Water, without any calories, is very important for our body and represents between 60 to 70% of the body weight. This corresponds to about 45 liters of water for a 70 kg person. The athlete who trains regularly has a larger volume of water in his body because he has more muscles and these contain 73.2% water against 10% in the fat mass. Where is the water? 60% in our cells and 40% in the tissues in which the cells are immersed: the lymph and the blood.Water to cool
When muscles require more energy during exercise, they release 70 to 75% of the energy mobilized as heat. This heat is evacuated mainly by a natural transfer of heat to the outside: convection. Water plays a secondary role in cooling the body even though this role is real. Thus, if playing sports makes us sweat more is because of the increase in energy expenditure (the “boiler” is running at full speed) and not because of a lack of water. It’s a sign that your body is working well!What is sweat made of? It depends on the environmental conditions, the intensity of the exercise, the level of acclimation to the heat but also the condition of the athlete. Sweat is 99% water and sodium, potassium, calcium, magnesium, zinc, iron, manganese and vitamin C, but this exact composition varies. For example, trained and heat-acclimated athletes excrete less sodium per liter of sweat (115 to 690 mg per liter) than trained and non-acclimated athletes (920 to 2300 mg per liter).
Water needed to burn energy
The body of an athlete will use a lot of carbohydrates during the effort. Some athletes anticipate the increase in energy demand by their muscles and choose a diet rich in carbohydrates. But when muscle cells use carbohydrates stored in the body, some of the water that was trapped in the muscles is released. Specifically, for every one gram of stored carbohydrate that the muscle uses, 2.7 g of water is lost. Water also plays a role in providing energy.
During a sporting event, the whole body gets into a fight: the muscles need more energy, the lungs move up a gear, the blood tries to satisfy the increased needs of all the organs. It is therefore logical that the waste is more important too. Water is essential for the body to dispose of its waste through perspiration, urine, stool and breathing. But beware: more water does not help to eliminate, it is simply necessary to avoid dehydration, situation during which our filtration system works less well.
To know when to drink, our body has a very effective mechanism: when changes in the sodium level or the amount of water in the plasma occur, receptors located in the brain at the level of the hypothalamus will cause hormonal changes and behavioral to avoid serious dehydration: the kidneys will better retain water and sodium and the feeling of thirst will trigger. Contrary to popular belief, the feeling of thirst is very reliable when it is not disturbed by external elements (taking certain medications, diseases, age).Humans have evolved as long-distance hunters. This gave us the ability to regulate our body temperature to the corus of prolonged effort in the heat, even with a lack of water. Man does not regulate his water balance instantly, it is a time drinker: the deficits in water and minerals are corrected at the following meals.The need to drink “in prevention” therefore appears to be useless. However, it is better to drink as soon as you feel thirsty, without waiting if you want to avoid dehydration.
Drink enough to avoid dehydration
When you do not drink enough to compensate for water loss, you may find yourself dehydrated. The heart has to work harder and the heat regulation mechanisms are outdated: the heart rate increases, the blood pressure decreases and the body starts to “overheat”.
It suffices for a slight water deficit of the order of 1% of body weight, or only 0.7 liters for a man of 70 kg, to reduce performance by 10%: the athlete can feel fatigue, headaches, nausea, heaviness in the legs, shortness of breath … When hydration decreases by 2%, the physical and intellectual performance of the athlete is impaired. Increased dehydration increases the risk of kidney stones and coma. The danger of heart attack or heart exhaustion also lurks when the athlete loses 6 to 10% of his initial weight due to dehydration.Finally, an athlete who is repeatedly dehydrated can suffer pain in muscles, tendons and ligaments. His risks of breakdown and sprains are increased.
When dehydration becomes too high, the blood volume decreases. The noble organs, the brain and the heart, no longer receive enough blood. To preserve them, the body tries to increase the circulation: it closes the vessels leading to less essential areas like the skin. The body temperature continues to rise while the cooling mechanism, sweating, is no longer effective. The difference between heat produced and heat evacuated is too great. It’s heat stroke! It can be deadly because our brain can not withstand temperatures above 41 ° C. But usually heat stroke occurs without being dehydrated, it is simply the diffusion of heat that has not had time to be done properly.
The movement of the muscles is achieved by the contraction of fibers inside the muscle cells. The contraction is done through ion exchanges, mainly potassium, sodium, magnesium and calcium ions. Dehydration can lead to an imbalance of ion exchange, especially via perspiration which makes Pkmarts.com us lose a lot of sodium: cramps are then manifested. This is the most common symptom to alert you to poor hydration (in quantity or quality – see below).
Dehydration can promote the development of tendon problems even if the exact reason is poorly understood.Risk of drinking too much: dilution hyponatremia
Hyponatremia corresponds to the decrease of the concentration of sodium in the plasma, that is to say the liquid part of the blood. It can occur when there is an excess of water over sodium. Excess water can reach 5% of the initial weight of the athlete. Drinking clear water or a weakly mineralized drink throughout an effort (single bottle of water) for several hours dilutes the blood. Your salt concentration collapses, it’s the dilution hyponatremia.How does hyponatremia happen? In endurance exercises, hyponatraemia is the consequence of inappropriate behavior: either “voluntary” hyperhydration or the consumption of an unsuitable drink that does not compensate for sodium losses caused by perspiration. The most affected are mainly the “less” athletes who do not monitor their contributions during the effort and consume drinks that are too low in sodium. When the effort is intense or very long, the risks of hyponatremia are greater.Hyponatremia is not always accompanied by symptoms. If there are, they are not specific: nausea, vomiting, dizziness, discomfort, confusion, agitations, fatigue, coordination disorders but the most common signal is the appearance of cramps. Then headaches and sweating of the feet and hands can become more and more important while the body temperature remains normal.
What to drink?
They usually provide too little sodium to compensate for the losses caused by perspiration. These are drinks to reserve for short-term efforts.
They contain as much sodium as there is in the cells of our body. Thus, it will facilitate digestion (no disorders of the concentrations between the different media) and replace the sodium losses caused by perspiration. An isotonic drink is therefore a first step towards a good drink of effort and performance. Count 500 to 700 mg of sodium per liter of drink.
They contain carbohydrates and electrolytes. During exercise, they provide energy to the muscles, help maintain blood sugar levels, and decrease the risk of dehydration or hyponatremia. It’s a good choice for performance but not all of them contain the right amount of minerals for endurance efforts.
It is best to sweeten the water if the exercise lasts more than 45 to 50 minutes or if it is intense. The optimal solution: take about 1 gram of carbohydrates per minute, that is to say 1 liter of a 6% carbohydrate drink per hour.Beverages containing more than 8% carbohydrates such as fruit juices, sodas, and some energy drinks (which often contain 10-12%) are not recommended during exercise. Indeed, they are much more concentrated than the blood in substances other than water molecules. To dilute these substances, the water passes from the blood to the intestines and the very sweet drink “stays on the stomach” because of the ionic imbalances. In the same way, avoid the table sugar in your drink: the large amount of present fructose can bloat you during the effort (to test however since everyone reacts differently). Choose dedicated powdered preparations or make your own mix with glucose, maltodextrin or similar sugar.
They are useful for athletes to rebuild muscle reserves of carbohydrates and repair tissue. Long-lasting, high-intensity training exhausts energy stores even if you have had an energy drink while you exercise. It is therefore important to redo its energy stock. These drinks are therefore useful after the efforts of ultra endurance.