Hydration-it is vital!!

Hydration and Exercise

  • The physical process of sweat evaporating from the skin’s surface causes heat to be lost to the surrounding environment. There is nothing you can or should do to stop yourself sweating, especially during warmer conditions when sweating is the first line of defence against overheating.

 This amazing process allows the body to cool itself during exercise but unfortunately it occurs at the expense of fluids. Dehydration can lead to reductions in performance and will present as symptoms such as dizziness, nausea and muscle cramps.


  • With sweat rates as high as 3 litres per hour (l/h) seen in endurance events, and as little as a 2% body mass loss leading to drops in performance, fluid replacement during exercise becomes extremely important.


  • Sweat rates are very individual and are dependent on numerous factors including body mass, exercise intensity, training status and environmental conditions. However, you can monitor your own hydration status during training.


  • An easy method of hydration assessment is to weigh yourself immediately prior to and immediately post-exercise. For accuracy, weigh yourself wearing minimal clothing so that you do not include any sweat trapped in the material, keep an eye on the amount of fluid you drink and monitor how much you urinate during the training session. Then use the following formula:

Sweat Loss formula

(Body weight before – Body weight after) + Amount of fluid intake – Urine output

  • During exercise you should aim to limit fluid losses to less than 2% of your body mass (1.4 kg for a 70 kg person). On the other hand you should never gain weight during a session – this is a clear indication that you are drinking too much and can also cause reductions in performance.


  • During endurance events this is to up to 100-150 ml of fluid every 15-20 min (3 mouthfuls) but will be less for shorter duration events and field athletes. During exercise lasting longer than 60 minutes, include a source of electrolytes, particularly sodium, which will help to retain fluid, stimulate thirst and enhance the absorption of carbohydrate.


  • Following exercise, aim to replace 150% of fluid losses (using the pre/post weighing method). If time is of the essence and you are training again within 4-8 hours, consume fluids as soon as possible but if you have longer to recover then speed is not as important. Ensure you consume a sodium-containing drink or a salted snack to ensure full rehydration.







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