Festival-goers enjoy the mud during the annual Boryeong Mud Festival at Daecheon Beach on July 18, 2015 in Boryeong, South Korea. The mud, which is believed to have benefical effects on the skin due to its mineral content, is sourced from mud flats near Boryeong and transported to the beach by truck. (Photo by Chung Sung-Jun/Getty Images)

Participants take part in the Color Run near the Eiffel Tower in Paris April 19, 2015. The Color Run is a five-kilometre race, held in cities across the U.S. and also worldwide, with the aim of promoting healthy living and to benefit a charity that organizers choose in each of the cities that the run visits. Participants are doused from head to toe in different colors at each kilometre. (Photo by Benoit Tessier/Reuters)

This picture taken on February 23, 2014 shows participants wearing dresses running half-naked in the annual 3.5 km Undie Run held in the Olympic Forest Park smog-covered Beijing. Some 200 participants took part in this event, many of them with gas masks, as dangerous smog blighted swathes of northern China in recent days. (Photo by AFP Photo/STR)

Owner Nicole Graham works with volunteers from CFA and SES tries to dig out her horse “Astro” who became stuck up to his neck in mud at Avalon Beach on February 26, 2012 in Geelong, Australia. The tide was fast-rising, but the rescuers managed to get him out in time. (Photo by Peter Ristevski/Newspix)

Participants take part in the Mud Day race, a 13km obstacle course, on March 24, 2017 in the Israeli Mediterranean coastal city of Tel Aviv. (Photo by Jack Guez/AFP Photo)

A woman takes part in an extreme run competition in Zhodino, east of Minsk, September 26, 2015. (Photo by Vasily Fedosenko/Reuters)

Participants run through coloured powder during the YARKOcross colour run race in Almaty, Kazakhstan, June 5, 2016. (Photo by Shamil Zhumatov/Reuters)

Couples participate in the “Running of the Brides” race in a park in Bangkok November 29, 2014. Seventy-five husbands and wives-to-be wore their wedding dresses and running shoes and competed in an event for a combined prize worth 1 million Thai baht ($30,460). (Photo by Damir Sagolj/Reuters)