Endometriosis is a disease in which cells of the lining of the uterus (endometrium) to grow beyond it. Along with menstrual blood they fall into the fallopian tubes and abdomen, where further take root and proliferate. In some cases this process contributes to active sports (gymnastics, figure skating, aerobics). This is why many doctors advise refraining from physical exertion during menstruation. On the causes, treatments and prevention of endometriosis told Terehina Olga Viktorovna, obstetrician-gynecologist, medical centre “Atlas”, candidate of medical sciences, doctor of higher category.