[pct-l] pct-l] footwear weight, was UL danger

[Yoshihiro Murakami]

There were a modulator variable --- Walking speed. The importance of
boots weight depend on the walking speed. This might be the crucial
points to interpret the footwear experiments.

Legg & Mahanty(1986) studied only five subjects on three conditions:
 No load / boots(1.5Kg)   VO2 resulted 0.85
 Backpack(24.9Kg)/ boots(1.5Kg)   VO2 resulted 1.17
 Backpack(24.9Kg) boots(5.1Kg) VO2 resulted 1.57
Their conclusion that each 100g increase in weight of footwear results
0.7-1.0% increase in VO2 is based on this data. So, the caution needed
to interpret their conclusion. Today, no one wear such a heavy boots.

Holewijin et al.( 1992) carried out their experiments and summed  up
the previous studies. I read this paper yesterday (I cannot do my work
!), and realized that no complicated situation exists.
  Their conclusion is: "the mass of footwear resulted in an increase
in the expenditure which was a factor 1.9-4.7 times greater than that
of a kilogram of body mass, depending on sex and walking speed".
  They  plotted the 6 experiments ( including 5 previous experiments )
by the walking speed and the oxygen uptake. The range of walking speed
was 4 to 12 Km/hr. The regression line was calculated. They said
"walking velocity affects dramatically the VO2 per kilogram shoe
mass".  To put it briefly, the importance of footwear weight is 1.9 at
4 km/hr, but 4.7 at 12Km/hr.

The economical walking speed must be between 4 and 5 Km/hr, based on
the previous experiments. So, when the footwear experiments, carried
out  in this economical speed range, resulted sometimes no statistical
difference of VO2 , because the importance of footwear is minimum.

Abe et al.(2008) also indicated the economical speed is 3.6-4.8Km/hr,
based their load carriage experiments.

My conclusion is:
The footwear weight is important for the speed hiker ( 6 Km/hr or more ).
The footwear weight in not so important as previously expected for
adequate walking speed ( 3.6 - 4.8 Km/hr )
More slower walking speed resulted more energy consumption.













2010/5/14  <abiegen at cox.net>:
>
>>From: "giniajim" <jplynch at crosslink.net>
> Subject: Re: [pct-l] footwear weight, was UL danger
> To: "Len Glassner" <len5742 at gmail.com>, "Yoshihiro Murakami"
>        <completewalker at gmail.com>
> Cc: pct-l at backcountry.net
> Message-ID: <9493944E07CB4D8A85C26FB2B88C2FAD at HomePC>
> Content-Type: text/plain;       charset="iso-8859-1"
>
> 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?
>
> My guess is yes. I remember reading another study a few years back that was done showing that walking/hiking faster uses less energy. The optimum speed was around 3 miles an hour. I picked up my pace because of that. So as you pass slower hikers who are complaining that the hike is so hard - keep in mind that for them, yes it is hard - at the pace they are going. If you can gently let them know that it would be easier if they were going faster, it might help them. Of course, everyone has different length legs, fitness levels, etc. so emphasize the gentle part. It is also another reason to go light. Heavy loads slow you down and by slowing down you are working hard plus you are working harder carrying the load - a double hit on your energy level.
>
> An interesting aside OT - another study looked at students who were good at math skills and those that found math "hard." Looking at oxygen usage, the ones that found math hard were using more oxygen than those that found it easy. So again, when your kids say they hate math because it is too hard - it's true. It is too hard for them because their brains are consuming more energy and working harder.
>
> TrailHacker
>
>
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-- 
Sincerely
--------------- --------------------------------------
Hiro    ( Yoshihiro Murakami )
HP:http://psycho01.edu.u-toyama.ac.jp
http://picasaweb.google.co.jp/CompleteWalker/
Backpacking for 30 years in Japan
2009 JMT, the first America.
------------------------------------------------------