The 16-year-old transgender athlete at heart of sports row in California

California's best high school athletes are competing this weekend at the State Championships.

The stadium in Clovis, a city in the foothills of the Sierra Nevada mountains, is dressed for the occasion. Huge banners welcome athletes from across the state, food stalls line the concourse and teenagers sell event programmes.

"Good luck to all the athletes and their coaches," the inside of the programme reads. Many of the athletes have trained for years and, for some, receiving lucrative university scholarships rests on their performance here.

But one issue, one competitor, is dominating the chatter. "Which one is she?" I hear a group of boys asking.

They're talking about AB Hernandez, a 16-year-old transgender girl, who is now the focus of a legal, political and cultural row. She was born a boy but has transitioned and now competes against the girls.

Hernandez is favourite to win the long jump and the triple jump and is also competing in the high jump. She led in all three events after preliminary rounds on Friday.

Her inclusion in the girls category has become a national conversation. Read more: World Athletics to introduce sex testing As she competes, a plane flies over the stadium trailing a banner, which reads "No boys in girls' sports." It was organised and paid for by two women's advocacy groups.

A small protest is also taking place on the road outside. "Save girls sports," one poster reads.

"XX does not equal XY," reads another. Aurelia Moore is a local mum and sport fan.

"These kids get up at the crack of dawn," she says. "They work out before school, they go to school, they work out after school, the weekends they work out.

And for that just to be taken away so that we can make a boy feel better is just it's wrong. It's very wrong." Transgender inclusion is a thorny issue but a vote winner for President Trump, who campaigned with a promise to "kick out men from women's sport".

He signed an executive order seeking to ban transgender women from female sport. Trump is now threatening to withdraw federal funding from California over Hernandez's participation in this athletics event.

In a social media post, he wrote: "As a Male, he was a less than average competitor. As a Female, this transitioned person is practically unbeatable." 'No special advantage' Transgender rights activists attended the event to support Hernandez, cheering her efforts in the high jump.

Jessica Schultz is a representative of the party for socialism and liberation, a communist political group. "All girls deserve to play in girls' sports and trans girls are girls," she says.

"So they don't have any extra extreme advantage than somebody who is naturally tall or has naturally wide wingspan like Michael Phelps. "I'm surprised that the president has time to concern himself with a high school athletic competition," she adds, "but it is not surprising because he has a lot of hateful ideals".

Hernandez has required security at previous events because of abuse against her. A video recently went viral showing her mother being harangued by mums of other student athletes.

One of the voices in the video is Sonja Shaw, a school board president for Chino Valley, a district of California. "I said, boys are boys, girls are girls," she says.

"And then, I turned to the stands and I'm like, 'is there anybody that's okay with a boy competing against the girls right now?'" Girls 'can't win' There are hundreds of thousands of high school students playing sport in California, but only a handful of publicised cases of transgender girls playing girls' sport. I ask Sonja if the issue is being overblown? "Absolutely not because it's growing," she says.

"You have girls who should be on that first-place podium. They work their whole life.

Their dream is to be a winner and they can't even win, they can't even compete against these boys." In response to the backlash about Hernandez's participation, California is now allowing more cisgender girls to compete here. They may also award two winners if Hernandez finishes first.

It's a messy and controversial situation and it's not going away..