Isotonic Sports Drink

What's this Science Bite about?

Isotonic drinks are commonly used by athletes, in particular middle and long distance runners. Isotonic drinks have a similar concentration to blood so it is quickly absorbed into the blood stream. Isotonic drinks are not really required when doing gentle exercise, water is sufficient for replacing the lost fluids.

If you are working out and sweating constantly for over an hour and a half, then isotonic drinks will help to replace lost fluids and give you a boost of energy, in the form of a small amount of simple carbohydrates (sugars).

When you drink water your thirst tends to be quenched very quickly and you may stop drinking before you are fully rehydrated. The flavouring in isotonic drinks has been added as it does not quench thirst easily. This is to make you drink more fluids to replace those lost during exercise.

Always remember to ask your parent or guardian to help you.

What you'll need

Fruit squash, water and some salt

  • 200ml fruit squash
  • 800ml water
  • Pinch of salt

How to make this drink...

  1. Mix the fruit squash with the water.
    Adding fruit squash to water

  2. Add a pinch of salt.
    Adding a pinch of salt to the mixture.

  3. Stir well to make sure the salt dissolves. Place in the fridge to cool down. Pour the drink into an empty sports bottle. Start drinking 10 minutes before exercise and throughout work out to stay hydrated and keep your energy levels up.


Glasgow Science Centre