Participants stretch their bodies as they pose for pictures before the Beijing International Marathon in Beijing, China, September 20, 2015. About 30,000 runners participated in the annual running event. (Photo by Kim Kyung-Hoon/Reuters)

In this photo provided by The Daily Free Press and Kenshin Okubo, people react to an explosion at the 2013 Boston Marathon in Boston, Monday, April 15, 2013. (Photo by Kenshin Okubo/AP Photo/The Daily Free Press)

P.S. All pictures are presented in high resolution.

Runners sleep before competing in the 2016 New York City Marathon in the Manhattan borough of New York City, NY, U.S. November 6, 2016. (Photo by Eduardo Munoz/Reuters)

Centenarian Sikh runner Fauja Singh poses for pictures after being the first person to officially enter for next year's Edinburgh Marathon on September 1, 2011 in Edinburgh, Scotland. A world record holder, aged 100, Fajua Singh has run seven marathons, all after his 89th birthday. He officially opened the entry process by signing up for his last ever 26 mile event in Edinburgh. (Photo by Jeff J Mitchell/Getty Images)

Costumed competitors run during the Marathon International du Beaujolais race near in the gardens at the castle of Pizay, November 22, 2014. Its 10th edition gathered more than 10,000 runners from 60 countries making their way on small roads, around and through the castles and vineyards, in the Beaujolais region. (Photo by Robert Pratta/Reuters)

Actress Andrea Barber crosses the finish line at the Rock 'n' Roll Los Angeles Halloween Half-Marathon and 5K benefitting the ASPCA, or American Society for the Prevention of Cruelty to Animals on October 26, 2014 in Los Angeles, California. (Photo by Rich Polk/Getty Images for CGI)

A runner in fancy dress participates in the Virgin London Marathon 2013 on April 21, 2013 in London, England. (Photo by Tom Dulat/Getty Images)

Participants wearing masks during a hazy day at the Beijing International Marathon in front of Tiananmen Square, in Beijing, October 19, 2014. (Photo by Reuters/Stringer)