When do I actually need electrolytes?
Last updated September 3, 2026.
Past about an hour of hard exercise, in heavy sweating heat, or during vomiting and diarrhea - the rest of the time, water covers it. The ACSM position stand is specific: electrolyte-carbohydrate drinks are recommended for exercise over one hour (sodium 0.5 to 0.7 g/L aids retention and guards against hyponatremia); under an hour, evidence shows little difference from plain water. A sodium review adds that even athletes do not need elevated day-to-day sodium - kidneys regulate ordinary losses. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What to do
- Under an hour: water: evidence shows no performance difference from electrolyte drinks.
- Over an hour, hard or hot: add electrolytes: sodium during the session, carbs past 60 to 90 minutes.
- Sick days count: vomiting or diarrhea is a real electrolyte situation - use an oral rehydration solution.
- Get seen if: confusion, cramps that will not stop, or dizziness after heavy sweating - heat illness and hyponatremia are medical events.
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