People make pictures in a Soviet-era vintage subway car, with a Soviet railways emblem on the side of it, parked in the Partizanskaya subway station in Moscow, Russia, Friday, May 15, 2015. Vintage Soviet-era metro cars were exhibited at the Partizanskaya subway station as part of festivities marking the 80th anniversary of the Moscow subway on Friday. (Photo by Pavel Golovkin/AP Photo)

Valery Bystritskii, 10, gets a fellow student into a lock at Bunny's Gym in July 2015 in Winchester, Tennessee. (Photo by Mike Saliba/Barcroft USA)

Meghan Umphres Leatherman, 9 nine months pregnant and dilated to 1cm seen lifting a heavy weight at her home town gym in Phoenix, Arizona. (Photo by Dave Cruz/Barcroft Media)

Teenagers on roller skates hold on to each other as they are pulled by a vintage car to move along a street in Havana, Cuba March 19, 2016. (Photo by Ivan Alvarado/Reuters)

A participant falls on vintage skis during a traditional historical ski race in the northern Bohemian town of Smrzovka February 21, 2015. (Photo by David W. Cerny/Reuters)

Ray Yang, a celebrity trainer, takes a selfie before the start of a workout session during TV program "The Body Show" at a gym in Seoul, September 19, 2015. Looks no longer centre only on the face in beauty-obsessed South Korea, where more women are hitting the gym to improve muscle tone and physical health. As the ideal of beauty evolves in a country that is a trendsetter in cosmetics and the pursuit of plastic surgery, women's fitness has become a growth business, say purveyors of health products, from diet supplements to dumb-bells. (Photo by Kim Hong-Ji/Reuters)

A motorcycle Majestic 350 CC 1931 is displayed on February 5, 2014 at the Grand Palais in Paris on the eve of an auction of luxury vintage cars. (Photo by Francois Guillot/AFP Photo)

A participant jumps on vintage skis during a traditional historical ski race in the northern Bohemian town of Smrzovka, Czech Republic, February 20, 2016. (Photo by David W. Cerny/Reuters)