[pct-l] footwear weight, was UL danger

[giniajim]

For what its worth, the most efficient speed on these charts seems to be about 80 meters per minute which is about 3 miles per hour.  I wonder if that's an efficient gait that developed over millions of years of human evolution?

  ----- Original Message ----- 
  From: Len Glassner 
  To: Yoshihiro Murakami 
  Cc: pct-l at backcountry.net 
  Sent: Wednesday, May 12, 2010 4:04 PM
  Subject: Re: [pct-l] footwear weight, was UL danger


  On Tue, May 11, 2010 at 8:49 PM, Yoshihiro Murakami
  <completewalker at gmail.com> wrote:
  >
  > But, it will be OK to send copy to a few friends for the study of ergonomics.
  > You can download PDF file from
  >
  > http://psycho01.edu.u-toyama.ac.jp/Abe(2004).pdf
  >
  Yoshihiro, IMO your interpretation (spelled out in an earlier post) of
  figure 4 is not correct. You have to look at how Cw is computed.  The
  Cw values include the added mass of the ankle weights as part of the
  calculation.  Let's say I walk 80m/min with no additional weight, and
  the Cw value is 'x'.  Next, I walk with 1.5kg attached to each ankle.
  My VO2 goes up in proportion to the added weight, so the computed Cw
  value remains the same - 'x'. The body mass of the test subjects was
  62kg, 1.5 kg is 2.4% of that, so in reality oxygen consumption
  increased by 2.4% when 1.5kg were added.  I think.

  Further confirmation of my interpretation is provided by figure 2,
  which shows efficiency for loads carried on the back.  If your view
  was correct, then the figures that all plot lower than the control (no
  load) figures would indicate that it is easier to carry weight on your
  back, than to walk unencumbered.

  OTOH, if you're right, I would point out that the subjects wore
  'light-weight training shoes'.  Those shoes were not part of the ankle
  weight, so the free lunch for carrying weight on the feet would be
  even higher, by perhaps .7kg or so.

  How all this relates to 'one pound of weight on the foot equals five
  (or whatever) pounds on the back', I dunno.  A two-minute search
  turned up this study:

  http://www.informaworld.com/smpp/content~content=a779402900&db=all

  I looked at Ryan Jordan's book 'Lightweight Backpacking and Camping'
  under 'Footwear'.  A 1906 book, 1953 Everest expedition, and the
  chapter author's own experience are cited with regard to the impact of
  footwear weight.  I also looked at 'The Complete Walker IV' and it has
  the same 1906 and 1953 references.

  -- 
  'Quotation is a serviceable substitute for wit' - Oscar Wilde

  Sent from home by my carrier pigeon.