What fluid and electrolytes are needed during continuous endurance physical activity/exercise of 1-4 hours in duration in adults (19 years or older) to maintain hydration?
Beverages provided in a volume that equals 100% of fluid lost during moderate- to vigorous exercise (65-85% VO2 max), and contain CHO (5.5-15% CHO)* and Na+ (55-164 mEq Na)* compared to non-carbohydrate-electrolyte solution (CES) beverages are more effective at maintaining hydration status (including thermoregulatory function) in hydrated young (20 – 35 years) men during 1-4 hours of moderate to vigorous, competitive or recreational activity in moderately hot and humid conditions. The amounts of CHO and Na+, as well as the volume of the beverage consumed are important factors for maintenance of hydration during higher-intensity activities, especially in the heat.
Care must be taken in choosing a beverage to be consumed during exercise, so as to avoid gastrointestinal distress and/or subjective feelings of discomfort, nausea, and bloating. Care must also be taken when applying these conclusions beyond the limited populations studied.
Limited research is available to evaluate the effectiveness of K+ in beverages consumed during exercise, relevant to hydration maintenance. Research is needed to determine fluid and electrolyte needs in:
- pregnant and/or lactating women
- athletes older than 35 years
- individuals exercising for prolonged periods of time in cold and/or dry climates.
The comparison between CES and non-CES beverages effect on performance was not evaluated in this question.
* See Conversion Table for information on converting mmol to mEq and mg and % CHO to grams.
- Grade I means there is Good/Strong evidence supporting the statement;
- Grade II is Fair;
- Grade III is Limited/Weak;
- Grade IV is Expert Opinion Only;
- Grade V is Not Assignable.
- High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
- Moderate (B) means we are moderately confident in the effect estimate;
- Low (C) means our confidence in the effect estimate is limited;
- Very Low (D) means we have very little confidence in the effect estimate.
- Ungraded means a grade is not assignable.