Isotonic Drinks

The use of isotonic drinks has increased rapidly in the past ten years - what was once the preserve of marathon runners and triathletes is now seemingly a part of everyone's diet.

Why should I consider Isotonic drinks?

Isotonic drinks such as Lucozade Sport are designed to replenish the fluid, energy and electrolytes that are depleted during exercise. This is vital for long distance events, but do you need them for everyday workouts? Let's look first at what is in isotonic drinks.

• Water: Fluid replacement is of course vital - if you don't keep your fluid levels up during exercise you can rapidly dehydrate, resulting in reduced performance.

• Electrolytes: Similarly, you need to replace the essential electrolytes that are lost when you sweat. Research shows that replacing these electrolytes will aid the digestion and osmosis of fluid into body's working muscles. They can thus assist in the process of rehydration.

• Energy: Finally there's the energy in isotonic drinks - this typically comes in the form of glucose, which is used by your muscles as fuel during exercise.

You can use these drinks during your workout, in which case they can help you to train longer than if you just drank water, or directly after exercise to improve the body's recovery rate. There is clear evidence that you can improve your recovery by starting glycogen re-synthesis as soon as possible after a workout.

However, these drinks aren't for everyone. There are several issues to consider:

• Calories: Most of these drinks contain five or six spoons of sugar - if you are looking to lose weight, these are empty calories that your body doesn't need.

• Workout length/intensity: The key to whether or not you need these drinks is how long and how hard you are exercising. The bottom line is that for workouts or runs of less than an hour, they simply aren't necessary. Instead, drink water during your workout, and eat something like a banana soon after to begin glycogen replenishment.

These drinks are a useful tool for long workouts and races, but for most people they are simply extra calories, cleverly marketed.