Protocols › Electrolytes

Electrolytes for rehydration after exercise

Goal: To replace the fluid lost in sweat after hard exercise, as trials of electrolyte drinks did.

Each protocol describes what studies used, for one goal or for one group of people. It is not advice for you: talk to a doctor before you start a supplement.

Updated 9 Nov 2026
Dose

A volume equal to the body weight lost. In one trial, the oral rehydration solution had 45 mmol of sodium per litre.[1]

Form

Oral rehydration solution, or a sports drink with 4% to 9% carbohydrate. Skimmed or low-fat milk also rehydrated better than water, with very low certainty.[1][2][3]

When to take

After exercise, when normal food is not available.[2]

How long

Fluid balance was measured for 3.5 hours after exercise.[1]

What studies found

26 athletes who lost 2.6% of body weight: 76.9% of the fluid stayed in the body with an oral rehydration solution, 73.9% with a sports drink and 58.1% with water.[1] A review of 19 studies: carbohydrate-electrolyte drinks may rehydrate better than water.[2]

Ask a doctor first

Healthy kidneys pass extra potassium and magnesium into urine. With kidney disease, or with some blood pressure medicines, potassium can build up in the blood.[4] Ask a doctor or pharmacist first if this applies to you.[4]

References

  1. Post-Exercise Rehydration in Athletes: Effects of Sodium and Carbohydrate in Commercial Hydration Beverages. Ly NQ, Hamstra-Wright KL, Horswill CA Nutrients, 2023. PMID 38004153
  2. Oral Rehydration Beverages for Treating Exercise-Associated Dehydration: A Systematic Review, Part I. Carbohydrate-Electrolyte Solutions. Borra V, De Brier N, Berry DC, Zideman D, Singletary E, De Buck E J Athl Train, 2025. PMID 38116803
  3. Oral Rehydration Beverages for Treating Exercise-Associated Dehydration: A Systematic Review, Part II. The Effectiveness of Alternatives to Carbohydrate-Electrolyte Drinks. De Brier N, Borra V, Berry DC, Zideman D, Singletary E, De Buck E J Athl Train, 2025. PMID 38116818
  4. Potassium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov