Running outside or treadmill

h squared said:

maybe i'm being a jerk,

Not at all. The "giant treadmill" thought experiment is a good way to
understand this. For the most part, the conceptual problems most people have
with this, stem from difficulties in stepping out of the earth's frame of
reference.

By making the treadmill belt really big, the earth's frame of reference is
out of ones field of view making it harder for it to obscure the picture.

Cheers,
--
Elflord

"Robert Grumbine" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <qCIXh.8477$oo5.2446@trndny06>,

Tony S. said:

"Robert Grumbine" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

In article <[email hidden]>,
Elflord <[email hidden]> wrote:
>On 2007-04-24, Robert Grumbine <[email hidden]> wrote:
>
>> The last two would lead towards your results. For the pace control,
>> find someone who can predictably jog on the road the same pace
>> that you do on the treadmill, and run with him. For the proper
>> running
>> on the treadmill, do not let the belt carry your foot back; be
>> running such that your foot is never being pushed or pulled by
>> the belt.
>
>This is just the equivalent of "braking" when running on the road (the
>road
>abruptly "grabs" the runners foot and "carries" it back). But why would
>anyone
>brake any more on the treadmill ? And why would doing that make a
>treadmill run
>any faster ?

No, it isn't. But to see what I'm talking about, you need either the
experience or a lengthy physics-oriented description. Since you don't
have the former (and I do, plus the physics) ... here goes ...

From your followups, you're considering a person who is either running
perfectly, or is doing overstride braking. Neither is involved here.
'Perfectly' in this case means that the runner's leg is moving backwards
(relative to his center of mass) at exactly his running speed. If he
does this on a treadmill -- and continues the follow-through correctly
as well -- then the situation is identical to if he's doing the same
thing on the road. The road may as well be a treadmill, and vice versa,
and either could be made a rolling log floating in water, with no effect
on the energetics.

But that's not what is involved in the distinction I'm talking about,
or that others have described.

Consider first the runner landing his foot on ground (v. treadmill)
with the foot moving back (relative to center of mass) more slowly than
his center of mass is moving forward, and doesn't apply extra force
to accelerate its motion relative to his center of mass back to running
speed. He slows down. The earth isn't supplying any forces to
accelerate
him horizontally.

Do this on a treadmill, however, and the belt certainly does supply
some force to accelerate your planted foot back to running speed
(relative,
again, to your center of mass). It won't succeed if your foot is
heading
back much too slowly, but it can do so if it's not a great deal off.

That input saves you some work. Not the entire workload. But there's
a fair amount work in a steady jog that is just getting the leg to
swing back and forth at the right speed, and the 'mill can supply a
portion
of the energy for the backswing.

Hmm. I want to believe you but I was already convinced that the physics of
running on a treadmill was the same as running on the road, but for the
wind
resistance. Wait a minute, once your body is in motion over the earth, it
stays in motion, according to Newton's first law, and is slowed only by 2
kinds of friction: air resistance and contacting the earth. Why isn't the
weight-bearing friction of the foot on the treadmill the same as the
weight-bearing friction of the foot on the road? The foot is also 'pulled
backwards' by the friction of contacting the earth while in motion running
on the road.

Let's look again at your phrase 'pulled backwards'. _Is_ the foot
'pulled backwards' in either situation?

Run along the earth. When you put your foot down, it stays exactly
where it was, in the earth-coordinate frame. Any 'pulled backwards'
is an illusion from thinking of your center of mass as a stationary
reference point (thence giving the notion of the foot being 'pulled
back'😉.
The work done by the earth against your foot is F*d -- but d is exactly
zero, so the work is also exactly zero. This is true regardless of
the speed your foot is moving at touchdown relative to your center of
mass -- once down, it stays put.

Now run on a treadmill. (Better, watch someone else run on a
treadmill.) Your foot lands squarely under your hip (center of mass).
When you lift it off the treadmill surface, however, it is somewhere
behind your hip (same relative position as on land). So d is distinctly
_not_ zero.

