Sodium-induced hyperhydration decreases urine output and improves fluid balance compared with glycerol- and water-induced hyperhydration

Abstract

Before 2010, which is the year the World Anti-Doping Agency banned its use, glycerol was commonly used by athletes for hyperhydration purposes. Through its effect on osmoreceptors, we believe that sodium could prove a viable alternative to glycerol as a hyperhydrating agent. Therefore, this study compared the effects of sodium-induced hyperhydration (SIH), glycerol-induced hyperhydration (GIH) and water-induced hyperhydration (WIH) on fluid balance responses. Using a randomized, double-blind and counterbalanced protocol, 17 men (21 ± 3 years, 64 ± 6 kg fat-free mass (FFM)) underwent three 3-h hyperhydration protocols during which they ingested, over the first 60-min period, 30 mL/kg FFM of water with (i) an artificial sweetener (WIH); (ii) an artificial sweetener + 7.45 g/L of table salt (SIH); or (iii) an artificial sweetener + 1.4 g glycerol/kg FFM (GIH). Changes in body weight (BW), urine production, fluid retention, hemoglobin, hematocrit, plasma volume, and perceptual variables were monitored throughout the 3-h trials. After 3 h, SIH was associated with significantly (p < 0.05) lower hemoglobin, hematocrit (SIH: 43.1% ± 2.8%; GIH: 44.9% ± 2.4%), and urine production, as well as greater BW, fluid retention (SIH: 1144 ± 294 mL; GIH: 795 ± 337 mL), and plasma volume (SIH: 11.9% ± 12.0%; GIH: 4.0% ± 6.0%) gains, compared with GIH and WIH. No significant differences in heart rate or abdominal discomfort were observed between treatments. In conclusion, our results indicate that SIH is a superior hyperhydrating technique than, and proves to be a worthwhile alternative to, GIH.

Effect of Glycerol-Induced Hyperhydration on a 5-kilometer Running Time-Trial Performance in the Heat in Recreationally Active Individuals

“…A simple and legal way to enhance plasma volume is to induce hyperhydration prior to exercise using glycerol. Indeed, glycerol-induced hyperhydration (GIH) has been shown to increase total body water by ~ 800 mL and plasma volume by ~ 8% [ 5 , 6 , 7 ] 2 h following the ingestion of 26 mL of water/kg body mass (BM) with 1.2 g of glycerol/kg BM.…”

Effects of skim milk and isotonic drink consumption before exercise on fluid homeostasis and time-trial performance in cyclists: a randomized cross-over study

“…Nevertheless, research involving these strategies are scarce. The interest of pre-exercise hydration recommendations have shown that the consumption of beverages with high amounts of sodium and different types of carbohydrates can reduce fluid loss and improve fluid balance during exercise [1,8]. Previous research involving pre-exercise consumption of chicken soup [9] and non-alcoholic beer [10] have shown improved fluid balance during exercise.…”

Effects of Field Position on Fluid Balance and Electrolyte Losses in Collegiate Women’s Soccer Players

“…Moreover, a greater proportion of the beverages ingested were CES in DF. This may have resulted in a greater sodium intake in DF and, therefore, better fluid retention and fluid balance compared to other positions [ 33 ]. One possible explanation is that MD and FW performed more runs and may not tolerate the ingestion of large volumes of fluids during training, consequently resulting in lower total fluid intake [ 34 ].…”