Olympic champion Caitlyn Jenner says trans UPenn swimmer Lia Thomas should NOT compete against biological women ahead of NCAA's board meeting to review its rules Thursday

Under the current NCAA rules, a male-to-female transgender athlete is allowed to compete on the women's side after completing one year of hormone-suppression.

'We need to protect women's sports, and the NCAA needs to make the right decision tomorrow,' Jenner said. 

Critics have suggested that amount of time is not long enough to rid any male physical advantage - and that trans athletes retain considerable power over female rivals because of their height and musculature.

UPenn and the Ivy League have publicly supported Thomas competing in swim meets. 'Lia Thomas has met or exceeded all NCAA protocols over the past two years for a transgender male student-athlete to compete for a women's team. She will continue to represent the Penn women's swimming team in competition this season.'

Jenner said that she believed with transitioning comes a certain responsibility.

'First of all, I respect her decision to live her life authentically, 100%, but that also comes with responsibility and some integrity. I don't know why she's doing this,' she said.  

'One, it's not good for the trans community. I mean, we have a lot of issues in the trans community that are very difficult and very challenging. We have a suicide rate that's nine times higher than the general public. But it's also not good for women's sports,' Jenner added noting that the topic has been around for decades.

'Maybe the rules need to be a lot stricter on a subject like this. The International Olympic Committee has been looking at this issue for a long time. Back when I was competing, we had the East German women, we had the Soviet women. I mean, when I did my last lifting workout at the Olympics, there was an East German discus thrower and this girl was so much stronger than I was, we were all wondering if it was down to male hormones.'

Bruce Jenner celebrates during his record setting performance in the decathlon in the 1976 Summer Olympics in Montreal, Canada

Decathlete Bruce Jenner won the gold medal for the decathlon of the 1976 summer Olympics

The NCAA said it plans to review its current guidelines for male-to-female trans athletes on Thursday, but has yet to comment on whether changes might be afoot. 

None of Thomas' fellow swimmers have voiced their opinion publicly on the matter, but some have spoken out anonymously to air their concerns, saying that Thomas is arrogant, her teammates are upset - and that their coach is just obsessed with winning.  

'The current NCAA policy regarding when transgender females can compete in the women's category can be unfair to cisgender females and needs to be reviewed and changed in a transparent manner,' said the American Swimming Coaches Association said in a statement at the weekend.

The Ivy League, Penn and Harvard have also issued statements showing their  support for Thomas and her participation in sports.

'The Ivy League reaffirms its unwavering commitment to providing an inclusive environment for all student-athletes while condemning transphobia and discrimination in any form,' the league said.

Olympic champion swimmer Michael Phelps, 36, has reacted to the ongoing debate over trans college athlete Lia Thomas competing on women's swim team

Last week, champion swimmer Michael Phelps described the controversy as being 'very complicated' - before adding that sports need a 'level playing field' to be fair. 

Phelps, the most successful and most decorated Olympian of all time with a total of 28 medals, compared the issue of athletes like Thomas to doping in order to secure a competitive advantage in the pool. 

Speaking to CNN, Phelps was adamant that something needed to be done about current NCAA guidelines that allow Thomas to compete against swimmers born female - but was unable to share any specific ideas. 

'I think this leads back to the organizing committees again because it has to be a level playing field. That's something that we all need. Because that's what sports are. For me, I don't know where this is going to go. I don't know what's going to happen.' 

Phelps, who also holds the all-time record for Olympic gold medals at 13, said he simply wants to see a fairness across the sport.   

'I believe that we all should feel comfortable with who we are in our own skin, but I think sports should all be played on an even playing field,' he said. 

'I don't know what it looks like in the future. It's hard. It's very complicated and this is my sport, this has been my sport my whole entire career, and honestly the one thing I would love is everybody being able to compete on an even playing field.'

Phelps  holds the all-time record for Olympic gold medals at 13. He says he simply wants to see a fairness across the sport