The issue has ramifications beyond the Games because Olympic standards tend to be adopted by groups like the International Association of Athletics Federations, track’s governing body, as well as national and local athletic organizations.

“The Caster Semenya issue just demonstrated the chaos that can occur if there is not a prescriptive way of addressing this,” said Dr. Joe Leigh Simpson of Florida International University. He is an expert on gender disorders and an invited participant at the Olympic committee meetings in Miami.

Although it may seem straightforward to decide who is a man and who is a woman, it can be a scientific and medical mess, experts said. Some with the male-determining Y chromosome, for example, do not respond to testosterone. They develop as females. Others, genetically female with two X chromosomes, have overdeveloped adrenal glands whose hormones are converted to testosterone. They have high testosterone levels, like men, and ambiguous genitalia. Are they to compete with men or women?

Athletes whose sex is ambiguous say testing can be invasive and traumatic.

One who has spoken up, writing an essay in the medical journal The Lancet, is María José Martínez-Patiño, a Spanish hurdler. She had sex testing at age 22 at the 1983 world championships in Helsinki. She received a “certificate of femininity.”

In 1985, she was tested again at the World University Games in Kobe, Japan. The night before her race, she was told, in front of her teammates, that there was a problem. It turned out that she has a Y chromosome and a genetic defect preventing her from responding to testosterone.