Electrolytes and sport: what to drink before, during and after exercise
by AUA Hydrate
We usually think about drinking during exercise. Yet performance and recovery are decided just as much before and after. Here is a simple protocol you can apply to running, cycling, the gym or hiking — with no kit and no complicated sums.
⏱ The protocol in brief
- Before (a long or hot session): 1 stick in 500 ml of water, finished 30 min beforehand.
- During (> 45 min): regular sips, every 15–20 min.
- After: 1 stick in 500 ml within 2 hours, then water as you like.
What you really lose when you sweat
Sweat is not just water: every litre carries off on average 900 to 1400 mg of sodium, along with potassium and magnesium. During an intense session or in hot weather, losing 1 to 1.5 litres an hour is nothing unusual.
Making that up with plain water alone dilutes the minerals you have left — the mechanism is explained in Why water alone is no longer enough — and opens the door to cramps, an energy slump and a post-session headache.
Before exercise: set off hydrated, not bloated
The aim: start the session with full reserves.
- In the preceding 2 hours: about 500 ml of water, in small sips.
- Long session (> 1 h) or hot weather: dissolve a stick of AUA Hydrate in those 500 ml. Sodium helps your body hold on to water instead of flushing it out before you've even warmed up.
- Avoid half a litre downed in one go at the last minute: gastric discomfort guaranteed.
During exercise: the rule of regular sips
The aim: replace what's going out, without overloading the stomach.
- Short session (< 45 min, moderate intensity): water is generally enough.
- Long or intense session, or high heat: 150 to 250 ml every 15–20 minutes of a lightly mineralised drink. One stick in 500 ml of water gives a concentration the stomach tolerates well — with no sugar, so none of the “crash” of classic sports drinks.
- Thirst is a late signal: by the time it arrives, the deficit is already there. Drink at intervals, not on demand.
After exercise: the recovery window
The aim: reload water and minerals to turn the session into progress.
The 2 hours after exercise are decisive: that's when the body repairs muscle fibres and rebuilds its reserves. A simple rule: drink about 1.5 times the weight lost during the session (weigh yourself before and after if you're curious), electrolytes included.
Magnesium and potassium contribute to muscle relaxation — useful too against the night cramps that sometimes follow big sessions.
The 3 most common mistakes
- Making up for it with soft drinks or beer. Sugar slows gastric emptying, alcohol dehydrates: two counter-productive moves in recovery.
- Drinking a litre of plain water in one go after the session. Without minerals, much of it leaves again straight away — and the dilution can heighten tiredness and headaches.
- Changing nothing in hot weather. Heat means double the losses. Sodium needs climb steeply from 25 °C.
💡 The AUA tip: if you were to keep just one moment for your daily electrolytes, find out which in our 5 key moments.
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