Dhruva Aliman does a back somersault as he dismounts from a slackline on the beach at Santa Monica, California on October 19, 2014. Slackline is a balance sport where a line of webbing is adjusted at different levels of tension between two anchor points and participants (called slackers) perform tricks and stunts including somersaults. (Photo by Mark Ralston/AFP Photo)

Vladimir Putin shows a hold to a young judo wrestler at the Regional Judo Center at the Arena Sports Complex in the Siberian city of Kemerovo on January 24, 2012, during his visit to the region. Putin is known for his passion for judo, in which he has a black belt. (Photo by AFP Photo/STR)

A competitor participates at the World Pole Dancing Championship 2012 held at the Volkshaus on November 10, 2012 in Zurich, Switzerland. The public's perception of pole dancing has recently changed to become a popular sport combining physical strength, technique and choreography. (Photo by Harold Cunningham)

Papai Simon Ole Mamai of the Maasai Cricket Warriors team from Kenya runs during a match against English team “The Shed” during “The Last Man Stands” cricket tournament at Dulwich sports ground in South London September 1, 2013. (Photo by Philip Brown/Reuters)

Men carrying a shrine jump over a bon fire, which means a wish for good luck during a traditional Chinese lunar new year celebration in Jieyang, Guangdong province, China, February 2, 2017. (Photo by Reuters/China Daily)

St Andrews University students skinny dip in the sea as May Day celebrations in St Andrews, Scotland on April 30, 2017. Hundreds of revellers ditched their clothes and bravely jumped into the bitterly cold North Sea. (Photo by Alamy Stock Photos)

A person jumps on a trampoline before Nathan's Famous Fourth of July International Hot Dog-Eating Contest at Coney Island in Brooklyn, New York City, U.S., July 4, 2017. (Photo by Andrew Kelly/Reuters)

An African immigrant tries to jump a fence into a ferry terminal in the western Greek town of Patras April 28, 2015. Afghan, Iranian and Sudanese immigrants, living precariously in abandoned factories in Patras, southwest Greece, try to stow away on nearby ferries to Italy as they seek a better life in Europe beyond crisis-hit Greece. (Photo by Yannis Behrakis/Reuters)