How to make sure you keep up hydration levels during sport
LAST WEEK we looked at the importance of maintaining good hydration during sport and exercise.
Exercise performance is optimised when the fluid balance is maintained, and it is impaired even with moderate levels of dehydration (of as little as 2 per cent of body weight).
There is considerable variety between people with regards to how much fluid they need. It is influenced by factors such as size, sweat rates, environmental conditions and different physical activities.
So specific circumstances need to be taken into account when developing a personal hydration plan.
Working out what you need
Thirst is not a reliable indicator. By the time you are thirsty you are already dehydrated. There are other practical methods you can use to measure hydration.
One quick way is to weigh yourself, in minimal clothing, before and after exercise.
You can also monitor urine colour and volume – to avoid dehydration, your urine should be pale and frequent.
Before exercise
Fluid intake guidelines developed by the American College of Sports Medicine recommend that you slowly drink about 5-7ml of fluid per kg of body (ie, a 70kg individual would take in at least 350-500ml) in the four hours before exercise.
If there is no urine production or the urine colour is dark, add about 3-5ml per kg body weight in the two hours before exercising.
The inclusion of a small amount of sodium or a salty snack will help to retain the fluids consumed.
During exercise
The goal of drinking during exercise is to prevent excessive dehydration and underperformance: this takes planning.
It is often not possible or practical to maintain fluid balance during exercise but as a good rule of thumb, optimum hydration would be achieved by trying to consume around 150-250ml every 15-20 minutes during the activity.
While plain water may be sufficient for moderate duration activities, it is generally recommended that people consume drinks containing 4-8 per cent carbohydrate for intense activities lasting longer than 60 minutes.
In relation to hydration strategies for competition, these should be practised in training to see what works best for each individual.
After exercise
In most cases, those engaging in exercise do not consume sufficient fluids to match water losses through sweating. As a result, training sessions are often completed with some degree of dehydration.
Rehydration after exercise needs to be carefully planned and should reflect fluid losses during training. This is why self- monitoring of hydration status is important.
To ensure you are fully hydrated after training and competition, you should apply the “150 per cent rule” – for every 1kg of weight loss you should consume about 1.5 litres of fluid.
Including a small amount of sodium in your post-exercise drink will speed up the rehydration process by maintaining the drive to drinking as well as promoting fluid retention.
In addition, drinks containing 4-8 per cent carbohydrate will enhance the recovery process by replenishing the body’s depleted glycogen stories.
What to drink?
Sports drinks are commonly used by athletes and are available in many different brands, flavours and types.
Despite scientific evidence supporting the use of sports drinks, consumption of plain water still has an important role to play in any overall hydration strategy.
Isotonic sports drinks supply water, some electrolytes (sodium and potassium) and a small amount of carbohydrate (typically 4-8 per cent).
Enhancing drink palatability may play an important role in promoting fluid consumption both before, during and after exercise.
Palatability is affected by factors such as temperature, concentration, sodium content and flavouring.
Drink temperatures should typically be about 10-15 degrees.
Flavour preference will vary greatly so it is best to try different formulations to see what works best for you.
- Dr Giles Warrington is a sport and exercise physiologist and lecturer in the School of Health and Human Performance at DCU