Hypervolemia induced by fluid ingestion at rest: effect of sodium concentration

Abstract

Beverages containing 120 mmol l(-1) Na(+) induce hypervolemia with a minimum incidence of gastrointestinal problems.

Is Sodium Supplementation Necessary to Avoid Dehydration During Prolonged Exercise in the Heat?

“…F luids containing sodium have been shown to increase plasma volume greater at rest (22,26,31,32,37) and to maintain plasma volume better during exercise (3,4) than water alone. Given the concerns of some about performance impairment from weight loss during exercise of only 2% body weight, recent guidelines recommend ingestion of sodium with fluids during exercise (1,2,6,7).…”

Compositional Aspects of Beverages Designed to Promote Hydration Before, During, and After Exercise: Concepts Revisited

“…The aforementioned study conducted by Fuji et al reported no differences in cumulative urine or plasma volume between 120 mmol/L or 180 mmol/L sodium concentrations, thus denoting that sodium levels higher than 120 mmol/L might not lead to additional benefits in terms of changes in plasma volume [ 193 ]. In a previous study, water and three solutions containing 60, 120, or 180 mmol/L sodium, respectively, were compared [ 194 ]. In trials separated by three days, eight euhydrated males ingested 16–17 mL/kg body weight (≈1 L) of one of the three formulations or water within 60 min, and were followed a total of 150 min under controlled environmental conditions [ 194 ].…”

“…In a previous study, water and three solutions containing 60, 120, or 180 mmol/L sodium, respectively, were compared [ 194 ]. In trials separated by three days, eight euhydrated males ingested 16–17 mL/kg body weight (≈1 L) of one of the three formulations or water within 60 min, and were followed a total of 150 min under controlled environmental conditions [ 194 ]. As expected, the 120 and 180 mmol/L solutions were shown to be more effective than the 60 mmol/L solution or water at reducing cumulative urine volume and promoting net fluid balance [ 194 ].…”

“…In trials separated by three days, eight euhydrated males ingested 16–17 mL/kg body weight (≈1 L) of one of the three formulations or water within 60 min, and were followed a total of 150 min under controlled environmental conditions [ 194 ]. As expected, the 120 and 180 mmol/L solutions were shown to be more effective than the 60 mmol/L solution or water at reducing cumulative urine volume and promoting net fluid balance [ 194 ]. However, gastrointestinal symptoms (diarrhea) were only reported in subjects allocated to the 120 (one subject) and 180 mmol/L treatments (six subjects) [ 194 ].…”

“…However, gastrointestinal symptoms (diarrhea) were only reported in subjects allocated to the 120 (one subject) and 180 mmol/L treatments (six subjects) [ 194 ]. Interestingly, a reduction in urine output and an increase in net fluid balance at 120–150 min was observed in individuals drinking the 60 mmol/L sodium solution compared to water intake in isolation, which shows a modest beneficial effect of beverages containing moderate to high amounts of sodium on pre-exercise fluid retention and hypervolemic response [ 194 ]. Of note, effects on water retention are unsurprising since drinks with high electrolyte content, such as ORS, have been shown to have higher BHI than commercial sports drinks and water [ 27 , 28 , 29 ].…”