Fifteen of the 558 athletes in the U.S. delegation at the Rio Olympics — or slightly less than 3 percent — had therapeutic-use exemptions in force during the games.
The exemptions, known as TUEs, came under increased scrutiny last week after Russian hackers broke into the database of the World Anti-Doping Agency and posted confidential medical information online from some athletes.
TUEs let athletes use otherwise-banned substances to treat long-standing medical conditions, such as attention-deficit disorder and asthma. Proponents argue those exemptions only level the playing field; critics say they can give competitors an edge.
The hackers largely targeted U.