For any physical sports, if we want to improve our performance, we must follow a process of "intensive training-overload-excessive recovery". After a period of intensive training, our bodies will enter a period of fatigue, and our athletic ability will also decline briefly. At this time, our bodies need a period of full rest, such as several days to several weeks.

The state of acute physical fatigue will be over-adapted to the intensity, thus improving our physical fitness and sports performance. Such a cycle is the basis of our progress. The rest mentioned here is not really doing nothing in bed, but reducing the intensity of training, such as easy running or other cross-training.

If this cycle is broken, for example, after intensive training, we will enter a state of overtraining (OTS), which means that when our overload accumulates to a certain extent, the balance between physical training and recovery will be affected, both physically and psychologically, which will lead to the long-term decline of sports performance. In this case, it often takes weeks or even months to restore our sports ability.

Serious hormone disorders, upper respiratory tract infections, sleep disorders, psychological stress and other situations may occur, affecting our lives and work.