|POSE - some numbers||gordo||7/1/10 6:24 AM|
Michael challenged me to use my head and it occurred to me that I had
never run the numbers to calculate how much power a pure POSE runner
could produce and what that would imply for speed. Here's a quick
slash at it. I won't take it personally if you find big holes. :-)
Pose makes the math easy by declaring that gravity provides the energy
for acceleration via gravitational torque. That's a complicated way to
say that potential energy is converted to kinetic energy and that none
is acquired through pushing off.
For this calculation, I have assumed a 100% conversion efficiency. I'm
also assuming a 10 second acceleration from zero velocity, a forward
lean of 20 degrees, a runner with a mass of 100kg, a COG at a height
of 1m, and a stride rate of 200 steps/second. Two comments about the
assuptions: 20 degrees is the forward lean I estimated for Asafa
Powell at the start of his 100, when acceleration is maximum, using my
protractor. The mass of the runner cancels out later.
The total energy acquired in ten seconds by having the COG fall is the
number of falls times the mass times the height of each fall times the
gravitational constant. m*g*delta h This is:
33.3 strides, dimensionless *
100 kg, the mass *
[cos(0) - cos(20degrees)] * 1m, delta h in meters *
9.81 m/s/s, the gravitational constant
This yields energy of 1972 joules.
Since all of this energy is converted to kinetic energy, and kinetic
energy is one half of the product of the mass and the square of the
velocity, we can easily solve for terminal velocity by taking the
square root of twice the energy divided by the mass.
This yields a velocity at the end of our ten seconds of 6.28 m/s.
How does this compare to elite 100m speeds? A quick check is to divide
the 100m distance by the terminal velocity. This tells us how long it
will take our runner to cover 100m at his highest speed, giving us a
We get 15.9 seconds to cover 100m at our top speed. The actual time is
going to be much higher, since we started at zero. We're not in the
ballpark, so there's no need for that much fanciness yet.
OK, what happens if we increase lean to a whopping 30 degrees?
We get 9.36 m/s ending speed and 10.6 seconds to cover 100m with a
full-speed running start. We're still not even close.
Let's do some sanity checks.
If the acceleration all came from gravity, what might an optimal body
type for a sprinter? Well, we need the COG up as high as possible.
That would mean big shoulders and skinny legs. Does that fit reality?
If we don't need to push off, there would be no need for cleats. How
many sprinters skip the hassle of the silly things? Again, we have
clues that more than gravity is at work.
If we watch the videos posted recently, we notice strong acceleration
ending at about the 50 meter mark, as everyone's head pops up. At the
last Olympics, Bolt dropped his arms and coasted in the last 20
meters. That tells us that the power we need is much higher at the
start of the race. That actually puts us farther from the ballpark,
What does all this tell us? That sprinters push off, hard. Really
hard. Is anyone surprised? I hope not.
Pose may well work for steady-state running. It may work as a valuable
set of cues for runners. But we can pretty conclusively state that it
cannot provide the power needed for sprinting. If my calculations are
correct. Have at it. :-)
|Re: [Minimalist Runner:36065] POSE - some numbers||Tuck||7/1/10 7:40 AM|
|Re: POSE - some numbers||gordo||7/1/10 8:43 AM|
Thanks. I should have said that gravitational torque can't provide the
Just for grins I calculated the forward lean needed to run 100m from a
standing start with constant acceleration. I solved d = a*t^2/2 for d
= 100m, t = 10 sec, and got 2 m/s/s as the required acceleration.
Acceleration of our fictitious runner is just terminal velocity
divided by our 10 seconds if we make the easy assumption of constant
Instead of solving, I just changed the lean(I'm using Excel) until I
got the required acceleration.
We need a forward lean of just over 67 degrees to run the 100m dash in
10 seconds powered by gravitational torque. This lean needs to be
constant over the entire 100m. :-)
Anyone who wants to double check is free to have my spreadsheet. Send
me an email if you want a copy.
|Re: POSE - some numbers||gordo||7/1/10 8:49 AM|
Wait, wait, it gets even funnier. I just realized that 67 degrees is
terminal lean. You need to start vertical and fall that far, three
times a second, to produce the required power. Quite the image. LOL
|Re: [Minimalist Runner:36093] Re: POSE - some numbers||Tuck||7/1/10 8:56 AM|
So you mean Pose isnt a perpetual motion machine? Darn it...
|Re: POSE - some numbers||gordo||7/1/10 10:31 AM|
On Jul 1, 9:56 am, Tuck <tuck...@gmail.com> wrote:Oh, but I assumed it was. Remember that 100% conversion efficiency?
It occurs to me that we're going to look really stupid if someone
shoots holes in my math. You did check it, right? LOL
|Re: [Minimalist Runner:36112] Re: POSE - some numbers||Tuck||7/1/10 10:56 AM|
Don't have time to. I'm filing this one under "good enough for government work". ;)
|Re: POSE - some numbers||HHH||7/1/10 11:42 AM|
I think I'll just run.
|Re: POSE - some numbers||gordo||7/1/10 5:56 PM|
Nobody noticed that I said our boy was taking 200 steps per second, so
you're not alone. At least the math lower down used the intended
|Re: [Minimalist Runner:36093] Re: POSE - some numbers||JZ||7/1/10 6:54 PM|
On Thu, Jul 1, 2010 at 11:49 AM, gordo <gaj...@gmail.com> wrote:
|Re: [Minimalist Runner:36092] Re: POSE - some numbers||Antonio A. Carrillo 'Peluko'||7/2/10 4:33 PM|
We all know that Pose has some holes, but your calculations are
First, you take angles the wrong way. Using this last formula, you
As I've said before, we know that Pose has holes in the theory, but
|Re: POSE - some numbers||gordo||7/2/10 5:16 PM|
Thanks for responding. I hoped that someone would be interested enough
to challenge my work. I haven't taken a physics class for more than
thirty years, but I always enjoyed the subject.
On Jul 2, 5:33 pm, "Antonio A. Carrillo 'Peluko'" <pel...@peluko.net>
> We all know that Pose has some holes, but your calculations areOK. How? I know that the image I ended up with is ludicrous and in no
way resembles how anyone runs, but where else can the energy come
from? Don't say that it's due to pushing off, it's got to somehow come
from gravity, does it not?
Um, what last formula? Mine? One you're looking at somewhere else?
Show me how. I'm not buying it without you showing me some work, or at
the very least presenting clear enough reasoning that I can go run the
>Actually, I've been hanging around the Posetech board for well over
two years, two and a half, IIRC. I've never seen any calculations or
any discussion at all on the subject. The one thread that dealt in any
way with physics involved running on a treadmill and was a fiasco
because too many folks didn't understand frames of reference and how
to apply them. They were unable to accept that lean is identical
whether on or off the treadmill, partly because Romanov got it
wrong. :D We really shouldn't go there unless we start a new
thread. ;-) Anyway, in my poking around the website, I saw nothing
like this. Can you give me a link?
