I don't know enough to make a judgment either way. It certainly seems rough. But, then again, they are sled dogs so I assume that's the kind of thing they live for.
I think I have more problems with the way they live when they aren't racing than when they are. I saw a think on Animal Planet. They interviewed a family that raises dogs for the race. They had like 30 dogs all chained outside to a stake. The chains were only 4 ft long. But, they fed them very very very good stuff. And gave them exercise.
So- heck, I donno!