hydration

Humans are made up of between 60 - 80% water. Through the day we lose water from our bodies through sweat, exhalation and excretion and if we don't replace it we start to become dehydrated.

When exercising, the rate at which we lose water from our bodies is increased and studies have shown that even a small (2%) drop in body weight through dehydration can cause a significant reduction in performance; 6-7% slower over 5 and 10km

Before exercise

The American College of Sports Medicine (ACSM) recommends consuming about 500ml of fluids about two hours before exercise, and 125-250ml immediately prior to exercise to delay the onset of dehydration.

During exercise

As soon as you start exercising you will start to lose fluids. Aim to drink 125-250ml for every 10-20 minutes of exercise. Studies have shown that you can maintain optimal performance if you replace at least 80% of sweat lost during exercise.

When exercising, always have a drinks bottle with you, especially if the workout is going to be longer than half an hour.

If you are competing in an event such as a race, it is advisable to find out what (if any) drinks will be provided along the route.

If you have only ever run with water and then take a sports drink like Lucozade on whilst racing you may find you have an adverse reaction to it.

After exercise

Researchers recommend that you should consume at least the equivalent of 1.5 times the fluid lost during exercise.

You can work out roughly how much you lose during a workout session by weighing youself before and after and taking one away from the other (remember to take into consideration any fluids you consumed during the session).

Work on the basis that 1kg lost body weight is about 1 litre of fluids. Don't drink all this fluid straight away, but aim to consume it within about an hour of finishing your workout.