I do agree that the theory is quite elegant. To engineering types like
myself, that makes it beautiful. Perhaps that's why I never thought to
run the numbers before. It felt so intuitive, so obvious. I was
surprised by the result. I really would like to see where I went
|Re: POSE - some numbers||tsedee||7/3/10 1:58 AM|
> Show me how. I'm not buying it without you showing me some work, or atGordo
check out the following paper,
please *do disregard* the fact that it is a comparison of a pose
runner and a heel striker.
if you focus on the claims regarding which forces are supposed to act
in forward movement in running, you will get the picture without me
having to try to recite it. obviously, it is not purely gravitational
there are the formulas/formulae you have been searching in order to
run them yourself ;-)
it becomes more clear how pose is meant and where the advantage of
efficiency is supposed to be derived.
enjoy ! (hopefully)
|Re: POSE - some numbers||tsedee||7/3/10 2:04 AM|
> So you mean Pose isnt a perpetual motion machine? Darn it...nobody ever said that
it's an error to confuse Pose with Lung-gom-pa ;-)
|Re: POSE - some numbers||tsedee||7/3/10 4:29 AM|
as my own conclusion let me add this:
i will describe it in reverse from the pose description (to suit
- the idea is to *let* passive mechanics and neuronal (self-evidently
*passive*) reflexes do the majority of the work in the stride. what i
mean for reference
- the runner is landing passively close under the body on an S-shaped
structure of the leg/foot, on the forefoot.
hereby the elasticity of the tendons/muscles is pre-loaded like a
spring or shock absorber.
- the bodyweight is travelling forward and the stored energy in the
previously described structure is released (still passively)
this *could* be called "push off" but it doesn't deserve this name as
the runner is NOT pushing off conciously or actively at all. so there
we have it, the moot point that leads to all the disagreement.
- the SKILL comoses from alignment of the body, the point where the
foot is dropped (passively) to land in order to do it in a way that
the runner is landing in an alignment to FALL FORWARD from (mostly)
immediately while his body weight is travelling forward over/forward
that support foot/leg driven by a mix of "GRAVITATIONAL TORQUE" and
momentum ... until the support foot/leg is un-weighted.
- the runner would now face plant if he didn't keep the "next" leg
ready in order to release it (passively) onto the next "support" point
(where he will be landing).
- in order to get that leg in the right place, the foot, once
unweighted is pulled vertically in the virtual/perceptional line of
the ankle/knee under the butt. the hamstring is used to do this pull
and the knee is allowed to come forward.
this keeps the stride comact, not unlike when an ice-skater performing
a pirouette is pulling in his/her arms in order to accelerate the
rotation .. (see the picture?)
the "pose" in the POSE is actually the position where the runner is
"standing" on support, balanced on the ball of foot "falling" forward
from and his other leg is folded underneth. this serves as a
perceptional reference for teaching the movement and (not last)
i hope from the explenations above, it becomes clear that the runner
has to do only the strict minimum in order to not impair the passive/
reactive part of the natural body movement/response.
not straining and pushing and jumping and what have you.
another key element is really the alignment and the balance of the
body upon landing in order to perform a most fluid re-direction of the
acting forces into forward movement. this is not at all such a simple
skill and while for some it's quiet intuitive many people have lost
their feeling for balance and have great problems to get that right.
it's really the feeling for the interaction with the natural
prevailing forces instead of fighting against them, catching the
bodyweight with pre tensed calves, pushing off and what have you.
and we have to diferentiate PERCEPTION, conceptual model, effort
and on the other hand the external appearance of the movement and the
prevailing forces which will be acting together in the end (while not
requiring to actively support them in the wrong place)
phew! (**catching a breath**)
my English is not the best, but i hope i could formulate something
that makes halfways sense and helps to explain what is possibly meant
one still has to run, that's for sure ;-)
|Re: POSE - some numbers||tsedee||7/3/10 4:34 AM|
|Re: POSE - some numbers||gordo||7/3/10 7:51 AM|
This is the kind of stuff I was looking for. Thank you. Now about the
I'm disappointed. The paper is very poorly written. If I was cynical
(I am) I'd say it was deliberately confusing. More on that below.
It fails to include key data that the researchers clearly possess,
namely the horizontal and vertical components of the ground reaction
force and the lean angle. This is the data I need to run the numbers.
Irrelevant data was, for some unknown reason, included. The paper
spends time talking about this irrelevant stuff, foot and swing leg
acceleration, for example. More time is wasted talking to no point
about the effect of changing the gravitational constant. Since the
paper is so short, this is a surprise, to say the least.
Near the end of the paper they derive some equations to state the
obvious: that gravity does contribute to angular acceleration. The
equations they derived look correct. Had they deleted the entire paper
prior to this point, nothing would have been lost. Clarity would have
been gained. To state in simple English what the equations say: the
angular acceleration provided by gravity is proportional to the sine
of the lean angle.
The conclusion was quite weak, and frankly, misleading. For example,
the first sentence: "Findings indicate that both runners’ bodies
rotate about a near stationary support foot at maximum horizontal
acceleration of the COM via a gravitational torque before the onset of
maximum horizontal GRF." Perhaps misleading is too kind a word. What
happened to conservation of momentum? We have a body moving in space
and we suddenly fix one end of it. What happens? Linear momentum is
converted to angular momentum. Then, AFTER the body rotates into a
positive lean angle, gravity can play it's small role, but this
sentence implies that gravitational torque is the entire motive force.
The true conclusion consists of only one sentence: "Gravity completes
no net work during stance in constant speed running, but achieves
angular work via a gravitational torque accelerating the COM in both
constant speed and accelerated running." Pretty strong stuff, eh?
Pretty weak is what I call it. How much work? What percentage of the
work being done? Only the important bits were left out. :-(
My assertion is that since the lean angle is generally small, and the
sine of small angles is itself quite small, it indicates that the
acceleration available by harnessing gravity is also quite small. I
maintain that it is so small that we can neglect it completely when
strong acceleration is called for. The paper does nothing to challenge
that assertion. By omission, it supports it, but that's only my
The paper is deliberately misleading without being actually wrong.
Romanov is one of the authors, so there should be no misunderstanding
of Pose Theory. My conclusion, then, is that this was probably done on
purpose in order to hide the negligible contribution of gravity rather
than to illuminate it, preserving the beautiful theory onto which so
much has been built. I did mention earlier that I am cynical. :-)
After reading this paper, my opinion of Romanov's scientific integrity
has fallen dramatically.
Sorry, guys, I'm starting to question in my mind whether gravitational
torque contributes anything useful to even steady state running. Maybe
I'll look at that another time. Does anyone know off the top of their
head where I can find force plate data for both vertical and
horizontal components of GRF? Lieberman perhaps?
IMO, Pose does offer a valuable set of cues for recreational runners
without access to a good coach. There's no doubt in my mind that these
can improve their running dramatically. It's too bad that science has
to be abused to sell it.
|Re: POSE - some numbers||gordo||7/3/10 8:12 AM|
This was nicely written and very clear, tsedee. Pose has a lot of
> read more »
|Re: POSE - some numbers||Dan Mozell||7/3/10 9:38 AM|
|Re: [Minimalist Runner:36253] Re: POSE - some numbers||Antonio A. Carrillo 'Peluko'||7/3/10 10:00 AM|
Hello gordo. Some little explanations inside. But first, I want to
clarify that I also think that the Pose gravity theory is, at least,
inaccurate, and at the end is only a Romanov's conjecture dressed up
as science to sell his method (and also borrowed by ChiRunning). After
all, for gravity to provide some energy *must* exist a fall, and a
runner doesn't fall. If there isn't a fall, the same energy you borrow
from gravity you have to return with some kind of muscular movement.
