The importance of sodium for athletes

 

by Elena Casiraghi

Sweating, and the evaporation of sweat that follows, is essential for humans, especially for athletes. Without it, the body would not be able to reduce the excess heat produced during exercise. This mechanism is part of the natural thermoregulation process: sweat evaporation absorbs a considerable amount of heat (2430 kJ/l), helping cool the body.

The effects of sweating

With sweat, however, the body loses minerals: mainly sodium and chloride, and to a lesser extent potassium and magnesium. The greater the effort, ambient temperature, humidity and solar radiation, the higher the sweat rate and, with it, the loss of these minerals. When losses are significant, replenishment is needed to help avoid several potential issues.

Sodium: how much is lost through sweat?

Sodium is the mineral found in the highest concentration in sweat. Potassium concentration is 6-8 times lower than sodium, while magnesium can be around 100 times lower. Clear evidence of sodium in sweat can be seen in the white marks left on clothing, especially around the neck and underarms: the more visible they are, the less adapted the athlete may be to the ambient temperature in which they train or compete.

What happens when Sodium is low

A sodium deficit can have serious consequences. In extreme cases it can lead to hyponatraemia, a condition that occurs when blood sodium levels are particularly low. It can be caused by high sodium losses through sweat and by excessive intake of mineral-poor water, or by a combination of both, and may occur during exercise, immediately after it and up to 24 hours later.

Hyponatraemia is certainly the most dangerous consequence to manage, but it is not the only one. Sodium deficiency also reduces the intestine’s ability to absorb water, increasing intestinal stress during exercise and reducing hydration status. Sodium is mainly absorbed in the ileum, the final section of the small intestine.

How to maintain sodium levels in training and racing

Athletes can rely on different products to help prevent sodium depletion. Options include powder mixes, electrolyte-based effervescent tablets and capsules containing only sodium chloride. In recent years, sports nutrition has evolved toward increasingly practical and diversified solutions. Alongside traditional supplements, sparkling ready-to-drink beverages enriched with sodium are now available and can be particularly useful for post-exercise recovery, especially when fatigue or reduced appetite make replenishment through food less immediate. The range has also expanded to include energy bars containing sodium and energy gels enriched with this mineral, including neutral-taste options. Having different formats available can be an advantage in long-duration endurance sports, where sodium losses increase progressively and so-called “flavour fatigue” may appear, reducing tolerance for the same flavours over time.

Alongside formulas that provide both carbohydrates and sodium, there are also calorie-free electrolyte-only products to dissolve in water. These solutions make it possible to replenish sodium without adding energy and can be especially useful during activities that are not particularly long or intense, but are performed in hot conditions, where maintaining hydration is a higher priority than fuelling.

Sodium and muscle cramps Sodium is often associated with muscle cramps. While its effects on muscle contraction are clear, it is still not fully established whether it is directly linked to exercise-associated cramps. The causes of cramps may be different. Although these cramps are more common in hot conditions, prolonged exercise and dehydration, it has not been proven that this is due to sodium loss, because heat, exercise-induced fatigue and dehydration may all play a role, particularly at nervous system level.

Two tips for improving performance

The variety of electrolytes supplements allows athletes to use training sessions to identify the solution best suited to their individual characteristics and to the environmental conditions they will face in competition. In any case, the right solution is the one that supports optimal gastric emptying and intestinal absorption. In particular, keep in mind:

• Timing: meaning when to drink: as a general indication during sport, take small sips of around 150 ml every 15 minutes, consistently. In case of heavy sweating, drink more frequently, roughly every 10 minutes. Do not wait until you feel thirsty: when possible, anticipate it.
• Heat acclimation reduces sodium losses through sweat: sweat sodium concentration may decrease by around 20-60% compared with a non-acclimated individual, although the extent of this reduction varies considerably from person to person. Why this difference? The reason is straightforward: the sweat of a non-acclimated runner is more concentrated in minerals than that of an acclimated athlete. Acclimation helps reduce the amount of sodium lost through sweat. In general, athletes who adapt to climate conditions (temperature and humidity) may improve performance on hotter and more humid days. This process takes 7 to 14 days, during which the body adapts to the higher temperature by increasing blood volume, which contains a large amount of water, reducing heart rate and increasing sweat rate.

Summary: Among the minerals found in sweat, sodium is lost in the highest concentrations. Sodium deficiency caused by increased sweating can affect not only performance, but also the athlete’s wellbeing. Choosing the right supplement matters, as does taking it with precise timing. Acclimation is a very useful strategy.

 

 

Bibliography

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- Sawka, NM, Montain, SJ. - Fluid and electrolyte supplementation for exercise heat stress. Am J Clin Nutr August 2000 vol. 72 no. 2 564s-572s.

- Noakes, T. - Lore of running. Ed. Human Kinetics, 2003.

- Baker, L.B. - Physiology of sweat gland function: the roles of sweating and sweat composition in human health. Temperature (Austin). 2019;6(3):211-259. doi:10.1080/23328940.2019.1632145.

- Baker, L.B. - Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Med. 2017;47(Suppl 1):111-128. doi:10.1007/s40279-017-0691-5.

 

NOTE: the information provided is for educational purposes only and is not intended to replace advice from your doctor or healthcare professional. The information is intended for healthy individuals; any dietary plan or exercise programme should be supervised by the legally competent professional under Italian law before being undertaken. Enervit SpA accepts no responsibility, as the information is provided for educational purposes only and anyone interested should consult their trusted specialist before starting any dietary or physical activity programme.