Hyper Mike said:
The running motion is actually significantly different running on a treadmill. I think you use your calves much less because the road is essentially being pulled from under you.
I don’t doubt the running motion itself is different, but it’s not for the reason he stated, since everything is relative. It’s still “ground moving relative to you”, whether or not it’s the “surface of the Earth” kind of ground or “rubber surface of the belt on the treadmill” kind of ground. You have the same momentum, relative to each respective surface. So why is one’s running motion on a treadmill different from running on good solid ground fixed to the Earth? I’ve mostly run on treadmills and personally notice only a slight difference, but let’s theorize.
The main difference would be, and this is probably the biggest one, the lack of air volume moving towards you (or you moving through it; same thing) when running on the treadmill. If you’re running at 8 MPH, there’s no 8 MPH headwind. It doesn’t seem like that would make a big difference, but I think it does. The secondary difference would be the machine’s softer surface. Perhaps not always softer (what if you’re running on grass?), but different from real ground. Bouncier. Returning much more of the energy from each footstep. (That explains the decreased calf usage.) Thirdly, the belt doesn’t exactly move at a constant speed, especially on poorer quality treadmills. When you’re in the air, it’s moving at a certain speed, and when your foot strikes the ground it squeezes the belt against whatever’s below it and because of friction the belt slows down a tiny bit before the motor can compensate (if it does). If your center of gravity moves back and forth just a little bit, then that force gets exerted forwards or backwards on the belt and speeds it up and slows it down. That effect might affect how you run. Fourthly, there’s the size of the machine, where you know you can’t take very big steps or vary your pace wildly or you’ll fall off the end or bang your knees on something like that… maybe you can’t swing your arms in exactly the same either way because there are rails in the way or just influencing your movements. Fifthly, maybe an element is psychological. Maybe you naturally don’t lean into the run or assume the same posture when you don’t have the same sensation of forward movement. Still, I think wind and bounciness are prime. It’s definitely not “the road being pulled out from under you” though. When I’m on the freeway driving 65 MPH, that would be identical to driving on a giant “roadmill” at 65 MPH with a huge fan blowing 65 MPH wind at the front of my car (which is nonetheless not moving relative to the surface of the Earth, but that’s irrelevant) as far as the car is concerned. Anyway, we’re all sitting here moving thousands of miles per second through space relative to the sun, or the center of the Earth, and so on.
Here’s something else, though. It annoys* me when I see gym-goers increase the grade of a treadmill so they’re walking up it at the steepest possibly slant, which, they probably think, is giving them a good workout because they’re walking uphill, and that’s harder than walking on level ground. It’s like a challenging hike, climbing up that steep hill, no? At least it’s burning plenty more calories than walking on level ground, wouldn’t you think? Since walking uphill is very tiring! And this would all be true, but… here’s what happens. After ramping up the treadmill, they hold tightly to the bar the entire time while walking on it. I never see anyone walking up that high-grade a treadmill and not holding onto the bar. They’d have to assume a different posture to do that on a real hill without a bar to cling to; a climb, with bent knees. Like climbing a flight of stairs. Anyway, think about it like this: you could have a treadmill that’s adjusted its slope to the point that belt is nearly perpendicular to the ground, and you could still walk on it if you held tightly to the bar. You could walk up a wall if you had an upwards-moving bar to hold on to that would pull you up. (The main exercise in that circumstance would be the “leg lift” aspect and not much else.) You could walk up a real hill and that would be good exercise, but if you held on to the back of something that pulling you up the hill, it would be the equivalent of walking on level ground. Or you could have a friend just push on your back as you walk up the hill. Same thing. So what I wonder is, do these people realize that when they make the treadmill that steep and hold on the whole time, they’re not getting any benefit from going uphill, at all? Also, the Calorie readout on the machine probably assumes the exerciser is doing all the work of walking up a hill, since it doesn’t sense backwards force on the grab bar, or lack thereof on the belt, but in actuality no additional Calories are being burned as compared with simply walking on level ground, and so is misleading. Maybe walking on a slant just feels nice for a change, or gives a little bit of arm exercise (you can do reverse-pushups of a sort while walking, I can imagine), but I do get the impression most of the time that the people walking uphill as described really think they’re “working it” and getting some sort of heavy exercise by going up so steep a slope, whereas in reality they’d be much better served just setting the slope to a slight angle above horizontal and walking without using any rails for support.
*I mean more like amuses, but this ought to be common sense… right?