Electrolytes explained
What electrolytes are, why they matter for endurance athletes, and how much you need.
By Lotte
Electrolytes — primarily sodium, potassium, magnesium, and calcium — regulate muscle function, nerve signaling, and fluid balance. Endurance athletes lose significant amounts through sweat and must replace them during long training and racing.
Key takeaways
- 1Sodium is the most important electrolyte for athletes — lost heavily in sweat
- 2Aim for 500-1000mg sodium per hour during exercise over 90 minutes
- 3Magnesium supports muscle relaxation and sleep — many athletes are deficient
- 4White residue on skin/clothing after exercise indicates you're a salty sweater
In this article
What are electrolytes?
Electrolytes are minerals that carry an electric charge in your body. The key ones for athletes are sodium, potassium, magnesium, and calcium. They regulate muscle contraction, nerve signaling, and fluid balance.
When you sweat, you lose electrolytes — primarily sodium — which must be replaced during long exercise.
Sodium: The most important electrolyte
Sodium loss through sweat ranges from 500-2000mg per liter, varying greatly between individuals. Inadequate sodium replacement during long events can lead to hyponatremia — a potentially dangerous condition.
Salty sweaters (white residue on skin/clothing after exercise) need to pay extra attention to sodium intake.
Magnesium and potassium
Magnesium supports muscle relaxation and sleep quality. Many athletes are mildly deficient. Consider supplementing with 200-400mg daily.
Potassium works with sodium to maintain fluid balance. A diet rich in fruits, vegetables, and whole foods typically provides adequate potassium.
Choosing electrolyte products
Options range from simple salt tablets to complete electrolyte drink mixes. Look for products with at least 300mg sodium per serving for exercise use.
Popular brands include Precision Hydration, SIS, Nuun, and LMNT. Test different products during training to find what works for you.
Recommended gear
Affiliate disclosure: Brick to Brick may earn a commission from qualifying purchases, at no extra cost to you. Unless a named method says otherwise, these are research-based recommendations rather than first-hand product tests.
Frequently asked questions
How do I know if I'm a salty sweater?
Look for white residue on your skin or clothing after exercise. If your sweat stings your eyes or tastes very salty, you're likely a heavy sodium loser. Sweat testing services can give you exact numbers.
Should I take electrolytes every day or only during exercise?
During exercise over 60 minutes and in hot weather, electrolyte supplementation is important. For daily use, a balanced diet usually provides enough. Athletes training heavily may benefit from daily magnesium supplementation.