Benefits of Sports Drinks
Broadly speaking, a sports drink is any beverage that is designed to help athletes replenish water, electrolytes, sugar, and other nutrients that are usually depleted after training or workouts.
Electrolytes
The human body maintains a temperature of 37 degrees centigrade by cooling off and dissipating extra heat through sweating. However, sweating is accompanied by the loss of body fluids and electrolytes (minerals such as calcium, magnesium, sodium, potassium, and their compounds). If this loss is not replenished, then it leads to dehydration and impaired performance. In the long term, it can lead to decline in muscular work and eventually circulatory collapse and heat stroke.
Electrolytes serve two general functions in the body - they control the osmosis of water between body compartments and they maintain the acid-base balance (required for normal cellular activities).
Glucose
Carbohydrate is one of the biggest sources of energy in the body and is stored as glucose in the liver and muscles. The normal body stores of carbohydrate in a typical athlete are:
70kg male athlete - Liver glycogen 90g and muscle glycogen 400g
60kg female athlete - Liver glycogen 70g and muscle glycogen 300g.
During strenuous exercise, carbohydrates are depleted from the body at a rate of 3-4 grams per minute. If this continues for more than 2 hours, then a large amount of carbohydrates will be lost and, if not replenished, will result in reduced performance. It normally takes about 24-48 hours to completely recover the lost carbohydrates.
Thus consuming carbohydrates before, during, and after exercise helps prevent blood glucose levels falling too low and maintain glycogen stores. However, since many athletes do not consume food before or during exercise, they consume drinks that replenish carbohydrates.
Re-hydration
The speed at fluids from a drink are absorbed into the body, depends on the speed at which it is emptied from the stomach and the rate at which it is absorbed through the walls of the small intestine. Higher the carbohydrate levels in a drink, slower is the rate of at which the stomach empties. Isotonic drinks with a carbohydrate level between 6 and 8 per cent are emptied from the stomach at a rate similar to that of water. Presence of electrolytes (such as sodium and potassium) in a drink will reduce urine output and enable the fluid to empty quickly from the stomach, thus promoting absorption from the intestine and encouraging fluid retention.
Sports drinks are divided into three types, depending on the levels of fluid, electrolytes and carbohydrate present in them:–
1. Isotonic (6-8 per cent carbohydrate),
2. Hypotonic (low level of carbohydrate), and
3. Hypertonic (high level of carbohydrate).
Isotonic drinks: These drinks quickly replace fluids and supply a lot of carbohydrates. Athletes involved in middle and long distance running, usually consume Isotonic drinks.
Hypotonic drinks: Hypotonic drinks quickly replace fluids without supplying too many carbohydrates. Jockeys and gymnasts, and other sportsmen who require fluids and not much of carbohydrates prefer Hypotonic drinks.
Hypertonic drinks: These drinks are used to top up muscle glycogen stores. In certain events, high levels of energy are required and thus hypertonic drinks are consumed during exercise. If taken during exercise, hypertonic drinks should be used in conjunction with isotonic drinks (so as to replace fluids).
Athletes can prepare their own sports drinks as follows:
Isotonic - 200ml of orange squash (concentrated orange), 1 liter of water and a pinch of salt (1g).
Hypotonic - 100ml of orange squash (concentrated orange), 1 liter of water and a pinch of salt (1g).
Hypertonic - 400ml of orange squash (concentrated orange), 1 liter of water and a pinch of salt (1g). The ingredients are mixed together and chilled.