Sport Nutrition Education Series

Sport Nutrition Education No. IV - Water - The Fountain of Life

Functions of Water

1. Regulates body temperature

2. Transports nutrients (e.g. glucose, electrolytes, oxygen, iron)

3. Carries waste products away (e.g. lactate, urea)

Fluid is Lost Through

1. Respiration

2. Perspiration

3. Evaporation from skin

4. Urination

Fluid is Gained By

1. Fluids (e.g. water, juice, soup, milk etc.)

2. Foods (e.g. fruits, vegetables, congee etc.)

3. Metabolism of nutrients (e.g. carbohydrate, fat, protein) releases water

Symptoms of Dehydration

1. Fatigue

2. Flushed skin

3. Shrivelled skin

4. Light headedness

5. Dark coloured urine

6. Delirium

7. Cramps

8. Heat stroke

Guidelines to Fluid Supplementation

Before exercise
Drink 8-24 oz (1 - 3 cups) of fluid one and a half to two hours before exercise, and drink 4-8 oz (? - 1 cup) of fluid 10 minutes before exercise.

During exercise
Drink 4-8 oz (?- 1 cup) of fluid every 15 - 20 minutes. Drinking small amounts of fluid frequently is better than drinking a large amount all at once because drinking frequently allows more efficient absorption and better tolerance to taking fluids.

After exercise
Drink 16 oz (2 cups) of fluid for every pound (or 0.5 kg) of body weight lost.

*	Weight loss after exercise is primarily from loss of body fluids and not fat because you need to burn 3500 kcal for losing a pound of fat.

Note: Every sport has its characteristics. The above guideline is more suitable for events which takes place outdoor, mid and long distance sports (e.g. cycling, long distance running, triathlon, soccer, tennis) and those which require high energy output (e.g. badminton, rowing, windsurfing, swimming). In addition, sports which require the wearing of uniforms with thick materials or long sleeves may enhance loss of body fluids (e.g. fencing, motor racing, American football). Those sports which are highly skill-dependent may not need to drink as much fluid as recommended above (e.g. shooting, gymnastics, bowling, lawn bowling, figure skating, high jump, long jump, sprint running, sprint swimming).

Choosing a Suitable Fluid Replacement Drink

-	for exercise which lasts 90 minutes or less, replacing with water is adequate
-	for exercise which lasts longer than 90 minutes, sports drink is a better choice for the following reasons: Supplies energy (carbohydrates) Commercial sports drinks available in the market normally contain 6 % carbohydrates, and are absorbed as quickly as water Maintain fluid and electrolyte balance

Beverages to Avoid During Exercise

1. Caffeinated beverages (e.g. cola type soft drinks, coffee, tea)

2. Alcoholic beverages (e.g. beer, wine, cocktail)
   * Caffeine and alcohol are diuretics which promote fluid loss.

3. Carbonated beverages (e.g. soft drinks, soda water)
   * Carbonation leads to sensation of stomach fullness and burping which decrease the desire to drink.

Thirst is not a reliable signal because when thirst is apparent the body's ability to regulate heat is already impaired. Therefore, one must make rehydration a habit and drink appropriate amount of fluid even when not feeling thirsty.

Dehydration can have detrimental effects, it may lead to heat stroke and even death!

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