Brazil's Fernanda Martins competes in the qualifying round of the women's discus throw event at the IAAF World Championships at the Bird's Nest National Stadium in Beijing on Aug. 24.(Antonin Thuillier/AFP/Getty Images)

Sweden's Michel Torneus competes in the men's long jump qualification at the Bird's Nest stadium in Beijing on Aug. 24.(Wong Maye-E/Associated Press)

Britain's Jessica Ennis-Hill competes in the javelin throw of the women's heptathlon event on Aug. 23.(Antonin Thuillier/AFP/Getty Images)

Jamaica's Shelly-Ann Fraser-Pryce celebrates as she wins the women’s 100m final at the World Athletics Championships on Aug. 24.(Mark Schiefelbein/Associated Press)

Jamaica's Usain Bolt wins the final of the men's 100m event on Aug. 23. (Fred Dufour/AFP/Getty Images)

Jamaica's Usain Bolt strikes a pose for the cameras after winning the the men’s 100m final on Aug. 23. (Kin Cheung/Associated Press)

Cuba's Maykel D. Masso competes in the men's long jump qualification on Aug. 24. (Lee Jin-man/Associated Press)

Germany's Lars Hamann competes in the qualifying round of the men's javelin throw on Aug. 24. (Adrian Dennis/AFP/Getty Images)

Raphael Marcel Holzdeppe of Germany celebrates as he clears the bar to win silver in the men's pole vault final on Aug. 24. (Kai Pfaffenbach/Reuters)

The hair of Natasha Hastings of the United States is blown by the wind before the women's 400m heats on Aug. 24. (Lucy Nicholson/Reuters)

Poland's Pawel Wojciechowski competes in the final of the men's pole vault on Aug. 24. (Johannes Eisele/AFP/Getty Images)

Rolanda Bell of Panama falls in the women's 3000m steeplechase heats during on day three of the championships on Aug. 24. (Alexander Hassenstein/Getty Images )

Shalane Flanagan (left) of the United States celebrates with teammate and bronze medalist Emily Infeld after the final of the women's 10,000m event on Aug. 24. (Pedro UgarteAFP/Getty Images)

Runners compete in the women's 10,000m final during the championships on Aug. 24. (How Hwee Young/EPA)

Rushwal Samaai of South Africa competes in the men's long jump qualification during the 15th IAAF World Championships on Aug. 24. (Dylan Martinez/Reuters )

Shawnacy Barber of Canada competes in the men's pole vault final during day three of the championships on Aug. 24. (Ian Walton/Getty Images)

Justin Gatlin (right) of the United States is embraced by his mother Jeanette after winning the silver medal in the men's 100m final on Aug. 23. (Wu Hong/EPA)

Joe Kovacs of the United States competes in the final of the men's shot put event on Aug. 23. (Franck Fife/AFP/Getty Images)

Britain's Greg Rutherford celebrates after winning the gold medal in the men's long jump final on Aug. 25. (Diego Azubel/EPA)

Estonia's Magnus Kirt competes in the qualifying round of the men's javelin throw on Aug. 24. (Adrian Dennis/AFP/Getty Images)

Jessica Ennis-Hill reacts after winning the heptathlon with 6,669 points on Aug. 23. (Kirby Lee/USA Today Sports)

Jamaica's Shelly-Ann Fraser-Pryce celebrates on the podium after winning the gold medal in the women's 100m final during the Beijing 2015 IAAF World Championships at the National Stadium, also known as Bird's Nest on Aug. 25. (Wu Hong/EPA)