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.

When athletes sweat a lot during tough workouts in the heat, they can lose a surprising amount of salt—up to more than a teaspoon of salt every hour.

Athletes don’t need to eat more salt than couch potatoes—our bodies adjust how much salt we lose, and most athletes already get plenty from their food.

If endurance-trained guys eat less salt for 9 days, their blood sodium drops — even if they drink enough water — especially when they bike in the heat. This suggests long-term salt intake might affect how their body handles hydration in hot weather.

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.

If endurance athletes drink a lot during long workouts and also take in sodium, it might help prevent low blood salt levels — but it probably won’t make them perform better just by itself.