How do you choose the ideal isotonic sports drink?

In addition to good taste, the ideal isotonic sports drink should meet five guidelines:

1. The ideal osmotic value for rapid absorption of carbohydrates and fluids

The osmotic value of a sports drink refers to the concentration of dissolved particles, such as carbohydrates and minerals, compared to the dissolved particles in the blood. This affects how quickly the drink is absorbed into the body and how long it stays in the stomach.

The ideal isotonic sports drink has an osmotic value equal to that of blood plasma, ensuring that both fluids and carbohydrates are absorbed quickly and effectively in the intestines. An isotonic drink typically contains 4 to 8 grams of carbohydrates per 100 ml. This not only promotes rapid fluid absorption but also provides the necessary energy.

In addition to isotonic sports drinks, there are also hypotonic and hypertonic variants, which differ in osmotic value. A hypertonic sports drink has a higher concentration of dissolved particles than the blood, causing the fluid to stay longer in the stomach and delaying absorption. This can lead to stomach and intestinal discomfort, as the body struggles to process the drink quickly. Hypertonic drinks often contain a higher percentage of carbohydrates, making them suitable for prolonged or intense exertion, but they are not always well-tolerated during physical activity.

On the other hand, a hypotonic sports drink has a lower concentration of dissolved particles than blood plasma, which allows for faster absorption of both fluids and carbohydrates. The drink is quickly emptied from the stomach and reaches the intestines, making energy available more quickly. Hypotonic drinks are often recommended for shorter efforts or situations where hydration is the main priority, but they usually provide less energy than isotonic or hypertonic drinks.

2. Why sodium and other minerals are essential in isotonic sports drinks

Since sweat is not made up of water alone, it is important to replenish the minerals we lose through sweating, especially sodium. This mineral plays a crucial role in retaining fluid in our bodies and helps prevent excessive fluid loss during exercise. Additionally, sodium affects our thirst response. It stimulates thirst and ensures that the ingested fluid stays in our cells for longer.

An ideal isotonic sports drink contains between 400 and 1100 mg of sodium per liter.

3. A neutral pH prevents gastrointestinal issues and tooth erosion

Organic acids like citric acid are often added to isotonic sports drinks to improve both shelf life and taste. However, these acids can significantly lower the drink's pH. A low pH can cause gastrointestinal discomfort and have a harmful effect on tooth enamel. Tooth erosion can even occur when the pH in the mouth drops below 5.5.

Athletes who frequently consume isotonic sports drinks should therefore choose a drink with a neutral pH of around 7.0. This helps prevent both gastrointestinal issues and tooth erosion.

4. The right carbohydrate ratio: 2:1 glucose:fructose for optimal absorption

During intense exercise, the body can absorb a maximum of about 60g of glucose per hour from the intestines due to saturation of the glucose transporter. In prolonged exercise lasting more than three hours, this becomes a limiting factor as the carbohydrate requirement exceeds 60g per hour. By consuming different types of carbohydrates, such as glucose and fructose, simultaneously, the total carbohydrate absorption can increase to 90g per hour or more, as absorption occurs via two separate transport channels in the intestines.

Scientific studies show that for intakes up to 90g of carbohydrates per hour, isotonic sports drinks with a 2:1 glucose:fructose ratio are a safe and effective choice for most athletes and contribute to better gastrointestinal comfort.
 

5. Choose a sports drink without synthetic sweeteners and flavorings: better for health and the stomach

Synthetic sweeteners and flavorings, such as aspartame or acesulfame-K, should be avoided in isotonic sports drinks at all times. While these substances may enhance the taste of the drink, they are not suitable for athletes. They can not only increase the risk of gastrointestinal issues but also have negative effects on the health of athletes. Therefore, it is crucial to choose an isotonic sports drink that contains only natural ingredients.