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Then following that logic the same should be said about gravity?
|posers have less knee shock|
Reduced Eccentric Loading of the Knee with the Pose Running Method
ARENDSE, REGAN E.¹; NOAKES, TIMOTHY D.¹; AZEVEDO, LIANE B.¹; ROMANOV, NICHOLAS¹; SCHWELLNUS, MARTIN P.¹; FLETCHER, GRAHAM²
¹ MRC/UCT Exercise Science and Sports Medicine Research Unit, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, SOUTH AFRICA; and
² University College of the Fraser Valley, British Columbia, CANADA
Medicine & Science in Sports & Exercise: Volume 36(2) February 2004 pp 272-277
Address for correspondence: Dr. Regan E. Arendse, MB.ChB., M.Sc., MRC/UCT Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Sports Science Institute of South Africa, P. O. Box 115 Newlands 7725, South Africa; E-mail: email@example.com.
Submitted for publication May 2003.
Accepted for publication October 2003.
|posers have less knee shock|
Some exerpts (full text freely available on the internet):
... "the aims of this study were to determine whether clinical gait analysis can distinguish between midfoot and Pose running in natural heel-toe recreational runners and whether the Pose method produces biomechanical changes that might be of value in the treatment or prevention of running injuries.
Twenty (20) male and female natural heel-toe recreational runners (height: 1.62 ± 0.29 m, mass: 75.9 ± 16.6 kg, age: 33.2 ± 12.7 yr), free of physical deformity or neurological abnormality, were recruited from running clubs in the Cape Town, South Africa, region. The mean ± SD 10-km time for the group was 54.3 ± 22.5 min (11.1 km•h-1). Written informed consent was obtained from the runners before their participation in the study. Ethical approval for the study was obtained from the Research and Ethics Committee of the Faculty of Health Sciences, University of Cape Town.
Test procedure TOP
A repeated measures experimental design (within-subjects) was employed. The runners were tested in each of three running styles. Initial biomechanical data were collected for the natural heel-toe running style. The runners were then instructed in midfoot and Pose running. The data collection procedure was repeated once the runners were able to run confidently with the two novel running styles. The running trials were conducted barefoot to aid reliability of marker placement on successive test sessions and reduce the effect differences in footwear between runners.
learning the Pose method required a total instruction of 7.5 h and comprised 1.5-h sessions daily on five consecutive days. The runners were encouraged to achieve the following postural changes and actions:
1. Align the acromium, the greater trochanter, and lateral malleolus in stance
2. Lean forward in the above posture and allow the body to fall forward and thereby initiate movement
3. At initiation of movement, lift the supporting foot by flexing the knee and avoid pushing away from the supporting surface
4. At successive stance phases, contact with the midfoot (ball of foot, not the toes) and avoid contact of the heel with the supporting surface
5. Maintain a flexed knee throughout the gait cycle
Running speed. TOP
The trials in each running style were undertaken at self-selected speeds. The runners were encouraged to maintain a constant speed for all three styles. A self-selected running speed was described as a running speed that he or she could select independently, that felt comfortable, and that would be representative of the running speed they each followed in an easy training run. The running speed for each trial was determined from the displacement of the sacrum marker in the x-axis of the laboratory co-ordinate system during the processing of the biomechanical data for each trial.
Data collection. TOP
Biomechanical data were collected with a strain gauge force plate (1000 Hz) (AMTI Inc., Newton, MA) that was mounted flush with the surface of the running track and a six-camera Vicon-370 Motion Analysis system (120 Hz) (Oxford Metrics, Oxford, UK). A modified Helen Hayes marker set (22) was used to collect kinematic data.
Biomechanical data were collected from 10 barefoot running trials in each style. The 10 trials were scrutinized for errors, and five complete trials of each runner in each running style were processed. The runners were unaware of the position of the force plate. A trial was considered successful when the runner made contact exclusively with the force plate with the right foot, all retro-reflective markers were tracked for the duration of the right-foot stance phase on the force plate, and there was no alteration in running style as observed from the runner with the naked eye and on review of the animation from the collected gait analysis data.
All biomechanical variables were collected and processed to C3D files with the Workstation® program by Oxford Metric (Oxford, UK). The C3D files were further converted to DST files using the Rdata2® program by Motion Lab Systems (Baton Rouge, LA). Processing of the raw data files was accomplished with the Bodybuilder® program by Oxford Metrics and the GaitLab® program by Kiboho Publishers (Cape Town, South Africa) to calculate the temporal-distance variables, ground reaction forces, knee and ankle joint angles, and power-time curves. All data were exported as text files for analysis in Excel® (Microsoft Corporation, Redmond, WA).
Selection of biomechanical variables. TOP
The biomechanical variables selected for this study were based on selected previous studies (6,14).
Temporal-distance parameters such as stride and step length and vertical displacement of the sacrum and left heel marker during a gait cycle were determined. The average horizontal (x-axis) and vertical (z-axis) displacements of the left heel marker over five running trials were used to determine the average stride length (m) and vertical foot displacement (m), respectively. The average vertical displacement of the sacral marker in the z-axis of the global reference system over five running trials, determined the average vertical body displacement (m).
