Why is H2O a liquid

The influence of H2O on the body


Three atoms, two chemical elements - every athlete and coach knows the H2O formula. Water is by far our most important food and is considered the most and best studied substance. Nevertheless, there is still a need for knowledge and intensive research is being carried out. Therefore, our water knowledge is subject to constant review and deepening.

Facts about our water body

The human body consists of 50 to 70 percent water. Two thirds of it is located within the body's cells. The average water content of different body tissues is quite different. It ranges from values ​​around 95 percent (blood plasma, lymph) to values ​​around 20 to 25 percent (bones, adipose tissue).

Function, absorption, turnover and delivery of the water

5 to 6 percent of the total amount of water is "converted" every day, i. H. renewed. The supply and excretion should be in balance. The biological half-life for water in the body (the time in which the water absorbed in the body has been reduced by half due to biological processes) is usually in the range of 7 to 14 days. The amount of metabolized water (the water turnover) doubles with physical exertion at altitude. The water in the body is required to ...

  • to transport vital nutrients,
  • to regulate the body temperature (cooling as well as heat storage),
  • To keep joints mobile and to absorb shock loads (brain, spine, internal organs, joint surfaces).

The water is absorbed by the small intestine (65 percent) and the large intestine (35 percent) by osmosis. The water used is mainly "disposed of" through breathing, the skin (depending on the intensity of exposure, ambient temperature, humidity) and the urine. At 140 heartbeats per minute, four times more water is excreted with the exhalation (about 60 to 70 milliliters per hour) than at rest. At lower temperatures and lower humidity, more water is exhaled through the lungs. The loss of water (and the electrolytes dissolved in it) through sweating should not be underestimated. With intensive training, it can be over two liters per hour.

Drink during exercise

Too much or too little water - that has always been a problem for people. A feeling of thirst is triggered when the water content decreases and there is an excess of salt. This triggers various key stimuli that are registered by receptors and processed in the brain to create a “feeling of thirst”. There is also a signal when the thirst has been quenched.

For training and competitions, it is often advisable to drink before you feel thirsty, as even small water deficits can reduce performance. The reduction in body mass due to water loss should not exceed two percent. Numerous studies on the connection between water loss and performance in the last two decades have resulted in no general guidelines for drinking quantities. Instead, it makes sense to let yourself be guided by your feeling of thirst.

What should be drunk in training and competition?

A daily requirement of 1.5 liters of water is assumed for the “average consumer”. Since food behavior has changed in recent decades, the liquid contained in food (fruit, soups, sauces) is also included in the calculation. The eight (still) recommended glasses of water (almost 2 liters) are more of an upper limit.

Electrolytes are liquids in which substances are dissolved in their ions (e.g. table salt / sodium chloride dissolved in Na + and Cl-) and which conduct electricity. They are of essential importance for all vital functions (e.g. muscle contraction, breathing, nerve function, water balance, growth). A distinction is made between iso-, hypertonic and hypertonic fluids:
  • In isotonic sports drinks, the concentration of electrolytes is in equilibrium with that in the blood, depending on the composition (e.g. sodium, potassium, calcium, magnesium / chloride, hydrogen carbonate, phosphate).
  • In the case of hypotonic beverages, fluid absorption is faster because they have a lower osmotic pressure. This can be superior to an isotonic drink and water in its effect on performance. Their consumption is also sensible in case of an accelerated recovery after training or competition.
  • Hypertonic sports drinks are absorbed more slowly because their osmolality is higher than that of body fluids and the fluid in the intestine must first be diluted, which removes water from the blood. They are rather unsuitable for athletes. Under certain circumstances, it can be useful to use them for the restoration. The “empty” carbohydrates (sugar) it contains could, however, be replaced more effectively with whole grain products and vegetables. Soft drinks and undiluted fruit juices are even more hypertonic and therefore unfavorable for athletes in training and competitions.
The oxygen required for the metabolic processes is inhaled with the air, bound to hemoglobin and transported to the cells with the 98 percent highly saturated blood. There are therefore very narrow limits to an even higher oxygen concentration for a further increase in performance. It is therefore not surprising that, in numerous experiments, drinking oxygen-enriched water has so far not shown any increase in performance in the vast majority of cases. Regardless of this, “oxygen-water” is advertised, among other things. with various blanket and unproven effects such as: "Improvement of alertness, condition, metabolism and overall an improvement in body functions" as well as "Support of aerobic metabolism, increase in energy level, stimulation of the immune system, improvement of digestion".
Drinks that contain stimulants such as caffeine are also popular with footballers, as many associate them with improved performance (in terms of endurance, speed, resistance to fatigue, reaction time, coordination). This can range from coffee or tea to energy drinks. The effect of caffeine depends on the dose. It starts after about 15 minutes. The breakdown has a half-life of 4 to 5 hours. In the case of energy drinks, attention must be paid to other ingredients (e.g. sugar) and their influence on performance. With five to eight cups of coffee drunk in a relatively short period of time, an athlete enters the area that was doping-relevant until 2003. Caffeine is currently on WADA's watch list. The same applies here: too much is unhealthy.

Water is our staple food, every trainer and athlete must be aware of this and consequently water consumption in its quality and quantity deserves a high level of attention. Young athletes should learn how to use their drinking water responsibly at an early stage. Developing and practicing a drinking strategy, as it is pursued by many top athletes, is part of it.

Further tips and information on drinking are compiled under the topic-related links.