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.

In this November 28, 1966 file photo, one of the 10 beagles involved in the first test of the Veterans Administration Hospital in East Orange, N.J. smokes a cigarette through a machine linked to its windpipe by a plastic tube to test any link between smoking and emphysema. (Photo by AP Photo)

“I think as mothers we are all just trying our best”. – Gisele Bundchen. (Photo by Mads Nissen/AFP Photo)

A visitor passes behind the sculpture “Puma-Dentist” made with plastic, wax and original heads of a puma and a hind by Austrian artist Deborah Sengl during an exhibition at the art gallery Deschler in Berlin April 15, 2008. (Photo by Fabrizio Bensch/Reuters)

Flowers are placed on a “comfort woman” statue during the weekly Wednesday protest in front of Japanese embassy demanding for an apology and compensation from Japanese government in Seoul, South Korea, July 22, 2015. “Comfort women” is the Japanese euphemism for women who were forced into prostitution and sexually abused at Japanese military brothels before and during World War Two. (Photo by Kim Kyung-Hoon/Reuters)

A plastinated body presented as a pole vaulter is exhibited at the Menschen Museum, Museum of Humans, in Berlin, August 29, 2016. The museum was caught up in a legal dispute with the district office of Berlin-Mitte for years before it was able to meet the requirements made by the court. (Photo by Sophia Kembowski/DPA Photo via Newscom)

Donald Ganslmeier, operator of the Motodrom, rides a motorbike inside the Motodrom during a press tour at Theresienwiese on the premises of the 182nd annual Oktoberfest in Munich, Germany, September 17, 2015. (Photo by Matthias Balk/EPA)

Hot air balloons take to the skies as they participate in the mass assent at sunrise on the second day of the Bristol International Balloon Fiesta on August 11, 2017 in Bristol, England. More than 130 balloons have gathered for the four day event, now in its 39th year and now one of Europe's largest annual hot air balloon events, being hosted in the city that is seen by many as the home of modern ballooning. (Photo by Matt Cardy/Getty Images)