Hydration and rehydration

Hydration in tennis
Hydration in tennis

Hydration / rehydration solutions:

The amount of fluid required for each individual depends on the metabolism, diet, activity and environmental temperature.

Wateris the most necessary element, participating in cellular exchanges, breathing, blood circulation, elimination of metabolic waste, which is why it is the main source of fluids.

Herbal teas – are often beneficial to athletes, without making abuse and taking advantage of the plant’s properties: some soothe (lime, valerian), others help with digestion (chamomile, mint, anise), others disinfect (thyme, mint). Eucalyptus empties airways, others have diuretic action (dill, anise, cherry tails, dandelion, parsley, celery).

As a rehydration drink, tea should be consumed as an infusion, which is why the water should be hot but not boiling. Thus, tea will also keep your mineral and vitamin contents (C, F, P, K & B2).

Mineral waters – are natural waters that contain different minerals that give them certain properties: some have more magnesium, some more calcium or fluorine, may be gaseous or not. Certain waters are diuretic, other digestive, and others known for their action on the liver or kidney.

It is not recommended to consume carbonated water at the table as it is salty and it swells in your belly.

A meal based on dried and salted products (cheese bread) gives more thirst than a wet meal (crumbs and fruits).

In any case, it is better not to drink during meals (too much liquid dilutes gastric juices and slows digestion).

The coffee – is very rich in niacin (Vitamin PP). When consumed in large quantities, it can be a source of 1-2 mg/ day of this vitamin. Tea and coffee contain caffeine, tannic acid (tannin) and aromatic substances.

The caffeine content is 1.5-5.5 g%. This substance stimulates brain activity, favors intellectual work, strengthens circulation and breathing, increases diuresis and excites gastric secretion. For this reason, tea and coffee infusions are indicated in sleepiness.

Milk – it does not quench thirst, but it is a very complete food that contains many very nutritious substances: proteins, fats, sugars, vitamins and minerals and can be eaten in the form of cheeses and yogurt. Its calcium content gives it sedative properties, which can be helpful in case of insomnia.

Fruit juice or vegetable juice – contains a lot of water (80-90%), small molecule carbohydrates (simple sugars), organic acids (citric and malic, tartaric), minerals (K, Ca, Mg, and vitamins (C, P, B1, B2, B6, PP). Although they have a sour taste, these juices are strongly alkalinizing due to their high content in basic salts and especially in potassium. Beverages outside the meals, juices, can bring a surplus of energy and precious vitamins, provided they are natural and consumed immediately after they have been prepared because vitamin C is very easily destroyed either by air or freezing or conservation.

Dehydration causes:

  • Under conditions of increased temperature and humidity, thermoregulation and dehydration problems inherently occur that speed up the occurrence of fatigue.
  • Under these conditions, perspiration will be more abundant and, consequently, the loss of water and electrolytes in the body will be greater.
  • There is a need to replace water and carbohydrates by ingestion, intra-effort, of liquids. In this case, it is good to know that at high temperatures, the carbohydrate content of the beverages to be administered must be lower, water being in this case a priority.

Research has shown that high or low concentration glucose is assimilated to equal parameters, recommending more dilute solutions that do not cause large body water losses.

The decrease in physical performance occurs when the body has a dehydration of 2% of the body weight, and a loss of 5% causes a decrease of the exercise capacity by approx. 30%.

Dehydration through abundant and long-lasting sweating (over 1 hour effort) also lowers blood volume and therefore blood flow to tissues can be compromised.

By sweating, a number of electrolytes are also lost, of which, in the first instance, sodium and chlorine.

The ionic components lost through the effort

Electrolyte Sweating Plasma


































Hydration / rehydration taxonomy:

From the data presented above, it appears that maintaining a long-lasting effort also requires a carbohydrate supply, supplementing the body’s limited “deposits” and at the same time replacing perspiration losses.

