Extra testosterone increased lean muscle mass and improved running endurance in a group of 48 nonelite athletic women, researchers report this week in the British Journal of Sports Medicine. What that means for elite athletes remains unclear, Inverse reports, especially in the case of high-profile athletes such as South African runner Caster Semenya (above), who has a condition that causes elevated levels of testosterone. She has been barred from this year’s World Athletics Championships because of those levels, and the International Association of Athletics Federations (IAAF) wants to ban Semenya from competing against other women. But the paper has its detractors: Some argue that its experimental setup is not relevant to women like Semenya (because her condition changes the way testosterone affects her body), and others point out that funding for the study comes from an IAAF-linked organization.
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