Michael Phelps: Controversy Around Trans Swim Champ Lia Thomas 'Complicated'

Olympic swimming champ Michael Phelps weighed in on the controversy around Lia Thomas, saying it's "complicated" but calling for an "even playing field" he admits he can't define, political news outlet The Hill reported.

Thomas, The Hill summarized, has "shatter[ed] school and national records" recently, shooting to fame – and into controversy.

"We all should feel comfortable with who we are in our own skin," Phelps told CNN host Christiane Amanpour. "This has been my sport for my whole entire career, and honestly the one thing I would love is for everybody to compete on an even playing field."

Phelps, aquatic sports site Swim Swam noted, was "Speaking from a doping perspective," and went on to say "he doesn't believe he ever competed in a clean sport."

"It has to be a level playing field," Phelps told Amanpour.

In terms of substances in an athlete's system that might confer an unfair advantage, rules from the NCAA regarding trans athletes and testosterone – a hormone present in people who are assigned male at birth – say that "a transgender female athlete can compete for a collegiate women's sports team after completing one year of 'testosterone suppression treatment,'" The Hill detailed. "Thomas is now more than two and a half years into her hormone replacement therapy."

But critics charge that testosterone levels notwithstanding, Thomas "has a natural advantage over cisgender women," The Hill explained.

The sports world continues to refine its policies around the issue. According to the Associated Press, the NCAA approved a new set of guidelines on Jan. 19 that specifies "a sport-by-sport approach for transgender athletes, bringing the organization in line with the U.S. and International Olympic Committees.

"Under the new guidelines, approved by the NCAA Board of Governors on Wednesday, transgender participation for each sport will be determined by the policy for the sport's national governing body, subject to review and recommendation by an NCAA committee to the Board of Governors," the AP article said.

But new guidelines themselves can spark objections, as was the case when close to 40 medical and sports authorities signed on to a statement condemning the International Olympic Committee's newly-revised policies regarding trans competitors at the Olympic games.

The statement suggested that the IOC's revised guidelines discount "the science on sex, gender and performance and focuses mostly on inclusion," UK newspaper The Guardian reported.

One of the statement's authors, Professor Jurgen Steinacker, who serves as the chair of World Rowing's Sports Medicine Commission, told the paper that women in athletics "face biological disadvantages compared to cisgender males that must be mitigated against."

Rights activists expressed doubts in turn about the critique of the IOC's guidelines.

"The case being made is to return to a bygone era of discrimination and exclusion justified by 'science,'" said sports policy expert Roger Pielke, Jr., who went on to add that "it'd be far more productive to work within the IOC Framework which is incredibly flexible when read fairly."