In shopping centres and sport nutrition stores you can find a wide array of sports drinks. Most well-known being Isostar, Gatorade and Powerade. These beverages contain ingredients the human body secretes or uses during physical activity for muscle contraction. The ingredients include minerals, carbohydrates or sugars, and in addition to that most of these beverages also include various (artificial) sweeteners, aromas and other additives that enhance the flavour. Some of them also contain various ergogenic aids that act as stimulants, such as caffeine or ingredients that in theory enhance certain metabolic processes, such as L-carnitine that aids the oxidation of fatty acids. Based on concentration of these ingredients in beverages and related osmolarity, sports drinks may be divided into isotonic, hypotonic, and hypertonic.
The first ones include 6-8% sugars, as this concentration enables the fluids to empty from the stomach and flow through the wall of the small intestine into the blood stream, the same as while drinking water. However, isotonic drinks contain carbohydrates that the body burns during physical activity. They also contain more minerals to replace the minerals lost through sweat and urination (the exact quantity is subject to individual) and thus prevent excessive urination. Hypotonic drinks contain smaller concentration of sugars, usually around 2-4%, and are suitable for sports that burn less sugar, such as running. Hypertonic drinks, on the other hand, contain greater concentration of sugars, around 10-13%, and are suitable particularly after physical activity to replace the used glycogen. Of course, hypotonic and hypertonic drinks also include minerals, such as sodium, chloride, potassium, calcium, magnesium, carbonate, phosphate, sulphate.