_If_ you're running with the foot speed equal to the treadmill speed,
then the treadmill applies no force to your foot (no need to accelerate
it to running speed, F = ma, but a is zero). So, again, the work is
zero.

_But_ if your foot is moving too slowly, the treadmill accelerates
it to running speed. F is not zero, now. d is never zero on treadmill
running. So, in this case, the treadmill does F*d work on your leg.
This is work that you don't have to do yourself, so the treadmill is
saving you a bit.

If you're running properly, the treadmill belt never accelerates
your foot, so does no work and we're back to the ideal situation of
having minimal difference between treadmill and road. (Wind resistence,
surface flexibility, etc. still differ, but can be compensated for
and/or are small effects.) But if you're running improperly, it is
indeed the case that the treadmill does work for you that you otherwise
do on the road, making the road slower running.

Consider a thought experiment:

Imagine a giant belt strapped around the equator of the earth, suspended on
rollers, that can be made to move. This is a strange treadmill, but it
qualifies as one I think.

Now imagine a second treadmill built entirely on top of the other treadmill,
which can be made to move in the opposite direction.

Now make the speed of the second treadmill cancel out the speed of the first
treadmill, so that, relative to the surface of the earth, someone standing
on it wouldn't move.

Ok, now take 2 equally talented athletes and let them race, one on the
ground, and the other on the second treadmill that is moving, not relative
to the earth, but relative to the other treadmill upon which it rests.
Assume the treadmill surface has been made the same as the surface of the
track on the ground next to the counter-rotating treadmills, and that
they're at the same height. Thus the running surface and the wind resistance
will be the same. Your argument is that there's a particular way the athlete
on the treadmill could run which would save energy in comparison to the
athlete running on the ground next to him.

Ah, Besso, we think of the strangest things when we run.

-Tony

Quoted message said:

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

steve common said:

Explain to me how silly I am

Hoo boy, there's an opening!

But you meant specifically with regard to this "treadmill's moving,
earth's not" business.

Here's a simple image which helps clarify things for my visual
intuition, which otherwise lags the rudimentary recollection of
mechanics still lodged in some dark corner of my brain (and probably
crudded up in a 20 year old layer of stubborn THC which never left the
system): imagine if the treadmill belt were orders of magnitude
larger.

My intuition is happy when I picture it a hundred meters wide and a
few km long, with dozens of other runners on it. But if it still
seems like it's "pulling" you meaningfully, think bigger.

Hell, let's say it's twenty five thousand miles wide and long and
covers the entire surface of the earth. An incomprehensibly large
motor is still moving it at that same seven miles per hour (at the
equator, where we're all vacationing). Everyone's on it, and
everything: streets, buildings, doggies, mountains, forests, trail
runners, meat, beer, strip clubs, oceans, and Luxembourg.

I bet by now it no longer seems to be pulling your foot, right? Or
your finger, let's hope.

hal said:

it might help to imagine running on a
big extra wide 100 mile long treadmill

Nice image.

And damn google groups. It had gone a day, day and a half maybe,
without showing any new posts, and then last night when it had
apparently caught up, I posted about a "supersized treadmill". Only
to find out this morning that you - and Tony too - had scooped me.

Ah well: strange minds think alike.

And google still isn't showing my last night's post, so I'm not
certain it (or this) will reach the group.

"Charlie Pendejo" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

hal said:

it might help to imagine running on a
big extra wide 100 mile long treadmill

Nice image.

And damn google groups. It had gone a day, day and a half maybe,
without showing any new posts, and then last night when it had
apparently caught up, I posted about a "supersized treadmill". Only
to find out this morning that you - and Tony too - had scooped me.

Ah well: strange minds think alike.

And google still isn't showing my last night's post, so I'm not
certain it (or this) will reach the group.

