PRETORIA, SOUTH AFRICA— There are female athletes who will be competing at the Olympic Games this summer after undergoing treatment to make them less masculine.

Still others are being secretly investigated for displaying overly manly characteristics, as sport’s highest medical officials attempt to quantify — and regulate — the hormonal difference between male and female athletes.

Caster Semenya, the South African runner who was so fast and muscular that many suspected she was a man, exploded onto the front pages three years ago. She was considered an outlier, a one-time anomaly.

But similar cases are emerging all over the world, and Semenya, who was banned from competition for 11 months while authorities investigated her sex, is back, vying for gold.

Semenya and other women like her face a complex question: Does a female athlete whose body naturally produces unusually high levels of male hormones, allowing them to put on more muscle mass and recover faster, have an “unfair” advantage?

In a move critics call “policing femininity,” recent rule changes by the International Association of Athletics Federations (IAAF), the governing body of track and field, state that for a woman to compete, her testosterone must not exceed the male threshold.

If it does, she must have surgery or receive hormone therapy prescribed by an expert IAAF medical panel and submit to regular monitoring. So far, at least a handful of athletes — the figure is confidential — have been prescribed treatment, but their numbers could increase. Last month, the International Olympic Committee began the approval process to adopt similar rules for the Games.

For female athletes, this may mean they were born with hyperandrogenism, a disorder in which they have hormone levels similar to those of a man.

Sometimes, the distorted levels result from conditions such as polycystic ovary syndrome, which causes a hormonal imbalance in the body, while other cases are pure hermaphroditism, where women are born with some male reproductive organs.

Nowhere is the issue more taboo than at South Africa’s High Performance Centre, a world-class sport facility located on the pastoral grounds of the University of Pretoria.

Few in and around the tight-knit community will talk on the record, although one scientist at the centre, who requested anonymity for fear of losing her job, says multiple players on one female team have had their undescended testes removed.

Lindsay Perry, another scientist, says sometimes whole teams of African women are dead ringers for men. “In football, some of the other girls were on the other end of the spectrum, you’re like, ‘No way that’s a girl,’” he says.

Caster Semenya, 21, who lives and trains at the centre as unobtrusively as possible, remains the unwilling poster girl for the issue.

In 2009, she was at the centre of an international controversy after winning the 800-metre world championship with a scorching time of 1:55:45, by an astounding two-second margin.

Her competitors were quick to point fingers at the boyish teenager, whose muscular biceps and husky voice inspired snide remarks. “These kind of people should not run with us. For me, she’s not a woman. She’s a man,” said Elisa Cusma, an Italian who placed sixth in the race.

The gender investigation began after officials received an anonymous complaint. “I have been subjected to unwarranted and invasive scrutiny of the most intimate and private details of my being,” Semenya said in comments released by her legal advisers at the time.

The results were never made public, but Semenya kept her medal and was eventually cleared to race. She continues to prepare here for her first Olympics.

“She’s truly a hero and a leader and a role model in this country. I don’t think we celebrate her enough,” says Elaine Salo, an anthropology professor at the University of Pretoria who has a poster of Semenya on her office door. “What is athletics if not the ability of the biological body to extend itself?”

Today, Semenya is cheering on her teammates at the South African open championships — for many, their last chance to qualify for the Olympics. There is no need for Semenya to race. She easily qualified weeks ago.

Instead, she stands in the stadium aisle, posing for the camera. In the background, Rihanna is on heavy rotation. “It happens all the time, all the time,” she says of the photo requests, laughing. “I’m used to it.”

She wears a tight turquoise polo over her fit, feminine body. Relaxed, poised and, it must be said, pretty, the young woman with an irresistible smile is almost unrecognizable from photographs taken during the height of the controversy.

“I know she gets treatment. What the treatment entails, I can’t give the details,” says Danie Cornelius, a track and field manager at the university.

“We all accept . . . and she accepts . . . within sports you have to perform within certain guidelines, or else it will be chaos,” says Cornelius.

“She feels it’s something she has to do.”

When asked about her treatment, Semenya demurred. “I can’t really say anything,” she said, looking at the ground.

In the 1960s, female athletes had to walk nude in front of a panel of experts who assessed their sexual credentials.

