In article <[email hidden]>,
Brian Baresch said:Quoted message said:Quoted message said:I'd have thought that a
treadmill was easier because it moves the 'floor' along for you, you
don't have to propel yourself.
Nonsense. That's like saying that because the earth is revolving, it just sort
of "moves the surface along for you", and "you don't have to propel yourself".
If you stand still while on the treadmill, you'll see that the "floor" does
indeed "move along for you" (just like the surface of the earth) -- but unless
you "propel yourself", you will move with it (again, just like the surface of
the earth).
Hmmm, I don't know about that. Seems to me that there's a difference
between moving one's mass, as on the road, and leaving that mass
stationary while moving one's feet below; more effort would be
required in the former. (I'm imagining, for comparison's sake, a
treadmill with a very loose belt but no motor, and running on it,
supplying the motive force for the belt, vs. having the motor move the
belt for me.) But I'm no physicist and not much of a physiologist, so
take that for what it's worth.
If you're running in good form, the treadmill and ground are very
nearly equivalent. The difference is up at your torso -- running on
ground, you have to shove the atmosphere out of the way of your torso.
Consider running at a steady pace (treadmill or ground). Your arms
swing back and forth at their cadence, which is the same for either
surface. Air resistence (for calm day) to this motion is the same
either way. You have some bouncing in your stride, center of mass going
up and down a little, but that's the same between treadmill and ground.
The landing forces/bounce are fairly similar between a rubberized track
and a treadmill (treadmill is probably more forgiving, returning more
landing energy, than asphalt or concrete, but pretty close to rubberized
track or grass/dirt).
Last thing to look at is the feet/legs in their swinging (landing's
already taken care of). Take your measurements from the hip joint
(center of mass). Running steadily along the ground, in good form,
your foot touches down moving backwards at precisely your running (forward
speed) for a net speed of 0. The touchdown neither slows you down,
nor speeds you up. You're running easily and steadily. Move to treadmill.
Your foot touches down moving backwards at precisely your running (treadmill
belt's) speed, for a net, again, of 0 between foot and surface. Your
touchdown neither speeds up nor slows down the treadmill belt.
For this reason, I use the treadmill or logrolling as a mental
illustration of what good form feels like, and if on a treadmill,
pay attention to whether I'm pushing or dragging the belt. In good
form, I'm cruising along steadily, the ground unrolling below me
as I relax and let the legs and arms do their nice, relaxed, efficient
swing back and forth.
Back to the original question ... treadmill is not the same as
outdoor running. There is the wind resistence difference, and the
slopes and bounciness of the surface. You also may run in to problems
with the treadmill for swinging your arms as you naturally do outside.
Perhaps the biggest practical difference is that on a treadmill, you
run an almost exactly steady pace and few people do that naturally outside.
This can be an advantage, or a disadvantage. Depends on the person and
what you're trying to do. It's generally better to race at a steady
pace.
--
Robert Grumbine http://www.radix.net/~bobg/ Science faqs and amateur activities notes and links.
Sagredo (Galileo Galilei) "You present these recondite matters with too much
evidence and ease; this great facility makes them less appreciated than they
would be had they been presented in a more abstruse manner." Two New Sciences
