Rachel McKinnon: Transgender athlete sets world best but rules out Tokyo 2020
Transgender athlete Rachel McKinnon says competing at the Tokyo 2020 Olympics is no longer "realistic".
The Canadian, 37, set a world best time in qualifying in defence of her sprint title at the Masters Track Cycling World Championships in Manchester.
McKinnon, who previously told BBC Sport she wanted to "try and make" next year's Games, said her chances have diminished following a crash in July.
"It's pretty much out of touch at this point," she said.
McKinnon, who says her highest elite world ranking is "around 85", told BBC Sport: "The Olympics was realistic until this past year.
"The progress I was making stalled with a crash last July so, had I kept improving and getting faster, it would have been possible.
"I am hopeful that at least one trans person will be the first ever into the Olympics in Tokyo."
McKinnon won her qualifying race in 11.649 seconds - a record in the female 35-39 sprint category - with American Dawn Orwick second in 12.063.
The final takes place on Saturday as McKinnon looks to add to the silver she won in the 500m time trial this week.
Some notable female athletes have said transgender athletes should not compete in female competitions.
They claim women who were born biological males retain a competitive advantage in some sport and have called for more research into the issue.
Ex-swimmer Sharron Davies said it will take female athletes "being thrown under the bus" at Tokyo 2020 before changes are made to transgender rules.
Prominent trans rights campaigner McKinnon has defended her right to compete, but said: "I've thought about giving up about half a dozen times a year at least.
"It's so stressful to even show up for me given the sort of attention I get.
"Every athlete has physical advantages and we're all trying to exploit them. So to single out a trans woman, when I lose most of my races, is a little unfair."
'It is excluding women and girls from their own category'
Former British Masters champion Victoria Hood, who competes in the same category as McKinnon but is currently injured, told BBC Sport that other riders "sacrificed" the opportunity to compete at the World Championships because "they don't want to compete" against McKinnon.
"The science is there. The science is clear - it tells us that trans women have an advantage," she said.
"The world record has just been beaten today by somebody born male, who now identifies as female, and the gap between them and the next born female competitor was quite a lot.
"The world record was two tenths of a second. I know that doesn't sound like a lot but it is.
"The gap between them and the next female competitor was four tenths, which to put into perspective in a sprint event like this, that would be 15m of the track, when sprint events are usually won by centimetres.
"It is a human right to participate in sport. I don't think it's a human right to identify into whichever category you choose."
Earlier this week, athletics' governing body the IAAF said trans female athletes must lower their levels of testosterone.
But Hood called on sports' governing bodies to "step up", saying they were "excluding" athletes born female.
"If people want to push this through some misguided idea that they are being inclusive, it is not inclusive. It is excluding women and girls from their own category. It's not fair," Hood said.
"The IOC need to make fair policies that are based on the science that we have, because if they can't then they are not fit for purpose.
"They are washing their hands of it and it is becoming more political than it is about science and biology."