Muscle Cramps: The Role of Electrolytes in Running and Cycling

Gros plan sur la transpiration d'un athlète, perte d'électrolytes à l'effort

You know the feeling: at kilometer 30 of a bike ride, or in the final stretch of a half marathon, a calf or hamstring suddenly seizes up and refuses to cooperate. Muscle cramps are one of the most frustrating interruptions in endurance sport, and contrary to popular belief, they're not just about a lack of water.

1. The myth of simple dehydration

Drinking more water doesn't prevent all cramps. When you sweat, you don't just lose water: you also lose sodium, potassium, and magnesium, minerals essential to muscle contraction and relaxation. Replacing only water without these minerals further dilutes your blood sodium concentration, which can promote cramping rather than prevent it.

2. The 3 key electrolytes for muscle contraction

  • Sodium: The most important for endurance efforts. It maintains your cells' fluid balance and enables nerve signal transmission to your muscles.
  • Potassium: Works with sodium to regulate muscle contraction. An imbalance can show up as a feeling of muscle weakness.
  • Magnesium: Plays a role in muscle relaxation after contraction, a deficiency is often linked to post-effort nighttime cramps.

3. How much sodium per hour?

Needs vary a lot from one athlete to another depending on your individual sweat rate, but a general target for endurance efforts is between 300mg and 700mg of sodium per hour. "Heavy sweaters" (often recognizable by white salt marks on their clothes after effort) tend to fall in the upper range.

If you're not sure where you fall, check your clothes after a long outing: the more visible the salt marks, the greater your sodium loss.

4. Factors that increase cramping risk

  • Heat and humidity, which increase your sweat rate.
  • A higher-than-usual training intensity.
  • Lack of sleep or recovery before the effort.
  • Insufficient carbohydrate intake, which fatigues the muscle faster.

5. Where Eracer fits into your strategy

Our formula combines a complete electrolyte profile (sodium, potassium, magnesium) with slow-release isomaltulose, to replace your mineral losses while maintaining stable energy. The goal isn't just to hydrate, it's to support muscle function from start to finish of your effort.

Test your dosage in training before applying it on race day, every athlete has a different sweat profile, and it's by repeating your routine that you'll find what actually works for you.

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This content is for informational purposes only and does not replace advice from a healthcare professional or registered dietitian. Consult a professional before changing your sports nutrition strategy, especially if you have a medical condition.