HYDRATION 

Fluid is vital for life; our bodies are made up of around 60% fluid.  You lose around 2 litres of fluid per day through natural causes. When exercising the movement of our muscles causes our body temperature to rise, in order to prevent us from over heating we sweat. As sweat evaporates from the skin it helps us to cool down.  Sweat contains water and sodium (salt,) therefore on the days you are training your fluid requirements are going to be higher. Any fluid and salt that is lost from the body needs to be replaced to restore the fluid balance. Failure to replace lost fluid results in dehydration which can impair training, competition and can compromise health.   Failure to replace the salt content can result in hyponatremia which can be fatal.

No specific volumes of fluid to be drunk to prevent dehydration can be given due to individual variability i.e.in training programme, some competitors will sweat more than others and sweat losses will be greater in hot weather. Therefore it is important you get used to your own fluid requirements, use the following recommendations as a guide to developing your own drinking plan to ensure you remain hydrated.

A guide to your fluid replacement:
Drink regularly throughout the day – e.g. Water, flavoured still waters, squash, cordial and hot drinks are suitable.
Ensure all your food has salt in.
Have a drink with each meal and snack – e.g. water, flavoured still waters and squash.
Keep fluids easy to reach, carry a water bottle with you.
Choose the flavour of drinks you like and keep them cool to encourage you to drink.
Avoid feeling thirsty at the start of your training – Do not rely on thirst to encourage you to drink as by this time you are already dehydrated.
Isotonic sports drinks are suitable to drink immediately before, during and after training as they contain sodium (salt) and a source of carbohydrate. The sodium will help you absorb the fluid and replace that lost through sweating and the carbohydrate will provide you with some energy.
Monitor the colour of your urine and the frequency of urination – The colour of your urine needs to be a light straw colour and urinating at frequent intervals. If your urine is darker in colour and you are not urinating frequently and only small volumes, then you are likely to be dehydrated.
Before:
4 hours before training - drink slowly approximately 5-7ml/kg body weight (i.e. 375 – 525ml if you weigh 75kg) – e.g. water, squash, flavoured still waters are suitable.

2 hours before training -If you have not produced urine or it is dark in colour drink slowly  approximately 3-5ml /kg (225-375ml if you weigh 75kg) examples as above.

During:Training for 1hour +
Have an Isotonic sports drink and an easily digested carbohydrate snack per hour (see table for examples).

Isotonic sports drinks are commercially available, check the label too see that they contain 4-8% carbohydrate (or 4-8g carbohydrate per 100ml) and 10-50mmol/L sodium  i.e. Lucozade Sport, PowerAde, Gatorade and supermarket own brand sports drinks  or alternatively use the recipe below to make your own.  Keep checking the website to see what Sports drink you will be provided at the check points during the event and get used to drinking these during your training.
Begin drinking early in training and drink SMALL volumes frequently this will help to avoid any stomach upset.

Drink approximately 300-400ml (1/2 to 1 pint) per hour of training for smaller competitors, when the weather is hot >600ml per hour).
Drink approximately 800ml (1 ½ pints) per hour for bigger competitors and those who are heavy sweaters, again when the weather is hot your fluid requirements will be higher.
Be careful not to drink too much, over drinking can be more dangerous than dehydration and can cause hyponatremia.

After excercise:
Regardless of how long your training session is for you will continue to lose fluid and salt afterwards through ongoing sweat and urine losses so drink well immediately following training.

An isotonic sports drink is suitable to drink immediately after training.
Drinking plain water is suitable if taken with a snack containing salt immediately after training.
Continue to drink well with all snacks and meals.
Continue to monitor urine colour and frequency of urination as previous.
 

Recipe to make an Isotonic Sports Drink
50-70g sugar, 1litre of water or sugar free squash, 1/5th teaspoon (1g) salt.   Dissolve sugar in warm water and add to remaining 900ml cold water/sugar free squash

Or
500ml unsweetened fruit juice, 500ml water, 1/5th teaspoon salt (1g) (Taken from the Dietitians in Sport and Exercise Nutrition website www.disen.org/)

Summary
When training you need to drink more to replace the fluid and salt lost from sweating.
·         Get used to your own fluid requirements and develop a drinking plan to help you keep hydrated.

·         Check the colour of your urine and the frequency you urinate.

·         In hotter weather you will need to drink more.

·         Drink isotonic sports drinks during your training.

·         Do not over drink.

This information should be read in conjunction with the page on hyponatremia