Iterative assessment of a sports rehydration beverage containing a novel amino acid formula on water uptake kinetics.

ABSTRACT

PURPOSE: Rapid gastric emptying and intestinal absorption of beverages is essential for rapid rehydration, and certain amino acids (AA) may augment fluid delivery. Three sugar-free beverages, containing differing AA concentrations (AA + PZ), were assessed for fluid absorption kinetics against commercial sugar-free (PZ, GZ) and carbohydrate-containing (GTQ) beverages. METHODS: Healthy individuals (n = 15-17 per study) completed three randomised trials. Three beverages (550-600 mL) were ingested in each study (Study 1 AA + PZ [17.51 g/L AA], PZ, GZ; Study 2 AA + PZ [6.96 g/L AA], PZ, GZ; Study 3 AA + PZ [3.48 g/L AA], PZ, GTQ), containing 3.000 g deuterium oxide (D2O). Blood samples were collected pre-, 2-min, 5-min, and every 5-min until 60-min post-ingestion to quantify maximal D2O enrichment (Cmax), time Cmax occurred (Tmax) and area under the curve (AUC). RESULTS: Study 1 AUC (AA + PZ 15,184 ± 3532 δ‰ vs. VSMOW; PZ 17,328 ± 3153 δ‰ vs. VSMOW; GZ 17,749 ± 4204 δ‰ vs. VSMOW; P ≤ 0.006) and Tmax (P ≤ 0.005) were lower for AA + PZ vs. PZ/GZ. Study 2 D2O enrichment characteristics were not different amongst beverages (P ≥ 0.338). Study 3 Cmax (AA + PZ 440 ± 94 δ‰ vs. VSMOW; PZ 429 ± 83 δ‰ vs. VSMOW; GTQ 398 ± 81 δ‰ vs. VSMOW) was greater (P = 0.046) for AA + PZ than GTQ, with no other differences (P ≥ 0.106). CONCLUSION: The addition of small amounts of AA (3.48 g/L) to a sugar-free beverage increased fluid delivery to the circulation compared to a carbohydrate-based beverage, but greater amounts (17.51 g/L) delayed delivery.