Isotonic drinks are designed to provide athletes with energy and important minerals in a particularly effective manner. However, only a few of the commercially available isotonic drinks can do this – and there are healthier alternatives.
For many people, isotonic drinks are part of sport, after all they are supposed to supply the body with energy, liquid and sweated-out nutrients. In particular, the electrolytes sodium, potassium and magnesium are lost when you sweat.
Your body usually has a certain level of these minerals. When a drink has the same concentration, it is said to be “isotonic”.
Isotonic drinks: how they work
In order to understand what is special about isotonic drinks, you have to deal with the phenomenon of “osmosis”. Imagine a cell in the human body: It is separated from the environment by a cell membrane. On both sides of the membrane is water (after all, we are mostly made of water) in which minerals such as sodium are dissolved. If the concentration of these minerals is different on either side, this is compensated for by drawing water to the side with the higher concentration. This process is known as “osmosis”.
Now let’s apply this to an isotonic drink: since it has the same nutrient concentration as our body, it can pass through the digestive tract without the body having to dilute it with water. With a hypertonic drink (e.g. cola) it would be different: the body would have to compensate for the high nutrient content by diluting the cola with water in the digestive tract. This would temporarily remove liquid from the blood and the digestive tract would have to work harder.
Isotonic drinks, on the other hand, get into the blood quickly and easily. There the contained sugar and the electrolytes are transported to the cells. Isotonic drinks quickly provide energy and important minerals.
Isotonic drinks: do you need them?
According to experts, as long as you only exercise moderately (i.e. less than about an hour at a time) you do not need isotonic drinks – it is sufficient if you quench your thirst with water.
The situation is different in competitive sports: if you do intensive sports for several hours, you should fill up your electrolyte stores. Studies also show that sugar helps maintain performance.
