We have two groups of people or better to say scientists and specialists that have their own ideas and theories and approvements.
- People that are relay on genetic related ideas that mostly consider rule of Y chromosome on men and how some genes' rules will not be diminished only by hormone therapy or non genetically engineering methods.
Chloie Jonsson, 34, who transitioned more than eight years ago, is legally recognized as female in the state of California. Despite the medical community's consensus that transgender women do not have a competitive advantage over cisgender (nontrans) women, Jonsson's application to participate in CrossFit's women's division was rejected with a bizarre letter claiming she and her supporters do not understand "the human genome" and "fundamental biology." In response, Jonsson filed suit against the fitness giant.
The letter from CrossFit general counsel Dale Saran reads:
"We have simply ruled that based upon [Chloie] being born as a male, she will need to compete in the Men's Division. The fundamental, ineluctable fact is that a male competitor who has a sex reassignment procedure still has a genetic makeup that confers a physical and physiological advantage over women. ... Our decision has nothing to do with 'ignorance' or being bigots — it has to do with a very real understanding of the human genome, of fundamental biology, that you are either intentionally ignoring or missed in high school."
Later, Saran disputes the statement made by Jonsson's attorney that "by all accounts, both physically and legally, Chloie Jonsson is a female."
"This is simply wrong as a matter of human biology and if you can't see that, there really isn't much to talk about," writes Saran, citing Encyclopedia Britannica. "Chloie was born, genetically — as a matter of fact — with an X and a Y chromosome and all of the anatomy of the human race. Today, notwithstanding any hormone therapy or surgeries, Chloie still has an X and a Y chromosome."
To add some details to group one's idea, if you think of some genes and their rules in men that makes them more accurate and more muscular than women in the field of physical activities, you'll get to the point of how to control or change behaviour of these genes in the body of a man to make him woman, both muscularly and neurologically which is not possible for now because we need some very detailed and powerful calculations to know the exact equilibrium of a man genome as if he was a woman.
To change the complicated mechanism of Y chromosome on Biochemistry and behaviour of other chromosomes we have so much to learn and we need very fast computers to simulate the behaviour of molecules and new formation of mass body.
- And we have other ideas by people who insist on level of hormones that has a great effect on mass of bone and muscles in men and women regardless of how their sex and genome is.
Eric Vilain, Director of the Center for Gender-Based Biology and Chief Medical Genetics Department of Pediatrics at UCLA, says of any perceived advantage a transgender woman may have, “Research suggests that androgen deprivation and cross-sex hormone treatment in male-to-female transsexuals reduces muscle mass; accordingly, one year of hormone therapy is an appropriate transitional time before a male-to-female student athlete competes on a women’s team."
A great article and detailed explanation by an example that helps to answer your question is here.