The funny part is all of us were thinking about it long enough to come up
with those images. When I was out on my pre-dinner run, I was pondering it
the whole time. I saw Heather's post and I like the not knowing part of it,
but decided to post my obscure version anyway. Scale shows it right away.

Don't know what's with newsgroups syncing up these days, but it appears to
be getting worse over time.

-Tony

h squared <[email hidden]> wrote

Quoted message said:

if this isn't the case, then donovan is right and people should
always try to run in the most favorable direction relative to
the earth's spin when trying to set a personal best 🙂

I'd never consider that. I wouldn't want to have an asterisk next to
my PR. It would be like running a downhill marathon -- wouldn't
count.

steve common <[email hidden]> wrote

Quoted message said:

MarkH said:

You'll have as much luck as trying to demonstrate how cold
fusion really helps you generate free electricity.

Oh dang! Does this mean the 200$ I sent to that Nigerian
scientist who emailed me about his invention won't help make a
better world?

Probably. But if you send him another couple of grand, he'll cut you
in on the $10M inheritance he's trying to get out of Nigeria.

Charlie Pendejo said:

hal said:

it might help to imagine running on a
big extra wide 100 mile long treadmill

Nice image.

And damn google groups. It had gone a day, day and a half maybe,
without showing any new posts, and then last night when it had
apparently caught up, I posted about a "supersized treadmill". Only
to find out this morning that you - and Tony too - had scooped me.

Ah well: strange minds think alike.

it's ok 🙂 all i did for a minute was to howl, "does nobody read my
poooooooooosts?"

but all in all, when i'm making such strange posts it's nice to have
other people posting the same thing on their own, ya know (even if we
are all just strange 🙂 so it's ok.

also, i thought the differences in our big treadmills was kinda funny:

game show scenario:
host: "charlie and tony visualize a giant treadmill situated on the
equator where everyone is taking a vacation. charlie's treadmill even
comes with amenities like alcohol and friendly girls. but heather
imagines a stark unending grey belt in a white and sanitary room without
a single smudge or mark upon the walls."

"it's time to play, ---.> spot the german <--- !!"

ok, maybe that joke will only be funny to my bf who has to live with me...

Quoted message said:

And google still isn't showing my last night's post, so I'm not
certain it (or this) will reach the group.

i saw it there, whew! do you always use google to read and post to usenet?

h

hal said:

"...heather imagines a stark unending grey belt in a white and
sanitary room without a single smudge or mark upon the walls."

"it's time to play, ---.> spot the german <--- !!"

Hehe.

I can relate; and my bio-maternal heritage is Euro-mutt majoring in
German. Believe me, I was conflicted about the German oven when
renovating my kitchen.

Quoted message said:

do you always use google to read and post to usenet?

These days, yeah.

Elflord said:

When you're running on the surface of the earth, the earth may be more or
less indifferent to *your* activity, but it's not mutual. The earth is just
like a super-duper good treadmill belt that is completely resistant to your
attempts to perturb its perfectly uniform rotation.

I would agree 100%, given all the beautifully-imaged arguments of the past
days from all quarters.

But why doesn't it make a difference if I run clockwise or anti-
(counter-) clockwise along the equator on the Earth (and, by extension, on
a treadmill positioned the opposite/same direction as the rotation)?

Tell me that the other components are negligible in all cases, but don't
try telling me it's identical in all cases. Or can you?

I know this is boring but bear with me please, my second remaining neuron
just died of alcohol poisoning :-P

h squared said:

but heather
imagines a stark unending grey belt in a white and sanitary room without
a single smudge or mark upon the walls.

what is it with this charlie guy anyway?! :-P

Charlie Pendejo said:

Hoo boy, there's an opening!

Did I comment on your body parts?

Quoted message said:

Hell, let's say it's twenty five thousand miles wide and long and
covers the entire surface of the earth.

