Supplements are now found in every race, and fill the shelves of supermarkets as well as sports shops: sports drinks are now inseparable companions of every amateur athlete even if often we do not know exactly what we are drinking. Are we sure we are drinking exactly what our body needs when it is engaged in physical exertion, with heat or not, and therefore with abundant or normal sweating? We asked this to Dr. Sara Cordara, an expert in nutrition and sports integration and collaborator of the Centre for Sports Medicine of the Faculty of Motor Sciences of the University of Turin.
What supplements to drink when doing sport
“For training sessions that last less than an hour, it is not necessary to use a supplement: the water is enough and advances,” says the expert. “When you exceed the hour it may make sense to drink sports drinks. The important thing is to know that sweating disperses mainly chlorine and sodium, and among those on the market would be good to choose hydro-saline supplements that can really restore these two salts.
These are the ideal values of a hydro-saline supplement, to be compared with the label of those on the market:
Sodium (Na) = 600 / 1000 milligrams per litre
Chlorine (Cl) = 600 / 1000 milligrams per liter
Potassium (K) = 50 / 250 milligrams per litre
Magnesium (Mg) = 10 / 100 milligrams per litre
Calcium (Ca) = 50 / 200 milligrams per litre
Here you can read the difference between isotonic, hypotonic and hypertonic sport drinks and the indications on how to recognize them and when to use them for your workouts. And if in doubt, know that supplements are neither drugs nor doping and yet even drinking too much when doing sports can pose some risk.
Isotonic drinks are those that have an osmolarity equal to that of human plasma, which usually ranges between 280 and 330mOsm/kg. Precisely because of this substantial equivalence of concentration of the solute, isotonic drinks are the most suitable when it comes to rehydrating the body quickly, for example during intense physical activity in conditions of high temperatures: the same osmolarity of the sport drink and plasma makes sure that the electrolytes necessary to rehydrate (mineral salts) are provided without altering the balance of the solution of the plasma. For the same reasoning isotonic drinks are also those indicated when there is a need for immediate energy. This does not mean that all isotonic drinks are also energetic: they are energetic when they also have a carbohydrate component of about 8%.
Hypotonic drinks are those with an osmolarity lower than that of plasma, i.e. with a lower amount of solute in them than that found in human plasma. Even hypotonic sport drinks allow rapid rehydration, but there is a price to pay: having a lower concentration of moles within them substantially dilute the concentration of salts of human plasma, with the result of decreasing the feeling of thirst but also to impoverish the supply of electrolytes needed. What hypotonic drinks cannot do (or only to a limited extent) is provide immediate energy, due to their low carbohydrate content.
Hypertonic drinks are those with a higher concentration of solute than that of human plasma: this higher osmolarity is given by the presence of a high content of carbohydrates, which is useful to provide long-term energy but certainly not to rehydrate or energize on the moment. There is also another consequence of the intake of hypertonic drinks: because of their higher concentration of moles compared to plasma they tend to attract liquids into the intestine, precisely because of a matter of osmolar balance of the human body, with the potential consequences of dehydration and diarrhea.
What sport drinks should I use?
Given that up to an hour of physical activity, even intense, and in normal temperature conditions, the natural water associated with normal consumption of fruit and vegetables is sufficient and advances to bring liquids, minerals and other components necessary to combat dehydration, in addition to the hour of sport and in conditions of intense heat are certainly indicated isotonic drinks and partly hypotonic ones: When you sweat, you lose more liquids than mineral salts (sweat is a hyperosmotic liquid, with a concentration of solutes of about 80-180 mOsm/l well below 280-330 mOsm/l of plasma) and unless you need high energy needs, you do not need to resort to hypertonic drinks.