The sodium problem
Why most electrolyte drinks are built for taste, not sweat, and how to work out what you lose.
Sweat is mostly water and salt. Sodium is the electrolyte you lose most of by far: typically 20–80 mmol per litre, which is roughly 460–1,840 mg. Potassium and magnesium are lost in much smaller amounts.
Yet most electrolyte tablets carry 200–300 mg of sodium. That's fine for a lunchtime jog. It isn't enough for a three-hour ride in July, or for anyone who finishes a session with salt crusted on their cap.
Know your number
Weigh yourself naked before and after an hour of training, and note what you drank. Each kilogram lost is about one litre of sweat. Salty sweaters (white marks on kit, stinging eyes) sit at the top of the sodium range.
- Under 0.5 L/h and not salty: water and food are usually enough.
- 0.5–1.5 L/h, or salty: 500–1,000 mg sodium per hour in long sessions.
- Over 1.5 L/h in heat: consider more, and test it in training.
What we built
SaltSalt · £32
High-Sodium Electrolytes carries 1,000 mg of sodium per stick and no sugar, so you can dose sodium independently of carbohydrate. On long days, pair it with Carb 90Carb 90 · £39
Dual-Source Endurance Fuel and you control both dials separately.