Does not the shoe absorb some impact?
  • In the last years, multiple gait studies have appeared  where it seems that mid foot/forefoot strike reduces the initial impact against the ground when running. Accordinh to this, if you land on your midfoot or forefoot, even barefooted, you will reduce therefore the forces that come to your muscles and knees during the training in comparison with a runner who lands on his or her heel

    My doubts are the following ones: does not the midsole of the slipper reduce the quantity of energy that rises up to muscles and kneesWhere do they measure up these forces about which we have spoken: in the treadmile or in the legs of the athlete?

    It seems logical to me that a piece of rubber will absorb part of the energy created in the initial contact; that is probably the reason why we tend to be careless of our stride when running shod, as we trust the shoes will make the work for us. C. McDougall wrotte about it in his famous book,

    My take is that we are careless because shoes absorb some impact...and we assume less force should be coming up to our lower legs. Unfortunatelly, this will probably encourage you to land on a unnatural way and heel strike.

    Nevertheleess, if you use a rubber midsole in zero drop (or less han 4mm) shoe, you will reduce the impact on your knees because you will still land midfoot or forefoot, at least if you manage to increase your gait up to 180 steps and are able to land smoothly.

    In other words: if you use a zero drop senaker with some rubber midsole, you wil loose feedback of the terrain and your nerves on the feet will have less info...but forces coming up to your lower legs will decrease. 



    ...or maybe I am missing somethig here :D



  • Fernando,

    Great question - I've written on this very topic several times, including in this article from Lower Extremity Review: http://lowerextremityreview.com/article/foot-strike-in-runners-influence-on-injury-risk.

    Basically, yes, a cushioned shoe sole will reduce the loading rate of impact. If you are a heel striker it makes perfect sense to wear a cushioned shoe because the shoe will reduce the impact rate dramatically compared to a barefoot heel strike. It is not atypical in a barefoot forefoot strike to see no vertical impact peak at all, though sometimes one will be present (in part probably related to overstriding). The point though is that a similar impact in a shod heel strike versus a barefoot forefoot strike occurs with the leg joints oriented differently (most obviously the ankle), so the impact is applied to the body in different ways in the two conditions. Studies typically measure impact at the foot-ground interface via a force plate and not at the level of individual joints because the latter would be two invasive (e.g., implanting sensors into joint capsules). Thus, for the latter we rely on modeling studies that may or may not be 100% accurate.

    The question of whether adding cushion to a forefoot strike is beneficial is one that I am not sure I have the answer to off the top of my head. I think it has been looked at a few times, but would need to search for the relevant papers. But, I will say that the moment you add a shoe to the foot it changes the sensory information as you point out, and I have video of many runners in minimal, zero drop shoes who continue to heel strike at a much higher frequency than barefoot runners. So the benefits of cushioning in a zero drop shoe may be tied to whether or not your form adapts in that shoe.

    Complicated, but fun to think about!

    Pete
    Helping runners run | Main Site: www.runblogger.com | Personal Site: www.theblogologist.com
  • I could´t pass to see your answer before. Thanks, anyway.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />


    I think the problem with a zero drop cushioned shoe maybe the fact that it encourages you to over stride and, for some people, as you said, it even causes heel strike, as a normal cushioned one. It is not my case, but for many it must be as you mentioned.


    But still I think it may reduce the forces that “climb” your lower leg.


    Trouble is that a lot of people cannot possibly believe that running in shoes with a very thin midsole is helpful and could reduce impact forces by retraining stride and leading you to use your calf muscles as natural cushioning. Intuition tells them that running over a huge piece of rubber protects them against the asphalt; but, they forget the fact that this protection is causing you other imbalances, like ovestriding and heel strike. It is the kind of stuff about which your mate, Jay Dicharry, talks in this article of the Mini and the Tahoe.


    Sometimes I talk about it forums and is kind of preaching in the desert: people just cannot believe, and they fear the consecuences of running in a very light and simple shoe with a thin midsole. It is somehow counterintuitive.


     

  • Yes, it's a difficult concept to get across, I still get asked all the time if it hurts to run in minimal shoes. People don't give their body enough credit! Cushioning can be good, but it can also cause problems. It's a matter of maximizing the good and minimizing the bad for each individual.
    Helping runners run | Main Site: www.runblogger.com | Personal Site: www.theblogologist.com

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