Electrolytes have become one of the most talked-about topics in sports nutrition and in everyday life. The largest recent scientific research (Baker et al, 2022) shows that electrolyte losses vary dramatically between individuals, assessing data from almost 2,000 sweat tests. Two athletes completing the same workout in the same conditions can lose completely different amounts of sodium, potassium and other minerals through sweat. That means hydration strategies should be more personalised than most people realise.

From marathon runners and cyclists to HYROX competitors and gym-goers, more athletes are asking do electrolytes really improve hydration, reduce cramping and support physical and cognitive performance?

The short answer is yes — but the details matter.

In this article, share published research articles and cover:

• What electrolytes actually do?
• Who needs electrolytes?
• Which electrolytes matter most for athletes?
• How much sodium and other minerals people lose in sweat?
• Why is sweat composition different between individuals?
• How to replenish electrolyte sweat losses?
• How everyday athletes can build smarter hydration strategies?
• Common mistakes people make with electrolyte supplements

This article is crafted for runners, triathletes, cyclists, gym-goers, team sports players, hybrid athletes and anyone training regularly.

What Are Electrolytes?

Electrolytes are minerals that carry an electrical charge when dissolved in fluids such as blood, sweat and water. The main electrolytes involved in exercise performance include sodium, potassium, magnesium, calcium and chloride (Baker et al, 2019).

These minerals help regulate fluid balance, muscle contractions, nerve signalling, blood pressure, energy production, recovery and temperature regulation, all important factors in exercise performance. Without adequate electrolyte balance, performance and recovery can both suffer (Suarez-Ortegón et al, 2024).

Why Are Electrolytes Important During Exercise?

During exercise we sweat in order to cool ourselves, and this sweat also depletes the body of sodium and other essential electrolytes (Lara et al, 2016). If these losses are not replaced appropriately, athletes may experience increased perceived effort, fatigue, muscle dysfunction, increased cardiac strain, headaches, dizziness, reduced endurance, reduced quality of recovery and increased risk of hyponatraemia (low blood sodium levels causing cells to swell) during prolonged exercise (Baker et al, 2022).

When you exercise, energy metabolism and muscle contractions produce heat in the body, known as metabolic heating, and sweating is the body’s thermoregulation mechanism of cooling (Baker et al, 2022). The problem is that sweat does not only contain water but also contains electrolytes — particularly sodium and chloride. Sodium, as the major ion in extracellular fluid, has a well reported role in fluid balance, maintenance of plasma volume and cellular function during exercise (Ranchordas et al, 2017).

Electrolytes become especially important during long runs or rides, HYROX or indoor training with heavy sweating, doubles training days, hot weather sessions, football and rugby or any high-sweat rate training, as it is these circumstances which replete the body’s electrolytes more quickly.

Which Electrolyte Is Most Important for Athletes?

Sodium is the key electrolyte lost in sweat

While magnesium and potassium receive a lot of attention online, sodium is by far the most important electrolyte lost during exercise, as well as the most abundant, followed by chloride (Choi et al, 2019). Sodium is the most abundant ion in extracellular fluid, meaning a depletion of sodium is strongly linked with the performance-compromising symptoms of dehydration.

Despite this as an overarching rule, research published in the Journal of the International Society of Sports Nutrition found enormous variability in sweat sodium concentration among marathon runners (Lara et al, 2016). The study showed sodium losses can differ several-fold between athletes, even during similar exercise conditions ranging from 160mg / litre to 2,220mg / litre. This is one of the most important findings in modern hydration science.

Some athletes are naturally “salty sweaters” and lose large amounts of sodium during training. Others lose much less, explaining why some runners finish long runs covered in white salt marks, cramp more frequently in hot conditions, feel exhausted after sweating heavily and ultimately need more aggressive hydration strategies

Conversely, others perform well with relatively little electrolyte supplementation and see little variation in their performance in warmer conditions.

What Electrolytes Do You Lose in Sweat?

The main electrolytes lost in sweat are summarised in the table below:

Most research shows sodium and chloride dominate sweat losses while potassium losses are meaningful but considerably lower than sodium. Magnesium and calcium losses through sweat are usually relatively small compared with daily dietary intake, but can be worth consideration.

This is important because many electrolyte products market magnesium heavily, despite sodium being the major performance-related concern during prolonged sweating.

How Much Sodium Do You Lose in Sweat?

