What does the ideal isotonic sports drink contain?

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Depletion of carbohydrate stores in the body and dehydration are the two main causes of fatigue in endurance exercise. Because endurance athletes often take too much or too little carbohydrates, and often in the wrong concentration, the absorption of carbohydrates and fluid is not always optimal. As a result, performance loss can occur, and gastrointestinal symptoms can develop. By choosing a qualitative isotonic sports drink, these symptoms can be prevented to some extent.

Besides a good taste, because a pleasant taste encourages you to drink, the ideal isotonic sports drink meets the following criteria:


The osmolality (osmotic pressure) indicates the number of particles (carbohydrates, electrolytes, ...) in a drink and determines the absorption rate in the intestines. In a drink with fewer particles than in blood plasma (= hypotonic) less carbohydrates are often supplied while a drink with more particles (= hypertonic) has a negative effect on fluid absorption which increases the risk of gastrointestinal symptoms. Therefore, an isotonic sports drink contains as many particles as the blood plasma (270-310 mOsm/l), and is the ideal compromise in situations where both rapid absorption of water and energy are required.

Ideal sugar combination and concentration:

An isotonic sports drink preferably contains ± 60 g of carbohydrates per litre. At a higher concentration, gastric emptying slows down and the drink often becomes hypertonic. Maltodextrin should be the main component of a qualitative isotonic sports drink. This is a chain of glucose molecules that has a lower osmolarity in solution than sugars. Moreover, maltodextrin is not too sweet and and not as sticky as sugar. Ideally, the maltodextrin is further complemented with a sugar combination of glucose, sucrose (~ table sugar) and / or fructose in a ratio of 2 parts glucose versus 1 part fructose. This allows the body to absorb up to 90 g of carbohydrates per hour during exercise, while drinks without this 2:1 ratio are limited to just 60 to 70 g per hour.

Rich in sodium:

Sodium is the most important electrolyte in sweat. The addition of sodium to sports drinks stimulates thirst and therefore the fluid intake. In addition, sodium causes you to urinate less, so that you can retain more of the fluid you drink in your body and thus prevent dehydration. Although the sweat and sodium losses during exercise vary greatly amongst individuals, the average sodium loss is ± 1150 mg per litre with a range of 460 to 2300 mg per litre. Do you often have "white deposits" on your clothes after exercising? Then, during endurance efforts, you should opt for an isotonic sports drink with a higher sodium content (e.g. 800 to 900 mg/l). For a less "salty sweater", 400 to 500 mg of sodium per litre is already sufficient.

Acid free (Neutral pH):

Citric acid or other organic acids are often added to sports drinks to improve the taste and to increase shelf life. These drinks usually have a high acidity. The pH is a value that indicates acidity: the lower the pH, the more acidic the solution. Tooth enamel dissolves at a pH lower than 5.5. Since sports drinks are usually consumed sip by sip, their residues often remain in the oral cavity for a considerable time. Therefore, athletes who drink isotonic sports drinks on a regular basis should rather pick an isotonic sports drink with a neutral pH (~ 7.0).

Free from unnecessary additives and allergens:

Extra additives, such as vitamins, increase the osmolality of a sports drink. In addition, vitamins do not add any value to an isotonic sports drink because a vitamin deficiency does not develop within a period of several hours. Natural ingredients should be the preferred components of an isotonic sports drink, while allergens and artificial additives are best minimised / avoided as much as possible. In doing so, only a few athletes will be excluded from being able to use the drink.

After finishing reading this article, you finally know what to look out for during your search for the ideal isotonic sports drink!