When Chelsea Mitchell, ranked as the fastest girl in the 55-meter dash in Connecticut high school track, showed up for a competition last year, she knew it would be a challenge. Her competitors included two biological males who said they identify as girls. Mitchell, a senior at Canton High School, had seen the speeds posted by the two. She was aware that other girls had lost to athletes born as boys who identify as girls. But at the time, she says, she “could feel the adrenaline in my blood.” That adrenaline wasn’t enough, though. Mitchell came in third behind the...