The Curve - does it lie about its calories? (I think so)

bored_geek

My gym is still feeling the New Year's Resolution crush, and so finding free treadmills has been tough. The other day I broke down and went for a run on one of these "self-powered" treadmills, called the curve.

Now I'm used to running 5 miles in 45 minutes, on an incline, and having the treadmill spit out ~700 calories. I ran for 15 minutes on this thing -- not too fast, oscillating between 6.6-7.2 -- and it spits out 400 cal. Although it "felt" harder, I can chalk this up to lack of experience on one of these machines. I think 25cal/min is the equivalent of a sprint, and way too high for my level of exertion.

Anyone have experience with these things? How accurate are they, really?