Is sodium the most underestimated nutrient for athletes?

When it comes to sports nutrition, protein, carbohydrates, and creatine usually take center stage.

Conversely, sodium is often perceived as a nutrient that should be limited. Its image is largely associated with excessive salt consumption and its potential effects on cardiovascular health in the general population.

However, this view does not always correspond to the reality for athletes.

During intense or prolonged exercise, especially in summer, sodium is one of the main minerals lost through perspiration. In some disciplines, these losses can become significant enough to influence hydration, performance, and recovery.

So, should you consume more sodium when exercising? Does this apply to all athletes? And why is this mineral so often overlooked?

Here's what scientific literature shows.

Sodium is not just salt

Sodium is a mineral essential for the body's functioning.

It is the main electrolyte present in extracellular fluid and is involved in numerous physiological functions.

It is found naturally in some foods, as well as in sodium chloride, better known as table salt.

Contrary to popular belief, sodium is not just there to flavor food.

It notably contributes to:

• maintaining fluid balance;
• nerve impulse transmission;
• muscle contraction;
• maintaining blood volume;
• the absorption of certain nutrients, particularly glucose in the intestine.

In other words, it is directly involved in several mechanisms essential for sports practice.

 

Why is sodium often misunderstood?

For several decades, health authorities have recommended limiting salt intake in the general population.

This recommendation primarily targets people who consume a lot of ultra-processed products, which are often very high in sodium.

In sedentary individuals, excessive salt intake can contribute to increased blood pressure in some sensitive people.

The problem is that this message is sometimes systematically applied to athletes.

However, an athlete who trains several hours a week, sweats profusely, and participates in endurance competitions does not have the same physiological constraints as a less active person.

Sodium losses can then become significant and modify needs.

Sodium is neither a "good" nor a "bad" nutrient: it all depends on the context, the level of physical activity, and losses due to perspiration.

 

What is the role of sodium in athletes?

In athletes, sodium participates in several essential functions.

Maintain hydration

Sodium promotes water retention in the extracellular compartment.

It thus contributes to maintaining blood volume and facilitates rehydration after exercise.

This is also why sports and recovery drinks generally contain sodium.

Promote water absorption

In the intestine, sodium is involved in glucose transport.

When glucose and sodium are simultaneously present in a drink, water absorption is more efficient.

This is one of the principles on which rehydration solutions are based.

Participate in muscle contraction

Like potassium, sodium is involved in the propagation of nerve impulses that allow muscle fibers to be activated.

Without these ion exchanges, muscle contraction simply could not occur.

 

Why do we sweat so much sodium?

Sweating helps to limit the increase in body temperature during exercise.

But it doesn't just contain water.

It also contains various electrolytes, of which sodium makes up the largest part.

Losses vary enormously from one athlete to another.

They depend notably on:

• outdoor temperature;
• humidity level;
• duration of effort;
• intensity;
• training level;
• genetics.

Some people lose less than 500 mg of sodium per liter of sweat, while others exceed 1,500 mg/L.

This also explains why some athletes observe white salt traces on their clothes or skin after a workout: it is simply the sodium left by the evaporation of sweat.

 

What are the consequences of insufficient sodium intake?

Contrary to popular belief, for some athletes, the problem is not consuming too much sodium, but losing more than they take in.

When losses become significant without being compensated, several consequences can appear, especially during prolonged efforts made in hot weather.

Less effective hydration

Drinking only water is not always enough to compensate for losses due to perspiration.

Sodium helps maintain blood volume and promotes fluid retention in the body. In its absence, part of the water consumed is eliminated more quickly by the kidneys.

Result: despite significant water consumption, rehydration may be less effective.

A decrease in performance

Moderate dehydration is already capable of impairing physical performance, especially in endurance sports.

It can lead to:

• an increase in heart rate;
• a greater sensation of effort;
• a decrease in the ability to maintain high intensity;
• earlier fatigue.

Sodium alone does not improve performance, but it contributes to maintaining the fluid balance essential for their preservation.

The risk of hyponatremia

A lack of sodium becomes particularly problematic when associated with excessive water consumption.

In this situation, the sodium concentration in the blood can decrease significantly: this is called hyponatremia.

This complication remains rare, but it is well documented during long endurance events such as marathons, Ironmans, or ultra-trails.

Symptoms may include:

• nausea;
• headaches;
• confusion;
• vomiting;
• in the most severe cases, neurological complications requiring urgent medical attention.

Contrary to popular belief, hyponatremia is most often linked to an overconsumption of water not compensated by sodium intake, rather than a simple lack of salt in the diet.

For endurance athletes, the goal is not to drink as much as possible, but to gradually replace water and sodium losses depending on the duration and conditions of the effort.

 

Do all athletes have the same needs?

No. Sodium needs vary greatly depending on the individual and the type of activity practiced.

A weightlifter doing a one-hour session in an air-conditioned gym will generally not have the same losses as a runner participating in a marathon in 35°C heat.

The athletes most concerned include:

• long-distance runners;
• cyclists;
• triathletes;
• practitioners of hybrid sports such as HYROX;
• team sports players playing outdoors;
• people training for long periods in hot weather.

Some people are also described as salty sweaters, meaning they have a particularly high concentration of sodium in their sweat.

They can sometimes be recognized by certain signs:

• white marks on clothes after exercise;
• salty-tasting skin;
• visible deposits on caps or backpack straps;
• a strong sensation of thirst after long workouts.

For these athletes, sodium needs during prolonged efforts may be higher than average.

 

How to meet your sodium needs?

In most cases, a varied diet largely covers the daily needs of a person engaged in moderate physical activity.

However, during long training sessions or those performed in hot weather, some strategies may be relevant.

Do not systematically eliminate salt

For an athlete who sweats profusely, voluntarily eliminating salt from all meals is generally not recommended.

The sodium naturally present in foods, combined with that provided by table salt, helps compensate for daily losses.

Adapt sports drinks

For efforts lasting more than about an hour, especially in hot environments, a drink containing both:

• water;
• carbohydrates;
• sodium;

can facilitate hydration maintenance and the gradual replacement of losses.

However, the necessary quantities depend on many factors and must be adapted to each athlete.

Observe your own reactions

The best strategy often remains individualized.

If you sweat profusely, regularly engage in prolonged efforts, or notice significant salt deposits after your workouts, it may be relevant to pay particular attention to your sodium intake during long sessions.

 

Key takeaways

Sodium is probably one of the most misunderstood nutrients in sports nutrition.

Often presented as an element to be limited, it plays an essential role in maintaining hydration, nerve impulse transmission, muscle contraction, and blood volume regulation.

For athletes who sweat little, a balanced diet is usually sufficient to cover their needs.

However, during prolonged efforts, competitions, or training sessions carried out in hot weather, sodium losses can become significant and justify an adapted rehydration strategy.

The goal is therefore not to consume as much salt as possible, but to intelligently replace what the body loses during exercise.