Considering how much sodium is in sweat is where hydration science becomes especially interesting, and the short answer is sweat sodium concentration varies enormously between individuals.  A large review published in the Journal of Applied Physiology (Baker et al, 2022) analysed nearly 2,000 sweat tests from multiple studies, and reported typical sodium concentrations ranged from around 20 mmol/L to more than 80 mmol/L. In practical terms, that can mean one athlete loses literally four times more sodium per hour than another ranging between 460mg and 1900mg.

Another study on professional male team sports athletes (football, baseball, basketball and American football) found some individuals lose more than 1,500 mg of sodium per litre of sweat (Ranchordas, 2017). For athletes with high sweat rates, total sodium losses during long training sessions can become substantial and explains why generic hydration advice often might not quite meet individual needs.

Why Do Some Athletes Sweat More Salt Than Others?

Several factors influence sweat electrolyte concentration and as the most abundant mineral, sodium has been the subject of the most research studies. As the sweat glands release ‘primary sweat’ it travels through the sweat duct and some sodium chloride is reabsorbed back into the body before the ‘final sweat’ reaches the skin (Baker, 2019). This process is also influenced by the hormone aldosterone.

Is ‘salty sweat’ due to genetics?

Some people naturally reabsorb sodium less efficiently in their sweat ducts (Eichner, 2009) so even after sweat is released from the gland, sodium levels can vary. The efficiency of the sodium reabsorption process can determine the sodium level in final sweat on the skin.

How does heat adaptation effect sweat sodium?

Athletes adapted to hot environments often become more efficient at conserving sodium, with lower sweat sodium levels recorded (Buono et al, 2018). This is thought to be due to improved sodium reabsorption capacity of the eccrine sweat gland. (Buono et al, 2007). This can of course be due to specific heat acclimatisation training, or a natural adaptation to the season.

Does Exercise intensity affect sweat sodium levels?

One of the most strongly supported factors in recent scientific literature is intensity of exercise (Baker et al, 2022). Higher intensities can increase sodium losses, and not just because of an increasing volume of sweat. Sodium concentration can rise with intensity, while potassium concentration reduces (Klous et al., 2021). 

Does a higher sweat rate mean more sodium loss?

Athletes who sweat heavily may lose large total amounts of electrolytes as high sweat flow rate allows less time for the active and passive reabsorption of sodium, chloride and potassium in the sweat duct (Baker, 2019). This provides a double edged sword as there is more total volume of sweat in ml, but there is also a higher electrolyte concentration in each ml of final sweat.

Does a high sodium diet give athletes saltier sweat?

Dietary sodium intake has been found to influence sweat composition by up to 10-12% (McCubbin et al, 2019) when daily sodium intake was doubled. In this instance the mean sweat sodium increased by just 6mmol/litre, (around 130mg) which won’t realistically effect an athlete’s event hydration protocol. A systematic review highlighted two research trials where the impact of dietary sodium on sweat sodium was even smaller, and not statistically significant (McCubbin, and Costa, 2018). Current consensus suggests sweat rate, genetics and heat acclimatisation play a larger part in determining how salty an athlete’s sweat is (McCubbin, 2025).

Training status

Well conditioned athletes may demonstrate different sweat responses compared with recreational exercisers. As fitness improves, so too does the efficiency of sweat ducts at reabsorbing sodium, resulting in lower sweat sodium concentrations in more highly trained athletes (Hoch and Watso, 2026). This factor ties in with the notion that more well trained athletes could well also be more heat acclimatised due to more hours of training (in warm conditions), so the two factors are closely linked. Despite fitter individuals typically having lower sweat Na+ concentrations, more well-trained athletes may have higher sweat rates (L/hour), so even with lower sodium concentrations, may lose more sodium overall.

Do Electrolytes Prevent Cramping?

This is one of the most searched questions online and the true answer is nuanced, as there appears to be three main types of cramp (Eichner et al 2008). Risk of ‘heat cramping’ also called sweat cramping appears to be minimised by electrolyte supplementation (McCubbin, 2025). Electrolyte imbalance can contribute to muscle dysfunction, especially during prolonged exercise in hot conditions resulting in debilitating exercise associated muscle cramps (EAMC).

However, exercise-associated muscle cramps are complex with current evidence suggesting cramps may involve multiple factors including:

• Neuromuscular fatigue (Sulzer et al, 2005)
• Inadequate conditioning (leading to neuromuscular fatigue) (Maughan and Shirreffs, 2019)
• Hydration status (Eichner et al, 2008)
• Sodium losses in some individuals (McCubbin, 2025).

