Sport and hydratation, when water is not enough

Instead of what old believes stated, during sport drinking is necessary. In fact, rehydrating the organism is essential due to the waste of liquids, which might be also substantial in case of prolonged and strong-competitive-effort sports. Besides being counterproductive, lack of drinking might even reveal to be greatly dangerous to the organism, which risks to suffer serious damages.

Even though in most cases “mere” water might be absolutely enough, especially to people playing sports at medium-low levels of strength and following an adequate and varied diet, to people more strongly committed or even playing competitive or medium-long lasting sports mere water is not enough.

It is necessary to restore not only the mineral salts lost sweating, but also new energies ready to be used, in order to allow to continue playing sport.

Not every drink or supplement fits, and that which fits some kind of situations might not fit other ones. One of the elements to be strongly taken into account in the choice of the adequate drink is its osmotic pressure.

Osmotic pressure is the result of the amount of solutes (mineral salts, sugars etc.) dissolved in a solvent (water). At an equal amount of solvent, the higher is the percentage of solutes, the higher osmotic pressure is. Liquids tend to move from a low osmotic pressure region towards a high osmotic pressure one, until the pressure of the two components is balanced.

Human plasma, too, has its own osmotic pressure. As a result of this, for drinks with such amount of solutes as to be hyperosmotic (hypertonic drinks) for what concerns plasma, it will take a medium-long period of time to enter the haematic flux. For isosmotic drinks (isotonic drinks, i.e. at equal osmotic pressure) it will take less time. It will take a very short time for hyposmotic drinks (hypotonic drinks at low osmotic pressure).

Therefore, during competitions it is important to choose isotonic or hypotonic drinks. In such kind of drinks, for each 100 ml of water there is an average amount of less than 5g for carbohydrates; less than 45 mg for sodium; less than 20 mg for potassium and less than 12 mg for magnesium.

Another feature to take into account is the type of sugars dissolved in water. Indeed, the various types of carbohydrates tend to have different glycemic index, i.e. the tendency to lead the organism to release insulin. During sport, the body tends to oppose insulin release. For reasons on which we are not going to dwell, it would be better to avoid to “force” this process by taking high glycemic index glucides. Therefore, as to sugar, we would rather prefer fructose (to glucose) since its glycemic index is about 22.

glycemic's index % of some sugars
fructose: 22
lactose: 46
saccarosio: 64
glucose: 95
maltose: 102


Traslated by Manuela Mercurio