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Foot lengthening and shortening during gait; a useful parameter to investigate foot function?

Discussion in 'Biomechanics, Sports and Foot orthoses' started by NewsBot, Nov 2, 2013.

  1. NewsBot

    NewsBot The Admin that posts the news.


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    Foot lengthening and shortening during gait; a useful parameter to investigate foot function?
    N.M. Stolwijk, K.L.M. Koenraadt, J.W.K. Louwerens, D. Grim, J. Duysens, N.L.W. Keijsers
    Gait & Posture; Available online 30 October 2013
  2. Admin2

    Admin2 Administrator Staff Member

  3. Leopold

    Leopold Member

    Very interesting results. I wonder what this study would show if it was conducted after a 10K run or marathon.
  4. terigreen

    terigreen Active Member

    Very interesting article. I wonder if a heel lift put into the posterior shoe would help at all? Shorting the Achilles tendon can really affect the gait cycle.


    Teri Green
    Atlas Biomechanics
  5. efuller

    efuller MVP

    Foot length was calculated as the distance between the marker at the heel and the 2nd metatarsal head.
    •Foot length represents Hicks mechanism in the foot and is easy to implement in gait analysis.

    Why did they choose the 2nd and not the first? The heel to 2nd met distance might correlate well with "windlass shortening", but the windlass mechanism of Hicks would be the first met to heel distance. I wonder if they found out about the windlass mechanism during the write up after the data was gathered?
  6. Not true, Hicks wrote about all of the MTPJ's. But agreed, heel to 2nd is an "interesting" choice.
  7. efuller

    efuller MVP

    With the extra leverage of the sesamoids there would be the greatest shortening with the first ray. You are right that he did talk about the lesser mpj's. However, the slip of the plantar fascia to the fifth phalanx is much less than 100%. So, not all the MTPJ's all the time.
  8. Yep, no argument from me there. "Not all the MTPJ's all the time" is something that continues to fascinate... I'd love to see a study of the rate and magnitude of dorsiflexion motion across all the digits during gait, if we got cross sectional diameter of the met heads to go with, now that'd be interesting. I still think there could be a dichotomy, from digit to digit, on windlass impact at STJ based on STJ axial position.
  9. One of the biomechanical off-shoots of Hicks' study of the plantar fascia (i.e. central component of the plantar aponeurosis) and his "Windlass Effect", that is rarely ever mentioned, is how the plantar fascia generates a metatarsal ray plantarflexion moment even during relaxed bipedal standing, without dorsiflexion of the digits. The posteriorly directed tension force from the plantar fascia pulling on the proximal phalanges of all the digits generates a significant metatarsal ray plantarflexion moment that will tend to resist metatarsal bending with plantar forefoot loading. Ultimately, this metatarsal plantarflexion bending moment from the plantar fascia is very important in helping prevent metatarsal stress reactions/fractures during weightbearing activities.

  10. Yeah agreed, I want to say redundancy, but actually its a progressive load system that we have, fabulous engineering. So, the question becomes, why does this system fail? I got a guy coming to me at the moment who is grossly obese, he knows it, he's a bright guy... but he's relatively young and probably >20 stone- the motors on my chair won't lift him. Why hasn't he got plantar fasciitis?
  11. efuller

    efuller MVP

    Another interesting thing to think about is why this might be a useful parameter to investigate foot function. Is there power production from the midfoot? If the shortening seen in propulsion is forefoot plantar flexion on the rearfoot, then there could be some power (joint moment x joint vellocity) production from the midfoot. If there is power production, it still might not be significant relative to ankle power production.

  12. Are the plantar intrinsic contractions concentric or eccentric at this time? I think Kelly's work says concentric in which case the intrinsics have got to be adding power into the system-right?
  13. efuller

    efuller MVP

    Yes, of course. I guess my interest is in how much power they contribute. Or, how much passive elastic energy there is in the plantar fascia.
  14. I think we've got passive Joules from the fascia- sorry my lap-top down at the moment, but it is on this site somewhere. Can't be doing with that kind of search on my phone...
  15. I believe Ker et al calculated midfoot deformation energy at 17 Joules during simulated running (Ker RF, Bennett MB, Bibby SR, Kester RC, Alexander RMcN: The spring in the arch of the human foot. Nature, 325: 147-149, 1987). I would image the energy production from midfoot deformation is much less during walking.

    Attached Files:

  16. Luke Kelly et al's 2014 research on the plantar intrinsics found that the plantar intrinsics function both in the arch lengthening and arch shortening phase, in other words, they function both eccentrically and concentrically, with EMG activity being highly correlated to the vertical component of GRF (Kelly LA, Cresswell AG, Lichtwark GA: Active regulation of longitudinal arch compression and recoil during walking and running. J.R. Soc Interface. 6;12(102):20141076. 2014).

  17. efuller

    efuller MVP

    In light of Luke Kelly's work. It makes you wonder if the authors of the article at the start of the thread are aware of the principles of physics in relation to energy production and absorption. The amount of energy production would be more useful than whether or not there was foot elongation.


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