Spiked

Importance of Fluids in Performance - by Dave Gould

Water is essential for human life and whilst not strictly a nutrient it performs many essential functions in the human body. Healthy adults can survive for many weeks without food but they can live for only a few days without water. The human body is made up of around 75% water which is essential for maintaining body processes like digestion and absorption of food and blood circulation.

Consuming fluid at regular intervals during exercise is therefore essential to safeguard health and optimise performance. Failure to maintain fluid levels during exercise particularly in the heat and during endurance events can be dangerous.

Exercise generates heat, which must be released to prevent the body overheating. Sweating is the most important body mechanism to control this temperature rise and is linked to the need to maintain body temperature within narrow limits of 37-38ºC. The amount of sweat that you produce and loose depends on a number of factors. These include: the intensity you are exercising; the duration; the temperature and humidity of your surroundings and your own individual physiology

It is essential that fluid lost as sweat and through breath is replaced, or performance will be impaired and the fluid loss could even be life threatening. Loss of fluid left unchecked leads to dehydration. Dehydration results in premature fatigue and increases the risk of heat illness. Dehydration disturbs fluid and electrolyte balance in the body, can damage the energy producing processes of the muscle cells and put increased stress on the heart. In response to dehydration, the body triggers responses in an effort to conserve fluid and return itself to normal.

Physiological Effect	% body weight lost as sweat
Impaired performance	2%
Capacity for muscular work declines	4%
Heat exhaustion	5%
Hallucinations	7%
Circulatory collapse and heat stroke	10%

Preventing Dehydration in Exercise

Drinking fluids during exercise is the best way to prevent dehydration and maintain physiological function. Consumption of fluid before, during and after exercise is now widely endorsed as the primary measure in preventing dehydration during all sports.

Simple steps in your fluid plan to remain hydrated and maintain performance

1. Accustom your body to increased fluid intake during training and competition.

2. Ensure you are fully hydrated before taking any exercise. Never start exercising in a dehydrated condition. It is generally recommended that you should drink 500ml fluid 2 hours before exercise.

3. Avoid large amounts of alcohol the night before you exercise. Alcohol has many side effects on performance including: Increase water excretion (Urination) and hence promotes the risk of dehydration; it reduces the bodies’ ability to regulate temperature and sugar levels and hence the later may increase the risk of hypoglycaemia.

4. Always remember that thirst is not a good indicator of the status of the body's fluid stores. It is generally recommended by sports physiologists that a performer takes small volumes 125-150 ml of water regularly every 15-20 minutes during exercise. Do not wait until you are thirsty before drinking.

5. Although plain water can be helpful remember that it does not provide electrolytes or additional carbohydrate to boost energy intake. It has been shown that specially formulated isotonic sports drinks are superior. This is particularly important for intense exercise which lasts for up to an hour. A sports drink containing up to 8 g Carbohydrate and electrolytes per 100ml can speed up water absorption, provide additional fuel, delay fatigue and hence improve performance. Look for Hypertonic Drinks.

6. After exercising, start to re-hydrate immediately. Do not wait for several hours. Take at least 500ml of a specially formulated sports drink.  Again this is particularly important after intense periods of training and exercise. However it is generally recognised that sports drinks may be better than water at speeding recovery after exercise. The problem with drinking plain water is that it causes a rapid fall in plasma osmolality and reduces the drive to drink even before sufficient fluid has been consumed to replace losses. The addition of electrolytes, especially sodium and potassium to a drink, reduces urine output in the post exercise period and is effective in increasing the fraction of the ingested fluid that is retained, thus effectively promoting re-hydration.

7. Wear appropriate clothing to allow sweat to evaporate effectively. This free flow of air also supports the body’s ability to cool down.

8. Think about your training environment. On hot and humid days the evaporation process is less efficient and you need to sweat even more to control body temperature. This is particularly important in countries with predominantly hot and humid climates. Therefore it is important to think about the following:

• Time of day ( On hot days train early or late in the day)

• Gym environment ( Is your training gym well ventilated with good air flow)

• Ensure sufficient recovery and rest periods to accommodate for hot and humid weather conditions.

9. Sports scientists have noted that in hot conditions the body’s priority is to replace water rather than carbohydrate. So it is important to drink water or a dilute carbohydrate drink rather than a more concentrated carbohydrate drink. Conversely if you train on a cold day and sweat only a little it may be more beneficial to drink a more concentrated carbohydrate drink.

10.  

    Finally always stick to the guidance that you need to drink before, during and after any training, exercise or competition activity.