Artists perform during the Closing Ceremony of the Rio 2016 Olympic Games at the Maracana Stadium in Rio de Janeiro, Brazil, 21 August 2016. (Photo by Sergei Ilnitsky/EPA)

Japan' s Kaori Sakamoto competes in the women' s single skating short program of the figure skating event during the Pyeongchang 2018 Winter Olympic Games at the Gangneung Ice Arena in Gangneung on February 21, 2018. (Photo by John Sibley/Reuters)

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.

DJ Deadmau5 arrives at Spike TV's “2011 Video Game Awards” at Sony Studios on December 10, 2011 in Los Angeles, California. (Photo by Christopher Polk/Getty Images)

George R.R. Martin, Lena Headey, Sophie Turner, and other cast and crew of Game of Thrones have faced the winds of winter – or anyway, a bucket of ice water – with the popular charity challenge. HBO’s Game of Thrones gives fans chills in every episode. But as the Ice Bucket Challenge for ALS research has exploded across the internet, the cast and crew of the shocking show gave themselves goosebumps as they stepped up to get soaked.

In this Wednesday, March, 5, 2014 photo, Afghan female boxers practice at the Kabul Stadium boxing club, Afghanistan. The women, who are 18 and older, don't have much more than determination, and a trainer who runs them through their paces, watches as they spar, corrects their technique, tells them when to jab, how to protect themselves, when to power through with a left and then a right. (Photo by Massoud Hossaini/AP Photo)

Giant Olympic rings are towed on The River Thames past The Tower of London on February 28, 2012 in London, England. (Photo by Peter Macdiarmid/Getty Images)