So what does this all mean? Snow shoeing is almost as efficient at burning calories as interval running and a little better than spinning. I should note the running numbers came from my last mile intervals run, the snow shoeing was from when I went out with SF and we "ran" a little over a mile and then hiked the rest, and the spinning was from an interval set. I wouldn't be surprised if a complete running workout in snow shoes is more efficient at burning calories than running. Running in snow shoes is pretty tough and so far I haven't been able to run much more than 1 mile. I'm not surprised the spinning numbers are the lowest since it is a non-impact workout.
I was pretty surprised at the amount of calories I burned. Snow shoeing isn't the best workout if you're trying to train for speed or do intervals, but it's a great option when there is 8" of snow on the ground, like there is right now. I plan on taking the snow shoes out again this weekend, and hopefully make it running 1 1/2 miles.