Electrolytes

Minerals (sodium, potassium, magnesium) lost through sweat that must be replaced to prevent cramping.

electrolytessodiumpotassiumhydrationsweat

Understanding Electrolytes

Electrolytes are minerals — primarily sodium, potassium, magnesium, and calcium — that carry electrical charges in your body and are critical for muscle contraction, nerve function, and fluid balance. You lose them through sweat, and losing too much without replacement can cause cramping, nausea, and in extreme cases, dangerous hyponatremia.

Sodium is the most important electrolyte for endurance athletes because it's lost in the highest concentration through sweat (about 500–1,500 mg per liter). Sweat rates and sodium concentration vary dramatically between individuals — some runners are "salty sweaters" who leave white residue on their clothes and need significantly more sodium replacement.

During races longer than 60 minutes, electrolyte replacement matters. Sports drinks contain electrolytes, and many runners supplement with salt tablets, electrolyte capsules, or high-sodium drink mixes. The goal is to replace a portion of what you lose — perfect replacement during exercise isn't possible or necessary, but preventing severe depletion is critical.

Key Facts: Electrolytes

Key facts and insights about electrolytes that every endurance athlete should know.

Sweat contains 500–1,500 mg sodium per l

Sweat contains 500–1,500 mg sodium per liter, varying by individual

Average sweat rate

Average sweat rate: 0.5–2 liters per hour during running (depends on heat and intensity)

Hyponatremia

Hyponatremia (dangerously low sodium) is more common than dehydration in marathons

Salt tablets typically contain 200–400 m

Salt tablets typically contain 200–400 mg sodium per capsule

Pro Tips: Electrolytes

If you see white salt marks on your clothes, you need more sodium than average — add salt tablets to your race plan

Drink to thirst during races rather than on a fixed schedule — overhydrating without sodium causes hyponatremia

Test electrolyte products during training: some runners prefer tablets (SaltStick), drinks (LMNT, Nuun), or food (pretzels)

Increase sodium intake the day before a hot-weather race to pre-load electrolyte stores

Frequently Asked Questions About Electrolytes

Usually not. For runs under 60 minutes in moderate conditions, water is sufficient and your next meal will replace lost electrolytes. In extreme heat or if you're a heavy sweater, an electrolyte drink for runs over 45 minutes can help.

In a pinch, yes — table salt provides sodium and chloride. But commercial electrolyte products also contain potassium, magnesium, and other minerals in balanced ratios, plus they're easier to consume during exercise. A simple solution: add a pinch of salt to your water bottle.