And other question is that once you are moving forward at constant
speed, you don't need more energy to move forward (apart from wind
resistance, etc), so the need for the gravitational torque or any
other kind of forward push is limited. My personal point of view is
that gravity can't move us forward, but can help to make the most of
our muscles by redirecting forces applied to the ground while we run.
I refer to the d = a*t^2/2. For forward movement (almost horizontal,
I'm not selling anything.
In those forums this kind of discussions become messy easily. For
|Re: POSE - some numbers||gordo||7/3/10 10:39 AM|
On Jul 3, 11:00 am, "Antonio A. Carrillo 'Peluko'" <pel...@peluko.net>
> Hello gordo. Some little explanations inside. But first, I want toI agree completely with all of this.
I only looked at the energy required to perform the necessary work.
The vertical movement of the COG makes a certain amount of energy
available for conversion to kinetic energy. Ludicrous in practice, but
it nicely illustrates the problem. A lot of energy is required.
Getting it all from gravity raises some practical concerns.
I agree that your equation is correct for the case of a constant lean,
with the legs providing the power to maintain that lean. In that
situation, the legs, not gravity, are creating the movement. This
would be the real-world case. The one where virtually none of the
forward motion is caused by gravity. :-)
Sorry, I used a colloquial phrase that means that I require more proof
before believing the assertion.
Yes, thank you. I recall simbil having his head on straight(another
colloquialism) in the discussion on treadmill running physics.
Posetech seems to be down at the moment. I'll search later.
Thank you, Gordo
|Re: POSE - some numbers||michaelchasetx||7/3/10 5:29 PM|
I agree with that, Gordo. Ever since I read Steve's comment about hip
extension, I have gone back and reviewed POSE videos and videos of
100m and 200m sprinters ... champions have great hip extension in
slow motion for sprinting ... and the POSE videos show a muted hip
action. Maybe POSE method is more efficient for very long distances,
but not for sprints.
|Re: POSE - some numbers||Brad Cooley||7/3/10 7:25 PM|
The image of "falling forward" and lifting my feet quickly has
improved my running form, but the idea that gravity provides much
energy for running is a pure falsehood. It may help "get you started"
in a sense initially, but does not provide a significant ongoing
contribution. If you think of a ball rolled with a push, it will roll
at a speed proportional to the force applied indefinitely on a
frictionless surface. Add friction and additional force equal to or
greater than the friction is required to maintain motion. Likewise,
the runner must also continuously overcome friction by applying
force. Sprinters do not have large quads from lifting their feet.
|Re: POSE - some numbers||tsedee||7/3/10 9:19 PM|
the point i was making above regarding the reflexes:
the muscles ARE working, no doubt
my calves and quads are *very* solid ...
the point is HOW (in which manner) this work is achieved.
what i am aiming at is that it *happens* on a subconscious bodily
there is no need to know when to "fire" any of the muscles
consciously, believe me.
whatever may be actually going on in detail, there is the major part
of the stride that we have literally to let happen.
so in short, our western "over analyst" and "thinker" approach seems
to be completely counter productive to the ability to let things
happen, because as soon we know something we tend to develop the
desire to control it with the mind.
even the alignment and movement pattern should be set up (acquired/
trainded/drilled offline) in a manner that they literally work "by
but now consider: the single real *CONTROL* in the run is the feeling
and manipulation of the leaning angle
it seems obvious that the gas-pedal is not driving the car but the
engine is providing the force.
so no need to prove that the pedal doesn't drive the car (i don't mean
a pedal car but an ICE one)
nonetheless, the pedal and the skill of handling it is the major tool
to consciously control the acceleration (and interaction with the
engine) in the perception of the driver.
> Erfahren Sie mehr »
|Re: POSE - some numbers||tsedee||7/3/10 9:51 PM|
it depends on the skill, speed and strenght of the runner.
looks like some elements are increasing in a certain proportion to
- pull height (how high the heel being pulled towards the butt)
- "stride length"
- hip extension (?)
i believe that these elements are the collateral products of running
speed, none of them being an actual "driver" but they are recruited by
the speed as a reaction/response of the body or are an effect of
increasing ground reaction force..
|Re: POSE - some numbers||gordo||7/4/10 6:06 AM|
|Re: POSE - some numbers||tsedee||7/4/10 1:29 PM|
|Re: POSE - some numbers||gordo||7/4/10 2:08 PM|
On Jul 4, 2:29 pm, tsedee <2ced...@gmail.com> wrote:Yes, it measures horizontal and vertical forces versus time. What's an
ice running video got to do with one? If the implication is that no
horizontal force can be applied with the feet to the ice, I beg to
differ. I run on ice all winter. It's a great drill. It has a
surprising amount of friction. On a true frictionless surface, he
would never move an inch.
I don't need force plate data any more. Canute's explanation of why
gravity cannot possibly provide any forward acceleration is quite
clear and intuitive. I should have thought of it. I like to think that
I would have, given time. We'll never know. I should have known that
someone had already looked at the problem and solved it.
|Re: POSE - some numbers||tsedee||7/5/10 8:12 AM|
it was meant slightly in joke, you know.
i do know what a force plate is, even though my affection for pose may
have qualified me as a moron in you scientific eyes :-)
and it's not just from videos that i know running on ice as i am
having loads of occasion to do so and can tell from experience.
i just found it a funny association ...
nice for you that you have found a soul mate in Canute ...
as i often tell my son, it doesn't simply matter if the calculations
are correct but much more if the formula is fully applicable.
or else one might end up reading a sun dial at night using a
i didn't exactly mean to make an esoteric dope out of myself, however.
i am out for a run ...
|Re: POSE - some numbers||gordo||7/5/10 9:57 AM|
On Jul 5, 8:12 am, tsedee <2ced...@gmail.com> wrote:My reply was slightly in joke, as well. Aren't conversations fun when
you can't read facial expression or hear intonation?
Most of my experience arguing with people has been with other
engineers. There's a certain style that I've grown accustomed to over
the years. Canute does have it, although I have no idea whether he's
an engineer or not. I'm sorry if I've left the impression that I think
that you aren't intelligent, it's not intentional. We're all different
and this medium doesn't lend itself well to nuance.
Exactly right. That's why the whole idea of gravitational torque
somehow powering a runner is so confusing. It's just flat wrong, but
it feels really right because you can fall forward to initiate motion
and the body automatically responds. The treadmill physics threads at
Posetech went in circles because the folks who believed in what they
felt could not agree with those who believed in physics. The crux of
the problem here is that gravitational torque is only capable of
producing angular momentum, not linear momentum orthogonal to the
gravitational field. In other words, it can only power a faceplant.
Your body doesn't like to do those and reacts at an unconscious level,
making it feel like gravity is pulling you along. Linear momentum is
created only by the push off from the ground that cancels the angular
momentum created by leaning. In the sense that an impending fall
creates an automatic response, GT *can* be said to power a runner. :-)
At the end of the day, what's really most important in learning to run
better is how it feels and the imagery you use, whether or not it's
technically correct. From this standpoint, I think that Pose does a
good job. It does annoy me that in order to present a science-based
image for marketing purposes, they get the science wrong ... Science
is getting a bad name in the public eye these days because people are
twisting it for political and financial gain. Examples are found in
the courtrooms of the US, in the global warming arena,
environmentalism, health, you name it. Many people are learning to
distrust science. A number of examples can be found here on the board.
That's a shame because I think that the human race is totally screwed
without a bunch of scientific progress, PDQ. Perhaps that's why I'm a
little too enthusiastic about all of this, maybe I'm transferring some
of my anger.
