HCG is one of the most important substances used in post-cycle-therapy.HCG, or Human chorionic gonadotropin, which is derived from the urine of pregnant women, is an injectable drug available commercially in the United States as well as many other countries. Its function is to stimulate hcg vialsgonadal steroid hormones by causing the production of androgens in the testis and also as a substitute for luteinizing hormone (LH) to stimulate ovulation. Among athletes, HCG is used to stimulate natural testosterone production during or (more usually) after a steroid cycle, which has caused natural production to be reduced or halted. Stopping a steroid cycle abruptly can cause a rapid loss in the athlete's newly acquired muscle, especially when endogenous androgens are absent. When HCG is used to stimulate natural
production, a notably pronounced crash may be avoided.