[pct-l] footwear, blisters

[Yoshihiro Murakami]

Jim is right!

I have not imagined the hydration, but I found a scientific paper on
this topic. There was a linear correlation between skin hydration and
friction coefficient. And they said that the influence of moisture was
more prominent in women. See attached figure and abstract.

Diana's case might be caused by the hydration. I don't know how much
she drinks in a day. But, if she drink more water, the  friction
coefficient of her foot will change.

I drink much in a day, eat much , and I drink 1 litter in a night. So,
there is no hydration problem for me. Moisture control is needed for
me, because I use high-cut boots.

The training will prevent blister formation as Shroomer said,  but I
think if training is necessary, it also indicated the incompleteness
of footwear system.

Before my first trail of JMT, I tested various boots,  insole, and
socks, and I made some blisters, and I found  the conditions for
blister formation. Hereafter, I have never experienced blisters. I am
always controlling my moisture level of socks. I notice the small
space between socks and boots plays important role to prevent
blisters.

There are may articles on blisters. I will search and read other
papers in future, because I have enough time today.




J R Soc Interface. 2008 Nov 6;5(28):1317-28.
Influence of epidermal hydration on the friction of human skin against textiles.
Gerhardt LC, Strässle V, Lenz A, Spencer ND, Derler S.

Laboratory for Protection and Physiology, EMPA, Swiss Federal
Laboratories for Materials Testing and Research, St Gallen,
Switzerland. christian.gerhardt at empa.ch
Abstract
Friction and shear forces, as well as moisture between the human skin
and textiles are critical factors in the formation of skin injuries
such as blisters, abrasions and decubitus. This study investigated how
epidermal hydration affects the friction between skin and textiles.The
friction between the inner forearm and a hospital fabric was measured
in the natural skin condition and in different hydration states using
a force plate. Eleven males and eleven females rubbed their forearm
against the textile on the force plate using defined normal loads and
friction movements. Skin hydration and viscoelasticity were assessed
by corneometry and the suction chamber method, respectively.In each
individual, a highly positive linear correlation was found between
skin moisture and friction coefficient (COF). No correlation was
observed between moisture and elasticity, as well as between
elasticity and friction. Skin viscoelasticity was comparable for women
and men. The friction of female skin showed significantly higher
moisture sensitivity. COFs increased typically by 43% (women) and 26%
(men) when skin hydration varied between very dry and normally moist
skin. The COFs between skin and completely wet fabric were more than
twofold higher than the values for natural skin rubbed on a dry
textile surface.Increasing skin hydration seems to cause
gender-specific changes in the mechanical properties and/or surface
topography of human skin, leading to skin softening and increased real
contact area and adhesion.

2011/3/2 Scott Williams <baidarker at gmail.com>:
> All good points.  Jackass's pitch for training hard before you hit trail is
> right on.  It doesn't just toughen your muscles, it litterally toughens you
> feet.  I often had sox in shreds at different times due to misjudging how
> long they would last, and only wear one pair of light weight running sox,
> but didn't get one blister.  I think it was due to lots of training
> beforehand.  The first several weeks on trail are really ugly on people's
> feet.
>
> Shroomer
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-- 
Sincerely
--------------- --------------------------------------
Hiro    ( Yoshihiro Murakami )
Blogs http://completewalker.blogspot.com/
Photo http://picasaweb.google.co.jp/CompleteWalker/
Backpacking since about 1980 in Japan
2009 JMT, the first America.
2010 JMT, the second America.
------------------------------------------------------