As an endurance athlete, it's critical to remain hydrated during training and competition.  Think Ali Brownlee carrying his brother Johnny over the line in Cozumel in 2016 for a recent example of how dehydration can end your race (and hopes of a world championship)!
However, remaining hydrated isn't just achieved through drinking water. It's also crucial to maintain an appropriate balance of electrolytes in your body.

cyclist with helmet opening hydration electrolyte tablets

In this blog, we will explore what electrolytes are, what they do, why the body needs them, and the benefits of electrolytes for endurance athletes.

What are electrolytes?

Electrolytes are minerals that have a natural positive or negative electrical charge when dissolved in a liquid, such as water. The most common electrolytes in the human body include sodium, potassium, calcium, magnesium, chloride, and bicarbonate. These electrolytes are essential for the proper functioning of the body, including maintaining fluid balance, regulating blood pH levels, and facilitating muscle contractions and nerve impulses.

What do electrolytes do?

During exercise, your body loses electrolytes through sweat, and if not replenished this can lead to dehydration, cramping, and fatigue. Sodium, for example, plays a significant role in regulating fluid balance in the body, as well as in muscle and nerve function. Potassium is critical for maintaining proper heart function, and calcium is essential for both muscle contractions and bone health. Magnesium is involved in energy metabolism, adaptation to training and the regulation of muscle and nerve function. 

athlete sweating during an endurance activity

An electrolyte imbalance will mean we cannot function properly with varying degrees of severity.  Electrolyte imbalances can lead to muscle cramps, numbness/tingling in limbs, nausea, extreme fatigue, confusion, diarrhoea or vomiting or arrhythmias. 

Electrolyte drink benefits

One of the easiest ways to replenish lost electrolytes is by drinking an electrolyte drink. These drinks usually contain a combination of electrolytes and are often sold as an effervescent powder or tablet which dissolves in water. Electrolyte drinks can help an athlete in several ways.

  • Improved hydration: electrolytes facilitate fluid absorption so that fluid is absorbed from the gut more effectively which can improve hydration and performance. 
  • Reduced risk of muscle cramps: sodium and potassium in particular play a role in muscle contractions. Replenishing these minerals can help to reduce the risk of cramp impacting your performance. 
  • Improved endurance: maintenance of proper hydration and electrolyte balance can delay the onset of fatigue therefore benefitting performance. 

female athlete with hydration tablets

How electrolyte drinks help endurance athletes

Endurance athletes are particularly susceptible to dehydration and electrolyte imbalances due to the prolonged duration and intensity of their training and competition. Especially if training and racing in the heat. Electrolyte drinks can help endurance athletes to maintain proper fluid balance, prevent muscle cramping and swelling of extremities (blood pooling) and even promote gut comfort when taking on carbohydrates. Altogether, this will help improve overall performance.

To maintain adequate hydration levels by drinking enough water and electrolyte-containing fluids, The American College of Sports Medicine recommends that athletes aim to consume a fluid volume equal to the amount lost through sweat during exercise, which is typically 0.4 to 1.8 L/hour. 

athlete on a hike

How to calculate sweat rate?

  1. Weigh yourself (ideally nude or with as little clothing as possible).
  2. Complete your training – making a note of how much you drink during training.
  3. Immediately after training weigh yourself wearing the same as in step 1.
  4. Sweat rate can then be calculated by the following equation:
  5. Sweating rate = pre-exercise body weight - post-exercise body weight + fluid intake/exercise time in hours). 

It is, however, important to note that this does not consider the concentration of sodium in the sweat, which can be highly variable between individuals even with the same sweat rate. Understanding whether you are a ‘salty sweater’ can help in determining the strength of electrolytes needed in your electrolyte drink. For example, if you find salt deposits on your skin or training kit, you are likely to be a salty sweater and would benefit from a higher sodium electrolyte solution (e.g. 1000mg sodium or more).  

Additionally, consuming foods rich in electrolytes like magnesium, potassium, and calcium can also help prevent cramps.

What foods contain electrolytes?

Some examples of foods that are high in these electrolytes include:

  • Bananas (400-450 mg of potassium per banana)
  • Sweet potatoes (542 mg of potassium per 100 grams)
  • Almonds (80 mg of magnesium per 28 grams)
  • Spinach (157 mg of magnesium per 90 grams)
  • Dairy products (300 mg of calcium per 1 cup of milk or 245 grams)


Electrolytes are essential minerals that play a crucial role in various bodily functions, especially for endurance athletes. Maintaining proper fluid balance and replenishing lost electrolytes can help prevent dehydration, reduce muscle cramping, and improve endurance performance. Incorporating an electrolyte drink before, during, and after exercise can support endurance athletes to maintain optimal performance in training and racing.

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