Buddies are often used in physical education institutes. This is a concept called over-repair.

Simply put, when a person is stimulated when using muscles, and the size of muscles determines the weight that muscles can bear and the time of use (one's strength and endurance), then the number of muscle fibers of each person will not change. Too much stimulation will break the muscle fibers. After a long period of inactivity, sudden heavy physical labor or two days after exercise will cause common phenomena such as soreness or tearing pain, which is the performance of muscle damage. At this time, the human body needs protein to supplement. Protein, if the human body is a house, then this thing is the raw material of cement and so on. They can be materials for human body repair, and of course they also need the promotion of androgen. Exercise increases the secretion of androgens, which is one of the reasons why women are not as strong as men and cannot secrete more androgens to stimulate muscle fiber repair. In addition, sleeping and resting muscle fibers can heal broken muscles. Interestingly, they will repair themselves thicker than before, which means they are stronger.