Part of the scientific method is admitting when you're wrong. Pose
would actually gain scientific credibility by admitting that the
physics was not technically correct and explaining that the imagery
was correct in terms of biology, another science.
No worries. You did not.
Sounds good to me.
|Re: [Minimalist Runner:36403] Re: POSE - some numbers||Barefoot Ben||7/5/10 11:34 AM|
I really don't want to go into the physics details but as an anecdotal
example, in the video below you can see Paul Tergat desperately trying
to lean forward (and over stride) to get to the finish line faster than
Haile G. who came from behind in a magnificent surge to win the
gold medal in the Sidney 2000 10000m race.
Now, in my honest, scientifically unproven, opinion, the slight forward
lean they DO seem to demonstrate is related to counter-balancing the
legs weight as the legs reach much farther backwards.
It would be great if someone could do some picture analysis and
try to determine the weight distribution at each point in the stride cycle,
where the center of mass is and how the body weight is distributed.
around it. (I'd love to see this animated but I really don't have the time
and the know how to do it)
|Re: POSE - some numbers||gordo||7/5/10 11:50 AM|
Leaning clearly works, and not just to counterbalance the legs. At any
steady-state speed, you will need a net forward lean to induce your
legs to produce the horizontal power required to overcome frictional
losses, within your body and without. Since the legs tend to
counterbalance each other to a first approximation, I'd expect that
the lean you see is mostly needed to maintain speed. To any extent
that the CM of the legs is behind the GCM, yes, leaning will be
required as a counterbalance.
What a great finish. A good example that breaking form doesn't speed
|Re: POSE - some numbers||runs_with_kona||7/5/10 6:43 PM|
I think Paul Tergat was trying to prevent a face plant. Look at the
|Re: POSE - some numbers||gordo||7/5/10 7:02 PM|
On Jul 5, 9:12 am, tsedee <2ced...@gmail.com> wrote:You'll be happy to know that I found something to disagree with in his
analysis of GT and how the angular momentum it creates gets canceled
out. He's claiming that you need to land in front of the GCM to
accomplish this. This actually increases the angular momentum that's
trying to make you fall face down instead of canceling it out. From
one of his comments, simbil is/was vigorously arguing the way I think
it should be, that you need a push off to neutralize the angular
momentum. I've got more archives to wade through before I fling myself
on that one. The argument may be over for all I know. :-)
Everyone makes mistakes. The only sin is failing to admit mistakes,
because they then become anchors that hold you back. BTW, if you
haven't watched "The Importance of Mistakes" by John Cleese, you
should. It's excellent. It's a video of a lecture he gave. I saw it
back in the late 80's, so you might have to search a bit, but it's
well worth it. IIRC, he was basically speaking at a lectern, so if you
could find an audio file, it would probably be just as good.
I did find a blog entry where Canute talks about some vigorous non-
objective discussion, as it were, about the role of gravity on the
Posetech board. Based on the date, February 2009, I was a member then,
although I was in Mexico for a month and not keeping up very well. I'd
like to go back and search for it, but the forum has been down since
Friday. Given my experience there, I expect that if the thread didn't
put Pose in a good enough light, it was deleted. It may well have been
deleted before I could see it. :-( I'm aware of several threads that
vanished. We'll see.
|Re: POSE - some numbers||gordo||7/5/10 7:07 PM|
Could be. I just watched it several times and it's hard to tell with
him behind Geb like that.
|Re: POSE - some numbers||tsedee||7/11/10 4:04 PM|
> That's why the whole idea of gravitational torque
> The crux of the problem here is that gravitational torque is only capable of
> Linear momentum is created only by the push off from the ground that cancels the angularwhat makes you say "only" and why is there a need to "cancel" it?
the targeted process is redirecting (in order to make use of it) the
force onto a linear trajectory by use of the enrgy from ground
reaction force, not active "push off".
(according to Newton's third law)
in an ICE engine, linear force is redirected into torque obviously
(here it's the other way around) without being cancelled, so
redirection seems to be a viable process.
> It's just flat wrong
admittedly that is a moot point.
lets take time to check out the following articles on wikipedia
regarding scientific TRUTH (?):
how absolutely obvious is science and what is right and wrong anyways?
for sure i don't mean to publish Dr. Romanov's work to the point of
making it open source.
but let me quote a little bit from the book POSE METHOD OF TRIATHLON
TECHNIQUES (ISBN 978-1-934013-02-1)
chapter 15 is dedicated to the subject of ground reaction force.
please find below a list of the given references by number.
ground reaction force is the force that the ground exerts in response
to any force that you exert to the ground.(1.)
it's the Third Law of sir Isaac Newton.
ground reaction force is a non-propulsive force (2.) not an active
force that would your body forward.
it reacts to force you apply to the ground, including body mass as
well as your muscular efforts.
on p.74 he is pointing out (in section) "The Conflicting Views of the
While everyone agrees that ground reaction force exists, that seems to
be about the end of any consensus about how it affects running.
Doris Miller (3.) concluded: "It is incorrect to attribute the entire
GRF-time history to the action of the foot-ankle-leg of the support
limb. The support limb simply transmits the force to the ground and,
theoretically need not make any contribution to the push."
Peter weyand (4.) countered by insisting: "At any speed, applying
greater forces in opposition to gravity would increase a runners
vertical velocity on take-off, thereby increasing both the aerial time
and forward distance traveled between steps."
if we take that approach to explain how to increase sprinting speed,
we would have to reject Joseph Hunter's (5.) findings: "faster
athletes tended to produce only moderate magnitudes of relative
vertical impulse". and a " flight time just long enough to allow
repositioning of the lower limbs."
this clashes with the hypothesis that propulsion can be maximised
through extra extensions of the stance limb (6.)
and when comparing long jumping with running (7.) (8.)
there is basically no such thing as pushing forward. (7.) the
horizontal "propulsive" component appears only at the end of the
support for merely a 100th of a second.(8) ...
(9.) - - my brief conclusion, if you try to push the body forward by
pushing with you support leg on the ground, you can increase your
efforts only in a vertical direction, moving your body up.
let me cut it short now to come to a point.
(10. 11. 12) discuss vertical oscillation and (13.) explains the
principle of body weight on support (falling from) and makes it clear
that on the moon while having only 1/6 we loose our ability to run.
shouldn't we be faster if gravity wouldn't slow us down?
however, the books explains the reasoning behind the theory and
practice of the method (i don't do that here) and compares it with
available scientific opinion and research while putting it into
relation and explaining a concept of movement.
i can't see for what reason and by which criteria or norm Romanov or
POSE should admit their mistake?
it can only be decided by your own judgment if it makes sense for
yourself, if you like the idea or which way you are biased or
check out that book maybe first (i am mentioning above) could be a fun
i can really recommend that one.
if not enlightening (it surely is), at least it would give you the
right handhold to apply appropriate critique (!)
not least you would learn what POSE (completely) is trying to teach
instead of trying to wring it out of the people bit by bit through
the mentioned reference list follows here:
1.) Bartlett R "Linear and angular kinetics". Introduction to Sports
Biomechanics F & FN Spon, 2001, p.
2.) Zatsiorsky, V.M "Kinetics of human motion". Champaign: Human
3.) Miller I.D. "Ground Reaction Forces inDistance Running". In
Biomechanics of Distance Running. P.R.
