Sports drinks not only help athletes hydrate after exercise but also provide electrolytes, sugar and other nutrients that can be depleted during physical exertion. There are many variations of sports drinks on the market and each has a specific concentration of fluids and minerals that make it appropriate for a unique purpose. During exercise the body heats up causing us to sweat, which is the body’s natural mechanism for cooling the body. As the body is made up of 60 to 70 percent water physical excursion begins to cause dehydration. If dehydration reaches too high a level it can cause negative reactions to the body and performance1. Sports drinks help to replenish fluids by supplying the body with carbohydrates, electrolytes, and water.
Carbohydrates in sports drinks provide fuel to the body and brain as well as some of the flavouring found in sports drinks. Carbohydrates are stored in the body as glucose and are the most effective source of energy the body has during exercise as they are the easiest for the body to burn. As carbohydrates burn quickly during exercise they need to be replaced to keep up Energy levels. Sports drinks containing carbohydrates help to fuel the body with a rapid energy boost, especially in endurance styled events but also exercises and activities which have more of a stop-start movement pattern2. Sports drinks also contain Electrolytes which are the essential minerals that are lost through sweat during exercise including Sodium, Potassium, Calcium, Magnesium, Chloride, Bicarbonate, Phosphate and Sulphate. These salts and minerals are necessary for correct functioning of the nervous system and muscle tissue, delivering oxygen to maintain muscle function, and the flow of fluid in and out of cells.
There are three main types of sports drinks on the market; Isotonic, Hypertonic and Hypotonic3. Each has a different concentration of nutrients, carbohydrates and water and therefore can have different effect on rehydration level it gives your body. It is important to know the effects of each type of sports drink to choose which is right for you and the exercise you are undertaking. Isotonic sports drinks are made to replicate the body’s natural concentrations of nutrients and water. Isotonic refers to a state of equilibrium where the body’s natural levels are in balance allowing equal pressure of fluids to enter and exit the body’s cells; this in turn causes cells to maintain their natural balance of water. Most sports drinks are isotonic. Hypertonic sports drinks have a lower proportion of water in comparison to nutrients and typically have a higher concentration of carbohydrates. Once a hypertonic drink enters the body the imbalance of nutrients and water causes osmotic pressure which draws water out of cells. Hypertonic sports drinks are used to supplement daily carbohydrate intake normally after exercise to top up muscle glycogen stores. Because hypertonic drinks deplete the water levels within cells it is important that when used during exercise these are used in conjunction with isotonic sports drink in order to replace fluids. Hypotonic sports drinks work in the opposite way to Hypertonic containing a higher proportion of water, and a lower level of sugar than naturally occurs in the body. As this drink has a higher water component than nutrients osmotic pressure causes water to naturally enter into the body’s cells and to quickly replace fluids. Hypotonic sports drinks are great for replacing fluids quickly without the additional carbohydrates.
When should sports drinks be used? When sports drinks are consumed up to an hour before exercise they provide the body with carbohydrates which increase the body’s store of glucose energy in the muscles and Liver, and sodium which reduces urine water loss before exercising. During exercise sports drinks are ideal for replacing lost fluids and increasing energy. After exercise sports drinks can increase the rate of rehydration, replenish essential minerals lost through sweating or provide a quick source of carbohydrates to help with glycogen replenishment.
Sports Drink Supplements are commonly presented & sold as Formulated Supplementary Sports Foods in Australia. Sports drinks are not a sole source of nutrition and should be used in conjunction with an appropriate physical training or exercise programme. Not suitable for children or pregnant women. Should only be used under medical or dietetic supervision. Always read label prior to use.1. Coyle (2004), Fluid and fuel intake during exercise. Journal of Sports Science, 22: 39-55