a pre-exercise hyperhydrating agent.
METHODS: Ten (n = 10) participants completed three randomized trials each separated by one week. For each trial, participants reported to the laboratory in an overnight fasted and rested condition. A baseline measurement of urine (volume, USG), body mass (BM) and a capillary blood (bicarbonate (HCO3), haemoglobin (Hb) and haematocrit (Hct)) was collected prior to initial ingestion of their respective condition (control: 25 ml/kg artificially sweetened water; NaHCO3 (B): 25 ml/kg artificially sweetened water +0.3 g/kg NaHCO3; NaHCO3 + glycerol (BG): 25 ml/kg artificially sweetened water +0.3 g/kg NaHCO3 + 1.2 ml/kg glycerine). The fluid loads were consumed in 4 aliquots at t = 0, 20, 40 and 60 min and consumed within 5 minutes. At 60 min intervals (180 min total), participants were asked to provide a urine sample, BM and blood samples.
RESULTS: Urine volume was highest over the 3-hour period in the control vs B and BG conditions (p > 0.05). USG initially declined in all conditions (until 60 min), then increased in a similar pattern whereby BG was higher (1.016) than G (1.012), and G was higher than control (1.006) at 180 min. Unsurprisingly, HCO3 was elevated in both B (29.3 ± 0.4 mmol/L) and BG (28.2 ± 0.5 mmol/L) conditions compared to control (24.3 ± 0.6 mmol/L). Hb declined as a function of time in all conditions (p < 0.05), whereby Hct did not change significantly over the 180 min period (p > 0.05).
CONCLUSIONS: These preliminary data suggest NaHCO3 + glycerol induces the greatest amount of water retention, however NaHCO3 alone may also induce a significant hyperhydration when compared to water alone.