Athletes can lose between 2-3 litres of sweat during 90 minutes of intense exercise, particularly in hot and humid conditions. They can also lose as much as 2-3 kg (4-6 lbs) in bodyweight during the same period. This amount of fluid loss will certainly have a negative affect on performance.
Ideally to counteract dehydration, athletes should consume 200-400 ml (7-14 oz) of cold water or a suitable carbohydrate solution 5 to 10 minutes prior to the start of their event. During the any intervals, they should try to drink another 300-500 ml (10-17oz) of a sports drink. During hot weather or strenuous training sessions, coaches should try to provide their athletes with 150-250 ml (5-8oz) of drink about every 20 minutes.
Following a match or hard training session, it's essential that lost fluids be replaced. Water on its own is fine, but to replace fluid AND replenish energy stores, a high carbohydrate drink may be more suitable.
The right carbohydrate drink taken before and during composition can postpone fatigue and stabilize blood sugar preventing light-headedness, headaches, nausea and "jelly-like" muscles. However, not all carbohydrate drinks are created equal. Too much carbohydrate or sugar can actually hinder performance.
A solution that contains 40% carbohydrate empties the stomach much slower than plain water (which is 0% carbohydrate). This means that high sugar drinks such as Coca Cola, regular Lucozade, Exceed High Carbohydrate Source and Gator Lode (up to 40% carbohydrate) are NOT the best fluids to consume before or during exercise.
The ideal sports drink should contain 6-8% carbohydrate. It should also contain a small amount of salt. Sodium concentration in the blood can reduce due to sweating and drinking lots of diluted fluids. If it gets too low it can lead to nausea, headaches and blurred vision. Adding just a pinch of salt can offset this potential danger.
Sodium is also an electrolyte. Electrolytes help control the passage of water between body compartments and they also help to maintain the acid-base balance of the body. Electrolytes (or lack of them) have been associated with muscle cramps in the latter stages of sport games.
Here are some effective sports drinks currently on the market suitable before and during a match or training session:
Drink 200-400 ml (7-14oz) of a suitable sports drink 5 to 10 minutes before the start but no earlier unless it's several hours before the start. During any intervals drink up to 300-500 ml (10-17oz). In hot climates try to drink 150-250 (5-8oz) ml every 20 minutes or so.
Within two hours after the event you should aim to consume 100-200 grams of carbohydrate. Muscles are depleted of carbohydrate stores, which need to be replenished as quickly as possible. Sometimes it can be impractical or unpalatable to eat a large meal immediately afterwards. High carbohydrate drinks offer a convenient alternative.
The sports drinks mentioned in the table above are good but this is one of the few occasions when taking a high carbohydrate drink is preferable.
You may have heard of "isotonic" sports drinks that have been "scientifically developed in conjunction with top athletes". But it's very easy to make your own, low-cost carbohydrate drink that is just as effetive!
Isotonic means a fluid containing electrolytes and 6-8% carbohydrate (such as the sports drinks in the table above). To make your own add 200 ml (7oz) of concentrated orange juice (orange squash) to 1 litre (34oz) of water and add a pinch (- teaspoon) of table salt.
Hypotonic is a fluid that contains electrolytes and a very small amount of carbohydrate. This is used in very hot conditions where fluid replacement is the most important factor. To make your own add 100 ml (3.5oz) of concentrated orange juice to 1 litre (34oz) of water and add a pinch (- teaspoon) of table salt.
Hypertonic refers to a fluid that contains a large amount of carbohydrate and is ideal for refuelling after a game. To make your own add 400 ml (13.5oz) of concentrated orange juice to 1 litre (34oz) of water and add a pinch (- teaspoon) of table salt.