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| ST |
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Jim, You are right I certainly do not speak for Pose. I am not a poser but, use aspects of the style hence my curiousity about it. I support your effort to distill and clarify the points. That is what I am looking for as well as an opportunity to learns about some things of personal interest to me that came up during this thread. My earlier responses about your questions were related to the possiblity for equivocation in the simple answers you wanted. I was hoping you could rephrase as you are doing so they were more explicit and just handling one concept at a time. JY, Thankyou for the response. Your academic background does not sway me positively or negatively. Your knowledge and ability to convey it will. I told you my background so you would understand that I can comprehend what is being discussed. And, if you think I was denegrating you I apologize. Asterix, Agreed, starting fresh is what I want. And Jim's questions were meant to bring some order to this discussion, and that is what each of you are now doing. I respect you for continueing to participate in this discussion and I meant no disrespect to you with any of my comments to Jim. To all, I hope that Jeremy finds some time to participate. And I also hope that he is treated with respect for his efforts. He is raising a family, trying to make a living and become a good athlete. I wish I had his PR's I am still too busy for the rest of the day to participate effectively but, I am following what is being posted. I am trying to better understand the flaws in my running style (which my coach said I had) because, I had the speed, endurance and interval strength but did not achieve my ultimate goal. Thanks for continueing this thread. It is however gettng long so if you start another post here what it is. |
| ST |
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Asterix, I think opinion about what Romanov is saying is the problem. I am not looking for an argument but an opportunity to understand if he is describing something that violates the laws of physics or another technique that may be useful to some. I think the article is a good starting point and want to first learn if there is anything wrong with the Physics in it. Specifically, does it violate 'accepted' laws of gravity? How does this motion really work? What role does gravity play in it? Is there a more efficient way to interact with gravity? I think with everybody participating in a friendly discussion we can look at where anyone thinks his technique (not his explanation) violates these laws and continue from there. You and Jim have been most vocal about this. So perhaps one of you could restate exactly why and we can analyze Romanov's articles with that point in mind. I would restate it but, I still don't see it (that does not mean I am right or wrong). |
| Asterix |
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Definitely agree and that is what I think JimFiore is trying to clarify. Those who profess to believe in POSE or follow POSE or be certified POSE coaches are giving varying and contradictory interpretations of what POSE (ie Dr R) is saying. JHuffman has in several threads been very clear that gravity is pulling the whole body forward. Gatorade was very specific in this thread that there is no conscious push-off in POSE. You have stated that there is a push-off and 'gravity do the work' only applies to letting the foot fall back to ground. POSE guru Jack (as cited on the forum in this thread) seems to be quite clear that gravity can pull the whole body UP a hill. Who is describing the correct POSE?
I've provided numerous cites to the POSE site that talk about 'gravity doing the work' where there is no mention of it referring to foot falls, so that suggests your interpretation is not correct POSE. Hopefully JHuffman or other certified expert can clarify. If you want to start with the specific article referenced, then let's look at the concluding statement: "So to sum it all up, there is push off in running, but it happens by itself. Muscular elasticity does it for us and we actually use our voluntary muscular efforts just to hold the body right." My interpretation is that this is saying the only push off is resulting from energy stored in the muscles due to absorbing the previous stride. Does this differ from your reading of it? Since we know that the human body is not a lossless system, we can therefore conclude that this statement is physically impossible. There MUST be continual application of additional energy to the system in order to maintain continuous motion. This, of course, isn't even touching on the 'falling forward' concept, which we can save for the next article, or the very confusing language used throughout the rest of the article that make a definitive interpretation difficult. |
| ST |
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In the full context of the article, I interpreted this sentence of summation to mean that there is push-off, it is muscular effort/energy being expended and that it is involuntary at least in the pose style. Voluntary muscular efforts are also being expended to hold the bodies form. And some gravitational energy is being stored through the elastic mechanism of muscles/tendons and also released during this pushoff. I agree with you, we are not yet discussing falling forward. Jim can you concur with this? Or do you have a different interpretation? |
| Asterix |
