SPORTS DRINKS AND DEHYDRATION

A lack of carbohydrates stored in the body and dehydration (a loss of body fluid e.g sweat and exhaling hot air rough your noise and mouth) are two factors that will limit prolonged exercise.

Dehydration
Sweating is the way in which the body maintains its core temperature at 37 degrees centigrade. This results in the loss of body fluid and electrolytes (minerals such as chloride, calcium, magnesium, sodium and potassium) and if unchecked will lead to dehydration and eventually circulatory collapse and heat stroke.

The effect of fluid loss on the body is as follows:
% body weight lost as sweat Physiological effect (effect on the body)
2% Impaired performance – Lack of concentration
4% Muscle strength declines
5% Heat exhaustion
7% Hallucinations
10% Circulatory collapse and heat stroke


What drinks to keep away from?
Diuretic drinks are drinks that pass straight through the kidneys without being absorbed by the body, such as: Tea, coffee, pop, drinks similar to red bull and alcoholic drinks such as Larger.

How to check you are hydrated
The easiest way to check is when you go to the toilet. If your urine is any darker than a light straw yellow then you are likely to be dehydrated, so check when you go to the toilet, when riding, that your urine is clear.

What is wrong with water?
Drinking plain water causes bloating, stops you feeling thirsty and thus further drinking. It stimulates urine output and therefore is inefficient at retaining water in the body. A poor choice where high fluid intake is required (riding motocross bikes). Water contains no carbohydrates or electrolytes.

Sports drinks – 3 types
There are three types of sports drinks all of which contain various levels of fluid, electrolytes and carbohydrate.

TYPE CONTENT
Isotonic Fluid electrolytes and 6 to 8% carbohydrate
Hypotonic Fluids electrolytes and a low level of carbohydrate
Hypertonic High level of carbohydrate


Which is most suitable?
Isotonic – quickly replaces fluids lost by sweating and supplies a boost of carbohydrate. This drink is the choice for most athletes. Glucose is the body’s preferred form of energy therefore it may be appropriate to consume Isotonic drinks where there carbohydrate source is glucose in a concentration of 6% to 8% - e.g. High Five, SiS go, Boots Isotonic, Lucozade Sport.

Hypotonic – quickly replaces fluid lost by sweating. Suitable for athletes who need fluid without the boost of carbohydrate – jockeys and gymnasts.

Hypertonic – used to supplement daily carbohydrate intake normally after exercise to top up muscle glycogen stores. In ultra distance events high levels of energy are required and Hypertonic drinks can be taken during exercise to meet the energy requirements. If used during exercise Hypertonic drinks need to be used in conjunction with Isotonic drinks to replace fluids.

Dental Care
Sports drinks commonly contain citric acid. All acids have an erosive potential but the method of drinking will influence whether or not those acids effect the teeth. Sports drinks should be consumed as quickly as possible, preferably with a straw and not to be held or swished around the mouth. Retaining drinks in the mouth will only increase the risk of erosion. Refrigerated drinks will have a reduced erosive potential as the acid dissolution constant is temperature dependant and cold drinks are absorbed more quickly.

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