Scott's decision to haul the sleds by manpower instead of by dogs was a probably the most costly of his decisions. Amundsen, on the other hand, had calculated how long his dogs would last and after their usefulness as sled haulers he planned on killing them and using their meat to feed the men of his team.
As the temperature sinks below -20°C (-4°F), friction no longer heats the snow enough to create or maintain a liquid film. As a result, the ice surface feels rougher and the sled becomes harder to pull.)
“Man-hauling” required men strapped into harnesses to drag heavy sleds. Henry “Birdie” Bowers said, “I have never ... so nearly crushed my inside into my backbone by the everlasting jerking with all my strength.”