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What does that mean? The article quote says "Muscular elasticity does it for us", which to me says that the energy stored when the previous stride was absorbed is this energy being expended you refer to, with no conscious (or voluntary) pushing. Or are you saying that if you are running POSE, then the additional energy you must add to the system to compensate for our non-lossless system is involuntary (I guess compared to non-POSERs who voluntarily add this energy)? |
| ST |
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As to pose I think your last sentence is correct. But, lets not bring in the non-pose style at this time. I think the reference to elasticity means that it causes a reflexive reaction or that at some point the elastic property alone forces us to do the rebound. But, we are still putting in energy. |
| JY |
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If you want to answer the question about push off I suggest just looking at the data regarding loading and propulsive forces of the muscles involved in the push off. I reference the POSE research article from Med Sci Sports and Exercise posted on the POSE tech website. http://www.posetech.com/library/dr-02-04-004.html#TT2 Specifically, look first at the data in Table 2. http://www.posetech.com/library/images/msse/table2.gif At this relatively slow speed, peak vertical impact forces using the POSE technique are 0.78 times body weight, but propulsive forces are much higher (1.97 times BW) suggesting the input of significant muscular activity driving this propulsion, rather than just cashing in on stored energy and elastic response. This is answered in greater detail by the information in Table 4. http://www.posetech.com/library/images/msse/table4.gif Here you see that the knee generates 35% more power than it absorbs, indicating energy put into the system even if you got 100% return. Same story with the ankle, which generates 20% more power than it absorbs. So, with POSE, there is energy put into propulsive actions at the foot and knee. While this table shows lower concentric work done by the knee with POSE, there is no reduction in work done by the ankle with POSE. It is interesting that the evidence suggests, to me anyway, that POSE is less efficient at returning energy. Although the technique reduces loading forces at the knee, midfoot and rearfoot running results in lower power outputs than power absorption across the knee. Similarly, while there is no difference in ankle power generation across the ankle, ankle loading is higher with POSE. So, with POSE you appear to get back less than you put in with the shorter stride. I’d say that the semantics whether it is a conscious or unconscious push is irrelevant. There is a great deal of muscular activity present in the extensor activities generating propulsive force in POSE and in “normal” running. This propulsive force goes well beyond the tensile activity required to stabilize the muscle and allow for energy storage and return by the elastic component of the tissue. |
| Asterix |
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So your answer to JimFiore's 4 question posted Aug 14 at 3:19pm (near the top of page 17) would be "correct" to all? |
| Asterix |
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Am I misreading the article, or does it imply that it if you land on your forefoot, then you must be running POSE? Those tables you cite only give heel-toe, midfoot and POSE as options. I thought many people land on their forefoot without following the rest of POSE descriptions. |
| ST |
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1. Yes, but I would reword the last phrase to 'these two sources contribute to forward motion'. Because, the addition of other components has not been ruled out it would be incorrect of us to say otherwise. We will eventually discuss the presence of other components and then we may or may not add to this. But, for now, with the change in the statement a logician cannot say our conclusion does not follow from our statement. Although, this is not a proof, we are not trying to create a proof 2. Yes 3. I don't know the answer to this at this time. I am not precisely clear on what Jim means. When and how does this application occur? I think I will eventually say Yes but, I want him to clarify it for me. 4. I don't think it matters whether it is voluntary or involuntary if we are trying to understand the physics of the technique. I think whether it occurs is what matters. But, when I can answer #3 I will answer #4. Hopefully Jim can clarify #3 for me and also respond to our earlier question about our interpretation of Romanov's summary sentence. My lunch break is over. I will come back after my dinner break. |
| JimFiore |
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One of my difficulties has been the use of the term "involuntary". At times, this word has been used to imply that no energy is being added to the system. I don't care if it's reflexive or voluntary in the traditional sense, what I care about is whether or not energy is being added, and I see that you agree that energy IS being added. This squares nicely with JY's post. And let's be honest here, there's no fooling proper instrumentation. Thus, do we all agree that the push-off is comprised of two sources of energy: 1) the stored energy of the landing which is released on the next stride, and 2) some additional energy imparted by the muscles (whether or not it's a reflex action is immaterial as even a reflex causes muscle contraction and the expenditure of energy)? As Asterix has asked, it seems at least ST is in agreement with the four statements. I don't know about others. |
| ST |
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JY, Thanks for the sites. Now you have added to my homework. http://moon.ouhsc.edu/dthompso/gait/kinetics/GRFBKGND.HTM Look at this URL it has a simplified (and old) explanation of some of the points in your post. I think the diagrams are useful in understanding the tables and maybe for future discussion. |
