What is an unfair advantage in sports?

We at Short Wave have been following all things Olympics, from the medals and new records to the ugly accusations that two women boxers aren't really women. Last year, the boxers failed gender tests, according to the International Boxing Association. The IBA claims the women have a "hormonal imbalance" that gives them women an unfair advantage. The International Olympic Committee has condemned these claims and defended the boxers' right to compete in the women's category. But this Olympics is far from the first time the gender of athletes has been questioned.

But this Olympics is far from the first time the gender of athletes has been questioned.

NPR's Embedded podcast has a new series called Tested that gets into this history of sex testing in elite sports – and track and field in particular. In this excerpt of the podcast, host Rose Eveleth digs deep on a big question: What constitutes an "unfair" advantage on the track?

Listen to the full Tested series now.