From: kja@cbnewsf.cb.att.com (krista.j.anderson)
Subject: Re: Help with muscles...
Organization: AT&T
Date: Thu, 10 Sep 1992 17:56:01 GMT

In article <1992Sep5.041103.23310@cc.umontreal.ca>, cholette@JSP.UMontreal.CA (Cholette Martin) writes:
> 
>  Hello, I have been training in the martial arts ( Karate ) for several years
>  now and I still have a problem with my flexibility. When I train several
>  times in a week, my muscles become stiff and sore due to overstretching I
>  guess. I stretch every time I train , before training. I would like to know
>  what is the best way to stretch to attain maximum flexibility? Is it 
>  every day, every second day?  Do I pull hard for a short while or do I
>  pull soft for a long time ? When my muscles hurt, do I stretch them or do
>  I wait for several days for the pain to dissappear before I stretch again?

I also study martial arts and looked up muscles and stretching a
while ago.  First of all, the reasoning behind stretching is that a 
longer muscle is less likely to tear than a shorter muscle.

For the maximum stretch, do stretch daily.

I'm not sure what you mean by a hard pull versus a soft pull.  It's
best to stretch the muscle as far as it will go without pain, but
not beyond.  Stretches while the muscle is contracted are equally
effective as stretches while the muscle is relaxed, but injury is
less likely if the muscle is relaxed.  For myself, at home I
stretch slowly and gradually; in class I do the usual bombastic
stretching of high kicks, etc.  The careful stretching at home is
supposed to prevent injury from less cautious stretching in class
and so far it's working.  We also stretch one another when we are
the most heated during class, and that's supposed to be the best
stretch of all.  There's a technique that's supposed to be very
effective of stretching to the limit (or having someone else
stretch you), allowing the muscle to relax in that position and
then stretching to that limit and so on.

On stiff and sore muscles, these don't sound like strained muscles
to me, although I'm certainly not a doctor.  To me, stiff and sore
muscles sounds more like a buildup of lactic acid.  I was just
reviewing cell respiration recently.  Each cell metabolizes glucose
and some other things (like proteins, fatty acids and glycogen) and
then stores energy in a molecule called adenosine triphosphate
(ATP).  It can also metabolize ATP into adenosine diphosphate
(ADP).

One molecule of glucose can start a series of complex reactions
yielding a net gain of 36 ATP molecules plus some other energy that
is immediately used or given off as heat.  Normally, 2 ATP
molecules are manufactured using anaerobic respiration and 34 are
manufactured using aerobic respiration. 

However, when exercising strenuously, not as much oxygen is
available for the energy needed for muscle contraction, so more
glucose, etc. is metabolized via the anaerobic respiration.  This
is a less clean way of getting energy, and lactic acid remains as a
residue.  While some lactic acid remains in the muscles, most of it
is sent out into the blood to the liver where later, when more
oxygen is available, it is metabolized aerobically.

We've all heard it said that we should walk or otherwise cool down
while moving after exercising.  I'm not sure of the reasoning
behind it, but can guess that either (1) non-strenuous movement
keeps the oxygen level high enough to return to normal rates of
aerobic/anaerobic cell respiration and to metabolize the lactic
acid in the muscles as well or (2) non-strenuous movement keeps the
blood flowing a bit faster in the veins toward the liver.  Unlike
arteries, veins aren't subject to pumping of the heart and depend
on 1-way valves and body movement instead.

Some others on the net have also mentioned that calcium and
potassium are needed to break down the lactic acid, so a well
balanced diet is necessary.

I get sore muscles if I do a different kind of exercise that
works weak, unfamiliar muscles and I'm sure they're not strained
but I did cool down ok, so maybe there are other reasons for
soreness.

I really wish I knew more details on these things but so far I
haven't found a satisfactory explanation of how exercise
strengthens and/or stretches muscles.

I did find out that skeletal muscles are made up of fibers composed
of thin actin filaments and thick myosin filaments.  The myosin
protein is the major structural material of the muscle thick
filaments and also acts as an enzyme to catalyze ATP to ADP
energy transfers.  Each filament has several nuclei and can be
thought of as several cells lined up (I think).  When relaxed, the
muscle fibers are about the length of both filaments; when
contracted, the thin filaments slide in between the thick
filaments, making the fiber length about equal to the length of the
thick filaments only. 

Now, I assume that the filaments can grow in length if the "cells"
of the filament undergo protein synthesis, mitosis and all that
good stuff or even if cells got larger with more protein
cytoplasm.  But why add cells rather than just replace old ones? 

Maybe if there is room to grow, then they grow, and stretching
provides the space?  Strengthening muscles, I guess, is adding
bulk, that is, more filaments to each fiber and more fibers to the
muscle.  So again, why would more cells grow rather than just
replace?  Perhaps when muscles are stimulated by repeated
contraction/relaxation, they grow more.  Maybe because some of the
myosin is used up, the "cells" are stimulated to replace it and
make enough to reach a certain plateau.  Then if you kept
exercising a lot, the plateau would never be reached and mass would
keep being added?

Another thing I used to hear is that you have to "break down" your
muscles and then rest to let them build up.  But I haven't found an
explanation of whether there is normal destruction of muscle
filaments (except that some myosin would be used up).  

A strained or pulled muscle is when some or all filaments of some
or all fibers of a bundle of muscle is torn.  It should be rested
until healed.  But to me, a strain is more of an acute, localized
pain, not general stiffness and soreness.

Question for another time:  Why does exercise improve muscle tone?