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An electrolyte drink combines water, electrolytes (mainly sodium) and often carbohydrates to help replenish fluids, minerals lost through sweat, and, in carbohydrate variants, energy during exertion.
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It is especially useful during long and intense exercise (heat, heavy sweating, endurance sports). However, if consumed frequently outside of training or in large amounts, it acts like a sugary fizzy drink with added salt – unnecessary calories, sugar and sodium.
What is an electrolyte (sports) drink?
An electrolyte drink is a beverage designed for sports and physical activity that combines water, electrolytes (especially sodium) and often also carbohydrates. It is designed to replenish fluids and minerals lost through sweat more efficiently during prolonged or intense performance, and, in carbohydrate variants, to provide energy. Unlike a regular fizzy drink, it has a more controlled composition and is formulated to support hydration – if used in appropriate situations, rather than as a regular thirst quencher throughout the day.
What does an electrolyte drink contain?
Water
Water is, of course, the key component of any electrolyte drink and is essential for proper hydration.
Electrolytes
Most commonly sodium (Na⁺), often also potassium (K⁺), and sometimes magnesium or calcium in smaller amounts.
Sodium is the most important because its losses through sweat are the highest – it helps to:
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retain water in the bloodstream
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support the absorption of water and glucose in the intestine (via the "sodium‑glucose cotransporter")
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replace losses through sweat (sweat is always “salty” – it contains sodium)
Potassium is important for muscle and nerve function, but in drinks, it plays more of a supplementary role.
Carbohydrates
Typically, drinks contain glucose, maltodextrin, sometimes fructose, or blends that serve as a quick source of energy during prolonged or intense exercise.
Types of electrolyte drinks by “strength” (osmolality)
Besides differing in their ingredients, electrolyte drinks also differ in osmolality – that is, by how many dissolved particles (ions and sugars) they contain. The “thicker” the drink, the more slowly it is usually absorbed and the more it can burden digestion.
From a practical perspective, you’ll encounter three types:
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Hypotonic – has a lower osmolality than blood plasma. It typically contains less carbohydrate (about 2–4%) and a reasonable amount of sodium. It is absorbed quickly and is mainly suitable for pure hydration, recreational sports, longer light activities in the heat, or those who tolerate sweet drinks poorly during exercise.
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Isotonic – has an osmolality similar to blood plasma, and its carbohydrate content is usually around 6–8%. This is the classic ‘electrolyte drink’ that both hydrates and provides energy, but it can be quite sweet and, in sensitive individuals exercising at high intensity, may cause a heavy feeling in the stomach. It is more suitable for longer or more demanding exercise, where you will also use the energy from the sugar.
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Hypertonic – is more concentrated than blood (very sweet drinks, concentrated juices, and some energy drinks or gels without enough water). It is not suitable as the main thirst quencher during exercise, as it can worsen hydration and initially literally ‘draw’ water into the intestine. In practice, it is used more as an energy source and should always be washed down with water or a hypotonic drink.
What is an electrolyte drink for?
The goal of electrolyte drinks is to support or accelerate hydration and provide the body with easily digestible carbohydrates.
Better hydration during prolonged and/or intense performance
During prolonged or intense exercise, you lose water and sodium through sweat. If you drink only plain water, some of the fluid is quickly excreted in urine and rehydration is less effective. A meta‑analysis shows that hypotonic electrolyte drinks can maintain plasma volume better than isotonic and hypertonic drinks or plain water – thus supporting blood circulation and thermoregulation.
The combination of sodium and carbohydrates is important, as it improves water absorption in the intestine and increases fluid retention. Reviews summarise that such drinks lead to better absorption and retention of fluids, and people are also more willing to drink them than plain water.
A similar effect has been shown for electrolyte drinks without sugar, which, compared with water, reduced urine output and increased the so‑called hydration index – that is, the proportion of fluid that actually remained in the body.
Performance support during endurance exercise
In endurance sports, it’s not only about hydration, but also about ensuring that the muscles have a continuous supply of carbohydrates as fuel. During prolonged exertion, electrolyte drinks help maintain blood glucose levels, partially spare muscle glycogen and support hydration thanks to sodium. The result is the "ergogenic effect" – that is, better endurance performance compared with water alone.
