School · Food and hydration · 45 s .
Sodium and heat
Salt in sweat, and running in a Mallorca summer.
Sweat carries sodium: on average around 900 mg per litre, but some people lose a few hundred and others well over a thousand. White salt marks on your cap or shirt are a hint you're a salty sweater.
For long or hot sessions, drinks with roughly 400–1,100 mg of sodium per litre help you absorb fluid and replace what you lose. Short runs don't need it.
In the heat, run early or late, slow down, wear light colours and carry water. Heat adaptation takes about one to two weeks of gradual exposure.
Long and hot: water with salt, and an earlier alarm.
Quick check .
What do white marks on your cap or shirt tell you?
On long or hot sessions, drinks with 400–1,100 mg of sodium per litre help.