No matter what dehydration is, it is caused by the decrease of extracellular fluid in our body. Extracellular fluid accounts for about 20% of normal adult body weight, while intracellular fluid accounts for 40%.
Our intracellular fluid is mainly K ions, and the extracellular fluid is mainly sodium ions. Their concentrations will affect the osmotic pressure of extracellular fluid. When too many K ions are lost internally, our intracellular fluid osmotic pressure will be less than the osmotic pressure of extracellular fluid, and the water in cells will be lost outwards. When we lose too many Na ions, the osmotic pressure of our extracellular fluid is less than that of intracellular fluid, and the external water will flow in, reaching the balance of internal and external pressures.
Sodium-potassium pump (also known as sodium-potassium transporter) is a protein molecule that exchanges sodium ions with potassium ions. For every ATP molecule consumed, three sodium ions are pumped out and two potassium ions are pumped in by reverse electrochemical gradient. Maintain the uneven ion distribution with high potassium in the membrane and high sodium outside the membrane.
Our cell membrane has a good relationship with potassium ions, so potassium ions can easily enter and leave the cell, but the relationship between cell membrane and sodium ions is not good, so it is difficult for sodium ions to cross the cell membrane, and certain conditions need to be met.
Dehydration of athletes in the process of rapid weight loss
Before the competition, athletes will seek some quick dehydration methods in order to lose weight quickly, because dehydration is the fastest way to lose weight.
Generally speaking, athletes will strictly control the intake of electrolytes in their diet a few days before the competition, such as sodium ions in salt and potassium ions in many fruits. This control will lead to the loss of fluid inside and outside our cells, the discharge of water, and the rapid weight loss, reaching the competition standard.
Comparatively speaking, it is impossible to lose weight quickly simply by doing aerobic exercise and controlling calorie intake. The reason is 1: Athletes with weight restrictions (such as weightlifting) have less body fat and little room for fat reduction. The second reason: the speed of consuming body fat is very slow. It takes several days to lose one kilogram without any energy in one day, and the efficiency is too low.
Side effects of short-term rapid dehydration
Short-term dehydration of athletes has an impact on sports events, but it has a great impact on long-term aerobic events and a small impact on short-term anaerobic events. Therefore, most people who lose weight by dehydration are athletes in anaerobic short-term competitions.
Effect of dehydration on thermoregulation
In order to regulate body temperature during exercise, people will sweat a lot to keep the internal environment stable, but when we dehydrate a lot, our body temperature will rise rapidly. Every time adults are dehydrated 1%, their body temperature rises by 0. 1-0.4 degrees Celsius. When their body temperature exceeds 40.5 degrees Celsius, heat shock appears, which is life-threatening.
This is why we should cover our sweat when we have a fever, because we should lower the temperature and prevent the high temperature from endangering our lives for a long time.
2. The effect of dehydration on aerobic exercise
Athletes who do aerobic exercise for a long time will lose a lot of water during the exercise, making the sticky blood more viscous because of dehydration. Coupled with endocrine disorders, muscle weakness caused by calcium ion loss can easily lead to sudden death of athletes.
3. The hazards of dehydration to safety
Dehydration will lead to the decrease of blood volume and the proportion of water in plasma, which is more likely to cause thrombosis. Secondly, due to the decrease of urine volume, urinary calculi are more likely to occur, which may be accompanied by renal function damage. Electrolyte is closely related to muscle contraction and nerve conduction, and rapid dehydration will also affect these two points.