The so-called “naked parades” were abandoned and gender verification was eventually done using chromosome tests, until the IOC called for their discontinuation in the late ’90s, saying the tests constituted an invasion of privacy.

For a decade, intersex athletes were dealt with relatively discreetly on a case-by-case basis. Then came Semenya, whose phenomenal win forced an entire bureaucracy on the issue.

Dr. Stéphane Bermon, coordinator of the IAAF working group on Hyperandrogenism and Sex Reassignment in Female Athletics, says the prevalence of women with higher levels of male hormones is greater than most believe.

They have an “unfair advantage,” he says: “more muscle mass, easier recovery and a higher level of blood red cells.”

Dr. Myron Genel, an endocrinologist who serves on the IAAF’s expert medical panel, says the hormone test is complicated.

Some athletes may have excessive levels of hormones, but their bodies do not benefit from them — most are insensitive to the extra hormones circulating in their system — so the expert medical panel must conduct a clinical examination.

The tell-tale signs are illustrated graphically in the IAAF rulebook, a sliding scale on everything from sexual organs to lower back hair and breast shape.

Loading... Loading... Loading... Loading... Loading... Loading...

“What’s been going on here, for over 50 years now, has been an attempt to modify and refine the rules so as to be fair but also to be scientifically accurate and appropriate,” says Genel. “We’ll get it right.”

Top-ranking Canadian sport officials are speaking out about their opposition to what they fear is another chapter in the checkered history of Olympic gender policing.

“We have a longstanding stance against gender testing,” says Paul Melia, the centre’s president.

“At some point we’re faced with the intrusiveness and degradation of privacy — the public outing of someone at a high-profile athletic event — and that doesn’t seem right,” he says.

Bruce Kidd, a prominent Canadian sport policy adviser who has worked with the cross-country expert committee on the advisory paper, says the IAAF’s test is “policing femininity.” He believes it should be abolished.

“It’s still the old patriarchal fear, or doubt, that women can do outstanding athletic performances. If they do, they can’t be real women. It’s that clear, it’s that prejudicial,” he says.

“Personal household and national income is far more relevant to performance than hormonal makeup,” he says. The countries with the highest GDP produce the most gold medals. The richer the athlete, the higher the likelihood of a winner, says Kidd. In other words, the salaries of your parents are a more accurate success indicator than testosterone.

“We don’t require this kind of radical equality for other factors that make a difference, so why should we single out this one?” asks Kidd.

Kristen Worley, a Canadian cyclist who failed to make the 2008 Beijing Olympic team, sits on the expert panel, advocating a more radical solution.

“What we’re trying to do, instead of having sport based on sex, we’re basing it on ability,” says Worley, who is also a transgender activist. “We’re moving away from the idea of sex-based sport.”

To most, dissolving the male and female categories is not a realistic option. “A lot of the discussion is wishing people could come as they are and be involved in sport,” says Karin Lofstrom, executive director of the Canadian Association for the Advancement of Women and Sport and Physical Activity.

On the other hand, she added, “it’s easy to say this (testing) isn’t right. But what do you put in place?”

Including more women on decision-making panels might help, says Lofstrom. They might fight what she calls a preoccupation with the “stereotypical feminine athlete” — the Anna Kournikovas of the world.

“If you don’t look like the perfect little tennis player, then you’re less a woman, and there’s potential to find some reason they shouldn’t be involved,” she explains.

“We haven’t conquered all the battles about women playing sport.”

The country needs a win to provide closure to a particularly traumatic three years for South Africa’s athletic community.

Following her investigation, officials at Athletics South Africa were found to have lied about her case, withholding important medical information from her and international authorities. Top executives were fired, sponsors pulled out and meets were cancelled.

“We’re a sport on the mend and we’re going to go places again; people are excited,” says Frik Vermaak, the new CEO of Athletics South Africa.

Doing right by Semenya is one of Vermaak’s priorities. “The correct message is she is a terrific athlete. That is the correct message. No more than that,” he says.

She is a female athlete, and is preparing to be judged as such, says Vermaak.

“Caster is not something out of the ordinary,” he says. “She’s a normal athlete.”