Tuesday, 8 July 2014

What should you drink?

Continuing the blog on hydration, I thought I would look at the different types of drinks and when they may be useful in different situations.

When training or exercising, athletes need to consider the intensity of their session, the duration of the activity and the environmental conditions, and how these may affect their sweat rates. For example, if their session is a light aerobic session in a cool environment, their sweat rates and energy needs are going to be lower than if they were training at a high intensity on a hot summer's day.

Some sports have very little change in environmental conditions such as swimming or indoor sports, whereas some sports involve varying conditions and therefore athletes need to understand how their body responds to different conditions and be prepared in order to ensure they maximise their training and recovery.

There are three different types of drinks, based on the solute concentration and their osmotic pressure. 

Hypotonic - generally contains less than 4g of carbohydrates per 100ml. It provides little energy, but will be taken up by the body quickly, and therefore ideal for recreational sports or shorter or less strenuous exertion.  Examples include:
  • Water
  • WeakCordial 
Hypertonic - this type of drink generally has more than 8g of carbohydrates per 100ml and greater osmotic pressure than bodily fluids. Its main aim is to supply energy and the fluid is taken up more slowly than water. Ideal use is 30-60 mins before exercise and immediately after sports.  They are also useful for athletes who find they need a bit more energy.
  • Milkshakes
  • Smoothies
  • Concentrated Fruit Juices 
Isotonic - this type of drink contains between 4-8g of carbohydrate per 100ml and has about the same osmotic pressure as bodily fluids. An Isotonic drink is taken up by the body about as quickly as water and they are intended to help hydration and provide energy.
  • Sports Drinks
  • Squash

Also considering the different times athletes may need to choose different drinks. 

Before Exercise - The main aims are to ensure the athlete is hydrated before exercise, as athletes will be able to meet energy needs through solid foods, therefore a hypotonic drink such as squash or water will be adequate. If it is prior to competition, and athletes struggle to eat, then isotonic drinks can help meet energy requirements while making sure athletes are hydrated. 

During - This will be dependent on the training programme. Many athletes will be fine with a hypotonic sports drink replacing fluid loss and athletes should choose drinks which are palatable to encourage consumption. However, if the training session or competition is high intensity and longer than 90 min, some athletes may need to include some energy, therefore an isotonic drink will meet an athletes needs. Other ways to meet this need if athletes prefer to drink water is to take a high carbohydrate snack to have alongside training which can be consumed at an appropriate interval. 

After - The session type and environment conditions will influence the athlete's choice of drink. After a  high intensity session, it is going to be important to replace energy and fluid needs. If an athlete is able to eat immediately after a session, a high carbohydrate snack alongside squash or water should be sufficient to meet their needs. However, if an athlete struggles to consume any food following a training session, a hypertonic drink which is high in carbohydrate will be able to support this. This is why many athletes now choose to drink milk or milkshakes after a training session. Athletes should be aware of when their sweat rates are high and make sure they adequately replace their fluid intake in the hour after a training session.

Athletes can monitor their hydration by comparing to a pee chart, a simple indication of their hydration status, with the idea to be on the paler side of the chart.  One of the main things is to to be happy and comfortable with what you drink. It could be the best drink which will help performance, but if the athlete doesn't like the taste they probably won't consume as much as is needed. 

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