During longer races, blends of several types of carbohydrates (e.g. glucose/maltodextrin + fructose) are often used. These use different transporters in the intestine and allow for higher rates of carbohydrate absorption and oxidation than glucose alone, which is especially noticeable when consuming higher doses above about 60 g of carbohydrates per hour.
For most endurance athletes, it is sufficient for the drink to contain a reasonable amount of carbohydrates (about 3–6%), enough sodium, and to be hypotonic or slightly isotonic. In such cases, an electrolyte drink is a practical tool for maintaining energy and performance during prolonged exertion.
Dehydration and its impact on performance and health – why is hydration important?
During physical activity (sports, work in the heat, or long hikes), the body loses not only water but also electrolytes – mainly sodium, potassium and chloride. These ions are key to nerve impulse transmission, muscle contraction, blood pressure regulation, and maintaining fluid volume in the blood vessels and tissues. If greater losses are not compensated for over time, dehydration occurs. When fluid loss exceeds >2% of body weight, performance can already deteriorate, heart rate increases, fatigue rises and thermoregulation worsens.
During physical activity, the main route of fluid loss is sweat:
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Sweat is mostly water, but it always contains electrolytes – mainly sodium, with smaller amounts of potassium and chloride.
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The rate of sweating is highly individual (climate, genetics, fitness, clothing, etc.), but for endurance athletes exercising in the heat, losing 1 litre of sweat per hour is not unusual.
When you lose fluids and don’t replace them:
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plasma volume decreases ("central hydration")
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cardiac output decreases – the heart must beat faster to maintain the blood supply to the muscles and organs
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heat dissipation from the body worsens (poorer thermoregulation)
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the subjective feeling of effort increases, and headache or lethargy may occur
Meta‑analyses show that during endurance exercise, dehydration of several per cent of body weight can reduce performance, increase heart rate and worsen thermoregulation – although the specific impact depends on intensity, duration, environmental temperature and fitness.
When and how should you use an electrolyte drink?
Before exercise, water is usually enough
Before training, the goal is to start reasonably hydrated – in this case, both dehydration and hyperhydration (excessive fluid intake) are undesirable. If you normally drink water throughout the day, it is usually sufficient to sip water or weak tea in the final 2–4 hours before exercise and avoid starting your training thirsty.
In hot weather, an electrolyte drink may be suitable even before exercise
An electrolyte drink makes more sense beforehand if you are facing longer or more demanding exercise in the heat. In such cases, it is advisable to slowlysipa small amount of hypotonic drink or water with a pinch of salt during the final hour to slightly increase sodium and fluid intake. Just before starting (15–30 minutes), a few sips of water or a light electrolyte drink are usually enough; drinking large volumes at once is more likely to burden the stomach than improve hydration.
For a regular one‑hour gym workout or a shorter run, you usually don’t need an electrolyte drink beforehand.
During exercise
Up to 60 minutesFor activities lasting up to about one hour (strength training, a group class, or a shorter run), most recreational athletes can manage perfectly well with water according to thirst – glycogen stores are sufficient and sodium losses are not significant in healthy individuals.
60–90 minutesDuring intense exercise lasting 60–90 minutes, especially in the heat and with significant sweating, a hypotonic electrolyte drink can provide an advantage – it helps maintain plasma volume and hydration better than plain water or classic isotonic drinks.
For a regular gym workout, an electrolyte drink is not necessary.
Over 90 minutesDuring endurance exercise lasting longer than 90 minutes (a longer run, cycling, tournaments or a triathlon), an electrolyte drink helps maintain hydration and performance. It is recommended to use a drink with:
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a moderate carbohydrate content of about 3–6% (30–60 g/l)
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approximately 20–40 mmol/l of sodium
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total osmolality below approximately 290 mOsm/kg (preferably hypotonic or slightly isotonic)
As a general guideline for fluid intake during endurance exercise, about 400–800 ml per hour is recommended, divided into smaller doses according to body weight, intensity and environmental conditions.
After exercise
After exertion, the goal is to replenish lost fluids and electrolytes and begin recovery. Recommendations for rehydration often mention a practical guideline: within a few hours after exercise, replenish approximately 1.2–1.5 litres of fluid for every 1 kg of body weight lost, ideally combined with a source of sodium (water plus saltier food).
