A Sodium Drink Enhances Fluid Retention During 3 Hours of Post-Exercise Recovery When Ingested With a Standard Meal

Abstract

The purpose of this study was to examine the efficacy of water and a 50 mmol/L NaCl solution on postexercise rehydration when a standard meal was consumed during rehydration. Eight healthy participants took part in two experimental trials during which they lost 1.5 ± 0.4% of initial body mass via intermittent exercise in the heat. Participants then rehydrated over a 60-min period with water or a 50 mmol/L NaCl solution in a volume equivalent to 150% of their body mass loss during exercise. In addition, a standard meal was ingested during this time which was equivalent to 30% of participants predicted daily energy expenditure. Urine samples were collected before and after exercise and for 3 hr after rehydration. Cumulative urine volume (981 ± 458 ml and 577 ± 345 mL; p = .035) was greater, while percentage fluid retained (50 ± 20% and 70 ± 21%; p = .017) was lower during the water compared with the NaCl trial respectively. A high degree of variability in results was observed with one participant producing 28% more urine and others ranging from 18–83% reduction in urine output during the NaCl trial. The results of this study suggest that after exercise induced dehydration, the ingestion of a 50 mmol/L NaCl solution leads to greater fluid retention compared with water, even when a meal is consumed postexercise. Furthermore, ingestion of plain water may be effective for maintenance of fluid balance when food is consumed in the rehydration period.

Fluid, energy, and nutrient recovery via ad libitum intake of different commercial beverages and food in female athletes

“…Findings from studies that have allowed participants to eat as part of the experimental protocol generally suggest that co-ingesting food and fluid improves rehydration, such that the magnitude of difference between beverages with different nutrient profiles (i.e. in terms of their potential to rehydrate) is attenuated (Maughan et al 1996;Brouns et al 1998;Ray et al 1998;Jones et al 2010;Pryor et al 2015;Campagnolo et al 2017;Evans et al 2017). Still, most studies have prescribed a small number of food items that may not reflect the participants' usual dietary behavior.…”

The effect of different post-exercise beverages with food on ad libitum fluid recovery, nutrient provision, and subsequent athletic performance

“…>1.25 L⋅ kg BM lost -1 ); and second, that the co-ingested food enhanced fluid retention -indeed, findings from previous studies that have allowed participants to eat as part of the experiment generally suggest that co-ingesting food and fluid increases retention of "simple" rehydration beverages (i.e. by delaying gastric emptying and attenuating osmotic diuresis) [13][14][15].…”

“…fluid volume and rate) and deny participants access to food. Studies that have allowed participants to eat during experiments generally indicate that the co-ingestion of food and fluid increases retention of "simple" rehydration beverages [13][14][15]. Still, most of these investigations have prescribed a small number of food items which may not reflect participants' usual dietary behaviour.…”

Bolus Ingestion of Whey Protein Immediately Post-Exercise Does Not Influence Rehydration Compared to Energy-Matched Carbohydrate Ingestion

“…It is unlikely that an athlete would not eat in the 4 h post-exercise period, and usually, this food intake would contain a mixture of macronutrients that might influence rehydration. A previous study [ 23 ] demonstrated that the addition of sodium to a rehydration solution still enhanced post-exercise rehydration, even when a standardised meal was consumed during the rehydration period. However, sodium and protein/macronutrients likely act via separate mechanisms to influence rehydration, and future studies should aim to examine the impact of eating typical recovery meals alongside various rehydration strategies to determine their combined success.…”

“…WP contained a small amount of sodium. Sodium is well known to enhance post-exercise rehydration [ 17 , 18 , 23 ], but sodium concentrations less than ~25–30 mmol/L do not significantly alter post-exercise rehydration. Therefore, the small amount of sodium consumed in the WP trial, which amounted to <6 mmol/L is unlikely to have influenced the rehydration responses in this study.…”