Sebastian Coe warns 'future of women's sport' at risk in transgender athlete debate

World Athletics President Sebastian Coe has said the "integrity and future of women’s sport" is at risk in the debate over transgender female athletes.

Coe spoke after trans US swimmer Lia Thomas who won the women’s 500-yard freestyle in the NCAA swimming championship in Atlanta last week.

University of Pennsylvania student Thomas, 22, made history as the first transgender woman to win an NCAA championship and reignited the debate over the rights of trans athletes to compete.

Critics of trans inclusion in women's sport claim trans women have an unfair competitive advantage because of physiological attributes, while supporters say taking female hormones and testosterone blockers levels the playing field.

In an interview with the Daily Telegraph, the two-time Olympic champion runner Coe said "gender cannot trump biology" and called to lengthen the time trans women must wait to compete in athletics after transitioning.

"You can't be oblivious to public sentiment, but science is important," he said. "If I wasn't satisfied with the science that we have and the experts that we have used and the in-house teams that have been working on this for a long time ... if I wasn't comfortable about that, this would be a very different landscape."

World Athletics requires transgender athletes to have low testosterone levels for at least 12 months before competing.

"We are asking for a greater length of [time] before competition because the residual impact of transitioning like that is more profound," Coe said.

"There is no question that testosterone is the key determinant in performance."

USA Swimming recently changed its policy to allow transgender athletes to swim in elite events if they undergo testosterone suppression for at least 36 months and their testosterone levels are below five nanomoles per litre.

Thomas competed on the men's team for three years before transitioning and moving to the women's team where she won conference titles in the 500, 200 and 100 freestyle. 

After her win in the 500-metre freestyle, she tied for fifth place in the 200-yard freestyle and placed eighth place in the 100 - the final swim of her college career.

One teammate, Reka Gyorgy, who came 17th in the 500-yard freestyle, wrote an open letter to the NCAA criticising Thomas' inclusion after she lost her spot in the NCAA finals.

Former Hungarian Olympian Gyorgy, a fifth-year senior from Virginia Tech, said: "Every event that transgender athletes competed in was one spot away from biological females throughout the meet."

Meanwhile, one of Thomas' closest rivals in the race disputed claims that the runners-up staged a podium protest over Thomas' win.

Erica Sullivan commented on a picture that appeared to show Thomas being shunned on the winners' podium by her teammates Emma Weyant, Sullivan, and Brooke Forde, who moved away to pose together separately.

According to SwimSwam, Sullivan wrote on Instagram "there was no protest" after the trio was criticised for leaving Thomas out of celebrations.

Sullivan reportedly wrote: "@DannyReds dude I was taking a picture with my closest friends from the Olympics. It was after the first group photo was taken. News sites have used that photo and taken it out of context."

In a debate on the rules surrounding trans athletes on Jeremy Vine on 5, British trans footballer Natalie Washington, who leads the Football v Transphobia campaign, said the bigger picture of trans participation in sport is more important than concentrating on individual examples.

"There's a temptation to use these individual examples to make a wider point about how 'trans women aren' really women' or whatever," she said, pointing out that while 5'8" Thomas appears taller than her teammates in some pictures, she is actually the same height as fellow competitor Weyant.

"Trans women are massively underrepresented in sport - we know sport is a really important thing for social inclusion - it makes people feel integrated in their communities, it helps people look after their physical and mental wellbeing" she said.