How and when do I use it?

• Before exercise in hot environments, where large sweat losses cannot be practically replaced: Pre-exercise hyperhydration can be achieved by consuming up to 10mL/kg body weight of fluid with a very high sodium concentration, ideally as close to plasma sodium concentration (i.e. 135mmol/L) as tolerated, within 1-2 hours prior to exercise. This concentration, as much as double that of typical ORS products, can be achieved by manipulating the ratio of product to water, or using commercially available products designed specifically for this purpose. Note that other strategies (i.e. glycerol supplementation) can also be used for pre-exercise hyperhydration.
• During exercise and sporting activities: Electrolyte replacement supplements may be useful in the following situations:
  • When targeted replacement of large sodium losses is desired. This may occur in events or individuals where there is a high rate of sweat loss, prolonged duration of sweating, or evidence of “salty sweat” (high sweat content of electrolytes). A personalised fluid plan should be made with the help of a Sports Dietitian; it is also noted that during ultra-endurance events, sodium replacement may also be achieved via food choices.
  • When electrolyte replacement is desired without an accompanying carbohydrate intake (e.g. undertaking training with ‘low carbohydrate availability” or exercise undertaken during a period of reduced energy intake).
• For the prevention and treatment of dehydration during diarrhoea and gastro-enteritis, particularly as guided by a Sports Physician. Note that ORS are recommended for these purposes since the priority is to rehydrate rather than consume energy/carbohydrate.
• In the restoration of moderate-large fluid deficits incurred during exercise or other dehydrating activities (e.g. “making weight”), where a targeted replacement of fluid and electrolyte losses will assist with more rapid and effective rehydration. Scenarios in which this might be useful include a short period of recovery until an exercise session, or after an exercise session late in the day where the athlete wants to rehydrate with minimal risk of sleep disturbances due to the need for a toilet break.

The athlete with a moderate-large fluid deficit should follow a rehydration plan tailored to meet their estimated fluid loss. Specifically:

• The athlete should consume a volume of fluid equal to ~ 1.2–1.5 times their estimated fluid deficit within 2-4 hours following the dehydrating activity, or as much of this volume as can be comfortably tolerated.
• Fluid intake should be accompanied by electrolyte replacement (particularly sodium) to optimise fluid retention. This may be achieved through food sources, via the salting of meals, or through the use of higher sodium sports drinks or electrolyte supplements, according to what is most practical. While intake of food sources can target other nutrition goals, it is noted that electrolyte supplements provide a known sodium content that may be more precisely achieved.
• Since the carbohydrate content of ORS and some sports electrolyte supplements is negligible, refuelling goals may need to be addressed separately