Gender identity and sports medicine: Inclusion and equal opportunities for athletes in competitions

_{Sports competitions have traditionally been divided according to the binary concept of male/female events in order to promote fairness and equity. Sexual identity and gender are complex concepts that include different conditions and should not be dicotomically determined. Among these, we can include persons with differences of sexual development (DSD) and transgenders. Therefore, sports regulators need to reconsider the traditional criteria and determine new eligibility rules for male/female categories. From this perspective, the concept of "athletic gender" has been proposed. Despite literature on this topic is scarce, a general consensus identifies testosterone (T) levels as the most important factor in determining the differences in sports performance between male and female athletes. Then, although imperfect, the use of T levels is actually the best method that can be used to separate athletes into male and female categories. Most of concerns and debates concern the issues raised by DSD and male to female (MTF) transgenders in women's sport, basing on the competitive advantage that higher androgen levels could provide to these athletes. This narrative review focuses on the view of sports medicine on this sensitive topic, examining relevant studies published in literature and current regulations on eligibility in female sports drawn up by the sports authorities.}