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Dehydration is the loss of water and fluids from the body, caused, among other things, by inadequate water supply and as a result of diabetes, in kidney disorders, as well as during intense physical exertion due to work or sport. Dehydration leads to the appearance of water-electrolyte disturbances. Its first symptom is fatigue.


In addition to fatigue, other early symptoms of dehydration are:

  •  Headache.
  • Dry mucous membrane of the mouth - dry or 'cotton-like' mouth.
  • Dizziness or lightheadedness.
  • Weakness.
  • Rapid heartbeat.
  • Dry, reddened skin.
  • Muscle cramps.
  • Dark coloured urine and low urine volume.


During physical activity, body heat rises very rapidly due to working muscles. One of the main functions of fluids is to maintain basal body temperature, so when body heat rises, the body compensates by sweating. As the sweat evaporates, the skin and blood (which flows through the vessels near the surface of the skin) are cooled. This cooled blood then flows back into the body, thus lowering the internal body temperature.

The body cannot cool itself properly when dehydration occurs. Serious injuries or illnesses associated with overheating, such as exhaustion and heat stroke, can occur when excessive fluid loss is not replenished during exercise and the body temperature rises. Symptoms of heat exhaustion include dizziness, weakness, racing pulse, low blood pressure, headache and elevated body temperature. Symptoms of heat stroke may include sudden cessation of sweating, clumsiness or stumbling, disorientation, vomiting and loss of consciousness. Death can occur along with heat stroke.

Dehydration reduces stamina and increases the risk of heat-related illnesses such as heat exhaustion and heat stroke. When the body becomes dehydrated, productivity decreases significantly. A water loss equal to 5 per cent of body weight, can reduce muscle performance by 20 to 30 %



Thirst is not a good indicator of water requirements!!
Because exertion weakens the thirst mechanism. When thirst becomes palpable, fluid reserves are already depleted and the early stages of dehydration are visible. At the time of thirst, the body has already lost up to 2% of its body weight in fluids, which has been shown to disrupt thermoregulation and reduce the ability to work by 10 to 15%

The colour and amount of urine excreted are good indicators of the body's hydration status. Urine should be clear and in large amounts, and urination should occur frequently throughout the day. Strongly concentrated urine is usually a sign of dehydration.

Weight loss during periods of exercise is another excellent indicator of fluid loss. It is important to weigh yourself before and after activity to monitor fluid loss. For every kilogram of body weight lost, drink 2 glasses of fluid to rehydrate. As the body can only absorb about 1 litre of water per hour, it is important to drink fluids before, during and after exercise to avoid the risk of dehydration. In fact, fluid replenishment must continue for at least 24 hours after vigorous, prolonged activity to restore lost fluids and electrolytes.


For most, cold water is an acceptable source of fluid replenishment. During prolonged exercise (lasting 60 minutes or more), diluted fruit juices (one part juice to one part water) or hypotonic drinks are preferred, which provide essential nutrients as well as small amounts of sodium. Sodium has been shown to increase the rate of absorption of water and carbohydrates from the gastrointestinal tract and encourage fluid retention after exercise.

Another benefit of drinking hypotonic drinks is that their taste actually encourages drinking. In fact, a recent study found that consumption of the drink by exercising boys aged 9-12 years resulted in almost double the fluid intake compared to plain water.

When exercising heavily, full-bodied fruit juices and other highly concentrated drinks should not be drunk. They create a feeling of fullness and can cause cramps. Fluids containing caffeine or alcohol should be avoided. They have a diuretic effect; that is, they promote the excretion of water from the body, causing the body to lose more fluid in the urine that is actually supplied by the drink. This loss of water, in turn, impairs temperature regulation, lowering defences against overheating-related illnesses. In addition, caffeine can cause stomach upset, nervousness, insomnia, headaches and irritability. Unlike water, caffeinated drinks such as coffee and tea are unable to cleanse the body of toxins. In addition, they contain substances called tannins, which reduce the absorption of many important minerals, especially magnesium, iron and calcium. Sweetened and carbonated drinks seem to be an even worse choice. The former contain so-called empty calories, as they carry no nutritional value. Carbonated drinks, on the other hand, contribute to gas accumulation in the intestines, bloating, a feeling of heaviness and many other intestinal problems.

Therefore, let us remember that for the proper functioning of our organism, we must take care of a positive water balance, most effectively ensured by taking hypotonic drinks containing a set of vitamins, minerals and electrolytes, which we lose during increased physical exertion or even ordinary metabolism.