Lord Coe has claimed "overwhelming support" among female athletes for sex testing, despite "challenges" in its mass implementation for the upcoming World Championships.
New rules requiring all athletes competing in the female category to take one-off cheek swabs or dry blood tests come into force on Monday but logistical complications - notably questions over their legality in France - means that the results may not all be processed by the start of the World Championships on September 13.
Coe, who is the president of World Athletics, said that more than 90 per cent of female World Championship competitors had now taken the test but the last remaining checks will have to take place when athletes assemble at their holding camps in Japan. It follows reports by Reuters of Canadian athletes being told that their tests did not initially comply with World Athletics' requirements.
The French Athletics Federation had planned to test athletes at the national championships but was told "such tests are prohibited under the French Bioethics Law enacted in 1994", the federation said in a statement.
"The federation is confident in World Athletics' ability to quickly find a solution and to ensure that French athletes can take part in international competitions under the best possible conditions," said the statement. The test is designed to detect the SRY gene, found on the Y chromosome, which triggers the development of male characteristics.
World Athletics has since been working with various federations to help athletes obtain tests at other meets or at their pre-World Championship training camps.
"We're working very, very closely with all our member federations to ensure that the majority of our female athletes are tested before the Tokyo Championships," said Coe, who regards the testing as vital to protect the integrity of women's sport. "The timeframe was tight. We knew that. The athletes are overwhelmingly supportive of this and have been very, very helpful in all this.
"There will be athletes that will be tested even in their holding camps in Tokyo. People have really been incredibly supportive, even when there have been some national frameworks that have added sort of complexity to this. France, of course, has its own national laws." World Athletics has made a contribution of around $100 for each test and have also helped federations find cost-effective solutions.
"By and large, the process has gone pretty smoothly, but it's not been without its challenges," said Coe. "It's been a very good example of the sport coming together and really good close cooperation."
World Athletics says that it became the first major sport in recent times to bring in biological sex testing in order to protect the "integrity of female women's sport". The forthcoming World Athletics Championships, which will have around 1,000 female competitors, is easily the biggest event at which athletes have been asked to comply with these rules.
It followed a series of rule changes in the sport over recent years, with transgender athletes banned from the female category in 2023 and athletes with differences in sexual development (DSD), such as the former Olympic 800m champion Caster Semenya, required in recent years to suppress their testosterone to be eligible for the female category.
The test will detect the SRY gene, found on the Y chromosome, which triggers the development of male characteristics. If the test is negative for the Y chromosome, the athlete is eligible to compete in the female category. A cheek swab is used to check for the presence of the SRY gene, while a dried blood spot test may also be used to measure the athlete's testosterone levels. The test only has to be taken once in an athletes' career, with World Athletics describing the test as a "highly accurate proxy for biological sex".
Coe says that it has the support of a vast majority of female athletes, although concerns have also been raised. The French Athletics Federation has been told that the test is illegal in France, meaning athletes are having to travel outside their home country in order to be tested. World Athletics now accepts that some tests will happen only once athletes have arrived in Japan ahead of the World Championships and that some results might not even be processed before the competition.
The governing body, however, was keen to keep the current timetable as the vast majority of the world's elite athletes will be at the event. One unnamed Canadian athlete told CBS that, according to healthcare providers she had liaised with, the policy was unethical, with a team-mate also describing the testing as "invasive" and its rollout a "mess".
World Boxing also approved the use of the SRY test in May when it introduced mandatory sex testing for all athletes. The IOC implemented "certificates of femininity" at the 1968 Mexico Games, but these chromosome-based tests were later deemed unscientific and unethical, leading to their removal before the Sydney 2000 Olympics.
The International Olympic Committee has previously described a return to sex testing as a "bad idea", but new president Kirsty Coventry has not ruled it out and has promised to implement a "cohesive" policy that protects the female category.