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[pct-l] from the ultra running list

The following post came from the ultrarunning mailing list and concersn
swelling (edema) in the hands and feet. This can cause blisters/black
toenails as well as discomfort in the hands. Through hiking is similar to
ultrarunning in many ways. For information on the ultra mailing lists, see
http://www.he.net/~mmahoney/ultra/lists.htm

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Date:    Thu, 16 Apr 1998 00:09:13 -0700
From:    Karl King <kking@EXECPC.COM>
Subject: Edema/simple answers?

If you dig into the physiology and biochemistry of the human body, you
quickly find that it is wonderful and complex system that often has
multiple modes for adaptation.

The swelling of hands and feet is likely to have multiple causes
depending on the circumstances.  Let's consider just a few.  Others may
find additional ones.

Electrolytes
The concentration of sodium in the blood must stay within certain
limits.

If more sodium is lost through sweating than is being ingested, plasma
sodium levels can fall to fatal levels.  Before that happens, the
regulatory mechanisms in the body will try to maintain viable levels.
If sodium is too low, water must be "lost" through urination and/or
transfer to extracellular spaces.  Water shifting into those spaces
makes hands and feet swell.  Swollen feet are much more prone to "black
toenails".  I used to get a few damaged toenails in each ultra.  Since
taking electrolytes, that has ceased and I now have 10 pink nails.  We
can see the swollen hands, but we are less aware of the swollen feet
because they hidden in our shoes.

Jay Hodde ( an "academic" with *real* ultra experience ) posted recently
on how excess sodium will be transferred, with water, to extracellular
spaces, also swelling those tissues.

Too little sodium, or too much sodium should both be avoided.  Too much
degrades performance, but too little is more dangerous in that it can be
fatal.

Pressure drop
As Randi and Dana pointed out, climbing in altitude can cause swelling
by means of physical pressure drop.  It wouldn't seem that the drop
would be enough to trigger that, but I got first hand experience in that
last Summer while on training runs at Vail, Aspen and Leadville.  A
climb of 400 to 2000' would regulary trigger urination and slight
swelling.  Descending reversed the swelling and increased my thirst to
make up the lost water.

Mechanical abuse
Last Summer there were questions about foot and ankle swelling after
running the Vermont 100.  My experience after finishing Vermont was that
when I took my shoes off, I couldn't believe I was looking at my own
feet and ankles.  They didn't hurt, they were just swollen by an
alarming amount.  It took days for the swelling to go down.  This, by
the way, was before I started regular use of electrolytes during a run.
My sodium intake at Vermont was insufficient, but not dangerously so.
Jay Hodde posted what I think is the most plausible explanation, that
the physical abuse from the roads led to increased capillary
permeability.  IE, the walls of the blood vessels allowed more water to
"leak" into the extracellular spaces. Jay's post can be read on Kevin
Sayers' website.  Also saved there is a post from Suzi T about wrapping

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