Is the belt running from Mao to Schawrtzy, or the other way? I'm coming to
believe that all this "none of it has any influence" stance is about as
defendable as Intelligent Design (unless...?). But I don't have a 10th of
the intellect or a % of the wit to take the challenge.

Quoted message said:

and Luxembourg.

OK so you wanna talk sexy to me ;-P

Charlie Pendejo said:

hal said:

"...heather imagines a stark unending grey belt in a white and
sanitary room without a single smudge or mark upon the walls."

"it's time to play, ---.> spot the german <--- !!"

Hehe.

I can relate; and my bio-maternal heritage is Euro-mutt majoring in
German. Believe me, I was conflicted about the German oven when
renovating my kitchen.

this is very off topic, but this tv episode cracks me up (i like all of
it but currently referencing the scenes with dewey (little boy) and
gretchen (german woman), one scene in the beginning and one around the 3
minute mark and then final one near the end of the clip)

you don't have to watch it to be polite 🙂 though. but talking about
being german made me remember it and want to post it.

heather
("i am pure evil!!" giggle..)

steve common said:

Elflord said:

When you're running on the surface of the earth, the earth may be more or
less indifferent to *your* activity, but it's not mutual. The earth is just
like a super-duper good treadmill belt that is completely resistant to your
attempts to perturb its perfectly uniform rotation.

I would agree 100%, given all the beautifully-imaged arguments of the past
days from all quarters.

But why doesn't it make a difference if I run clockwise or anti-
(counter-) clockwise along the equator on the Earth (and, by extension, on
a treadmill positioned the opposite/same direction as the rotation)?

Tell me that the other components are negligible in all cases, but don't
try telling me it's identical in all cases. Or can you?

I know this is boring but bear with me please, my second remaining neuron
just died of alcohol poisoning :-P

Sorry I took so long to follow up to this. The wanking thread was so much
more fun.

It doesn't make a difference because f = ma -- forces only care about changes
in velocity. If you move *everything* in the picture by a constant velocity,
it doesn't change it.

Or to do some calc:

f = ma = m (dv / dt )

if v1 = v + const, then

f1 = m ( dv1 / dt ) = m d/dt ( v+const) = m (dv/dt + 0 ) = ma = f

I think the horse is finally vaporised. Can we go back to wanking now ? (-;

Cheers,
--
Elflord

Donovan said:

Can we go back to wanking now ? (-;

You and steve, being consenting adults, may do near enough whatever
you like.

But I suspect you've both already reached your genetic potentials in
that department, so please don't pretend it's necessary training.

Charlie Pendejo said:

Donovan said:

Can we go back to wanking now ? (-;

You and steve, being consenting adults, may do near enough whatever
you like.

But I suspect you've both already reached your genetic potentials in
that department, so please don't pretend it's necessary training.

Besides devoting more time to it, I could also train harder, and research
more modern training methods. I'm certainly no slouch, but I'm not at Salvador
Dali's level either.

I didn't know "Adam Smith" was still alive and running for your team. Besides
being well known as an economist/philosopher, he's a pretty decent runner. I
only just squeezed past him in the final stretch.

Cheers,
--
Elflord

Donovan said:

I didn't know "Adam Smith" was still alive and running for your team.
Besides being well known as an economist/philosopher, he's a pretty
decent runner.

Indeed. In person the dude comes across as almost entirely right-
brained - you'd never guess he had such a keen mind for economic
theory.

And for the record I'm teamless.

Quoted message said:

I only just squeezed past him in the final stretch.

Then it seems he's improving, unless you're a few notches further from
peak shape than I imagine. This winter he was a little faster than I
was last fall, but not at your level.

Charlie Pendejo said:

And for the record I'm teamless.

One answer : join ASPTT Toulouse Athlétisme. You WILL progress. When I
joined I was a 3:38 marathoner, and now I'm a 2:55-er!

PS You could even get called out as you arrive in Central Park cuz they'de
think you were a foreigner ;-P