Arman Hall, Tony McQuay, Gil Roberts and LaShawn Merritt of the United States celebrate winning the gold medal in the men's 4x400-meter relay final on Saturday at the 2016 Summer Olympics in Rio de Janeiro. | AP
Arman Hall, Tony McQuay, Gil Roberts and LaShawn Merritt of the United States celebrate winning the gold medal in the men's 4x400-meter relay final on Saturday at the 2016 Summer Olympics in Rio de Janeiro. | AP

The United States' Allyson Felix crosses the line to capture the gold medal in the women's 4x400-meter final on Saturday at the 2016 Rio Olympics. | AP
The United States' Allyson Felix crosses the line to capture the gold medal in the women's 4x400-meter final on Saturday at the 2016 Rio Olympics. | AP

Mo Farah of Britain celebrates clinching the gold medal in the men's 5,000-meter final on Saturday at the 2016 Rio Games. | AP
Mo Farah of Britain celebrates clinching the gold medal in the men's 5,000-meter final on Saturday at the 2016 Rio Games. | AP