"I heaved until I thought my back might break"

Birdie Bowers, Scott’s irrepressible Lieutenant described pulling his sled in the deep snow in the same place, in words which seemed very apt:

…the most back-breaking work I have ever come up against… the starting was worse than the pulling as it required from ten to fifteen desperate jerks on the harness to move the sledge at all… I have never pulled so hard, or so nearly crushed my inside into my backbone by the everlasting jerking will all my strength on the canvas band around my unfortunate tummy.