Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

An Israeli teenager crawls through mud as he participates in an annual combat fitness training competition, as part of his preparations ahead of his compulsory army service, near Kibbutz Yakum, central Israel February 19, 2016. (Photo by Baz Ratner/Reuters)

Women take part in Belarus Cup in bodybuilding and fitness in Minsk, October 24, 2015. (Photo by Vasily Fedosenko/Reuters)

Commuters walk up the redesigned subway stairs at the Tanjong Pagar subway station on August 23, 2011 in Singapore. The subway stairs have been repainted in bright colours and slogans encouraging people to take the stairs, by way of promoting fitness in the city. (Photo by Chris McGrath/Getty Images)

A fireman from the London Fire Brigade, wearing a smoke helmet. (Photo by Topical Press Agency/Getty Images). Circa 1908

A woman wearing a bikini stands next to fuel pumps as she waits to top up fuel at a petrol station in Kiev, Ukraine, September 26, 2015. One of the largest networks of petrol stations in Ukraine organized a campaign in which anyone who showed up in swimwear at a particular gas station during specified hours would receive free gasoline, according to representatives of the company. (Photo by Valentyn Ogirenko/Reuters)

Competitors prepare backstage before the 2015 Brazil Miss and Mister Fitness contest in Sao Paulo, Brazil, June 18, 2015. Some 96 men and women from all across the country competed in the event. (Photo by Paulo Whitaker/Reuters)

David LaChapelle, Land Scape Anaheim, 2013, chromogenic print, 70 3/4 x 95 inches, 179.7 x 241.3 cm, edition of 3. Image courtesy of the artist and Paul Kasmin Gallery. (Photo by David LaChapelle Studio)