Mushers and theirs dog teams during the Sedivackuv long race, Orlicke Mountains, Czech Republic on January 28, 2016. The 240 Km (150 miles) race is a multi-day event, but was canceled today, two days early, because of poor snow conditions in the region. (Photo by David Tanecek/CTK via ZUMA Press)

A 10 km prologue dog sled race on the eve of the 2018 Beringia dog sled race in Russia' s Far East; the prologue race is part of the 2018 Russian Winter Dog Powered Sports Cup in Petropavlovsk-Kamchatsky, Russia on March 4, 2018. (Photo by Yuri Smityuk/TASS)

The images of U.S. Democratic presidential candidate Hillary Clinton (L) and Republican Presidential candidate Donald Trump are seen painted on decorative pumpkins created by artist John Kettman in LaSalle, Illinois, U.S., June 8, 2016. (Photo by Jim Young/Reuters)

Competitors ride a home-made vehicle without an engine on a downhill track in the Red Bull Soapbox Race in Santiago, Chile, November 27, 2016. (Photo by Jonathan Faus/Reuters)

In this Saturday, April 8, 2017 photo, a keeper walks camels to the Al Marmoom Camel Racetrack, in al-Lisaili about 40 km (25 miles) southeast of Dubai, United Arab Emirates. Camel racing is a big-money sport and fast thoroughbreds can fetch well over a million dollars. As rising temperatures across Gulf Arab countries signal the end of the winter camel racing season, Dubai is wrapping up its races with the annual Al Marmoom Heritage Festival that has drawn thousands of camels from across the oil-rich Gulf. (Photo by Kamran Jebreili/AP Photo)

The Al-Gaffal is an annual long-distance race between crews sailing 60-ft. traditional wooden boats called dhows and takes place in the Persian Gulf, between the island of Sir Bu Nair, near the Iranian coast and the Gulf emirate of Dubai. Photo: Traditional wooden boats, or dhows, compete at sunrise during the Al Gaffal race, a long-distance dhow sailing race, near Sir Bu Nuayr, near Sharjah May 18, 2014. (Photo by Martin Dokoupil/Reuters)

Colorado Gov. John Hickenlooper shows off his socks--one with Democratic presidential candidate Bernie Sanders and the other with Republican candidate Donald Trump – before entering his former brewpub for a book signing event to mark the release of his autobiography Thursday, May 26, 2016, in Denver. Hickenlooper, who is term-limited, is doing book talk rounds this week, reviving speculation that he is positioning himself to join Hillary Clinton's presidential campaign ticket. (Photo by David Zalubowski/AP Photo)

Participants compete in the Mud Day Race extreme run competition at El Goloso military base, outside Madrid, Spain, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (Photo by Juan Medina/Reuters)