Electrolytes are not a guaranteed cure for cramping but can reduce susceptibility of muscles to cramp (Lau et al, 2019). The takeaway message is that athletes with very high sodium losses may benefit from targeted sodium replacement strategies to minimise cramp risk.

Are Electrolytes Better Than Water?

Whilst water is healthy and supplements fluid balance in the body, electrolytes are better than water in driving rapid fluid update and therefore improving hydration levels. (Minegishi et al, 2020). This is because as sodium is absorbed in the small intestine it creates an osmotic gradient which quickly draws water across the intestinal lining and into the blood stream.

For short sessions under 60 minutes, water is often sufficient for most people, however, during longer or sweat-heavy sessions, electrolyte intake may improve hydration effectiveness.

Are Electrolytes Better Than Water?

Whilst water is healthy and supplements fluid balance in the body, electrolytes are better than water in driving rapid fluid update and therefore improving hydration levels. (Minegishi et al, 2020). This is because as sodium is absorbed in the small intestine it creates an osmotic gradient which quickly draws water across the intestinal lining and into the blood stream.

For short sessions under 60 minutes, water is often sufficient for most people, however, during longer or sweat-heavy sessions, electrolyte intake may improve hydration effectiveness.

Conversely, drinking large amounts of plain water during prolonged exercise without replacing sodium can dilute blood sodium concentration. To avoid sodium or general electrolyte depletion in the body, electrolytes are especially useful when:

• Training lasts longer than 60–90 minutes
• Conditions are hot or humid
• Sweat rate is high
• Multiple sessions are completed in one day
• Recovery between sessions is important
• Salt marks appear on clothing or skin, suggesting higher sodium losses.

Do You Need Electrolytes Every Day?

Yes and no! You need electrolytes, but not necessarily electrolyte supplements. Many people can meet electrolyte requirements through a balanced diet.

However, to meet the goal of matching electrolyte intake to actual losses, rather than unnecessary excessive electrolytes intake, regular exercisers and athletes may benefit from additional electrolyte support during periods of:

• Heavy training
• Heat exposure
• Long endurance sessions
• High sweat losses
• Travel and dehydration
• Illness involving fluid loss

Best Sources of Electrolytes for Athletes

Electrolytes can come from both food and supplements, with sports nutrition products typically providing higher levels of specific electrolytes depending on their intended function, or simply a convenient way of delivering them. The best source of electrolytes in a sports drink, should have a balance of all those lost in sweat, such as VOOM Hydrate Rapid electrolyte. For many athletes, combining a strong diet with targeted electrolyte supplementation around training works well.

Sodium sources

• Salted foods such as nuts or crisps.
• Soups and bouillons
• Cured meats and cheeses
• Electrolyte drinks such as VOOM Hydrate Rapid Electrolyte.
• Electrolyte chews, such as VOOM ElectroBytes

Potassium sources

• Bananas
• Potatoes
• Yogurt
• Coconut water
• Leafy greens
• Some electrolyte drinks

Magnesium sources

• Nuts
• Seeds
• Dark chocolate
• Whole grains
• Some sports drinks

Calcium sources

• Dairy products
• Fortified alternatives
• Sardines
• Tofu
• Some electrolyte products

What Does the Latest Sweat Science Tell Us?

Modern sports science is moving toward personalised hydration with some of the most recent research using and evaluating wearable sweat sensors. Laboratory sweat analysis demonstrates:

• Sweat sodium concentration varies dramatically between athletes (Baker et al, 2022)
• Sweat composition changes across exercise intensity and environmental conditions (Klous et al., 2021).
• Sweat testing technology is becoming more accessible
• Sodium losses matter more than many athletes realise (McCubbin, 2025)
• Generic hydration recommendations may not work for everyone

Other recent studies using wearable sweat sensors have tracked sodium and potassium concentrations in real time during cycling and endurance exercise (Pirovano et al, 2020)

The practical takeaway is clear: Athletes should not think about hydration as simply “drinking more water.” Effective hydration means replacing both fluid and key electrolytes according to individual needs.

How All Athletes Can Build a Smarter Electrolyte Strategy

Most people do not need laboratory sweat testing to improve hydration. Instead, recreational athletes and every day fitness enthusiasts can use practical signs and training context.

