February 24, 2023

Athletes sweat more often than regular people as they constantly expose themselves to rigorous training and exercises. Inorder to maintain thermoregulation, your body produces sweat; it is your body’s way of cooling you down. Your body loses water when you sweat. To add another layer of complexity to the issue, human sweat contains far more than just water. Electrolytes (electrically charged ions such as sodium, potassium, calcium, and magnesium) are also lost and must be replaced along with the fluid. While many electrolytes can be obtained from the food we eat, there may be advantages to replacing them during exercise as well; most notably sodium, which may be considered the most important electrolyte to replace during periods of heavy sweating.

The importance of proper hydration and electrolyte balance to performance cannot be underestimated, and these materials can be thought of as the foundation upon which everything else is built. When undergoing a rigorous training programme or competing, there is a significant drain on body stores of vital electrolytes to ensure that the resistance level can be maintained for as long as possible. The metabolic waste products will be expelled through perspiration, breathing, urination, and defecation, resulting in thirst - the need to replenish the water and electrolytes used in energy creation.

In case of improper consumption of water, dehydration can occur. Dehydration compromises cardiovascular function by decreasing blood flow to muscles and cardiac output. The resulting increase in heart rate causes a decrease in stroke volume. Hypovolemia hampers an athlete’s thermoregulation. The more hyperthermic an athlete is, the greater their work capacity decreases. Low blood volume, from dehydration also thwarts oxygen and glucose transport to muscle cells. At just a 2% loss in body fluids, an athlete’s performance is impaired. Fatigue and performance impairment caused by dehydration can cause athletes to compromise their physical mechanics. Therefore, dehydration not only impairs performance, it indirectly raises an athlete’s risk of injury and directly raises their risk for heat-related illnesses.

Apart from dehydration, athletes can suffer due to hyperhydration as well. Hyperhydration has no beneficial exercise performance effects. It causes serum sodium levels to dilute to less than 130 mEq/L leading to intracellular swelling and an altered central nervous system function. 

This is labelled symptomatic hyponatremia and can occur when athletes drink more than their fluid losses, deplete their extracellular fluid sodium by heavy sweat loss, or a combination of high fluid intake and excessive sweating. 

Symptomatic hyponatremia and dehydration are negatively associated with exercise performance.


Psychological Role of Electrolytes:

Modulators of Energy Production

Modulators of Energy Storage

Modulators of Energy Use (i.e. metabolism)

Regulators of Total Body Fluid Levels

Most Important Electrolytes: 

Sodium is found outside the cell and is primarily responsible for fluid balance.

Potassium is found inside the cell and regulates metabolism.

Magnesium regulates levels of other electrolytes and muscle relaxation.

Calcium regulates muscle contraction and heart rhythm. 

These electrolytes are mostly bound to chloride, bicarbonate, sulphate and phosphate ions.

What is The Correct Physiological Balance of Electrolytes?

-> Balance is unique to the person in question. Despite significant physiological similarities, we are all biochemically unique. Some athletes will require more electrolytes than others. Therefore, recognising that electrolytes play distinct physiological and psychological roles at the cellular level has led many sports nutritionists to advise athletes to pay close attention to their diets and consume a wide variety of fresh fruit, vegetables, naturally grown grains, and reared meats and fish as possible.

Safe Hydration Strategies:

1) Before Training or Competitions

Drinking excessively before exercise can have the opposite effect desired like gastrointestinal issues and impaired performance.

Choosing liquid fuel reduces gastric emptying time and residual intestinal load, which may be advantageous for nervous athletes or athletes who need to "make weight" before the competition.

2) During Training or Competitions

‍Maintaining proper hydration by drinking during exercising has the greatest beneficial impact on the performance of any single nutritional intervention.

Start drinking water early and at regular intervals, every 20 mins.

Replace sodium electrolytes during periods of heavy sweating

Advice Then Advice Now

Don't get into the habit of eating or drinking during a marathon race; some renowned runners do, but it's not beneficial. Athletes should begin drinking early and at regular intervals during exercise to consume fluids at a rate sufficient to replace all of the water lost through sweating or consume the maximum amount that can be tolerated.

It may be sufficient to use bodyweight change data to identify athletes with exceptionally high sweat volume losses and to monitor them during longer, hotter, or more intense training sessions and competitions. These athletes may benefit from having access to more fluids than other athletes.

Precaution: Telling athletes with higher sweat loss how much to drink or forcing them to replace their losses as quickly as those with lower sweat rates may cause more harm than good, especially if their losses exceed the stomach's gastric emptying rate.

3) After Training or Competitions

Making sure athletes refuel their depleted energy, fluid, and electrolyte stores after competition or practice is part of ensuring they are properly fueled for their next practice or competition. This may take up to 24 hours. Rapid muscle glycogen repletion is especially important after exercise if an athlete must exercise more than once in 24 hours. The body recovers best when an athlete begins refuelling as soon as they finish exercise

Despite their efforts to replace fluids, athletes are frequently mildly dehydrated after exercise. This can impair subsequent exercise performance.

Although an exact sodium recommendation has not been developed, the evidence regarding sodium's role in encouraging plasma and total body rehydration through increased sodium intake is clear. It may be beneficial to select fluids with flavour and sodium. This encourages athletes to consume more fluids.

After exercise, chilled beverages are also more commonly consumed and are beneficial.

Athletes should be warned that drinking beverages with more than 4% alcohol content may cause delayed physical recovery from exercise.

Calories consumed in the form of alcohol or fat may deplete needed carbohydrates, which are a priority for proper muscle glycogen synthesis.


Weighing oneself before and after the exercise is the best way to assess one’s fluid loss. Learning what works for your body and exercise habits, using a combination of scientific knowledge, recognising thirst sensations, and good old-fashioned trial and error are probably the best ways to discover what works for you or the athletes you work with. Talk to an expert sports nutritionist to determine your fluid and electrolyte intake.

Manali Chindarkar
Research Associate

Manali has a Master's in Nutrition and Dietetics with a specialisation in Nutrigenomics. She's into all things tracking. Her determination to solve problems makes her an approachable nutritionist and an integral part of iTHRIVE's research team.

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