The International Olympic Committee's decision to delay its verdict on updates to guidelines for transgender athletes before the Tokyo 2020 Olympics has provoked widespread debate.

Sharron Davies, British Olympic medallist and outspoken critic of the IOC's current guidelines for transgender athletes, has expressed her dismay that the governing body has not got any further in its assessment. 

The 1980 Olympic silver-medallist believes current research suggests that transgender women who transition post-puberty retain the residual competitive advantages of previous levels of testosterone. Furthermore, she believes that changes must be made to current guidelines before athletes head to the 2020 Olympics in Tokyo.

Taking to her Twitter page, Davies warned "If there is any doubt delay inclusion until proved science. Do not use women’s sport as a live experiment. That’s not right or fair."

Several high profile female athletes including Martina Navratilova, Paula Ratcliffe, Dame Kelly Holmes and Davies have expressed their concern to the IOC in a letter and called for more research into the area. 

The IOC's guidelines for transgender athletes are generally used as the precedent for most other sports federations. Under current guidelines set in November 2015 transgender women can compete in women's competitions without surgery to remove testes, as long as their testosterone levels remain below 10 nanomoles per litre.

By comparison, the average women’s testosterone levels tend to range between 0.12 and 1.79 nmol/l. Consequently, sporting federations have questioned current guidelines and have called for the IOC to reduce acceptable testosterone levels for female athletes to 5nmol/l.

The Karolinska Institute in Sweden recently released findings that show testosterone suppression for transgender women has little effect on an athletes performance even a year after commencing treatment.

First transgender women to compete in Tokyo 2020?
The topic of transgender women competing in sport has become increasingly contentious, especially as Tokyo 2020 edges ever closer and the IOC stands to make little progress.

Tokyo 2020 could feature the Olympics' first transgender athlete: Laurel Hubbard, a New Zealand weightlifter. She is yet to achieve the qualifying lift for the competition but has until April 30th 2020.

Hubbard, 41, who transitioned aged 35, previously competed in the men's competition before her transition. She has since won gold in the 87+kg at the recent Asian games and looked set to win the 2018 Commonwealth Gold before dislocating her elbow during the competition.

In December 2017, Hubbard was interviewed by the New Zealand media after achieving the silver medal at the 2017 World Championships.

"I would ask people to keep an open mind and perhaps look to the fact that I didn’t win as perhaps the evidence that any advantage I may hold is not as great as they might think," she said. 

Protecting women's sport or excluding transgender athletes?
It is clear that finding a middle ground in this divisive area in the sport will be hugely difficult and the inability of the IOC to reach a consensus is a testament to this.

This is, in part, a result of how fundamentally emotive and sensitive the issue of transgender participation is. At its very roots sport is about inclusivity and embracing diversity - everyone should be able to participate in sport, both cisgender and transgender athletes.

Yet, when we analyse the issue at an elite level the debate becomes more clouded and more complicated. Barriers exist already for women and girls in sport and many believe current regulations not only make it harder for women to reach the highest level but also but them at risk of injury.

More research is needed on this topic before the IOC will be able to come to a conclusion. Scientific facts will be required before any governing body is likely to make any change to regulations. A permanent solution is, clearly, a long way off.