Billie Jean King is among more than 60 athletes urging international track and field's governing body to rescind its new standard on natural hormone levels for female runners.

The tennis great joined the athletes in an open letter asking the IAAF to end its policy passed in April that limits testosterone levels for middle-distance runners. Two sports groups — the Women's Sports Foundation and Athlete Ally — released the letter Tuesday.

Soccer's Megan Rapinoe, hockey's Meghan Duggan and softball's Jessica Mendoza are among the signees. They say the standard discriminates against female athletes and "no woman should be required to change her body" to compete in sports.

World and Olympic 800-meter champion Caster Semenya recently challenged the policy before the Court of Arbitration for Sport. The policy requires women to take birth control pills to lower testosterone levels and is to take effect Nov. 1.

Rapinoe pointed to the wingspan of swimmer Michael Phelps and height of basketball player Yao Ming.

"This is just another way in which sport governing bodies police dominant female athletes — but never our male counterparts," she said.