Allyson Felix of the United States reacts after winning the silver medal in the Women's 400m Final on Day 10 of the Rio 2016 Olympic Games at the Olympic Stadium on August 15, 2016 in Rio de Janeiro, Brazil.

Allyson Felix of the United States celebrates winning gold in the Women's 4x400 Metres Relay final during day ten of the 16th IAAF World Athletics Championships London 2017 at The London Stadium on August 13, 2017 in London, United...More

Allyson Felix of the United States reacts after competing in the Women's 400 metres final during day six of the 16th IAAF World Athletics Championships London 2017 at The London Stadium on August 9, 2017 in London, United Kingdom.

Quanera Hayes of the United States and Allyson Felix of the United States react after competing in the Women's 400 metres semi finals during day four of the 16th IAAF World Athletics Championships London 2017 at The London Stadium on...More

Allyson Felix is photographed for ESPN Magazine, The Music Issue on January 19, 2013. PUBLISHED

Allyson Felix, English Gardner, Morolake Akinosun and Tianna Bartoletta of the United States react during round one of the Women's 4 x 100m Relay on Day 13 of the Rio 2016 Olympic Games at the Olympic Stadium on August 18, 2016 in Rio...More

TOPSHOT - USA's Allyson Felix smiles after competing in the Women's 400m Semifinal during the athletics event at the Rio 2016 Olympic Games at the Olympic Stadium in Rio de Janeiro on August 14, 2016. / AFP / OLIVIER

Gold medalist Allyson Felix of the United States poses on the podium during the medal ceremony for the Women's 400 metres final during day seven of the 15th IAAF World Athletics Championships Beijing 2015 at Beijing National Stadium on...More

Allyson Felix of the United States celebrates after winning gold in the Women's 400 metres Final during day six of the 15th IAAF World Athletics Championships Beijing 2015 at Beijing National Stadium on August 27, 2015 in Beijing,...More