Pose Clinic with Dr Romanov

I have just returned from a very enjoyable and informative weekend Pose Running Clinic led by Dr Romanov. I learned a lot of useful and thought provoking things about efficient running during the weekend, and will post my thoughts on some of these topics over the next few weeks. Meanwhile, in this posting I will summarize some of my main impressions.

It was a delight to meet Dr Romanov. The meeting confirmed that he is a charismatic person with many very valuable insights in to running. Previously in this blog I have expressed doubts about some of the biomechanical principles underlying Pose, and indeed I continue to have these misgivings. However, these misgiving need to be interpreted in light of the distinction which Dr Romanov himself makes between the psychological reality and biomechanical principles of efficient running. Psychological reality refers to the state of mind that facilitates the performance of efficient running. The biomechanical principles are the principles of Newtonian mechanics that govern the way in which we run.

On this weekend clinic, the main focus was on the psychological reality. In general, focusing the mind on biomechanical principles when running is unhelpful because conscious attempts to manage all aspects of running style while running interfere with the automatic mechanisms by which our body reacts to the forces acting on it. Indeed our perceptions of what we are doing can in some circumstances by quite different from the biomechanical events.

Two illustrations of this are provided by the Pose concept that gravity is a source of free energy, and the concept of gravitational torque.

Free energy?
In Dr Romanov’s book ‘The Pose Method of Running’ (2002 edition), chapter 12 is entitled ‘ The Free Falling Concept’. In that chapter, on page 62, he states ‘The great runner is not impervious to gravity; instead he taps into it as a readily available source of free energy. In the same way that the tremendous force of gravity inevitably draws a free falling sky-diver towards Earth, we can appropriate the force of gravity to run further, faster and with less effort.’ From the biomechanical point of view, this statement is at best misleading, and at worst simply wrong. When running on a level surface, the gravitational potential energy at the end of each gait cycle is the same as at the beginning of that cycle. Gravitational potential energy is proportional to height about the Earths surface. Therefore, gravity cannot be a source of free energy for a runner on a level surface. However, the important psychological issue is that a belief that we need to push off from strongly from the ground at the end of the stance phase in each gait cycle in order to run fast is very likely to lead to serious inefficiency and risk of injury by promoting over-striding. My weekend at the Pose Clinic has helped me refine my ideas about the best way to define ‘over-striding’, but that will have to wait for a later posting. The crucial point for the present discussion is that focus on correct biomechanical principles can lead to an unhelpful psychological approach. In contrast, the belief that gravity is a free source of energy might promote a less forceful push-off, thereby minimising the risk of over-striding.

Gravitational torque
Dr Romanov emphasises strongly that when the long axis of the body is leaning forwards, the force of gravity generates a torque that provides forward propulsion. One of my calculations presented in the side bar of this page suggests that the amount of angular momentum generated by gravitational torque is probably small compared with the angular momentum that arises from the fact that a body moving horizontally forwards will inevitably begin to rotate in a ‘head forwards and down’ direction around the point of support when the foot is held stationary on the ground. My calculation was based on model that is only valid for a rigid body that does not extend at the hips. In fact, appreciable extension at the hip is inevitable in the latter part of stance. At some point in the future I will present a more precise calculation taking account the effect of hip extension. However, I do not believe the more accurate calculation will lead to a substantially different conclusion, but in any case, the magnitude of the increase in angular momentum due to gravitational torque is not the most important issue. If we are to avoid an ever-increasing rotation in a face forwards and downwards direction, the effect of gravitational torque must be reversed by some equal and opposite torque at some point in the gait cycle. Hence, gravitational torque cannot provide forwards propulsion. This is the biomechanical reality. However, the psychological reality is that forward lean leads to increased speed. In fact this is most apparent when a sprinter accelerates from the starting blocks. The biomechanical fact is that it is not gravitational torque that provides the propulsion; it is the muscular actions that moves the legs forwards rapidly enough to avoid a face-down crash. However, focus on forward driving action of leg muscles is generally counterproductive, so the concept that gravitational torque provides propulsion might be a useful psychological reality.

