Studies have shown that the response of the cardiovascular and thermoregulatory systems, as well as indicators, were optimized when losses with sweat were replenished during exercise. These results are reflected in the following recommendations: during exercise, athletes should immediately begin taking fluid, and then continue to take it at regular intervals to consume liquid at a rate sufficient to replenish all of its loss with sweat, or drink as much as the body can tolerate. These recommendations show that the goal of fluid intake during exercise is to prevent any dehydration of the body, but admit that such a technique can be difficult in some circumstances. In most cases, only free fluid intake is not enough to fully compensate for its loss with sweat during the load, as in different people these losses are different. For example, light physical activity in a cold dry environment can give a loss of sweat equal to only 250 ml per hour, and a load in a hot, humid environment can trigger a loss greater than 2 liters per hour (some athletes lose more than 3 liters per hour). It is therefore important that athletes and workers consume the liquid in accordance with the prescribed regimen regulating the frequency and volume of fluid intake. Under ideal conditions, this means that it is necessary to know the individual intensity of sweating (it is easily estimated by recording the body weight before and after the load and the appropriate correction of fluid intake and loss in the urine) and develop specific individual recommendations regarding fluid intake during exercise.
It is recommended that the consumed liquid be colder than the ambient temperature (between 15 and 22 ° C (59 and 72 ° F), flavored to improve taste and stimulate its recovery.The liquid should always be available and be supplied in containers so that you can drink a sufficient amount and with minimal interruption in exercise.It is not surprising that people prefer flavored and sweetened drinks.It is important to prevent dehydration, since any step to increase free fluid intake will help reduce the risk of fuss Novena of health problems associated with dehydration and heat stroke.
In addition to providing athletes with tasty drinks, a number of other measures should be taken. They include the following:
- Educating coaches, educators, parents and athletes on the benefits of proper hydration. Periodical lectures, posters, leaflets and brochures can be part of this work.
- Creating conditions for obtaining fluid at any time. If possible, water sources should always be near, and there should not be any restrictions on the frequency of reception.
Practical advice and advice on fluid intake before, during and after exercise:
- Bring a drink with you. Wear a bottle or bag with liquid on your belt and / or take a refrigerator full of drinks (keep bottles with frozen drink all night so they stay cool for longer).
- Learn the signs of dehydration (unusual fatigue, dizziness, headache, dark urine, dry mouth).
- Find out where to find the liquid (drinking fountains, shops, etc.) and always carry money with you to buy drinks.
- Drink on schedule - not when you feel thirsty.
- Drink enough fluids to exercise to form a light urine.
- Plan the consumption of drinks during the competition. Practice drinking during physical training.
- Begin training in satiety.
- Know the intensity of your sweating, controlling your body weight before and after the load.
- Drink 24 ounces for every pound of lost body weight after the load (one average gulp of fluid is approximately one ounce).
- Completely restore the loss of fluid and sodium to achieve complete rehydration.
- Use more water inside than pour on the head. Watering the head with water does not reduce body temperature.
Adding the appropriate amounts of carbohydrates and / or electrolytes to the fluid replenishing solution is recommended for loads longer than 1 hour, as this does not impair the intake of water and may improve performance.
Carbohydrates are an important component of beverages, as they improve their taste, provide nourishment for active muscles and stimulate the absorption of fluid from the intestine. The benefits of carbohydrate nutrition during exercise for indicators are discussed in more detail in other chapters. Although carbohydrate nutrition improves performance, a large amount of carbohydrates in drinks is not always necessary. It is shown that consumption of beverages containing more than 14 g of carbohydrates in 8 ounces of servings reduces the rate of gastric emptying and liquid absorption.
It is recommended that sodium (0.5-0.7 g-l-1 water) be included in the rehydration solution consumed during a load lasting more than 1 hour, as this can enhance taste, promote fluid retention, and possibly prevent hyponatremia in those who are not, who consume liquid in excess.
Sweat contains sodium and chlorine more than other minerals, and although electrolytes in sweat are usually much lower than in plasma (plasma - 138-142 mmol-1, pot - 25-100 mmol-1), physical activity is more 2 hours a day can cause a significant loss of salt. Usually sodium deficiency among athletes and military personnel is not observed, since a normal diet often provides more than enough salt to replenish its losses with sweat. However, sodium losses can create problems. So, the incident with a tennis player suffering from frequent heat cramps is described. High sweating intensity (2.5 liters per hour) combined with sodium concentration in the sweat exceeding normal (90 mmol-h-1) caused the player to have muscle cramps. When he increased the daily intake of sodium chloride with food from 5-10 to 15-20 grams per day and increased the volume of fluid to be adequately hydrated, convulsions ceased.
It is also important to know that consumption of sodium chloride with drinks during exercise not only helps to ensure adequate fluid intake, but also stimulates a more complete rehydration of exercise. Both of these responses reflect the role of sodium in maintaining the urge to consume liquid and providing osmotic pressure to retain fluid in the extracellular space.
According to the provisions of ACSM, the sodium content in the beverage that compensates for fluid loss does not directly affect the rate of its absorption. This is because the amount of sodium that can be included in the beverage is small compared to the amount of sodium that is provided by the bloodstream. Whenever a liquid is absorbed, plasma sodium diffuses into the intestine under the influence of an osmotic gradient that facilitates the inflow of sodium. Sodium chloride is an important component of a sports drink, since it improves its taste, helps support the urge to drink, reduces the amount of sodium that blood should give to the intestines prior to fluid absorption, helps maintain the plasma volume during exercise, and serves as the main osmotic stimulus for volume restoration extracellular fluid after the load.
Wilk, Bar-Or gave an example of the influence of the composition of the drink on free fluid intake. Boys aged 9 to 12 years trained for 3 hours in high temperature with interruptions. During this workout, they drank one of three drinks to choose from. Among the drinks were water, a drink for athletes and a flavored, artificially sweetened drink for athletes (placebo). Boys drank a drink for athletes in 2 times more than water; placebo consumption was between these values. Fragrance and sweetness increased free fluid intake (placebo compared to water), and the presence of sodium chloride in the drink for athletes further increased consumption (ie consumed more drinks for athletes than for placebo).
These results are consistent with the physiology of thirst mechanism. People feel thirsty due to a change in the concentration of sodium in the plasma as a result of a decrease in blood volume. Simple water quickly eliminates the osmotic impulse of thirst (dilutes the concentration of sodium in the blood) and reduces the motivation, depending on the volume of blood (partially restores the volume of blood), thus quenching thirst. Unfortunately, this decrease in the consumption of liquid occurs mainly before absorption of an adequate amount. The osmotic impulse can be maintained by the presence of low levels of sodium chloride in the beverage.
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