Skeleton involves a person riding a small sled down a frozen track while lying face down. The sport is a more intense form of luge because skeleton competitors leap onto the sled and slide downhill head first. Skeleton athletes can reach up to 80 mph on straightaways, causing forces up to 5g, so the helmet is a critical component for attitude as well as safety.

Indian paramilitary forces march during the annual Republic Day parade on Rajpath in New Delh, January 26, 2013. Republic Day commemorates the 1950 adoption of India's constitution. (Photo by Kevin Frayer/Associated Press)

White smoke billowed from the chimney on the Sistine Chapel indicating that a new pope has been elected in St. Peter's Square at the Vatican, Wednesday, March 13, 2013. (Photo by Dmitry Lovetsky/AP Photo)

The official name for this tiny speck of land – the size of 12 football pitches – is Hashima, but few call it that. In English, its most commonly used name means “Battleship Island” and, viewed from a certain angle offshore, its silhouette is uncannily dreadnought in nature. It was a mining facility until 1974, when it was abandoned to the elements, before partially reopening as a tourist attraction in 2009. Photo: A decades-old television. (Photo by Mark C. O'Flaherty)

A girl plays with coloured chicks for sale prior to Easter celebrations in Byblos, Lebanon on March 22, 2015. (Photo by Jamal Saidi/Reuters)

A participant wearing a costume poses for members of the public before the 40th anniversary of the Sydney Gay and Lesbian Mardi Gras Parade in central Sydney, Australia, March 3, 2018. (Photo by David Gray/Reuters)

A worker manually changes the direction of the bonde, the typical tram line in Santa Teresa neighborhood, using a rope in Rio de Janeiro, Brazil, September 9, 2015. The Santa Teresa bonde, called “Bondinho” in Portuguese, is running with passengers as a part of a test period, after the service was suspended in 2011 following an accident that killed six people, according to residents. (Photo by Pilar Olivares/Reuters)

A female hippopotamus named “Mali”, which means Jasmine, eats fruits arranged to look like a cake during her 50th birthday celebration at Dusit Zoo in Bangkok, Thailand September 23, 2016. (Photo by Chaiwat Subprasom/Reuters)