As the debate around transgender athletes continues, ESPN's "Outside the Lines" investigates researchers' studies focusing on testosterone and the athletic benefits it can provide in Part 1 of a three-part series. ✔️ Subscribe to ESPN+ espnplus.com/youtube ✔️ Get the ESPN App: espn.com/espn/apps/espn ✔️ Subscribe to ESPN on YouTube: es.pn/SUBSCRIBEtoYOUTUBE ✔️ Subscribe to NBA on ESPN on YouTube: bit.ly/SUBSCRIBEtoNBAonESPN ✔️ Watch ESPN on YouTube TV: es.pn/YouTubeTV #espn #outsidethelines