Endurance runners in a super long, hot race who took sodium supplements every part of the way lost less body weight during the race than those who didn’t take any.

Ultramarathon runners who took more sodium during a super long, super hot race tended to lose less body weight — the more sodium they took, the less weight they lost.

Ultramarathon runners who take sodium supplements during long races in extreme heat keep more of their body weight, but those who skip the supplements might actually stay better hydrated, according to the researchers.

Taking sodium supplements during a long bike ride in cool weather doesn’t really change your body’s sodium levels if you're already drinking fluids whenever you feel like it.

Taking sodium pills while cycling doesn't seem to make well-trained cyclists faster during a 72 km ride in cool weather — they finish just as quickly with or without it.

Some athletes sweat out a lot of salt, and because everyone's different, a few need to eat more salt to stay healthy and avoid serious problems like low sodium or heat illness.