Solutions based on glucose and carbohydrates do not lead to artificial growth of performance, but are necessary for the continued normal functioning of the body under stress conditions.

Re-hydration of the intra-effort body is necessary and beneficial in all competitions lasting more than 60 minutes.

Rehydration is very important in the intervals between training and post-training.

Administration of prepared solutions will be based on:

  • losses incurred;
  • the duration of the training;
  • the nature of the training (volume, intensity);
  • the ability to recreate each athlete;
  • environmental conditions;
  • of place, etc.

Solutions and “sports drinks” must contain sweat-eliminated electrolytes but also other elements.

Claude Vincent points out that “life is a dehydration that starts from the early age and continues progressively to old age, because if the newborn has 85% water, the old man remains 60%.”

The sectors where we find water in the body:

  • intracellular sector – 3/4;
  • the extracellular sector – plasma and interstitial spaces, remains.

 Water contains air and mineral salts. Hydric need takes into account that one calorie burns with 1 cm3 of water. The water value is given by fresh, clear, odorless, sufficiently aerated (25-50 cm3 of gas), CO2, slightly salty (180-300 mg mineral salts/ liter).

For the body’s water preparation, French authors recommend between lunch and the beginning of the competition, a so-called “waiting ration”.

The waiting ration consists in consuming 250 ml of fresh fruit juice, soaked in honey every hour or 1 1/2%, so that the athlete ingestes about 750 ml of this composition before the competition. The last dose will be taken at least 30 minutes before the start of the competition.

-The restoration of the energy substrate, following the sport performance, is achieved starting with pauses between efforts.

– This gives the body water, carbohydrates and mineral salts, especially potassium and sodium, lost during the effort.

– In the event of a thirst, in small breaks, the athlete will be given to consume: warm tea, well-sweetened and flavored with lemon, vitaminized mineral water, or natural fruit juice, glucose-sweetened and slightly salty.

– If the break takes more than 10-15 minutes, then it can consume a glass of 200-250 ml of liquids.

It is recommended to slowly and slowly ingest 300-500 ml of alkaline liquids (milk, yoghurt, natural fruit juices, tea), which will also restore some of the lost mineral salts.

If ingested post-exertion, liquids cover losses and prepare to sustain the next effort, during the effort (intra-effort) high fluid consumption stimulates sweating and pools mineral salts in the body, causing acid-base imbalance. In the effort, liquids are consumed with caution, in small, personalized quantities, the ration of liquids being differentiated from sports to sports.

For rehydration, some authors recommend ingestion of about 300 ml alkaline liquids (sweetened natural fruit juice, cold milk, alkaline mineral water). It is recommended to add 20-25 g of pure glucose, fructose or natural honey, 1-2 g of sodium chloride, 1 g of potassium chloride, 10 g of vitamin B1 and 200 mg of vitamin C.

Another drink recommended by athletes contains 100 ml of the following: syrup glucose 50 g, Na – 60 mg, K – 17 mg, Ca – 30 mg, Cl – 70 mg, 50 mg phosphates. 100-150 ml of this solution is recommended, plus 150 ml of fruit juice, plus 10 mg of B1 and 200 mg of vitamin C. This is a physiological hydration accompanied by electrolyte balancing.

If we train in the hot season and there is a feeling of thirst and the break lasts at least 10 minutes, it is advisable for the athlete to consume small amount of water. Rinse mouth with water and drink a glass of mineral water or a drink of the following composition (for 12 athletes):

  • sugar – 900g;
  • juice from 9 lemons;
  • salt – 6 g;
  • vitamin C – 2000 mg;
  • vitamin B1 – 125 mg;
  • alkaline mineral water – 3 liters.

If we train in the cold season it is recommended to consume a 250 ml glass of the following drink (for 12 athletes):

  • sugar – 1500g;
  • juice from 9 lemons;
  • salt – 3g;
  • vitamin C – 2000 mg;
  • vitamin B1 – 125 mg;
  • warm tea – 3 liters.


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