People attend the Stranavigli Water Race held at the Naviglio Grande on July 16, 2011 in Milan, Italy. Stranavigli Water Race is an annual creative contest on the water. (Photo by Vittorio Zunino Celotto/Getty Images)

Pigs race around the track at the Pig Racing and Diving display at the Sydney Royal Easter Show on April 10, 2009 in Sydney, Australia. (Photo by Mark Kolbe/Getty Images)

Participants compete during the Strong Race event near Tukums, Latvia, May 3, 2015. More than 4,000 people participated in this 9 km endurance race with 33 different obstacles. (Photo by Ints Kalnins/Reuters)

A cloud of black smoke billows out the exhaust pipe of John Robertson's diesel dragster as he runs down the track during the 2015 NHRA Kansas Nationals, Friday, May 22, 2015, at Heartland Park in Topeka, Kan. (Photo by Chris Neal/The Topeka Capital-Journal via AP Photo)

Sebastien Bourdais, of Colombia, makes a corner during practice for the IndyCar auto race Saturday, June 13, 2015, in Toronto. (Nathan Denette/The Canadian Press via AP)

A participant competes in the “Nostalgic Ski Race” in the western town of Neuastenberg February 8, 2015. The “Nostalgic Ski Race” is held every two years with about 40 participants and is organized by the ski club of Neuastenberg, a town which was founded in 1713. The conditions for the participation in the race are vintage skis and dresses. (Photo by Ina Fassbender/Reuters)

A competitor reacts as she emerges from the water during the Tough Guy event in Perton, central England, January 26, 2014. The annual Tough Guy race – “the toughest race in the world” – at Perton in Staffordshire. Tough Guy claims to be the world’s most demanding one-day survival ordeal. First staged in 1987, the Tough Guy Challenge has been widely described as one of the hardest races of it’s type with up to one-third of the starters failing to finish in a typical year. (Photo by Darren Staples/Reuters)

Greyhounds compete during a race at Santiago city, March 8, 2014. With over 100 years of history, greyhound racing attracts people mainly from rural areas of Santiago every weekend. Some dogs come from Argentina, the United States and Ireland and can develop a speed of up to 80 kilometers per hour on a straight running track of about 200 meters, according to organisers. Bets range from $2 to $1,000 per race, offering a livelihood for breeders and gamblers. (Photo by Ivan Alvarado/Reuters)