Monday, September 10, 2012

Pose Theory - Three Primary Points of Confusion

Update August 4th 2013

It was recently pointed out to me that, although my points were correct, I was rather sloppy with my use of the words 'energy' and 'work' in this post. I will make corrections soon, but until then, I want to post the messages I received on Facebook as a reference. I've edited them slightly for readability, because they were take off a long Facebook thread.

John Port -
Hey Ken S, I read your links above [to this post], and you do a nice job of explaining and simplifying some concepts that cause many people reading the very large quantity of information available on Pose Method. Hope you don't mind me suggesting... In the first linked article you interchange term of energy and work. I know totally what you mean, but someone from a pure physics background may "pick it". Just to clarify for others who may not be into the physics side so much...Energy has an ability to perform "Work". Work is defined as W=Fd, so I pure physics terms Work is ONLY ever done when movement is created - something moves. E.g I bet there are a number of readers here who would say that if they were to push against a wall, that they would be doing work, in fact they may be surprised to learn that the work done pushing against a wall is 0 (zero) because the wall doesn't move. So, all I'm saying is that we have to be careful mixing terms of energy and work. Just because energy is present does not mean work is being done, just that it could be done. Also, for a runner, it absolutely is true to say that work is being done between the Pose position and the body going airborn at end of time on "stance": physics says so, because the body is vertically displaced, and any time force and distance are present, work must be being done (W=Fd). The question is not that work isn't done it is what direction (i..e work is being done and by what force
John Port -
Sorry hit return....last sentence... The question is not that work isn't done, it is in what direction (vertical and horizontal components) and what force is doing it.
Me - 
Cool! Thanks John. I'll fix the post soon.

First Point of Confusion - Where Does the Energy Come From?

When discussing Pose theory, the concept of energy production and consumption while running is confusing because it is usually assumed that we move forward when performing work and thus using energy. This is based on the assumption that forward motion in running is the result of pushing off with the legs. So for most people, Pose Theory is confusing because it states that the runner is not doing work when moving forward, because he is not pushing. Pose theory does state that no work is done by the runner when moving forward, but it does not state that the runner does not need to do work. This is an important and subtle point that is often overlooked.

According to Pose theory, when a runner is putting energy in to running he is not moving forward, and when he is moving forward he is not putting energy into running. How does this work? When running, the runner must do work against gravity to gain a position from which he can fall. In other words, the runner must expend energy to get into the Pose. Some of the energy from the work the runner performs against gravity is stored as potential energy, also known as “positional energy” or “energy due to position”. As the runner achieves the Pose, he has done work and expended energy, but has he not moved forward, he has simply gotten in to a position from which he can fall. Once in the Pose, the runner then falls forward. However, while falling forward, the runner is not expending energy or doing any work, other than what is needed to remain in the proper position. As he is falling, the runner is passively converting the stored potential energy into kinetic energy. In other words, the runner is not doing any work to move forward. He is simply falling.

It is important to understand that gravity is not creating energy; it is allowing the runner to recycle energy he has already expended while doing the work necessary to get in position to fall. Once in the Pose, potential energy is there to be used by the runner, and the runner can harness this energy more efficiently and effectively by developing his technique to work with gravity.

Second Point of Confusion - Gravity is a Downward Force. How Can it Be Used to Move Forward?

Gravity is a downward force, and there is no argument about that. However, all forces can be redirected. In fact there are many ways to redirect any force, and the ability to redirect force is the basis mechanical engineering. One of the most basic ways forces can be redirected is through the use of a lever. When a lever moves around a fixed pivot point, torque is created. Torque is the movement of an object around an axis.

So what does this have to do with running? When the body is held ridged while falling, it acts as lever, redirecting some of the downward force of gravity horizontally. When running and walking, the ball of the foot acts as the pivot point, around which the body torques, and this pivot point is made possible by the friction of the foot against the ground. It is important to understand that the redirection of gravity using levers is something that we witness and use every day. It is not some strange or esoteric phenomena; in fact it is so common we tend to take it for granted.

Third Point of Confusion - How Can You Lean Forward Without Pushing?

Inanimate objects fall over all of the time, and they are not able to push themselves. Inanimate objects fall over when they are unbalanced in some way. No one is worried that the Leaning Tower of Pisa is going to push itself over. They are worried that it is going to fall because it is positioned in way that is not balanced. Otherwise, it would simply be called the Tower of Pisa, and it would not be a tourist attraction.

Disregarding the effects of momentum provided by previous strides, a runner can still fall forward simply by placing his body in a position that is not in balance. This unbalanced position is called the Pose. The Pose unbalances the runner because his weight is redistributed up and to the front. If the runner is in the Pose, he can only remain in balance by applying pressure to the ground with the ball of his foot, using muscular effort to counteract the force of gravity. Once the runner relaxes and stops applying pressure to the ground, he will fall forward. He has no choice in the matter, gravity simply takes over, and as long as he remains rigid enough to act as a lever, then there will be a horizontal component to his fall.

It is important to understand that in order to lean forward the runner only needs to be unbalanced, so he does not have to push. It is also important to understand that the description I’ve given here only covers the special case of the first step. Once the runner is moving, momentum will further assist the runner with leaning forward.

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