Cavanagh, Editor. Human Kinetics Book, 1990, p. 203
4.) Weyand, P.G., Sternlight, D.B., Belizzi, M.J. and Wright, S.
"Faster top running speeds are achieved
with greater grund forces not more rapid leg movements." Journal of
Applied Physiology, Vol. 89. 200, pp
5.) Hunter, J.P., Marshall, R.N. and McNair, P.J. "Relationship
between ground reaction force impulse and
kinematics of sprint-running acceleration." Journal of applied
Biomechanics, Vol. 21 2005, pp. 31-43.
6.) Лeгкая атлетика: Учеб. Для институтов физ.культ./Под ред. Н.Г.
Озолина, В.И. Воронкина, Ю.Н.
Примакова.-Изд.Ч-е, доп., перераб.М.: ФизкулЬтура и спорт, 1989,стр.
7.) Уткин В.Л. Лрыжки в длину с разбега. биомеханика физицеских
упражнений. М.: Просвещение, 1989, стр.
8.) Донской Д.Д., Зациорский В.М. Биомеханика: М.: Физкультура и
спорт, 1979, стр. 185
9.)Payne, A.H. "Foot to ground contact forces in elite runners." In
Biomechanics Vol. 8B, H Matsui and K.
Kobayashi, Editors. Champaign: Human Kinetics, 1983, pp. 19-41.
10.) Cavanagh, P.R. "Biomechanics of Distance Running." Human Kinetics
Book, 1990, p. 117.
11.)Williams, K.R. "Biomechanics of Running." Exercise Sport Sciense
Review, Vol 13, 1985, pp. 389-441.
12.) Miura, M., Kobayashi, K., Miyashita, M., Matsui, H. and Sodeyama,
H. "Experimental studies on
biomechanics on long distance runners." In review of our researches,
H. Matsui, Editor. Dept. of Physical
Education, University of Nagoya, Japan, 1970-1973, pp. 45-46.
13.) Magaria. R. "Biomechanics and Energetics of Muscular Exercise."
Oxford University Press, Oxford,
1976, p. 128.
|Re: POSE - some numbers||gordo||7/11/10 4:45 PM|
On Jul 11, 5:04 pm, tsedee <2ced...@gmail.com> wrote:The angular momentum, if not canceled, will result in landing on your
face. Angular and linear momentum are NOT the same.
And how do we get GRF? We push on the ground. The harder we push, the
higher the GRF. GRF doesn't supply any energy, we do.
Redirection does work. In fact you could say that the tiny bit of
angular momentum from the very first fall only, where the GCM falls
from standing height to running height, is converted into linear
momentum by the legs pushing.
>Nothing in science is ever proven right. Newton's theory has, however,
stood the test of time at human speeds, and is generally accepted. If
you can find a case where it fails, I guarantee you lasting fame.
>I said exactly this above. What's your point?
You mean people can't agree how we run? Hard to believe. LOL
Sorry, gotta go. Dinner calling. Maybe more later.
|Re: POSE - some numbers||tsedee||7/11/10 4:48 PM|
looks like google groups doesn't support UTF-8 (the hieroglyphs were
meant to be in Cyrillic)
while i enter them they appear OK
sorry for that ...
> 6.) ìeÇËÁÑ ÁÔÌÅÔÉËÁ: õÞÅÂ. äÌÑ ÉÎÓÔÉÔÕÔÏ× ÆÉÚ.ËÕÌØÔ./ðÏÄ ÒÅÄ. î.ç.
> ïÚÏÌÉÎÁ, ÷.é. ÷ÏÒÏÎËÉÎÁ, à.î.
> ðÒÉÍÁËÏ×Á.-éÚÄ.þ-Å, ÄÏÐ., ÐÅÒÅÒÁÂ.í.: æÉÚËÕÌøÔÕÒÁ É ÓÐÏÒÔ, 1989,ÓÔÒ.
> 7.) õÔËÉÎ ÷.ì. ìÒÙÖËÉ × ÄÌÉÎÕ Ó ÒÁÚÂÅÇÁ. ÂÉÏÍÅÈÁÎÉËÁ ÆÉÚÉÃÅÓËÉÈ
> ÕÐÒÁÖÎÅÎÉÊ. í.: ðÒÏÓ×ÅÝÅÎÉÅ, 1989, ÓÔÒ.
> 8.) äÏÎÓËÏÊ ä.ä., úÁÃÉÏÒÓËÉÊ ÷.í. âÉÏÍÅÈÁÎÉËÁ: í.: æÉÚËÕÌØÔÕÒÁ É
> ÓÐÏÒÔ, 1979, ÓÔÒ. 185
> Erfahren Sie mehr »
|Re: POSE - some numbers||gordo||7/11/10 9:04 PM|
Great. I'll get right on that. Have you read all of these, or are you
cut-and-pasting impressive-looking footnotes from some Pose paper?
Not to be snide, but if you prove that gravity can power linear travel
on a level surface, a Nobel Prize is only the beginning of the honors
that you will collect. Go for it. I will happily nominate you. The
world will throw more money at you than they do at Microsoft.
Perpetual motion has been the Grail for centuries. No one has cracked
it yet. You claim that Romanov has. If so, why the heck is he still
coaching instead of cashing in?
Please explain in English how it works, don't send me off to read a
bunch of papers in Russian. The last paper gave me a headache before I
figured out that it was a smokescreen. I'm tired of showing you why
it's impossible. If it's so simple, why can't you explain it?
> read more »
|Re: POSE - some numbers||tsedee||7/11/10 10:18 PM|
Perpetual motion ?!
Holy foot !!!
> Erfahren Sie mehr »
|Re: POSE - some numbers||gordo||7/12/10 4:24 AM|
|Re: POSE - some numbers||tsedee||7/12/10 12:22 PM|
how stupid of me to go through the trouble of posting all this ...
same for me (but the other way around)
obviously we don't have to go too deeply into science if not even
getting a grasp of the very concept at all.
> Please explain in English how it works If it's so simple, why can't you explain it?
it's the (error in the) way you are trying to interpret it.
obviously "perpetual motion" is not the idea and it's not something
Romanov is claiming or I could possibly ever be able to explain.
so please dismiss that association.
let's get back to
> That's why the whole idea of gravitational torquethis is more like it.
so yeah, you put a foot in front of you to arrest the fall ..
but the idea is not to totally arrest the fall but to continue the
fall, using alternating placement of your feet under your body.
the skill is to do that in a way (placing the support) that keeps you
from hitting the ground, while at the same time you repeat/continue to
fall and fall and fall ...
that's the idea of a running style powered by gravity.
obviously you have to recover the legs eventually to have them
this process is not effortless.
your muscles will also tense as a reaction to support your body weight
and so on, so it has nothing to do with "perpetual motion" in any way
as your body is not "flying above the surface" in absence of any
effort but the physiological system is working nonetheless.
sensibly, even jumping on the spot would be taxing while one is not
even moving forward.
perpetual motion is not the point in any way. please understand.
this however doesn't exclude gravity to be an accelerating force
powering the run.
of course there are the components of the muscles, providing
elasticity, leg repositioning (pull) and support and the ground
reaction force (body weight) no one excluded these (but you?)
isn't it obvious that a runner is not a falling broomstick and
therefore can reposition his support? as well as he can position
himself to "fall forward"
considering that, why should your limited formula (of gravitational
torque) prove anything being impossible? (no offense, just pointing it
you didn't deny it exactly, that's true, but all you seem to be able
to accept is "push off" anyway.
however, consider i am by no means the right person to make you happy
(neither engineer nor copyist) and i don't take pleasure in argument
with a notorious naysayers who is too cheap and too proud to acquire
the answers to all his scientific questions (for 30$) and i am no
salesman either ..
you are tired pointing out that it's impossible while it makes me
laugh because it works for me.
heck, you can't seriously expect that i go through typewriting the
whole book on here just for the pleasure of our agreement.
let's go running.
run the way you please.