Proprioception and the point of support at foot-fall
The Pose Method places a very helpful emphasis on the role of body perception in efficient running. Dr Romanov emphasises that the proprioceptive sensations from the muscle and joints are crucial for accurate timing and direction of the muscle actions during running; especially for the action of pulling the foot from the ground at the end of stance. However, even here there can be a disparity between subjective experience and objective reality. At the Pose Clinic, it was stated that one should aim for the sensation that the foot lands beneath or even behind the body’s centre of gravity (COG). This statement is reinforced by the statement on page 311 of ‘The Post Method of Running’, that landing ahead of the body is a common error. However, the biomechanical realty that a torque imparted at some time during the gait cycle must be reversed at some other point in the gait cycle makes it almost mandatory that the point of support at foot-fall must be in front of the COG. When support is in front of the COG, the gravitational torque acts that tends to pull the body backwards and down, thereby compensating for the ‘face forward and downwards’ torque applied when the support is behind the COG. Though it seems a shame to be obliged to suffer this braking effect, it is imperative to avoid a face down crash. Rather enigmatically, this is implicitly accepted in the Pose Method criterion that the period on stance should consist of one video frame (33 milliseconds) from footfall to mid-stance (the Pose position when the point of support, COG and shoulder are aligned in an almost vertical orientation) and one video frame with between mid-stance and lift-off from stance. So there is a discrepancy between the recommended subjective perception and one of the observable criteria for good Pose Method running.

Time on Stance
For me the most thought provoking issue raised at the Clinic was the recommended duration on stance. I have previously suggested, on the basis of my own experience, that unless a runner is quite fit, he/she should be cautious about having period on stance of less than 120 milliseconds. My own experience has been that for runs of 15K or longer, if I spend less than 120 milliseconds on stance, I experience some pain over the metatarsal heads the following morning. However, using the technique recommended at the Pose Clinic I found that I was able to reduce my time on stance to 80 milliseconds while feeling that my footfall was fairly light. On the first day of the clinic I spent 20 minutes or less running with time on stance around 80 milliseconds, and the next morning I was aware of mild pain under my metatarsal head. However, on discussing this problem with Pose Coach, Mark Hainsworth, and also with Dr Romanov himself, I came to appreciate that it is likely that I can avoid this metatarsal pain if I allow my heel to rest lightly on the ground during stance. Contrary to the impression created by all of the diagrams in ‘The Pose Method of Running’, Dr Romanov does actually recommend lowering the heels to the ground. I have not yet had the opportunity to combine the technique I learned at the Clinic with lowering the heels to the ground, but once I have had the opportunity to test this, I will review my previous blog posting and perhaps revise my conclusions regarding time on stance.

The Clinic raised many other interesting issues; I hope to deal with several of these on my blog in the next week or two

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8 Responses to “Pose Clinic with Dr Romanov”

  1. Simon Says:

    Thanks for the summary, I tend to agree with the idea of a perceived reality as opposed to the physical reality and the blurry lines in Pose – this comes up time and again when trying to discuss the physical reality with Pose advocates.
    I hope you can take some useful ideas from the clinic too – I am not sure about the role of gravitational torque in running but I know the Pose method has many attributes that work very well in practice if you can get passed the psuedo-science that some Pose ideas are rooted in.

  2. Paulnm Says:

    I followed your linkn from Fetch.

    Thank you so much for this summary. I think it has resolved several issues I am having with adopting the POSE method of running. I think that when I run I’m possibly perceiving certain realities and should instead just focus on the psychological perception. I’ve been getting confused by trying to figure out how a thing is happening and it doesn’t fully make sense based from a biomechanical point of view.

    I seriously look forward to your future posts on these topics – I hope they are soon.

    Thanks
    Paul

  3. canute1 Says:

    Dear Paul and Simon,
    Thanks for your comments. I have posted some more thoughts on the role of perception today. The Pose Clinic provided a huge amount of very thought provoking material, so I hope to do a number of posts discussing this in the next week or two.

    The ultimate goal is to develop a description of running in which psychological reality is consistent with the biomechanical reality. I think this is possible, and will eventually lead to a method of running similar to Pose. I think that the problem with Pose is mainly that the psychological reality needs adjusting. I hope that only relatively small adjustments of the biomechanics are required.

    Canute

  4. Simon Says:

    My understanding of Gravitational Torque has been developing a bit, with help from JonasC on Posetech and this recent find: http://www-rohan.sdsu.edu/~csubiom/menu.swf
    See>> Chapter 5 – Angular Motion – Body Position and Linear Motion – Torque in running start

    It demonstrates the interplay between Gravitational Torque and the neutralising Torque produced by the muscles. The net result is that neither torque produces a rotation in the runner – this can be observer in real runners don’t seem to rotate.

    The final part of the puzzle for me is if the system is neutralised in terms of rotation, does that simply mean that the Gravitational Torque stimulates muscular activity to produce propulsion?

