Exercise or manual labor can cause sweating, especially when the outdoor temperature is high and humidity is high in summer. With sweating, a lot of water and electrolytes (mainly sodium salts) are lost in the body. The purpose of promoting fluid replacement is to make these lost substances be replenished in time and keep the internal environment stable. This is the most basic condition for maintaining physiological function and health.

Clear water is a commonly used rehydration drink, which can be quickly absorbed to improve the body's water shortage, and water is easy to get and cheap. However, as a drink for sports training or physical labor, clear water has certain limitations or shortcomings. It has no taste, and drinking too much sometimes causes some nausea, so athletes often stop drinking water before body fluids recover. Clear water is a sugar-free drink, so it can't provide energy for people who are exercising or working, just like a car running without oil. In addition, clear water basically contains no electrolyte, and the beverage with electrolyte tastes good, which can promote athletes to drink water and help maintain the balance of body fluids. Although clear water temporarily quenches thirst, it activates kidney function, in other words, it turns on the tap for kidney excretion and causes diuresis. This is because the salt in the body has not been supplemented, and only a lot of water has been drunk. If water can't stay in the body, it will cause diuresis and increase sweating, thus reducing the possibility of optimal recovery of water in the body.

Sports drinks developed on the basis of a large number of scientific research results are loved and widely used by the majority of athletes because they can not only promote the recovery of water and electrolytes, but also improve the training effect and competition results. The so-called scientific development means that the sugar (sweetness) and electrolyte (salinity) contained in sports drinks are appropriate, which not only makes people feel good, but also promotes fluid replacement during exercise. Moreover, the study also shows that sports drinks containing 6%-7% sugar and proper amount of sodium salt are absorbed faster than clear water, which accelerates the transportation of liquid and energy to sports muscles and achieves the effect of "delivering charcoal in the snow", that is, achieving the highest rehydration efficiency and refueling when it is most needed. It is not difficult to understand that drinking this sports drink will improve sports performance and sports efficiency.