> Erfahren Sie mehr »
|Re: [Minimalist Runner:36998] Re: POSE - some numbers||Tuck||7/12/10 3:00 PM|
"So says Erik Verlinde, 48, a respected string theorist and professor of physics at the University of Amsterdam, whose contention that gravity is indeed an illusion has caused a continuing ruckus among physicists, or at least among those who profess to understand it. Reversing the logic of 300 years of science, he argued in a recent paper, titled “On the Origin of Gravity and the Laws of Newton,” that gravity is a consequence of the venerable laws of thermodynamics, which describe the behavior of heat and gases."
I think it's pretty clear that gravity causes heat and gases, not the other way around, at least based on the various POSE threads we have. ;)
|Re: POSE - some numbers||tsedee||7/14/10 9:56 AM|
that was probably a hysteric reaction ...
i was simply receiving the impression whatever i may tell you, you
will ask for something else.
my bad, as i see it meanwhile ...
> Erfahren Sie mehr »
|Re: POSE - some numbers||gordo||7/14/10 7:17 PM|
On Jul 14, 10:56 am, tsedee <2ced...@gmail.com> wrote:All I ask is that you: a) spend half as much effort understanding
Newtonian physics as you do defending Pose, b) stop posting that
gravity can power the run, or c) explain, using Newtonian physics, why
I am wrong. Posting bibliographies or telling me that I don't
understand without explaining why I am wrong is a waste of time for
both of us and everyone still bothering to follow this thread. Here's
the argument that I would like to see you refute:
There is a fundamental reason that gravity can not power the run. It
is this: Gravity acts only in the vertical direction. In fact,
vertical is defined as that direction parallel to gravity. There can
therefore be no horizontal component to gravitational force. With no
horizontal component of force, there can be no horizontal acceleration
since a = F/m = 0/m = 0.
That's it. Forget running, forget Pose. What exactly is wrong with
|Re: POSE - some numbers||JasonH||7/14/10 7:24 PM|
I really don't want to get involved here but I would like to
understand how I 'flop' onto my bed or why I trip and fall if gravity
acts only vertically.
Its not just gravity we are talking about its about how our bio
mechanical structure interacts with gravity, i.e. our bodyweight.
If its any consolation I am just as confused as to why its hard to
understand why gravity makes us move.
From a math/vector point of view, yes gravity only acts vertically
that is why we need to be unbalanced for movement to take place. Its
like on a bike, you are not going anywhere by pushing down on a pedal
until you release your bodyweight on the foot behind first...
|Re: POSE - some numbers||gordo||7/14/10 8:37 PM|
On Jul 14, 8:24 pm, JasonH <jasonm...@gmail.com> wrote:Because both the bed and the ground are lower than you are. Try
flopping onto the wall some time. :-)
>True. However, gravity cannot power the run. Your body does that.
Gravity can and does stimulate your body to react automatically,
making it FEEL effortless, but it does not provide any actual
horizontal acceleration. The reason I asked Cedrik to stick to physics
and leave running out of it is that what running feels like gets in
the way of understanding the fundamental problem.
>It's not hard. That's why I'm getting so frustrated. This is high
school science. Gravity holds us down so that we can lean, bounce,
push off, jump, fall, etc. If we want to accelerate downward, it's
very helpful. If we want to accelerate horizontally, it's no help at
all. If we want to accelerate upward, it fights us the whole way.
If you unbalance, all that gravity can accomplish is to make you fall
down. It's what your body does to prevent the falling down that causes
The bike moves because you push with your legs. Gravitational force
holds you down so that you can push with your legs. Just like
Redefining "change of support" to refer to something that happens
internal to the mass that we propose to accelerate is a fundamental
error that obscures what is really happening. Let's not even get
started with the swimming. :-) Here's how to look at the bicycle
example that makes it exactly analogous to running:
The wheels of the bike support the mass(you plus the bike) that is
hopefully going to accelerate. You can change support by doing wheel
stands on alternate wheels. Leaning and doing this does not result in
horizontal acceleration. If gravity was powering horizontal
acceleration, it would.
|Re: POSE - some numbers||JasonH||7/14/10 8:43 PM|
I understand your point of view and will leave it at that and thanks
for sharing. I never find 'language arguments' all that interesting
|Re: POSE - some numbers||tsedee||7/15/10 12:38 AM|
let's try in small steps:
gravity is acting in vertical direction, downwards.
it is pulling objects toward the Earth at a rate of 9.81 meters per
the idea is is possible that gravity, in a cooperation with other
forces, can produce a resultant horizontal force vector.
the idea of the leaning body of the runner on support has to be
compared to Galileo's ball rolling down a sloped surface.
there the downhill velocity of the rolling body (ball) is a portion of
the free falling body where the acceleration by gravity is related to
the angle of the slope.
the ball rolls downhill by gravitational force which displaces the
general center of mass of the ball relative to the point of support.
so gravity (body weight, in this particular setting) produces a force
= gravitational torque.
this allows the assumption that from a certain body position gravity
can be used to produce work in horizontal direction.
|Re: [Minimalist Runner:37362] Re: POSE - some numbers||gk0...@gmail.com||7/15/10 1:03 AM|
But you don't want to get yourself any closer to the ground -- you're tying to move horizontally, not vertically; so every inch you let yourself fall you have to pick yourself up an inch, and there is no efficiency in that.
|Re: [Minimalist Runner:37365] Re: POSE - some numbers||OrionFyre||7/15/10 2:25 AM|
The only thing I can say after mistakingly think I could stand to read
I cannot believe that people who have absolutely no comprehension of
The single and only benefit that gravity gives us in our running
Everyone seems to be under the mistaken impression that moving
Fundamental understanding of physics and motion 101. The forces and
To envision the ease of horizontal movement perpendicular to the force
While we are neither as round, smooth or aerodynamic as a marble, and
The magic in our locomotion is our ability to utilize the compression
Once the weight of the individual is over the point of contact and the
Now, we know that the horizontal movement is devoid of any imparting
Putting it all together.