    Jonas had an interesting angle on it as well – his point was that the Gravitational Torque does produce movement, but the combination of it and the linear upward movement of the runner produce an effective forwards and upwards movement that is a combination of muscular effort (linear upwards) and the effects of gravity (downwards and forwards).

  5. canute1 Says:

    Dear Simon,

    Thanks for your comment and for the links.

    As you imply, leaning forwards plays a major role in accelerating at the beginning of a sprint. On account of the downwards pull of gravity acting though the centre of gravity (COG) located front of the point of support, the lean creates a tendency to rotate in a face-down direction. This destabilising tendency prompts the legs to provide a powerful thrust backwards, generating a forward-directed ground reaction. This forward directed force propels the body forwards while neutralising the gravity-driven tendency for face-down rotation; in fact it usually over-compensates producing a slight excess of rotation in the other direction that rotates the body to a more vertical orientation. The net effect is forward acceleration and re-orientation to an upright stance. Gravity provides the stimulus but the leg muscles do the work.

    When running at constant speed (as during the steady state of a long distance run) rotation is wasteful as it must be corrected within the gait cycle. During early stance when the COG is behind the point of support gravity will promote a slight backwards rotation of the upper body, but this is compensated for by a slight rotation in the opposite direction when the COG is in front of the point of support. These two opposing rotations waste energy, and can be minimised by spending a short time on stance. However, if time on stance is very short, vertical ground reaction force must be very large to provide the upwards impulse required to balance the downwards impulse arising from gravity acting continuously throughout the entire gait cycle, so in practice time on stance cannot be less than about 30-50 milliseconds, and is usually even longer.

    In the presence of wind resistance, the wind exerts a backward-directed force on the body tending to exacerbate the backwards rotation of the upper body in early stance. This excess rotation can be compensated for by a slight forward lean throughout stance. Although in this situation gravity facilitates the body’s response to wind resistance, it is actually the leg muscles that do the work to overcome wind resistance – by exerting a more powerful backwards push on the ground, thereby generating forwards ground reaction.

    In all of these situations, gravity provides a useful stimulus that facilitates the desired motion, but the work is done by the leg muscles.

    Canute

  6. pose guy Says:

    At the instant of maximum horizontal acceleration of the COM (Figure 1: solid vertical line), the horizontal and angular acceleration of the HT runner’s arms and trunk (AT) peak, whilst the angle of inclination of the COM (θ) is near vertical (Table 1). ….

    Material apparently copied without permssion removed by Canute, 12 June 2010

    • canute1 Says:

      Pose Guy, The material you had posted was taken from the article by Fletcher, Dunn and Romanov reporting a study of accelerated running presented at the 22nd ISBS conference in Limerick, Ireland, in 2009. Because you provided no evidence that you had permission to post this material I have removed the material you had copied, but I give the reference to the publication here so that readers can consult the original source.

      http://w4.ub.uni-konstanz.de/cpa/article/viewFile/3291/3092

      I have discussed the inconsistencies and peculiarities of the study on my calculations page (see side bar – and scroll down until your each entries made in 2009.

      The main problems are :

      1)There is a contradiction between the authors claim that the maximum horizontal acceleration of the COM occurs before the maximum horizontal GRF and equation 1a. Equation 1a shows that horizontal acceleration of COM is strictly proportional to horizontal GRF. Therefore, it appears that either figure 1 and the main conclusion of the paper are wrong, or equation 1a is wrong.

      2)Even if we accept that figure 1 is correct, it is illogical to conclude that gravitational torque might cause acceleration on the grounds that horizontal GRF reaches its peak value after the point of maximum acceleration of the COM while the data also show that gravitational torque reaches its maximum even later than horizontal GRF.

      3)The logic used by the authors in deriving equation 5 by substitution of equations 3 and 4 into equation 2 is peculiar.

      In my opinion, the conclusions of Fletcher, Dunn and Romanov should be treated with skepticism until these inconsistencies and peculiarities have been sorted out.

  7. pose guy Says:

    GT = gravitational torque (mg r sinθ), AT = arms and trunk, SL = swing leg, θ = angle of vector COP- COM to vertical, hor. = horizontal, vert. = vertical, vel. = velocity, acc. = acceleration, ang. = angular.
    However, at the same instant ….

    Because the material in this comment appears to have been copied without the permission of the authors or an approporiate reference, I have removed it, but give the reference to the source in my response to the comment above so that readers can consult the original source if they wish. Canute

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