The NCAA has been criticised for a "ridiculously complex" update to its regulations on transgender athletes.The governing body updated its policy after weeks of backlash directed at transgender swimmer Lia Thomas.The 22-year-old, who began to transition in May 2019, represented the University of Pennsylvania in a number of races last year, setting a number of records for the institution.Thomas met the eligibility standards set by the NCAA for women’s swimming events, but she was still subject to a deluge of criticism.After much public discussion on the situation – swimming legend Michael Phelps was among those to comment on the situation – the NCAA met on Wednesday and announced a number of changes to its regulations.There will now be a sport-by-sport approach to transgender athletes' participation "that preserves opportunity for transgender student-athletes while balancing fairness, inclusion and safety for all who compete."The new policy, effective immediately, is in alignment with recent regulation changes from the International Olympic Committee and the US Olympic and Paralympic Committee. 

Under the NCAA's former policy, transgender athletes were allowed to compete in women’s events if they had undergone a year of hormone-suppression therapy.

The new policy means they have to follow the rules of the national and international governing bodies, many of which require a certain testosterone level.

In Thomas’s case, neither USA Swimming or the International Swimming Federation have a clear policy on transgender athletes, meaning it is not yet known whether she will be able to continue to compete for the University of Pennsylvania.

Chris Mosier, a trans advocate and duathlete, called the new policy "ridiculously complex" on Twitter.

"After 'monitoring the situation' around anti-trans sports bills & their own calls for more research before even considering updating VERY out-of-date language in the 2010 policy, NCAA whipped up a ridiculously complex policy that will prove impossible for them to follow."

Anne Lieberman, director of policy for Athlete Ally, said it was "very alarming" that the policy was changed without due consultation.

"I have many more questions than answers," Lieberman said. "What is absolutely not a step in the right direction is the fact that the NCAA essentially let intense pressure about Lia Thomas specifically undermine process."

Since making headlines around the world, Thomas has been backed by equal rights activists, the Ivy League, and the University of Pennsylvania.

A spokesperson for Penn Athletics told NBC News they would work with the NCAA and continue to support Thomas.