In addition, excessive exercise can also cause irregular menstruation, and female athletes are typical examples. Excessive exercise in a short period of time will change the ratio of fat to muscle in women in a short period of time, and the body fat that produces estrogen will also decrease. In order to cope with high-intensity exercise, the androgen secreted by the adrenal gland will increase. Estrogen decreases, androgen increases, the hormone balance in women is broken, menstruation is naturally affected, and amenorrhea can occur in severe cases.