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Myths of Running: Forefoot, Barefoot and Otherwise

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kevin Kirby, Dec 16, 2012.


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    The New York Times published a very nice review article, including the latest research on running footstrike and running economy, that basically debunks all the "running barefoot-running on forefoot/midfoot is best" propaganda that has been spouted about over the last few years by the Church of Barefoot Running. It's nice to finally see some common sense in the popular media these days regarding this topic.

    Running: Forefoot, Barefoot and Otherwise
     
  2. Craig Payne

    Craig Payne Moderator

    Articles:
    8
  3. Bill Bird

    Bill Bird Active Member

    It would be interesting to do a short study of what the cushion equivalent of the average terrain in East Africa is. Assuming that is where we evolved our present day biomechanics over the last 3 million years or so. Soft sandy ground could well be about the same as 10mm of cushion. Just a thought.
     
  4. Charles Tully

    Charles Tully Welcome New Poster

    I am not a runner (I am an Alexander teacher and its far too much like hard work), I wear solid shoes most of the time and use my legs to absorb any impact (which there should not be) to move quietly about. When I convinced myself to give running a go I went out and got myself some 'running' shoes. I found out combined with the natural shock obsorbsion of my legs I did not go anywhere and the only way to gain propulsion was to stiffen my legs. It can be seen with the constant use of bouncy shoes the habit of stiff legs is quickly learned.
    Although I do not agree with the trendy marketing of barefoot running I think the ideas are worth exploring. I teach people to walk in a more gentle way and silent foot steps are a bonus, this lessens a lot of aches and pains.
     
  5. bruk

    bruk Member

    The only thing this article speaks to is running economy. Is it really accurate and objective to make a statement that applies to running in general based on one parameter?

    There is no mention of injury or impact. There is good research by Brian Heiderscheit that correlates Impact to injury, cadence to impact, and footstrike to impact.

    I don't see how this article "debunks all the "running barefoot-running on forefoot/midfoot is best" propaganda that has been spouted about over the last few years by the Church of Barefoot Running." Even the issue of running economy is debatable through research.

    I think Bill's statement is a good response to this article:
    "It would be interesting to do a short study of what the cushion equivalent of the average terrain in East Africa is. Assuming that is where we evolved our present day biomechanics over the last 3 million years or so. Soft sandy ground could well be about the same as 10mm of cushion. Just a thought."

    I suspect that there is no one absolutely correct form of running, but rather that running economy, joint stiffness, impact attenuation, footwear strategy, terrain, speed, ability, training history and intent are all interconnected aspects of running that make "ideal" running technique a moving target.
    I would guess that to be a good runner you would need to develop a variety of biomechanical skills like a pitcher: if you only throw fastballs your injury rate goes up, and you will be less succesful, versus learning to throw sliders, changeups and curveballs as well.
    I would hazard a guess that runners should be trained in, and develop, a variety of biomechanical strategies that best accommodate the blend of variables I mentioned above, at any given moment during a run.

    I could be wrong, I frequently am.
    __________________
     
  6. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    There is NO good research that correlates impact to injury. That is one of the myths. There is one published study that links impacts to tibial stress fractures and one still unpublished study from Irene McClay that links impacts to injury. That is all.

    Heiderscheit's research has looked at a number of strategies to reduce impact loading, NOT at impact loading actually being related to injury.
     
  7. bruk

    bruk Member



    I stand corrected.

    Not to be difficult, but would anyone here be willing to say that impact never has, never will have any relationship to injury?

    I do like Kirby's quote "It's nice to finally see some common sense in the popular media these days regarding this topic."

    How would we apply common sense to how impact affects muskuloskeletal tissues in a highly repetitive physical activity?

    I also like the quote that "common sense is neither."

    I love reading research, and I can't wait until it better connects humans in the real world to the numbers that I read about.
     
  8. efuller

    efuller MVP

    Probably not. The impact in human running is modulated by the CNS and is therefore a behavior more than a purely mechanical phenomena. There are studies that show that people adapt their running to surface hardness in 1 or 2 strides. If you run in such a way that the impact hurts, you modify your running, or stop running, so that it stops hurting.

    Eric
     
  9. bruk

    bruk Member

    My understanding of the research that I'm aware of is that impact predicts changes in biomechanical patterns, presumably to decrease pain or, as some surmise, to attenuate shock to more tolerable level.
    However, as Craig pointed out, there does not seem to be real evidence that impact actually produces injury.
    I would also venture to add, Eric, to your post, that running is more than not, an unconscious behavior modulated by the CNS. The motor pattern is Upper Motor Neuron, while the immediate adaptive responses to somatosensory input is Lower Motor Neuron. Our ability to attenuate changes in external stimulus, at least those that are more subtle than something pain-inducing, are likely reflexive through the spinal cord loop, and based in large part by initial sensory input from footstrike.
    So then my question is, "how does a runner's footwear strategy affect this sensory input, " and the follow up question; "if there is a difference in sensory input ( which I seem to recall good evidence that there is), how does that affect our CNS' reflexive, adaptive response, and is it an accurate response?"
     