Furhermore looking at the body as it's own force diagram the foward
Imagine if the back were to be straight to the force of gravity, with
|Re: POSE - some numbers||tsedee||7/15/10 2:38 AM|
looking at ground reaction force, according to Sir Isaac Newton's
stomp the ground and the ground stomps back.
this is a non-propulsive force that reflects the force applied to the
it arrests the downward movement of the body and reacts to all the
forces we apply, sending them back.
having said that, it becomes clear that a runner can produce different
patterns being detected by a force plate.
when heel striking or forefoot landing and what have you.
i don't mean to notice that there is a common way how "we" run, so
this is variable.
but forces will be reflected right back by ground reaction force.
the main peak of it being vertical as well, but *upwards*. (while it
depends on execution in regards of where this peak is located)
so ground reaction force pushes the body upward in nearly the opposite
direction of the gravity force.
our gravitational torque is the result of ground reaction and gravity
if (A) is the ground reaction force, (B) is gravity and (C) is the
resultant vector, the magnitude is AB 'sin0'
the angle '0' is the angle between (A) and (B)
C=|A| x |B|
|C| = |A| |B| 'sin0'
so gravity moves the body downward at a constant rate, ground reaction
force pushes the body off the ground in nearly the opposite direction.
the vector (C) represents the rotational motion of the body around the
point of support.
during this motion the center of mass (of the runner) moves in
horizontal direction as well.
the magnitudes of the components of the resultant vectors change
(according change of resultant vector angle,, which changes according
to the body lean of the runner)
to a certain angle, the horizontal component prevails over the
past that angle the relationship reverses and the vertical component
prevails over the horizontal.
conclusively, to a certain angle of lean one "falls forward".
from a certain point then does fall down.
|Re: POSE - some numbers||tsedee||7/15/10 2:47 AM|
i don't dispute the elasticity and loading of muscles and tendons.
this is also an important element.
the subject was about the role of gravity and leaning ..
however, thanks for the flattery anyway.
what "lean from the hips" ?!
|Re: [Minimalist Runner:37370] Re: POSE - some numbers||OrionFyre||7/15/10 3:00 AM|
On Thu, Jul 15, 2010 at 4:47 AM, tsedee <2ce...@gmail.com> wrote:
And..... wow, ok. I guess I won't try to explain the role of gravity
As for the flattery, concerning the general ignorance and supposition
|Re: POSE - some numbers||tsedee||7/15/10 3:04 AM|
|Re: POSE - some numbers||gordo||7/15/10 7:03 AM|
On Jul 15, 1:38 am, tsedee <2ced...@gmail.com> wrote:Good idea.
>We're all together here.
>But what about gravity without another force? That's the real
question. In order to power the run, gravity alone must be able to
generate horizontal acceleration. It's trivial to show that g plus
some a in the horizontal direction results in a horizontal
acceleration of a. :-) If you could show that it results in some
horizontal acceleration of a2 > a, I would accept that, although it
complicates things unnecessarily.
No, it doesn't. That comparison is invalid. Gary nailed this one. The
COM of the ball ends up lower than it started. The COM of a runner
does not unless he's falling down or running downhill. The potential
energy of the ball decreases, the kinetic energy increases. If you try
to claim that the runner falls forward, harvests the energy, directs
it forward, and then raises himself to fall again, we end up back at
the ludicrous case that started this thread, and on top of that, the
runner still has to supply all the energy.
I can live with this statement. The idea behind it is correct. I'd
like to see it reworded before it goes into the textbook. :-)
I'm OK with this. If we were somersaulting downhill instead of
running, I could even live with the analogy.
Any assumption is allowed. Don't forget, however, that it is
traditional to test our assumptions. Unfortunately, upon testing, this
one turns out to be wrong. The certain position is that of a runner
who is already leaning. That is the steady state running position. No
further decrease in the average height of the COG will occur, thus no
potential energy is available to convert into kinetic energy. The ball
is at the bottom of the ramp and has come to rest, if you will.
I think that using Pose imagery is valuable. I use it myself. Physics
could even be applied to justify it, if it was done correctly. I can
see why Romanov would resist correcting his analogies, though.
Everyone wants something for nothing. Something free is a huge
attraction to potential buyers. The idea that gravity can somehow
power a run implies that the runner doesn't have to. Free power! What
a sales pitch. :-)
|Re: POSE - some numbers||gordo||7/15/10 7:14 AM|
On Jul 15, 3:25 am, OrionFyre <orionf...@gmail.com> wrote:I know, I know. Everything you say, with one exception, is correct. It
needs to be distilled, however, because the complexity of the whole
springs and levers system is hiding the essential issue.
>This is the incorrect statement I referred to. ;) This IS the
|unk...@googlegroups.com||7/15/10 7:17 AM||<This message has been deleted.>|
|Re: POSE - some numbers||JasonH||7/15/10 7:20 AM|
I think I understand what you are thinking. No gravity itself does
not 'power' a run like the engine does to wheels on a car. No one is
suggestion 'free power' which is what I assume you meant earlier by
perpetual motion. Gravity does however set up the conditions under
which we can run by allowing the body to interact with gravity so its
'free' in that sense.
Also, yes we actually do fall vertically when we run even on level
ground which is why our head bobs up and down. Our muscle reactivity
recovers our vertical height so its not something we have to worry
about (like consciously 'push' back up vertically). Its a bunch of a
little falls in a row at each step to overcome friction, air
It comes down to our skill at our interaction with gravity.
We could not run without gravity so our interaction with it is
|Re: POSE - some numbers||gordo||7/15/10 7:31 AM|
|Re: [Minimalist Runner:37398] Re: POSE - some numbers||Tuck||7/15/10 7:50 AM|
Thank Heavens. ;)
|Re: POSE - some numbers||tsedee||7/15/10 7:57 AM|
> But what about gravity without another force? That's the realwhy not? so you don't want to know how to tap it?
if it would be more obvious, we wouldn't have to question it ...
by gravity's very nature/direction, it takes of course some doing to
draw benefit from it.
it's not impossible though.
gravity is a force we have to deal with when running anyways. no way
of course a vertical force will not miraculously become a horizontal
force driving me forward effortlessly without interaction, like some
missile in my butt =)
the question is rather how to interact with that force in the most
intelligent/beneficial way and make it part of a system of forces that
act in order to move me forward horizontally.
that's more than good enough for me.
but the way you put it, you are right.
while i am satisfied with my insights in the above mentioned regard,
technically i don't have to keep harping on the gravity thing, and i
agree that it is incorrect when isolated out of context.
in that regard, it doesn't make sense to claim that.
|Re: POSE - some numbers||tsedee||7/15/10 7:59 AM|
i hope it didn't take me too long to compile the above post ... and i
could make similar sense like Jason
|Re: POSE - some numbers||gordo||7/15/10 8:01 AM|
On Jul 15, 8:57 am, tsedee <2ced...@gmail.com> wrote:
> but the way you put it, you are right.Great. I move that we table this discussion.
|Re: POSE - some numbers||JasonH||7/15/10 8:09 AM|
Now that we agree that gravity is involved in running, the next thread
can be about what is the best way to integrate gravity into our
|Re: POSE - some numbers||gordo||7/15/10 8:13 AM|
I'd rather go to the dentist. LOL
|Re: POSE - some numbers||Splicer||7/15/10 9:27 AM|
From reading this thread, here is the takeaway as I understand it. I'm
not trying to argue, but am repeating back what I think I've learned.
If I'm off-base but you think the thread has gone on too long, feel
free to correct me off-list.
When standing still, all forces are at equilibrium. We us a little
muscle power to tilt forward and maintain tension through our core to
keep our body straight while standing on a non-frictionless surface,
and our body becomes a lever. Gravity is pulling on all of us but our
feet represent a fixed point. We begin to fall, and our upper body has
forward motion. That's a relatively small expenditure of energy for
the amount of motion we're getting because gravity is pulling. Yay,
free energy! Not much, but a little.
BUT then we take a step to avoid falling on our face. From that point
forward there is no more free energy. We have that small amount of
initial momentum from the descent immediately prior to the first step
and we maintain our forward lean. But so long as we are using muscular
energy to prevent us from hitting the ground, we get no more "boost"
At this point we want to continue to move forward, so we maintain the
slight forward lean for two reasons: first because expending energy
pushing our upper body mass backward would be counterproductive and
second to balance the lateral force we apply with our feet. If we
applied force without moving our center of gravity in the direction of
that force we would simply fall backwards every time we run forwards.
