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Keeping hydrated during exercise is extremely important. By drinking regularly, athletes can prevent declines in concentration and skill level, prevent excessive elevations in heart rate and body temperature and improve performance – good reasons for all athletes to make fluid replacement a key priority during training and competition.

Fluid requirements are affected by genetics, body size, fitness level, the intensity of exercise and conditions in which exercise is completed, so it is difficult to give general fluid requirements.

However, it is easy to measure your fluid requirements. Weigh yourself before exercise, and again immediately after. Each kilogram of weight loss during exercise is equivalent to approximately 1 litre of fluid. Add in any fluid or food that was consumed during exercise to get a good indication of fluid loss.

Example – I was 2kg lighter after an exercise session in which I consumed 1 litre of water. This means that my total fluid loss was 2 litre + 1 litre = 3litre. I should, therefore, be consuming 3 litres of fluid during an exercise session similar to my test session.

Some important tips:

  •  Begin exercise in good hydration – this means you should be drinking frequently during the day leading up to your exercise session
  • Drink 1 – 2 cups of fluid right before you start
  • Aim to match your fluid losses as closely as possible
  • It is important to drink during exercise for any exercise longer than 30 minutes. Try to drink small amounts regularly during exercise rather than drinking large volumes at one go
  • Drink 150% of your fluid deficit in the 4 – 6 hours following your session (eg. If you lost 3 litres during your test session, drink 4 and a half litres in the 4 – 6 hours following a similar session.)

Water or sports drinks are the best options to drink during exercise. Sports drinks have shown to be helpful in replacing both fluids and carbohydrates in exercise sessions longer than 1 hour. Bear in mind that if you are on a weight loss plan and are doing short exercise sessions (not endurance type exercise) it may not be necessary for you to drink sports drinks – discuss with your Dietician for more specific guidelines. If using sports drinks, choose those that contain 4 – 8 % carbohydrate and 10 – 20 mmol/L of Sodium (Na.)