The ground reaction forces of the five trials per runner per running style were averaged and specific variables selected (5,6,12). These included: the loading rate and magnitude of the vertical impact force peak, the vertical propulsive force peak, and the horizontal braking and propulsive force peaks. Due to the inconsistent presence of the vertical impact force peak in the midfoot style previously reported (3) the loading rate and magnitude of the vertical impact force at 25 ms of stance were determined. All ground reaction forces were expressed in multiples of BW.
The knee and ankle joint angles were limited to those about the y-axis through the knee and ankle joint centers averaged for five running trials per runner per style and analyzed (22). Kinematic data included the peak knee flexion angle in swing, the peak knee extension angle, and the accompanying ankle angle immediately before and at initial contact, and the peak knee flexion and ankle dorsiflexion angles in stance phase (°).
The knee and ankle power (W•kg-1) curves during stance phase were determined with an inverse dynamics method and a three degrees of freedom joint model in GaitLab® (Kiboho Publishers, Cape Town, South Africa). The peak negative and positive knee and ankle power values were determined from the data in an Excel® (Microsoft Corporation) spreadsheet.
Negative (eccentric) and positive (concentric) work (J•kg-1) values were calculated from the trapezoidal integration of the area below the negative and positive portions of the power-time curve, respectively.
Ground reaction forces.
Heel-toe running caused greater magnitudes and loading rates of the vertical impact force at 25 ms of stance and at peak magnitude compared with midfoot and Pose running (Table 2). The vertical propulsive force was similar between the heel-toe, midfoot, and Pose running. The horizontal braking and propulsive forces were less in Pose than heel-toe and midfoot running.
Knee and ankle joint angles.
The peak knee flexion during the swing phase was the same in all three running styles (Table 3). The knee flexed more in preparation for initial foot contact in Pose compared with heel-toe and midfoot running. The ankle in terminal swing was neutral in Pose compared with a dorsiflexed and plantarflexed position in heel-toe and midfoot running, respectively. The knee and ankle geometries in terminal swing of the respective running styles were maintained at initial foot contact. The peak knee flexion in stance was greater in the heel-toe and midfoot compared with Pose running. The peak ankle dorsiflexion in stance was greater in the heel-toe than midfoot and Pose running.
Knee and ankle work and power.
The knee power absorption (Table 4) and eccentric work (Fig. 2) were less in Pose running compared with heel-toe and midfoot running. The ankle power absorption (Table 4) and eccentric work (Fig. 3) were greater in Pose compared with heel-toe and midfoot running. The knee power generation and concentric work were less in Pose compared with either heel-toe or midfoot running (Table 4). There were no differences in ankle power generation and concentric work between the running styles.
"the term "pollyanna" entered the language to describe someone who is cheerfully optimistic. It then became by extension (and contrary to the spirit of the book) a somewhat derogatory term for a naïve person who always expects people to act decently, despite strong evidence to the contrary."
Unfortunately, the antagonistic responses of many posters on this thread would imply the second definition.
Actually, this article was discussed much earlier on this thread. Try page 8. While giving evidence of reduced impact force, this is exactly what one would expect from a shorter stride and faster cadence, POSE induced or not. Actually, the data is somewhat suspect, becuase the runners were running significantly while doing POSE vs the other techniques, making it easier to show reduced impact forces.
Still, the article is most informative in the way that it disproves the POSE philosophy. The authors could not find a significant reduction in vertical propulsive force with POSE. This means there is no evidence that POSE runners were pushing off any less than using other techniques. So, it's not just an issue of whether there is NO push off with POSE, it doesn't even look like there is substantially LESS push off with POSE.
These are the bits of information you can get from reading a scientific article critically, rather than just looking at the title.
Not that this bit of info will change anything. Back to it boys!
|unclear on the question|
The "science for running technique or mechanics"? What do you mean here. Do you mean can science DESCRIBE them? Certainly. A decent exercise physiology textbook ought to suffice for this. The physics of the running gait have been well explored, documented and described for decades
|my point exactly|
Both generic, relatively untrained mid-foot striking and pose running showed similar less peak knee impact forces, compared to heel striking. I think shorter cadence just goes along with the territory of not heel striking.
Two other tidbits: Table 4 shows "knee power absorption" (W/kg-1) is half in Pose (3.7) versus generic mid-foot (7.4) or heel striking (7.0).
Second, Figure 3 states the "knee eccentric work" (in J/kg) was in the vicinity of 0.14 for Pose versus 0.45 for either mid-foot or heel striking.
I am not sure what is the most important variable for safer running with reduced impact shock for a torn meniscus ---
Table 4 versus Figure 3. However, both are more relevant to the knee, as opposed to the "vertical impact force" () in Table 2, which is measured by footstrike, which is still less in Pose (0.78) and generic mid-foot (0.87) versus heel striking (1.2).
