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Quantify foot surface area

Discussion in 'Biomechanics, Sports and Foot orthoses' started by anv273, Jul 16, 2014.

  1. anv273

    anv273 Member


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    What is the total foot surface area? Is there any technique to measure it ? Also what is the area constituted by heel region,forefoot region and toes?
     
  2. Rob Kidd

    Rob Kidd Well-Known Member

    Such an odd question. Why would you want to? Surface area, that is. As to area constituted by different portions, well that could be interesting. Area, though is one question; maybe, just maybe the question you should be asking is volume. Volume speaks so much more in terns of mechanics, and the evolution of mechanics. From my work, on the evolution of tarsal elements, we are now turning to the questions of volume. Rob
     
  3. If you want to measure contact surface area you can use of Harris Heath type footprint mat and physically measure the area. The carbon paper type foot printing systems often have a grid to assist in this.

    One of my undergrads measured change in foot volume during the course of a day as his undergrad thesis. He used a bucket which he fitted with a baffle and a tap and measured the water displacement volume. Can't remember what he found.

    Either way such measures are going to be dependent on the size of the foot you are measuring- right?
     
  4. efuller

    efuller MVP

    In another thread you asked about measuring pressures. If you have a pressure measurement system and know the area of each sensel then you could just count the sensels that register a pressure and multiply by the area of the sensel.

    Eric
     
  5. Rob Kidd

    Rob Kidd Well-Known Member

    To Simon, As always we had to make do with what we have - a multivariate data set of tarsal elements of hominoids. From memory we have a data set of 19 linear interlandmark distances from the talus, 12 from the calcaneus, and 9 each from the cuboid, navicular and medial cuneiform. We have a data set from the other two cuneiforms but have yet to use them. Sample size is about 300. Now then, if, if, if. If the variables are all of the same type (ie not a mixture of angles and linear dimensions), and if one uses the coavariance matrix (as against the correlation matrix) and if one utillises a transformation to an exponent - typically the natural log, then the first principal component becomes a vector that closely approximates to size in multivariate space - that is, it seems also to closely approximate to volume. We are modelling on this at the moment to look at different volumes occupied by individual tarsal elements as a component of the whole tarsus. For years - and I mean years, note has been made of the differing proportions of the length of the tarsus as a whole as a component of the foot. Some work has been done on the 2 dimension aspect s of size of individual tarsals as a component of the whole, but not, we think, of volume. That is why we are going there.

    We predict that tarsal volume will speak much more about the evolution of the bipedal habit than more simple estimates of two dimensional size - largely since it accommodates for increase in relative mass (that is we eventually stand on two, not four), in addition to the kinetic issues of bipedalism (about which I know little).

    The first experiment was a reconstruction of body mass/height based upon the first PC of the talus, and then the calcaneus. This was undertaken by two of my third year anatomy student in the lab of the medical school at Witwatersrand in Johannesburg - they have specimens with death mass/height data. The end result was an incredibly accurate prediction of height, but not mass. But this should not be surprising - the death mass data was rat**** as they has all gone down hill before death; the height data was good. The kids had a load of fun doing it - Fiona Turnbull and Candy Woollard - perhaps because I sent them to Africa to do it! As always my "agent over there", Bernie Zipfel accommodated them for me. Its all good stuff, Rob
     
  6. Rob Kidd

    Rob Kidd Well-Known Member

    This thread seems have got lost. I post this only to "bring it back to life". Rob
     
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