1. Understand your sweat rate

If you finish sessions drenched while training partners barely sweat, your sweat rate, and hydration needs may be higher. Weighing yourself before and after training can help estimate fluid losses. The difference in pre and post session weights, minus any fluids consumed, can show fluid losses during the session.

2. Watch for salt residue

White marks on clothing, hats or skin often suggest higher sodium losses, either due to higher sodium concentration (mg/litre) or simply due to higher sweat rate (ml/hour).

3. Adjust for climate

Hot and humid conditions dramatically increase sweat losses as the body tries to avoid a rise in core temperature.

4. Match hydration to session length

A 45-minute gym session or easy run has very different requirements compared with a 3-hour bike race.

5. Prioritise sodium for long sessions

For prolonged exercise, sodium is usually the most important electrolyte to replace.

6. Don’t ignore overall diet

Daily intake of potassium, magnesium and calcium still matters for overall health and recovery.

What Should I Look for in an Electrolyte Supplement?

Not all electrolyte products are formulated equally, with different products targeting different electrolytes so for athletes training intensely or sweating heavily, look for:

• Meaningful sodium content
• Clear ingredient transparency
• Appropriate carbohydrate content for the session
• Easy digestibility and stomach comfort
• Evidence-based formulation

Some products underdose sodium, especially if you’re a high sodium sweater, while overemphasising minor ingredients, while others are formulated to deliver extremely high sodium content, which can be unnecessary for some people.

For endurance and sweat-heavy sessions, sodium content deserves the most attention, and it is worth noting that for the fastest hydration a hypotonic solution, with some carbohydrate content is most effective. This takes advantage of the sodium glucose cotransport molecules in the small intestine which pulls water (plus sodium and glucose) into the body more quickly. VOOM Hydrate offers a hypotonic solution with all 5 key electrolytes, as well as light refreshing fruit tastes to increase ‘voluntary drinking’.

The Future of Hydration: Personalised Sweat Testing

Sports nutrition is increasingly moving toward personalised hydration strategies with wearable sweat sensors and advanced sweat testing technologies making it easier to estimate sodium losses in real-world conditions.

In the future, athletes may routinely tailor hydration strategies according to:

• Sweat sodium concentration
• Sweat rate
• Climate conditions
• Exercise duration and intensity
• Individual physiology

For now, even basic awareness of sweat losses and electrolyte needs can help everyday athletes train and recover more effectively.

Conversely, drinking large amounts of plain water during prolonged exercise without replacing sodium can dilute blood sodium concentration. To avoid sodium or general electrolyte depletion in the body, electrolytes are especially useful when:

• Training lasts longer than 60–90 minutes
• Conditions are hot or humid
• Sweat rate is high
• Multiple sessions are completed in one day
• Recovery between sessions is important
• Salt marks appear on clothing or skin, suggesting higher sodium losses.

Frequently Asked Questions About Electrolytes

What are the symptoms of low electrolytes?

Symptoms can include fatigue, headaches, dizziness, muscle weakness, cramps and poor exercise performance.

Are electrolytes good for recovery?

Yes. Electrolytes help restore fluid balance and support recovery after sweating heavily. Being well hydrated then allows the body to more efficiently go through its natural inflammation process to then repair and recover.

Can you drink too many electrolytes?

Yes. Excessive intake — especially sodium supplementation without need — may be unnecessary or problematic for some individuals. High sodium electrolyte beverages should only be used for longer duration exercise or in particularly hot conditions which increase sodium losses.

Are electrolyte tablets effective?

They can be effective when matched appropriately to sweat losses and exercise duration. Effervescent electrolyte tablets are a popular option for convenience, although may not offer as quick hydration as a chewable electrolyte tablet which allows some electrolyte and glucose absorption through the gums.

Are electrolytes important in winter?

Yes. Athletes still lose fluid and sodium through sweat during winter training, especially indoors, or when layering up with clothing for outdoor training. Modern materials are good at wicking sweat away from the body so many people don’t realise how much they’ve lost.

Is coconut water enough for electrolytes?

Coconut water contains potassium but is often relatively low in sodium compared with the needs of heavy sweaters during endurance exercise.

