Hydration and Electrolyte Balance – The Winning Edge


Without proper hydration and maintenance of vital electrolytes during exercise, not only is winning impossible your very life depends on it.

One per cent dehydration can have up to a 15 per cent decrease in performance, with an increased heart rate, core temperature and less ability to keep going. Also, dehydration comes with an increased risk of heat-related illness such as heat stroke.

Endurance athletes may know about the dangers of dehydration however many don’t understand the dangers of over-hydration. Although standard recommendations for fluid replacement are available they may be too high for athletes with low sweat rates or too low for those with high sweat rates. It is best to individualize fluid replacement strategies.

During exercise, sweat output often exceeds water intake, producing a body water deficit (hypohydration). Exercise performance can be compromised by a body water deficit, particularly when exercise is performed in hot climates. It is recommended that individuals begin exercise when adequately hydrated. This can be facilitated by drinking 400 mL to 600 mL of fluid 2 hours before beginning exercise and drinking sufficient fluid during exercise to prevent dehydration from exceeding 2% body weight. A practical recommendation is to drink small amounts of fluid (150-300 mL) every 15 to 20 minutes of exercise (Latzka WA, et al. Water and electrolyte requirements for exercise. Clin Sports Med. 1999 Jul;18(3):513-24) For athletes performing high-intensity exercise in the heat, sweating rates of 1.0–2.5 L/h are common and this needs to be replaced.

Our electrolyte concentration in the body is controlled by a variety of hormones; these are mostly found in the kidney and the adrenal glands. And these specialized kidney cells monitor the amount of sodium, potassium, and water in the bloodstream The main electrolytes exist in the form of calcium, chlorine, magnesium, phosphate, potassium, and sodium that can be obtained from fluids, supplements, and foods. Sodium, Potassium and Magnesium are vital and combined with glucose and water is an essential supplement (drink) to any serious athlete who is pushing themselves to the point of exhaustion.

When exercising at extreme levels over time these electrolytes are lost in sweat and exhaled breathing. Sodium chloride is the primary electrolyte in sweat, with potassium, calcium, and magnesium present in smaller amounts. If not replaced an imbalance can cause muscle spasms, kidney failure and cardiac arrhythmias that can lead to coma and death.

Too much water can kill.

Athletes drinking too much during exercise can cause over-hydration known as exercise-associated hyponatremia. It occurs when athletes drink even when they are not thirsty and the sodium content of blood is diluted to abnormally low levels. Drinking too much water when profusely sweating over a prolonged exercise period also can overwhelm the kidney’s compensation mechanism and reduce the body’s ability to remove water (Loyola University Health System. “Drinking too much water can be fatal to athletes. “Science Daily, 2 September 2014).

Female endurance athletes reportedly have the highest risk for the development of Hyponatremia. As many as 45% of female race finishers in the New Zealand Ironman triathlon developed hyponatremia compared to 14% of male race finishers (Speedy, D. B., Noakes, T. D., & Schneider, C. (2001). Exercise-associated hyponatremia: A review. Emergency Medicine, 13, 17-2).

There are many good sports electrolyte replacement drinks available always carry and use these and have them readily available.


Excessive electrolytes can also cause serious adverse health events. Always follow directions on the supplement/sports drink and as given by your healthcare practitioner.

This may seem difficult to work out but there are some basic guidelines that may help.

  1. Acclimatise
  2. Don’t let fluid loss be more that 2% of body weight.
  3. Drink small quantities of water at regular intervals every 15 – 20 mins during heavy exercise.
  4. At the beginning in the middle and at the end of high intensity exercise that causes profuse sweating use an electrolyte replacement (follow the directions on the product).
  5. If you feel the onset of adverse symptoms cramps, altered level of consciousness or coordination problems. Stop and cool down Revive rest and hydrate Survive know your limits.

Hydration and Children

In a study undertaken at McMaster University in Canada of eight to 10-year-olds involved exercising in a climate chamber, then receiving a drink and being measured for hydration they reported that Milk was better than water to rehydrate kids: The authors stated that Milk is better than either a sports drink or water because it is a source of high quality protein, carbohydrates, calcium and electrolytes and replaces sodium lost in sweat and helps the body retain fluid better.

Timmons, an assistant professor of paediatrics of the Michael G. DeGroote School of Medicine, said active children and adults usually don’t drink enough to stay hydrated during exercise, so they often have a “hydration disadvantage” when they start their next period of exercise. McMaster University. “Milk better than water to rehydrate kids”, study finds. – Science Daily. Science Daily, 23 August 2011.

By Russell Setright

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