Not necessarily true. While vertical impact force does measure the force at the foot, the peak rate of impact force generation is really the main determinant of pounding for the whole body. This initial portion of the force curve that they chose not to show in the article develops too quickly to be absorbed by the counteraction of muscle, and this impact shock is clearly transmitted up the leg.
The eccentric loading is indicative of force transmission to the knee, as more forces will produce a greater flexion of the knee to absorb those forces. However, what is actually measured is the work done by the muscles to absorb the forces rather than transmit them. For instance let's say you jump off a fence and first allow your knees to bend, then jump again from the same height and keep knees from bending. When you do not bend the knees you'll feel a lot more shock, while the eccentric loading at the knee will be less.
|my point exactly|
Important caveat, stride length was much less in Pose, although running speed was similar in all 3 methods:
2.2 m stride in generic mid-foot and heel-toe, 1.5 in Pose.
approx. 3 m/sec speed in all three methods.
So short stride is not instinctively automatic with mid-foot running.
Pose is a combination of attributes - landing with bent knee, rapid cadence, BOF landing under the center of mass. You don't have to call it "Pose" if that makes you happy, there is no patent on freedom of expression.
The fact remains, these techniques allowed the Pose runners to have MUCH LESS knee impact shock and still be able to run at a self-selected comfortable speed equal to heel-strikers or generic mid-foot strikers. That alone is worth millions in saved orthopedic surgery every year.
I didn't have to give up running after a meniscus injury but had found that it was too painful to run the old way. My
|less shocked now|
Conceptually it is also easy to see how the Pose form reduces knee impact shock for the meniscus-challenged person:
The meniscus is horseshoe shaped and converts vertical impact compression forces into a radial outward expansion. When the circumference of the horseshoe is torn it expands more than normal, exposing the round femoral condyle to the planar contact area of the tibial plateau during the knee impacts.
From this it is obvious that if you land with your knee slightly bent, the compressive force is not perpedicular to the tibial plateu due to the force vector having a partial horizontal component along with a smaller vertical component, instead of with heel striking having almost 100 percent of the force vector being in the vertical component, which totally explains why I had bone-on-bone pain after a lateral oblique meniscus tear, but no pain during pose running.
A second conceptual analysis shows that during Pose running the ankle joint acts like a hinge and the knee joint like a hinge, which absorbs energy because among all slight bending can occur upon impact and energy can be absorbed by tendons and muscles which stretch.
A third conceptual analysis, which others have pointed out, shows that a shorter stride length and faster cadence distributes the vertical impact shock of travelling a given distance into more individual footstrikes, hence there will naturally be less impact per footstrike.
Another conceptual benefit to the knee is the increased ligament and muscle strength from doing the drills -- hopping, lunges, etc. which are not quite as rigorous as actual running but which help with holding the knee capsule together during impact sports such as running.
Another conceptual benefit to the knee, which may be argued, is the lesser vertical oscillation with Pose, which was not noted in this research but has been shown in other research. This is partly due to a "soft" landing style that Pose tries to teach by using some very awkward physics explanations. But if you try if and do the drills, you will see that there is a softer landing. You can run faster barefoot without feeling the road impact this way than you might without any instructions other than to be told to simply run mid-foot striking and with a fast cadence.
I'm leaving for a business trip so I don't have time to read the 40 pages on the POSE method, but here is my personal experience. I hope it helps those who are considering the Pose.
I had experienced knee problems for years, but I was able to keep running by wearing Cho-Pat knee straps. I heard about the Pose four years ago, bought the DVD and gave it a try. My diary isn't handy, but from memory, here is the progression.
Weeks 1-3 sore calfs, hip pointers, mild plantar fasciitis in both arches. Would run the Pose for 30 sec and off 30 seconds.
Weeks 4-12 Knee pain gone. Calf, hip, and fasciitis pain gone. Still a lot slower using the Pose. Built up until I could run the POSE for 5 minutes. Still wearing the Cho-Pats.
Months 3-6 Able to run Pose for most of my running, landing on forefoot. Realized the Cho Pats were no longer needed. Tossed them. (Haven't worn them in 4 years since.)
Month 6 Ran a time trial over a known 8 mile course. Four minutes slower using the Pose method than my previous time.
Months 6-12 Experimented with different form changes. Realized that pushing off added greatly to speed. Dropped the Pose method. Read "Programmed to Run" and added those techniques to the Pose approach.
Year 1 Ran 8 mile time trial. Finally! I was as fast as before changing to forefoot strike a year ago.
Year 2 Continued to work on forefoot strike. Set Tennessee state record for 800m, M55-59
Year 2-4 Still using a forefoot strike. Knee problems have not returned.
Bottom line. Switching to a forefoot strike eliminated my knee problems. It took nearly a year to return to my former speed and I had to modify the Pose method by pushing off to do so. In my opinion, the Pose is a good starting point for runners who land hard on the heel or have knee problems. The Pose drills are useful in switching to forefoot strike. I still do them. Still, for me, the Pose approach of not pushing off just didn't work. Pushing off makes me a much faster runner.