South Africa's double Olympic champion Caster Semenya must take drugs to reduce her testosterone levels if she wants to continue competing, after losing a landmark case against athletics' governing body.
The Court of Arbitration for Sport rejected her appeal against new rules restricting testosterone levels in women runners, which the IAAF said were designed to "create a level playing field in female sport".
CAS admitted the rules were discriminatory towards athletes with DSD (differences in sexual development), which Caster Semenya has, but said "such discrimination is a necessary, reasonable and proportionate means of achieving the IAAF’s aim".
Three people close to the case shared their reaction to the ruling with talkRADIO.
Marilyn Okoro: 'I'm hugely relieved'
GB 800m runner, lost to Semenya in the 2009 World Championship final
Image: Marilyn Okoro/Twitter
"I'm hugely relieved. It kind of just restores your faith to know people are really fighting for the integrity and the longevity of female sport.
"In January 2009 I'd seen her run a pretty mediocre race. So fast forward to August and seeing her demolish the field - I was a bit like 'wow - how am I ever going to be able to compete against someone like Caster, fairly?'
"I didn't truly understand until recently when I looked at some of the data and some investigations that have been done.
"Her advantage is not her fault, but ultimately I feel like I'd like to be on a level playing field as the girls that I line up against.
"It has deeply affected my life and my career so you've just got to stand up for what you believe in. In terms of sponsorships, people look at results and if you're not placing in those finals, ultimately no one really cares.
"I know there's going to be a lot of relieved athletes out there, that are going to go into training with a renewed sense of 'justice is being done'."
Dr Alun Williams: 'It's the wrong decision'
Reader in sports and exercise genomics at Manchester Metropolitan University. He gave evidence to CAS on request of Caster Semenya's legal team
Dr Alun Williams, centre. Image: Alun Williams/Twitter
"I think it's the wrong decision.
"It's only in these events (400m-1 mile) where the IAAF think they have some evidence that DSD athletes have an advantage. And actually the scientific evidence is very very thin.
"If you look at the difference in male and female world records from sprinting right through to marathon, it's fairly consistent at around 10%. So there's no particular reason why a regulation should only apply to a very narrow range of running events.
"The only way to prove DSD athletes have an advantage would be to have a well controlled, randomised trial with two groups of people: one taking a placebo and one taking something that reduced their testosterone.
"If Caster Semenya takes the medication and if her performances do go down that's not really evidence of something. That is an anecdote.
"The idea that you could have a male category, a female category and then an 'intersex' category - all you've achieved is taking the debate about one dividing line into two dividing lines.
"I'm disappointed for Caster Semenya and other DSD athletes as well. What they're now faced with is a series of unpalatable choices: either compete against males, which is completely unrealistic, or compete in other events.
"A significant reason why some people can make it to the elite level of sport and others can't is because of a rare combinations of genes that make them different.
"But the IAAF and other authorities are quite relaxed about that because it doesn't challenge the distinction between male and female categories."
Sharron Davies: 'We've got to stop being so PC'
Former GB Olympic swimmer
Sharron Davies. Image: Sharron Davies/Twitter
"For 20 years I competed against East Germans, who were full of testosterone and I knew no matter what I did I couldn't physically compete with them.
"If you carry the Y chromosone, which means you go through male puberty and produce that benefit, then that's not a fair playing field.
"Do you say that the seven people Caster races in the Olympic final have to give up their opportunity to win a gold medal or do you say that Caster gives up her opportunity to win a gold medal? As much as I feel very sorry for Caster, I fall on the side of the other seven athletes.
"We've got to stop being so PC that we're not allowed to talk about this. Socially, people should be allowed to live the way they want to live without harming anybody. But sport is primarily about biology.
"In 1976 they used to do sex testing, which I would like to see brought back. It's not at all degrading. They just put a cue tip on the inside of your mouth and that's it.
"Do we have to create an extra category? I don't know but I think we need research and open debate.
"I feel very sorry for Caster and it should have been sorted out 10 years ago."