Hydration

What’s all the fuss?

Water is vitally important whether you exercise or not. It helps the body to regulate temperature, transport nutrients and oxygen, it carries away waste products, helps to detoxify the kidneys and liver and dissolves vitamins and minerals for the body. In general, we need about 2-3 litres of fluid a day to be properly hydrated.

Hydration for exercise

Exercising will increase your fluid needs. The more you sweat, the more you need to drink to replace the lost fluid. Some people naturally sweat more than others and even small sweat losses can cause fatigue. The fitter you become the more effectively your body will need to keep itself cool—so more sweating! Training harder and longer or in hot and humid surroundings will also make you sweat more.

Replenishing the Body

It is important to limit dehydration whilst exercising. Just 2% dehydration can lead to a 10% reduction in exercise performance. One way to do this is to try to replace fluid at the rate that the body looses it. Don’t leave it to voluntary fluid intake (i.e. when you feel thirsty) that will be too late and you’re only likely to replace half of what you’ve probably lost. The best way to estimate how much fluid (sweat) you lose is to weigh yourself before and after exercise. Each kilogram of weight loss is equivalent to one litre of fluid loss. Try to replenish fluids during exercise as well as after you finish.

Dehydrating Conditions

Certain conditions can cause dehydration to be accelerated. In hot or humid weather the body needs more fluids, this is also true for cold conditions and if you’re at high altitude. If you have a cold or the flu then you should drink more water to help the body fight off the illness.

What fluids?

Water is best, but milk, juices and other beverages are about 90% water so they can meet hydration needs. Caffeinated beverages and alcohol act as diuretics and increase fluid loss.

Before Exercise

Always start every session well hydrated. Drinking 400-600ml of fluid 2 hours before exercise will help hydrate the body.

During Exercise

Aim to drink enough to limit fluid lost through sweating

After Exercise

How much fluid you need to drink depends on how much you’ve lost. Drink 1 litre for every kg of weight lost during exercise