  10. Craig Payne

    Craig Payne Moderator

    Articles:
    8
    Its doesn't mean impacts are not a problem, its just the strength of evidence supporting the link is just not there. You would kind of think it was, given the strength of the claims on how evil high impacts are.

    See the threads we have had on impacts.
     
  11. efuller

    efuller MVP

    I agree that the response is unconscious as the runner is not really aware of exactly what they are doing. However, at some level, there is a choice that the runner makes on how they run. For example, one of the modifications to different surfaces that is made is the knee angle at contact. I doubt that this is a lower motor neuron response. Yes, there will be reflexes that are lower motor neuron responses that will modulate impact as well.

    Eric
     
  12. Benno Nigg has some prospective research showing decreased injury rate in runners with greater impact forces. Therefore, impact forces can't be assumed to be the major causative factor in the majority of running injuries, though they are certainly responsible for some running injuries. Remember, impact forces also increase bone density over time. Thus, the therapeutic goal should be to optimize impact forces for each individual during running, not always just reduce them.
     
  13. Dana Roueche

    Dana Roueche Well-Known Member

    I enjoyed the article and find it consistent with my own experience. The first thought that came to mind was related to what Bill Bird wrote. The 10 mm of cushioning was combined with the hard surface of the treadmill. I assume it implies that you can translate that into shoes with 10 mm of cushioning used while running on pavement. If you run on soft, natural trails consisting of dirt, sand and gravel, would something less than 10 mm of cushioning be best? I certainly find that the surfaces I run on are soft enough that little to no cushioning at all results in the least fatigue over the course of my runs.

    I don't care how people want to classify certain shoes, if you run on natural, soft surfaces, all you really need is something to protect the skin on the bottoms of your feet....... I can think of the perfect shoe for that.

    Dana
     
  14. davsur08

    davsur08 Active Member

    Dr. Kirby,
    If impact forces cannot be assumed as the major causative factor than how does tissue stress occur? Mueller et al. (2008) (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2579907/) reported high stress (peak plantar pressure, plantar pressure gradient, shear stress) in areas under the foot where skin breakdown is most likely to occur. If impact forces are external forces (subject to surface hardness) than stress is the an internal force within a body in response to the external force right? If the resultant stress is beyond the the zone of optimal function of a particular tissue, causes injury. Dr. Kirby you have taught me to think this way.
     

    Attached Files:

  15. David:

    I was waiting for someone to comment on this posting since I purposely meant it to be provocative. Thanks for taking notice.

    You are correct that ground reaction force (GRF), which is an external force, acting on the plantar foot will result in forces (e.g. compression, tension and shearing forces) and moments (rotational forces) acting within the body to resist the potentially deforming effects of the externally applied GRF. In addition, GRF, acting externally on the foot, will also cause external moments acting across the joints of the foot and lower extremity.

    GRF, for running, has traditionally been measured by force plates and has two types of peaks on the force vs time curve (see illustration below). Originally, for rearfoot striking runners, the initial high frequency GRF peak was called the impact peak and the second lower frequency GRF peak was called the propulsive peak. Then, in the 1980s, Benno Nigg and coworkers proposed calling the two peaks the passive peak and the active peak to better describe the finite ability of the central nervous system's afferent-efferent neural response time relative to the duration of these GRFs.

    Therefore, when I say "impact forces" and when most biomechanists say "impact forces", we are most of the time very specifically referring to the initial high frequency curve of the GRF vs time curve that is only seen in rearfoot striking runners since this curve corresponds to the time when the heel of the foot/shoe is first contacting the ground. As a result, when I said:
    ......I specifically meant the impact force curve of the GRF vs time curve in heel striking runners.

    If you read enough biomechanics research, you will also note that the term "impact forces" is generally reserved for this initial high frequency peak of GRF. As a result, this "impact force" seen only in rearfoot striking runners does not necessarily correlate with the magnitudes of internal forces and internal moments which are thought to cause the vast majority of running injuries in all runners (see Benno Nigg's data below showing inverse correlation between impact forces, loading rates and injury frequency).

    Hope this helps clarify my thoughts on this subject and helps you to be more critical when you read these papers since the term "impact force" is definitely not synonomous with "ground reaction force" within the international biomechanics community.:drinks
     
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