It's 10 below, but they're ready to go

Sled dogs prepare for a race at a meet in Lincoln, Maine. Races vary from four to 10 miles, depending on the number of dogs on a team. Sled-dog drivers call themselves 'mushers,' but they never say 'Mush!' (perhaps a corruption of the French command, 'Marche!'). To get a team going, a musher yells 'Hike!'