hydrat Water represents 60 to 70% of the body’s weight. 90% of the blood plasma, 40% of the bones, 70% the muscles consist of water. It seems that drinking not enough water is the cause of some repetitive conditions: strained muscles, tendinitis.

Lire la suite...;">

Jean-Philippe SAMEL


Did you know that when you feel thirsty, your organism already has in a deficit of about 1.5 litres of water? Did you know that a loss of water of 2% that is not compensated (i.e. 1 litre for a person of 70 kg) causes a decrease of 20% of your performance?
Hours of training are of no benefit just because you have not drunk enough before, during and after the physical effort. 

Therefore regular rehydration is essential.

It has a physical role
Water represents 60 to 70% of the body’s weight. 90% of the blood plasma, 40% of the bones, 70% the muscles consist of water. It seems that drinking not enough water is the cause of some repetitive conditions: strained muscles, tendinitis.
It has a functional role
Water is the most fundamental food.
It is the solvent of most foods and waste that may transit by osmosis through cell membrane, which enables the cell to feed and eliminate the waste.
It has a thermo-regulatory role
I move so I’m warming!
The mechanical performance of the “muscular motor” is of about 25% and goes with a production of warmth (75%). This increases the body temperature that is regulated thanks to the perspiration and then the evaporation of sweat which cools down the body.
This mechanism can lead to a very important loss of water.
With an air temperature of 28°C, a long distance runner can lose up to 2 litres per hour in order not to explode due to the heat!
It has a role that is necessary to enzymatic reactions
Water permits biochemical exchanges (synthesis, degradations, oxidations, reductions, energy transfer, etc.). All the enzymes are proteins and all the cellular proteins must have enzymatic activity: thus, the main protein of the muscle, the myosin, is an active enzyme, the ATP (adenosine triphosphate).
It has a shock absorber role
When a fall is unavoidable, the cerebrospinal liquid serves as “crash-pad” and prevents your brain from hitting strongly against the cranium. Therefore it is better to maintain the liquid level…

Definition of dehydration
Dehydration is the reduction of the quantity of water contained in our bodies.

Water divides into 2 systems:
2/3 of intracellular water, rich in potassium inside the cells
1/3 of extracellular water, rich in sodium in the liquids: blood, bile…
The intra- and extracellular environment are separated by an osmotic membrane permeable to water and impervious to mineral salts.

If the concentration of mineral salts is modified, the liquid of the less concentrated solution spreads to the more concentrated solution creating problems in the metabolism that can be more or less serious: this is the phenomenon of dehydration.
The mechanism of dehydration
dehydration by water loss in the extracellular sector.
Most of the time, this has happened when your shirt is soaked.
Filling up (with water) is usually done by natural instinct.

dehydration by loss of salt without water loss:
The water moves directly from the extracellular sector to the cells with circulatory troubles occurring.
Salt intake may be necessary depending on the advice of your doctor.

Dehydration due to an equal loss of water and salt often happens in hot countries and during endurance training over several hours. There is a weakening of the saline concentration in both sectors that must be compensated by 3 to 4 g of salt/litre of water.
Causes of dehydration
The length and the intensity of the physical effort condition the water loss.
One session of physical rock climbing will “pump” differently than a sequence of a steady route of 6 lengths in the mountains.

The climatic conditions, the sun and the wind play an essential role on dehydration.
Be aware of false impressions created by a nice refreshing wind …

Take into account:
- the air temperature, especially cold air which dehydrates as effectively as heat but less evidently.
During an indoor competition, a badly air-conditioned gymnasium may quickly become a real oven. 
Do not forget to water the climber so he “cooks” slowly without getting dehydrated!
- the humidity of the air (hygrometry): the more humid the air , the more difficult is evaporation; and the more the body heats up, the more the body dehydrates to compensate. A challenging and vicious circle!
- the altitude in the mountains. Dry and cold air “burns” the lungs and provokes important evaporation of water with each breath.
The lack of filters (dust, CO²) increases the intensity of the sun’s rays and causes the heating-up of the rocks which may reach 60° at 4.000 m…

Clothes must permit the body’s evaporation and at the same time protect the body from air temperature variations.
Get rid of your airtight suit, the one used “to sweat more and lose more fat”, which is a rather harmful aberration. If you can, use synthetic fibres that evacuate perspiration perfectly and dry quickly.

Health concerns: high temperature, diarrhea, dysentery, traverler’s diarrhea provoke quick dehydration.
Consequences of dehydration
Generally speaking, the effects of dehydration on an athletic person are usually the same as on a non-athletic person:

Muscular and tendinous incidents: cramps, strained muscles, tendinitis
Increase of the interior body temperature
Increase of the heart rate
Decrease of the volume of systolic ejection (bloodstream)
Problems of the urinary system (stones)
Bad supply of blood to the small blood vessels (risk of frostbite)
Digestive problems
Feeling of illness, tiredness and the urge to stop

Decrease of the performance during a non-compensated water loss:
With 2% of water loss (i.e. 1L for 70kg), the performance decreases by 20%
With 3%, the duration of the effort decreases by 20%, the heart rate increases by 5%
With 4%, VO2 max is reduce by 20%
With 5% (i.e. 2,5L for 70kg), the duration of the physical effort decreases by 40%, the heart rate increases by 10%...

Never forget that the privation of water leads to death faster than the lack of food

The right amount

The daily ration of water is obtained by:
50% in solids (40 to 60% of water in meats, 60 to 85% in fruits, 40% in bred)
and 50% in drinks (preferably non-alcoholic ones…)

The hydric ration depends of the total caloric intake.
It can be expressed by the formula: 1 ml of water / 1 burnt calorie (3 L / 3000 cal.)
However that formula should be adapted to the type of activity and the climate…

A person needs 2,5 litres / day without performing any physical activities.
However, 6 litres of water (100% liquid) are essential in summer in a desert, without doing strenuous efforts, otherwise the amount would even be higher …
Drink before the activity
During the warm-up, the level of hydration must stay at the right level to avoid exposing your “muscled passages” to a state of dehydration.
Therefore you should drink slightly mineraled water (waiting ration).
Drink during the activity
It is essential to drink small quantities every 10 min to compensate the regular water loss: 0,5 to 1 litre / hour.
The water can be slightly salty (a pinch) to compensate the loss of mineral salts (sodium). Add also carbohydrates (honey, 25g / litre) to prevent hypoglycaemia.

When it is cold, drink hot drinks!
It is better to use up your energetic fuel for the activity rather for the fight against the body’s cooling.

It is easily said, but not always easily done!
For easy drinking at the belay station of the 3rd length, it is the best to use the water pocket (2 litres) with a flexible straw that you put in your backpack, or the more expensive solution: the Camelback type.

In winter, when climbing in crags or bouldering: taking a thermos for hot drinks is a good solution.
Drink after the activity
Every water loss of more than 3% of the body’s weight (1,5 L for 70 kg) has to be compensated within 24 hours.

At the end of the activity, you must drink mineraled water until you are full and at mealtime, a soup may help to compensate de hydric loss.

Recommendations to instructors of people who train occasionally, beginners and/or children.
You have now been informed about the benefits of correct hydration.
That principle, which is part of the healthy lifestyle of an athlete, contributes your performance and helps to prevent injuries.

Encourage the people close to you to take plenty of fluids (as yourself!) during your athletic activities.