AIGLE, Switzerland -- Cycling's governing body updated its eligibility rules for transgender athletes Thursday with stricter limits that will force riders to wait longer before they can compete.
The International Cycling Union (UCI) increased the transition period on low testosterone to two years and lowered the maximum accepted level of testosterone.
The previous transition period was 12 months, but the UCI said recent scientific studies show that "the awaited adaptations in muscle mass and muscle strength/power" among athletes who have made a transition from male to female take at least two years.
"Given the important role played by muscle strength and power in cycling performance, the UCI has decided to increase the transition period on low testosterone from 12 to 24 months," the governing body said after a management board meeting.
The UCI also cut the maximum testosterone level allowed in transgender athletes to 2.5 nanomoles (nmol) per liter instead of the current 5.
"This value corresponds to the maximum testosterone level found in 99.99% of the female population," the governing body said.
It added that the adjustment "is intended to promote the integration of transgender athletes into competitive sport, while maintaining fairness, equal opportunities and the safety of competitions."
The rule will go into effect on July 1.
The International Olympic Committee updated its own guidance on transgender eligibility in November but left it to individual sports bodies to set their own rules.
The IOC said then that "athletes should be allowed to compete but unfair advantage needs to be regulated."
Critics of transgender athlete policy have argued that some physical benefits are retained by women who have gone through male puberty.
Swimming's world body, FINA, is due to publish its policy on transgender athletes Sunday.