| ST |
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Jim, I am in agreement with you but, please clarify #3 for me. |
| JimFiore |
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Arg! I accidentally deleted my post. Anyway, it seems that we can reduce item one to whether or not any additional sources (besides a muscular "push" and the release of stored energy of impact) contribute to horizontal displacement. Item two is taken care of and as we all seem interested in whether or not additional energy is involved, and not whether or not the muscle contraction is reflexive, item four is moot. (This reinforces JY's data. I have always said that there's no fooling proper instrumentation.) That leaves item three: 3) In order to return the leg back to its starting position in the stride, the inefficiency indicated in item #2 above requires the application of additional energy (i.e., "muscular energy"). What I am saying is that recoil alone is insufficient to return the leg back to its starting position so some additional energy is required. That is, recoil alone will be insufficient to return the leg to the same height and form. In keeping with the comments on item one, this additional energy would come from muscle contraction and possibly some other source. It seems to me that the muscular push has both horizontal and vertical components and thus can serve as the source (along with recoil) for both items one and three. That leaves only one thing in the big picture, and that's whether or not there is some other source for item one (horizontal displacement) and item three (vertical displacement). Are other pose advocates in agreement so far? |
| JY |
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All subjects were recruited based on being naturally heel strikers. The POSE subjects were individuals taught to run POSE by Romanov. The other subjects were taught to run in a on-POSE midfoot landing style. A good comparison between some of these same variables in heel vs mid/forefoot strikers come from articles published by Peter Cavanagh, most interestingly when he compared biomechanics of elite vs regular female runners, and then broke down the elite women into heel vs forefoot strikers. (Int. J. Sports Med; 8:107-118, 1987) |
| ST |
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I would get a lot more work done if this wasn't getting interesting...LOL Jim, jumping a head a little but still trying to clarify #3 is it something like a/ new trailing leg pushes off at some angle between vertical & horizontal also countering downward gravitational force, b/ new leading leg lifts adding to weight shift from (a) which both contribute to move CM forward, c/ then gravity and some muscular effort brings new leading leg back to ground underneath CM. |
| JimFiore |
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JY: A couple items popped out at me when reading that article. The first was that these heel strikers were given 15 minutes to learn a midfoot technique while they were given 7.5 hours of training to learn Pose. Can we assume that they were really running midfoot? Further, the diagrams of the three style are not much help. The heel and midfoot diagrams are pretty much mid-flight with the major difference being the angle of the foot/ankle, while the Pose diagram is mid support stance. In terms of methodology, I am curious about the use of a measurement at 25 millisecs. As they are measuring POWER output and absorption, the length of time is very important (power being the rate of energy expenditure). It would be interesting to see graphical depictions of these items with respect to time. A very high power peak over a short time may represent less energy than a broad curve with lower absolute peak. Also, how do we know that the curves are similar for all landing styles or that 25 msec represents equivalent points in the curve for each? I would say that this article is far from definitive, although I agree with your basic analysis. As always, the devil is in the details. |
| JY |
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Jim, Most papers wil show the raw curves off the force platform to allow for that sort of analysis. Yeah, the paper has many flaws, and I would not use it to discuss biomechanical featurs of the normal running gait. However, if you're discussing the radical new concept of POSE running, it's really the only source to show you haven't invented a new paradigm of forward motion. Good luck with the laborious slog through your four central questions. I lack the patience for that discussion and need to cut directly to the chase. |
| ST |
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Points well taken Jim. This article is looking at loads on the joints, not necessarily efficiency. The assumptin that 15 minutes is enough is debatable. However, I don't know what else they could do about the force measurements since they say they are for the full duration of the foot strike. Nonetheless, we are still jumping ahead on our discussion of pose and gravity. |
| ST |
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JY I understand where you want to go with this and I would like to know that as well. Moreover, I really want to know why my calves cramped in the last 200 meters of my races and think it was a style problem. But, we have to get through the initial analysis so we can deal with the statement about "pose concept violates the laws of gravity". I think that is what we are doing right now. Jim, Can you respond to my attempt to clarify #3 ? |