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[pct-l] from the ultra running list - blisters

Here is a copy of a post from the ultra running mailing list about blisters.

By the time you get to Warner Springs you will probably be limping horribly
from yours, I know I was. Careful attention to electrolyte (salt) intake
may help you avoid this perril. Ultra runners probably have as good a
handle on footwear/blister/eating on the run as any group of folks your
likely to meet. I hope this post saves someone a thousand painfull steps
this spring.
-Brick
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Date:    Thu, 19 Feb 1998 12:56:44 -0800
From:    Karl King <kking@EXECPC.COM>
Subject: Re: water and blistering

The primary causes of blisters in ultra runners are two:

poor mechanical fit of shoes and socks, and/or

insufficient sodium in the body due to losses while sweating.

What happens in the latter condition is that as a runner sweats in hot
conditions or very dry conditions, sodium is lost thorugh the sweat
glands, and is deposited on the skin ( white side burns, crusty clothes
).  If additional electrolytes are not ingested to replace the losses,
the sodium concentration of the blood plasma begins to decrease. The
body will adjust kidney function, and plasma concentrtion of the hormone
aldosterone to help maintain sodium concentration.  If, however, not
enough electrolytes are taken in, the sodium level of the blood will
fall to seriously low levels.  At that point, water from the blood
plasma will be transferred into tissues external to the circulatory
system, causing hands and FEET to swell.  Those swollen tissues are less
able to support the mechanical abuse of running on them.  Friction spots
in the shoes become the site of blister formation.

Thus, Marv Skagerburg's comment that heat, not water causes blisters.
It is the heat that drives the sweat rate up, the sodium levels down,
and ultimately leads to blister formation.  Wetting the feet, the head,
the shirt or whatever helps cool the body and reduce the sweat rate.

Before I worked on my electrolyte formulation, I had the black toenails
like many ultra runners ( 6 at one time ).  Since using the electrolytes
on my hot runs, all toenails got a rest from the damage and have grown
back. Now there are 10 pink ones down there. I changed nothing else of
significance in my training and racing.

Stay cool, replace your lost electrolytes, and blisters and black
toenails will be greatly reduced or eliminated.

Karl King
kking@execpc.com

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