How can drinking a lot of boiled water after sweating lead to water poisoning?

We know that there are two kinds of liquid components in human body, namely ECF (extracellular fluid) and ICF (intracellular fluid). Extracellular fluid can be divided into plasma and interstitial fluid.

In human body, most water is stored in cells to maintain necessary physiological reactions. A small part exists in intercellular fluid and plasma. But the problem is coming again. Is this a change of water? Can the water in the cell flow outside? Can the water outside stay in the cells?

The answer is yes. The liquid exchange between intracellular fluid and intercellular fluid is described in detail below.

Intercellular fluid and intracellular fluid. I believe you still remember the experiment in high school biology: the separation of plasma and wall. When the onion skin is put into high concentration salt water, the water in the onion skin cells gradually separates out. This principle is the same in the human body. And the ions used are basically the same-sodium ions in sodium chloride. If the concentration of sodium ion in interstitial fluid suddenly rises, the water in the cell will be precipitated (the reason is the separation of plasma and wall mentioned above, if you haven't done experiments, please imagine pickles). On the other hand, if the intercellular fluid is suddenly filled with a large amount of water, which reduces the concentration of sodium ions, some water will also enter the cells.

If we think about the mechanism carefully, the decrease of extracellular fluid concentration is the cause of water poisoning, then the emergency treatment method is relatively simple-intravenous injection of saturated physiological saline. Although saturated physiological saline also contains water, it can quickly separate water from nerve cells, thus alleviating life-threatening situations.

Again, let's start with the mechanism. Generally, it is difficult for us to control the amount of "going out", but we can control the amount of "going in" and the way of going in. After sweating, drinking plenty of water in a short time and supplementing electrolytes are the guidelines for preventing water poisoning. Friends who have personal training in fitness may remember that the coach often said that drinking water slowly and taking a bite is just drinking a lot of water because of thirst in a short time. At the same time, the electrolyte in sports drinks will also reduce the risk of water poisoning. But water poisoning is a very extreme situation, and normal fitness enthusiasts generally don't have to worry too much.