| 02/07/2016 | 0 Comments More


It is important to understand the need to keep your body hydrated.

Whenever you exercise you lose fluid, not only through sweating but also as water vapour in the air that you breathe out.  The harder and longer you exercise and the hotter and more humid the environment the more fluid you will lose.  If this fluid is not replaced, dehydration will follow.  This will have an adverse effect on your physical performance.  This article explains why it is so important to drink fluids to avoid dehydration.

As mentioned previously the main cause of fluid loss is through sweating.  When you exercise your muscles produce extra heat.  This extra heat needs to be dissipated to keep your inner temperature within safe limits – around 37038degrees C, if this is not done then heat stroke can occur.  Water is therefore carried to your skin via blood capillaries and as it evaporates you lose heat.


The amount of fluid loss depends on four factors:

  • How hard you are exercising.
  • Length of time exercising.
  • The surrounding temperature and humidity.
  • You as an individual.

During 1hr of exercise an average person could expect to lose around 2pints of fluid.

Some people sweat more profusely than other do, even when they are doing the same exercise.  This depends on body weight and size (a smaller body generally produces less sweat), your fitness level (the fitter and better acclimatised you are to warm conditions, the more readily you sweat due to thermoregulation), and some people just sweat more than others.


Dehydration impairs performance and has an adverse effect on health.  It places extra strain on the heart, lungs and circulatory system, which means the heart has to work harder to pump blood around the body, which causes exercise to become harder.

A loss of just 2% in your weight will affect your performance by 10-20%.  If you lose 4% you may experience nausea, vomiting and diarrhoea.  At 5% your performance will decrease by 30%, while 8% will make you become dizzy, weak and confused.

As the body becomes dehydrated the less able it is to cool itself, causing your body temperature to rise.  If you carry on exercising without replacing fluids, your body temperature will continue to rise until you suffer fatigue or heat stroke.


  • Make sure you are well hydrated before you start exercising.
  • Drink whilst exercising; take as much fluid as you feel comfortable with.
  • Drink freely after exercise to replace fluids lost.  Do not wait until you feel thirsty, as this means you are already dehydrated.

It is virtually impossible to drink too much – drinking too little is more often the problem.


Water is a good fluid replacer.  This is mostly what you are losing in sweat and what your body needs.  For most types of moderate exercise, lasting up to an hour, you cannot go wrong by drinking plenty of water.

Drinking sports drinks can have added benefits in certain circumstances:

  • It can replace water lost through sweating.
  • It can provide some carbohydrate to spare the body’s dwindling reserves of glycogen and maintain blood glucose.
  • It can provide minerals to speed water absorption and maintain blood volume.

Ordinary soft drinks and fruit juices are too concentrated in sugar to be used as fluid replacers during exercise.  They empty more slowly from the stomach than plain water because they must be first diluted with water from the body, thus causing a net reduction in body fluid.  In fact they can exacerbate dehydration.

Coffee, tea, cola or any other drink containing caffeine, can be used as a stimulant in both endurance and sprint based activities.  However when it comes to dehydration they are not good because caffeine is a diuretic which causes the body to excrete more water.

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Category: Health News, Nutrition

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