So I think the point of the POSE visualization is to keep us from
constantly and inefficiently continuing to pull ourselves upright
after every step. It's not so much a matter of letting gravity pull us
forward but a matter of stopping ourselves from pulling our body
weight backward when we're trying to run forward and need to maintain
the forward lean to keep from falling backwards. We have to keep from
falling backwards, so maintaining that slight lean is much more
efficient than leaning forward and straightening up over and over
again. The difference in efficiency leads to a feeling like getting
I've found it useful to visualize a huge rubber band tied around my
waist and the top of a hill, to help me relax and run up the hill. It
doesn't mean that there is an actual rubber band, but imagining it
must lead to some unconscious change in my body mechanics. I don't
think the difference is purely mental.
How far off the beam am I?
|Re: POSE - some numbers||gordo||7/15/10 10:09 AM|
|Re: [Minimalist Runner:37397] Re: POSE - some numbers||JZ||7/15/10 11:57 AM|
Its a bunch of little falls in a row at each step to overcome friction, air
Yes, but don't leave out the important fact that the "little falls" are preceeded by little "push-offs".
|Re: POSE - some numbers||JasonH||7/15/10 12:02 PM|
Don't open that can of worms again :)
Yes, there is a passive push to regain the vertical height lost at the
last fall. Please, no one try and actively push, you will be asking
for trouble :)
|Re: POSE - some numbers||HHH||7/15/10 12:07 PM|
As the guinea pig for the group, a few months ago, I did a hard run
and "actively" pushed off just to try it out. I didn't injure myself
but I could feel the pressure on my plantar muscle and achilles tendon
and I was sore after the run. If I were to keep it up, I would have
seriously injured myself down the road. With proper form and
technique, the push off is passive and automatic . . . I call it the
"energy return" from proper running. If you land correctly, lightly
and lift quickly, the reward is huge and the push is automatic without
actively trying . . . the uncoiling will launch you through the air.
|Re: POSE - some numbers||JasonH||7/15/10 12:10 PM|
Exactly Harry. Pushing off delays the proceedings and increases the
eccentric contraction of the PF and Achilles area which is bad news.
|Re: [Minimalist Runner:37426] Re: POSE - some numbers||JZ||7/15/10 1:26 PM|
I agree, there should be no active or conscious push-off. From the point of view of physics, however, you have to go up before you can come down. I thought this thread was about the actual physics of running (rather than the perception), which is why I brought that up. It seems to me that it is a crucial point, because the energy that you might gain (or elastically recover) from falling towards the earth, you have already expended (and more) from moving yourself away from the earth.
That is the take home message that I got from reading this thread, anyway.
|Re: [Minimalist Runner:37446] Re: POSE - some numbers||Tim Butterfield||7/15/10 2:04 PM|
On Thu, Jul 15, 2010 at 3:26 PM, JZ <joza...@gmail.com> wrote:
That's what I get also. Sure, you use gravity, but it's more like a
I just took another look at the pose tech site and noticed something
|Re: POSE - some numbers||JasonH||7/15/10 2:15 PM|
Yes the Pose is the 'lowest' point of the GCM. At this point the
elastic response is loaded and ready to fire. Now if we can just pull
our foot on time we will get the best 'rebate' we can get. The 'S-
stance' is the spring being loaded via bodyweight/gravity. Then we
'recoil' just enough to change support again.
There is the 'falling' vertically then there is the 'falling' forward
(gravitational torque phase if you buy the theory). Its probably a
bad re-use of the term :)
On Jul 15, 3:04 pm, Tim Butterfield <timbutterfi...@gmail.com> wrote:
|Re: POSE - some numbers||JasonH||7/15/10 2:20 PM|
I should point out to remember in constant speed running there is very
little fall at each step. Its probably best to think of it taking
place in between the figures in the diagram right after the Pose.
|Re: POSE - some numbers||tsedee||7/15/10 2:37 PM|
as a rough aim, vertical oscillation is estimated at 4-6 centimeters
in very good runners (in track and field and also in the pose method)
other running styles advocate 6 inches = 15.24 centimeters of vertical
just to put the "inefficiency" it into relation.
On 15 Jul., 23:04, Tim Butterfield <timbutterfi...@gmail.com> wrote:
|Re: [Minimalist Runner:37467] Re: POSE - some numbers||JZ||7/15/10 3:54 PM|
Once we get airborne, then it's easy to move forward because the only force opposing our forward movement is air resistance (which is relatively small at running speed, I think). The main drain on our energy would seem to be the energy needed to oppose the force of gravity in order to get us airborne. So, if we can minimize the effort we exert against gravity to only the very minimum needed to get us airborne, then we should be able to run as efficiently as possible. I think that's what Romanov is trying to tell us, maybe.
AFAIC, and I think gordo did an outstanding job of debunking this, there is no falling forward aspect to running. If you are running efficiently, it may feel like you are falling forward, but in actuality, you are not.
|Re: POSE - some numbers||Nick J||7/16/10 1:25 AM|
Damn, I love this thread.
Personally I will take away the elastic band visualisation for uphill
running as the thread highlight, I'm definitely in need of some help
with my hills at the moment. Clearly POSE, Chi et al struggle with
the concept of hills (just have a look at Dreyers crab like hill
style, mental, right?) Oh and when we run back down again we should
heel strike? Nah, clearly the branded running styles are of a limited
For all of us that run trails, mountains, cross country and off-trail,
the additional variables are far too much for a running form with
limited rules to adapt too.
Just look at the running styles of the great ultra distance runners,
not nuch, if any forward lean. Keeping the lean going for a long
amount of time at a reasonable clip would need additional muscular
energy, especially over trails, I recon that's why it feels more
comfortable to run upright.
> Joe- Masquer le texte des messages précédents -
> - Afficher le texte des messages précédents -
|Re: POSE - some numbers||gordo||7/16/10 5:23 AM|
On Jul 16, 2:25 am, Nick J <nick.je...@gmail.com> wrote:I do think that they also have practical value, depending on what
technical flaws you need to correct. I just heard 'gravitational
torque' used one too many times as though it meant something and went
off. It doesn't mean that the imagery isn't quite useful.
That's my preferred terrain, and I admit to using Pose imagery. I also
use the imagery from 'Master the Art of Running', by Balk and Shields.
They take an Alexander approach. There is a lot of overlap.
>Leaning is for acceleration. Running upright is for running at a
steady pace. The real difficulty is learning to feel what upright is.
For most people, it feels like leaning a bit forward. :-) So that's
what you tell people. Imagery can be very useful if properly applied.
There is no one path to good running, there are many. Just because one
particular path works for you, it doesn't mean that another will not
need a different route.
|Re: POSE - some numbers||tsedee||7/16/10 5:53 AM|
to add my final comment:
gravity doesn't drive "us" forward when "we" run.
anyone saying that it does not is actually right (for his case and
but one has to know how to tap it and that's a skill.
anyone can run without these considerations and is free to believe
what he/she likes, of course.
and i am off for a holiday ... will try POSE swimming (harr harr)
|Re: POSE - some numbers||Andy Southerland||7/16/10 6:40 AM|
that's the one where you "sink" forward?