Treadmill or real running: which burns more calories?

I'm training for a 10K in a few weeks and multiple people (runner friends and two personal trainers) have told me that running on a treadmill is equivalent to running downhill in the real world. I was advised to always bump up the incline on the treadmill a notch or else it's too easy. Seems to work for me. (Raising it up was like experiencing gravity for the first time.) I've also been told that running outside works extra muscles - the ones for balance and changing direction and not-tripping and stuff - that you don't necessarily use a lot on the treadmill. I suppose that's true; on the treadmill I can just pound away but outdoors I'm constantly having to deal with uneven pavement, tree roots, other pedestrians, etc.

Not an answer, but running at a sustained 7.5 mph at nearly 3 bills is no small feat. When you lose the weight, you'll probably be a badass.

two people in a (slowly moving) train (both facing forwards).... one, for no good reason, is running on a treadmill. by some strange chance the treadmill is set to the same speed as the train. the surface of the treadmill that he's running on is moving backwards at the same speed as the trees that go past the train windows. another, curiously, has fallen through a hole in the floor, but, by running at the same speed as the train, along the tracks, has escaped death. the surface that he is running on goes past at the same speed as the trees that go past the train windows. [walks away, sobbing, in frustration]

As a high school cross country runner who is pretty damn good about pacing myself, I'de also have to say that a treadmill is less "effort." I know I run about 8 minunte miles outside. If I haven't run in a while and I do an 8 min/mile pace on a treadmill, I feel like I can fun forever on the treadmill whereas I can only go about 4 miles the first time around outside. To me, the difference is outside, I have to propell my self forward whereas the treadmill bring me back to the starting self lessening self-actuated propulsion.

Try to think of it in terms of the amount of work you are accomplishing. An outdoor run transfers a mass from one place to another. Running in place move it up and down, and flutters the legs back and forth. I'd suggest shorter outdoor runs. Fewer impacts on your knees and ankles, same amount of workout.

maybe treadmill speed calibration is optimistic? makes users feel good...

The newsgroup rec.running should also help. Check the threads in these search http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&safe=off&c2coff=1&q=overground+treadmill+biomechanics&btnG=Search. Oh, and also try another search substituting biomechanics for kinematics.

You don't need physics necessarily. If you "can't run on the road" but "can run on a treadmill" then the treadmill will burn more calories because you'll actually do it. I don't run much (once a year I get an urge to run, then I run 5 or 7 miles a few times then I realize "Oh yeah, I hate running!") but a treadmill seems about equivalent to me in terms of effort. Depending on the road surface my body takes much more of a pounding out of doors. My favourite surface to run on is trails with a nice carpet of pine needles (if you can have a favourite place to run if you don't like running that is).

no it doesn't. it's physical nonsense. imagine having a movie camera runing alongside someone who's running on the ground. if you look at the film it's like he's stood still and the ground is zipping by under him, just like a treadmill. they are equivalent (in that sense; see other comments here for differences in hardness, wind, psychology etc).