CHOICE OF SUGAR
Sugar selection is very important. Fructose is suitable, since a solution containing it rapidly reaches the stomach and, besides, it does not need insulin - which is always very low during hard physical activity - to enter muscular fibre. Maltodextrins are also ideal for refueling with energy, especially when they are mixed with fructose.

SALTS
Some years ago, many athletes used very high quantities of common salt in order to enrich their drinks. Together with causing stomach problems, salt itself does not help in recovery of prevention of lacks in general, but it sometimes causes  a larger imbalance. Sweat contains a minor quantity of sodium compared to blood, and, therefore, consuming more salt than water can elevate the quantity of a substance which is already excessively present in our body, by giving only a small quantity of what it needs. According to Costill, an authoritative American physiologist, we have to consume no more than 40-50 milligrams of sodium every 100 grams of water. Potassium and magnesium must always be present in quantities of 10-20 milligrams per 100 grams of water (concentration similar to that of plasma).

CONCLUSIONS
An athlete must know that the ideal drink contains little salt and sugar, in order to allow rapid absorption of nutrients in the intestine. All the ingredients (carbohydrates and minerals) must assure that the osmotic concentration of the drink is the same (isotonic) or, better, lower (hypotonic) than that one of plasma, - 280-300 mOsm/l (unit of measurement for the concentration of a drink).
Please note that a drink conceived to through the stomach very quickly can also avoid all those problems caused by liquids that become stagnant.