Landmark study supports controversial Caster Semenya ruling

The governing body of world athletics welcomed a landmark study showing high testosterone helped women run better, saying it justified their decision to bar Olympic champion Caster Semenya from key races.

In a controversial ruling earlier this year, the Court of Arbitration for Sport upheld the IAAF regulations which require women like Semenya, with higher than average natural female testosterone levels, to take medically-prescribed drugs to lower their testosterone levels or be kicked out of competitions.

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A 28-year-old double Olympic champion, Semenya has a medical condition called hyperandrogenism, which boosts her testosterone count. The athlete has refused to take hormone suppressing medication to comply with the regulations.

In a study in the British Journal of Sports Medicine, Swedish researchers found women with higher testosterone could run longer and had more lean muscle mass.

The International Association of Athletics Federations - which governs track and field - embraced the study as proof it had done the right thing in barring South Africa's Semenya for high testosterone levels, a primarily male hormone.

"The IAAF introduced a testosterone limit for the female category for the sole purpose of maintaining fair and meaningful competition for women," it said in a statement on Wednesday.

The study, it added, "reinforces our evidence-based conclusion that high testosterone levels give female athletes a significant advantage in some athletic events."

Study sheds light on testosterone benefits for women

Medical professionals had believed that testosterone fuelled strength and endurance in men, but the benefits for female athletes were previously unclear.

No longer, according to the researchers from Karolinska Institutet in Sweden, and other institutions.

"Our study supports a causal effect of testosterone on physical performance, as measured by running time to exhaustion, in young healthy women," said the researchers, whose study was released on Tuesday.

There was no immediate reaction from Semenya, whose barring from the 800-metre race in September's World Athletics Championship sparked controversy throughout the sporting world.

Her case became a test of where sports authorities draw the line when it comes to athletes whose bodies fall outside standard ranges or who change gender then seek to compete.

On Tuesday in Qatar, the IAAF revamped the rule to add transgender competitors to the list of restricted athletes.

It had based its ban on evidence that it had partly funded and which drew criticism; scholars from the University of Colorado at Boulder said they could not replicate the study and found 17 to 32 per cent of the data used was wrong.

Earlier this year, a Court of Attribution for Sport said while the testosterone regulation was discriminatory, it was "necessary, reasonable and proportionate" to protect "the integrity of female athletics."