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Nutrition

Electrolytes — Their Role in Hydration and Performance

By Dr. Crionna Tobin, Phd, Optimum Nutrition, Head of Nutrition & Education

What Are Electrolytes?

Electrolytes are minerals that help regulate fluid balance, nerve function, and muscle contractions. Key electrolytes lost in sweat include:

  • Sodium: The most abundant electrolyte in sweat, essential for retaining water in the body and maintaining blood pressure.

  • Potassium: Supports muscle function and helps balance fluid levels.

  • Magnesium: Plays a role in muscle relaxation and energy production.

  • Calcium: Important for muscle contractions and nerve signalling.

Sodium is particularly critical because it facilitates water absorption and prevents hyponatremia (low sodium levels), which can occur if you drink excessive water without replenishing sodium.

Do I Need to Take Electrolytes?

Whether you need to supplement with electrolytes depends on the intensity and duration of your activity, as well as your sweat rate. Sodium concentration in sweat varies widely, from 460 to 1840 mg per liter<sup>3</sup>. For athletes engaged in prolonged or high-intensity exercise, electrolyte replacement becomes crucial to maintain performance.

Practical guidelines:

  • For short, low-intensity exercise (under 1 hour), water is usually sufficient.

  • For workouts lasting longer than 60 minutes or in hot conditions, consider electrolyte-rich drinks or snacks. Examples include sports drinks, or salty foods like pretzels or crackers with water, or water with added electrolytes.

  • If you’re unsure about your sweat rate, weigh yourself before and after exercise. For every kilogram lost, replace it with approximately 1.5 litres of fluid.

References

  1. Sawka, M.N., and T.D. Noakes (2007). Does dehydration impair exercise performance? Med. Sci. Sports Exerc. 39:1209-1217.

  2. Cheuvront SN, Kenefick RW. Dehydration: physiology, assessment, and performance effects. Compr Physiol. 2014 Jan;4(1):257-85. doi: 10.1002/cphy.c130017. PMID: 24692140.

  3. Baker, L. B., Ungaro, C. T., Barnes, K. A., Nuccio, R. P., & Reimel, A. J. (2016). Validity of regional sweat rate predictions in athletes. Medicine & Science in Sports & Exercise, 48(9), 1934-1946.

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