An electrolyte drink after exercise makes sense mainly if you have another hard workout or match soon afterwards, or if you have completed a long race in the heat with heavy sweating. If it was just a regular workout lasting 60–90 minutes and you eat normally afterwards, the literature shows that water combined with a regular meal (including salt) is fully sufficient to return to euhydration (optimal hydration status).
Electrolyte drinks have risks and are not suitable for everyone
1. Risk of overweight, obesity and metabolic diseases
From an energy perspective, electrolyte drinks are essentially sugary drinks with added electrolytes. They usually contain around 4–8% sugar, i.e. tens of grams of carbohydrates per half‑litre, similar to fizzy drinks. A systematic review shows that frequent consumption of sports drinks is associated with higher rates of overweight, obesity, diabetes and cardiovascular disease. This mainly concerns cases where electrolyte drinks are consumed ‘just because’ or by recreational athletes performing low‑intensity exercise.
2. Tooth decay and enamel erosion
Sports drinks are often acidic (with a pH below 5.5) and also contain a mix of simple sugars (glucose, fructose and sucrose). Therefore, they have similar cariogenic and erosive potential to other sweet drinks, such as fruit juices or fizzy drinks. Frequent sipping throughout the day significantly increases the risk of tooth decay and enamel erosion, especially in children and adolescents.
3. Excessive sodium intake
For athletes, a higher sodium content in the drink is desirable, but for the general population, especially children, it is not. The authors of a study warn that sports drinks may contain more sodium than children and non‑athletic adolescents need, and regular consumption can contribute over time to an increased risk of hypertension and cardiovascular disease.
4. False “health halo effect” – perception as a healthy drink
Researchers point out a marketing problem: sports drinks are often presented as part of a ‘healthy, sporty lifestyle’, even though, from a nutritional perspective, they belong among sugary drinks with limited added value. Therefore, the authors recommend that the non‑athletic population clearly prefers water as its main drink and does not perceive sports drinks as generally "healthy beverages".
How to prepare a homemade electrolyte drink
The basic principle is simple – try to roughly match what the research on sports drinks recommends. The drink should be hypotonic, contain a moderate amount of carbohydrates (about 3–6%), and enough sodium (about 20–40 mmol/l, i.e. approximately 1.2–2.3 g of table salt per litre).
For 1 litre of drink, a basic recipe might look like this:
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800–900ml water
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100–250ml 100% fruit juice (orange, apple, grape work quite well) or freshly squeezed juice
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1/4–1/2 teaspoon table salt (about 1.2–2.5 g)
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optionally, a tablespoon of sugar or honey for more energy and a sweeter taste (this can be adjusted depending on how demanding and long your activity will be)
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lemon or lime juice for flavour (optional)
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If you’re losing weight, it’s better to skip electrolyte drinks
If you are trying to lose weight, regularly sipping electrolyte drinks is more of a hindrance than a help. Most commercial sports drinks contain similar amounts of sugar to fizzy drinks (tens of grams per half‑litre), which can significantly increase your calorie intake.
At the same time, electrolyte drinks mainly make sense during prolonged and intense exercise, typically lasting over 90 minutes, when it is necessary to replenish fluids, sodium and energy at the same time. For most recreational workouts (a gym session, shorter run, or group class), an electrolyte drink is not necessary – you can easily obtain energy and electrolytes from regular food and water.
You can include electrolytes without sugar
If you exercise intensely and sweat a lot, but are also losing weight and don’t want unnecessary calories from sugar, a reasonable compromise can be an electrolyte drink without sugar. Studies show that drinks containing electrolytes alone (especially sodium) can, compared with water, improve fluid retention and reduce urine output without increasing energy intake.
Bottom line
An electrolyte drink can be a useful tool if used at the right time – mainly during long and intense exercise, when you sweat a lot and need to replenish not only water but also sodium and some energy.
For regular recreational training, water and normal food are usually sufficient, or you can use electrolytes without sugar. If electrolyte drinks are consumed frequently outside of sports, they can contribute to obesity, high blood pressure or tooth decay.