Hydration References & Electrolyte Articles

1. Baker, L.B. (2017). Sweating rate and sweat sodium concentration in athletes: a review of methodology and intra/interindividual variability. Sports Medicine. 47(Suppl 1). pp. 111–128.
2. Baker, L.B. (2019). Physiology of sweat gland function: The roles of sweating and sweat composition in human health. Temperature (Austin). 6(3). pp. 211–259.
3. Baker, L.B., De Chavez, P.J.D., Nuccio, R.P., Brown, S.D., King, M.A., Sopeña, B.C. and Barnes, K.A. (2022). Explaining variation in sweat sodium concentration: effect of individual characteristics and exercise, environmental, and dietary factors. Journal of Applied Physiology. 133(6). pp. 1250–1259.
4. Baker, L.B., De Chavez, P.J.D., Ungaro, C.T., Sopeña, B.C., Nuccio, R.P., Reimel, A.J. and Barnes, K.A. (2019). Exercise intensity effects on total sweat electrolyte losses and regional vs. whole-body sweat [Na+], [Cl−], and [K+]. European Journal of Applied Physiology. 119(2). pp. 361–375.
5. Baker, L.B., De Chavez, P.J.D., Ungaro, C.T., Sopeña, B.C., Nuccio, R.P., Reimel, A.J. and Barnes, K.A. (2019). Exercise intensity effects on total sweat electrolyte losses and regional vs. whole-body sweat sodium, chloride and potassium concentrations. European Journal of Applied Physiology. 119(2). pp. 361–375.
6. Buono, M.J., Ball, K.D. and Kolkhorst, F.W. (2007). Sodium ion concentration vs. sweat rate relationship in humans. Journal of Applied Physiology. 103(3). pp. 990–994.
7. Buono, M.J., Kolding, M., Leslie, E., Moreno, D., Norwood, S., Ordille, A. and Weller, R. (2018). Heat acclimation causes a linear decrease in sweat sodium ion concentration. Journal of Thermal Biology. 71. pp. 237–240.
8. Choi, D.H., Kitchen, G., Kim, J.S., Li, Y., Kim, K., Jeong, I.C., Nguyen, J., Stewart, K.J., Zeger, S.L. and Searson, P.C. (2019). Two Distinct Types of Sweat Profile in Healthy Subjects While Exercising at Constant Power Output Measured by a Wearable Sweat Sensor. Scientific Reports. 9. Article 17877.
9. Eichner, E.R. (2008). Genetic and other determinants of sweat sodium. Current Sports Medicine Reports. 7(S4). pp. S36–S40. 
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13. Klous, L., de Ruiter, C.J., Scherrer, S., Gerrett, N. and Daanen, H.A.M. (2021). The (in)dependency of blood and sweat sodium, chloride, potassium, ammonia, lactate and glucose concentrations during submaximal exercise. European Journal of Applied Physiology. 121(3). pp. 803–816.
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15. Lau, W.Y., Kato, H. and Nosaka, K. (2019). Water intake after dehydration makes muscles more susceptible to cramp but electrolytes reverse that effect. BMJ Open Sport and Exercise Medicine. 5(1). Article e000478. 
16. Maughan, R.J. and Shirreffs, S.M. (2019). Muscle cramping during exercise: causes, solutions, and questions remaining. Sports Medicine. 49(Suppl 2). pp. 115–124. 
17. McCubbin, A.J. (2025). Sodium intake for athletes before, during and after exercise: review and recommendations. Performance Nutrition. 1(1). Article 11
18. McCubbin, A.J. and Costa, R.J.S. (2018). The impact of dietary sodium intake on sweat sodium concentration in response to endurance exercise: a systematic review. International Journal of Sports Science. 8(1). pp. 25–37.
19. McCubbin, A.J., Lopez, M.B., Cox, G.R., Caldwell Odgers, J.N. and Costa, R.J.S. (2019). Impact of 3-day high and low dietary sodium intake on sodium status in response to exertional-heat stress: a double-blind randomized controlled trial. European Journal of Applied Physiology. 119(9). pp. 2105–2118. 
20. Minegishi, S., Luft, F.C., Titze, J. and Kitada, K. (2020). Sodium handling and interaction in numerous organs. American Journal of Hypertension. 33(8). pp. 687–694.
21. Pirovano, P., Dorrian, M., Shinde, A., Donohoe, A., Brady, A.J., Moyna, N.M., Wallace, G., Diamond, D. and McCaul, M. (2020). A wearable sensor for the detection of sodium and potassium in human sweat during exercise. Talanta. 219. Article 121145. 
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