4 top athletes barred from competing in their Olympic events because their natural testosterone levels are deemed too high

• Caster Semenya, Aminatou Seyni, Margaret Wambui, and Francine Niyonsaba have been barred from competing in their preferred Olympic event because of their natural testosterone levels.
• World Athletics passed hormone regulations in 2018.
• The rules say intersex women must lower their natural testosterone levels with medication in order to compete.

World Athletics passed hormone regulations in 2018 that bars intersex athletes from competing in international competitions like the Olympic Games.

The regulations prevent intersex women, who naturally have higher levels of testosterone than non-intersex women on average, from competing in any running event between 400-meters and a mile unless they take medication or have surgery to reduce their testosterone levels.

Athletes like South African Olympic gold medalist Caster Semenya have protested against the regulations, saying the rules are a violation of human rights.

Here are the four intersex women who have been disqualified from competing in their preferred events at the 2021 Olympic Games or barred entirely because they don't fit the World Athletics' requirements to run.

South African gold medalist Caster Semenya was barred from the 800-meter race

Caster Semenya is a two-time Olympic gold medalist in the double 800-meter event. In 2018, she was barred from competing in international competitions in her preferred event due to the regulations by World Athletics.

The regulations specifically prohibit intersex runners who do not suppress their testosterone levels to run in any event between 400-meters and a mile long.

When she tried to use the medication to reduce her levels, Semenya said the treatment made her "constantly sick."

She is currently in a legal battle with World Athletics to run in her preferred event.

"Even though the hormonal drugs made me feel constantly sick, the IAAF now wants to enforce even stricter thresholds with unknown health consequences," she said in court documents.

Semenya was forced to compete in the 200-meter event during Olympic trials and failed to qualify for the games held in 2021.

Kenyan bronze medalist Margaret Wambui is barred from competing in the 800-meter running event

Kenyan Olympic bronze medalist Margaret Wambui competed alongside Semenya in 2016 in the 800-meter event. She too was barred from competing in her preferred race due to elevated testosterone levels.

Wambui, who also refuses to take medication to reduce her testosterone levels, suggested World Athletics introduce a third category to international sport's competitions to include intersex people.

"It would be good if a third category for athletes with high testosterone was introduced - because it is wrong to stop people from using their talents," Wambui told BBC Sports Africa.

She will not compete in the Olympic Games held in 2021.

Burundi's Francine Niyonsaba will run the 10,000-meter event at the 2021 Olympics, an event she has raced in twice

Silver medalist Francine Niyonsaba also competed with Wambui and Semenya in the 2016 Olympics. The Burundian runner was barred from the 800-meter event, her preferred category, due to World Athletics' regulations.

Niyonsaba qualified for the Olympics held in 2021 running the 10,000-meter event, an event she is ranked 63rd in globally.

Previously, Niyonsaba ranked second in the world for the 800-meter sprint.

Niger's Aminatou Seyni is barred from running in the 400-meter race, an event she is ranked fifth in globally

Nigerian runner Aminatou Seyni clocked the fifth fastest time in the world for the 400-meter sprint in 2019, making her a contender to watch going into the Olympic Games in Tokyo held in 2021.

However, Reuters reported the runner was concerned she would not be able to compete in her preferred event to qualify for the Olympics because of hormone regulations outlined by World Athletics.

"It broke my heart when I was told I couldn't run in my favorite 400m event because I had higher testosterone," Seyni said in an email to Reuters. "I didn't want to take any medical steps... My hormones are natural."

She will run the 200-meter event in the Olympics, where she ranks 44th globally.