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[IP] exercise....

	I can most definately understand the frustration that some of us
experience with blood sugar control / pumping & exercise.  The physiology
of exercise (even without diabetes in the picture!) is quite
remarkable..... and amazingly complex.   What we are attempting to do, not
only as diabetics, but as pumpers (especially in regards to exercise)
deserves a standing ovation & an never-ending round of applause!  If I may
share some ex phys with those of you interested - perhaps this may make
some of your exercise sessions a little smoother.  It may explain some of
the seemingly inexplainable highs(?), & perhaps even a reason for the
occasional "disappearing boluses"(?) discussed in the past on this list.  
	I myself am an exercise physiologist, aerobics instructor, recreational
runner, & MM507 Humalog user.  If I do a terrible job with this
explanation, you are welcome to email me privately & I will try again....
:-)  Forgive the length of this post, but I hope that some of you will find
this useful.
     	In the non-diabetic who begins an exercise session, the body quickly
begins use of glucose for fuel.  Please realize that this initial
increasing "uptake" or use of glucose by the body cells CANNOT begin to
happen without enough insulin around!  *This explains why, if your sugars
are high & your insulin balance incorrect (not enough) as you begin
exercise, your blood sugars MAY NOT come down.  Often times, BS levels that
begin high can go even HIGHER as exercise continues.  This actually occurs
for a number of reasons, the most influential of which is the liver.  If
your body cells cannot access glucose due to insufficient insulin levels,
the liver often "perceives" this as a "lack of sugar" & "mistakenly" dumps
more glucose from its stored sources (the process of glycogenolysis).  This
same "dumping of stored glucose" can occur from muscle tissue AND the
kidney as well & which again, in those of us with diabetes, can lead to
rising blood sugars even during exercise!   Many people often ask, "If our
bodies have such LARGE amounts of stored glucose, why is it that those of
us with diabetes can't pull from those stores to avert a low?"  The reason
is: we are low because there are high levels of insulin in the blood in
comparison to what is needed & -  *INSULIN INHIBITS that process!*
	As the exercise continues (in the non-diabetic), & blood glucose levels
begin to fall, there is a drop in circulating insulin levels & increase in
resistance.  Hormonal influences are involved, including the catecholamines
- epinephrine (adrenaline), cortisol, growth hormone.  During prolonged
exercise, & despite this drop in insulin levels, muscle tissue can continue
to use glucose for energy. Non-active tissue with these insulin level
drops, minimize their uptake - therby "saving" the glucose for active
muscles.  The hardest thing that we are trying to do, probably more so if
not dealing with Humalog, is to "match" that drop in insulin levels.  If we
attempt a pre-exercise decrease in insulin levels & it is too early or too
drastic, we may see a rise in glucose during exercise.  If our decrease is
too late, or not enough - we are all too familiar with the hypo scenario!
Hence the recommendation for 10-15grams CHO prior to & every 30min with
exercise if no immediate circulating insulin level drop is possible. 
	Amazingly, the body has MANY ways to insure glucose levels remain
adequate.... including pulling from stored sources (liver, muscle,
kidneys); utilizing a greater % of fats for energy, thereby saving some of
the glucose.  Also, amino acids (proteins) can be converted to glucose (the
process of "glyconeogenesis" - the making of new glucose).  As well as
lactic acid.  That's right - LACTIC ACID can become GLUCOSE!  Exercise
intensity plays a BIG role here!  The higher the intensity of exercise, the
greater the immediate draw for glucose (from liver & kidney & muscle)....
and the greater the production of lactic acid (the "burn") -----> remember,
lactic acid is eventually converted to glucose!  Certain modes of exercise,
particularly  "anaerobic" type - short bursts of high intensity activity
(ie.. skiing, soccer, hockey, sprinting, etc.) yield much higher lactic
acid levels post activity.   Higher lactic acid levels converted to
glucose, can easily contribute to elevated blood glucose levels -
eventually intended to be stored in the muscle tissue.  This process can go
on for HOURS after an exercise bout..... explaining the need in some cases
for the extra supplemental boluses.  And, perhaps the reason for the
"disappearing boluses" - utilized immediately in this dynamic / ongoing
process & never really affecting the blood glucose levels.  Of course,
realize too that the increased metabolism & the replenishment of the
liver/muscle/kidney stores that occur post exercise may also cause LOW
blood sugars HOURS later!  "Your Milage May Vary" so the BEST thing you can
do is to learn what is the "usual" pattern for you... and realize that a
different type, intensity, frequency, or duration of exercise may change
things for you.  (Dianne..... your idea about a higher temp basal rate for
you post unusual/intense exercise is a good one.  Worth a try - keep us
posted!)  Training will serve to decrease the amount of lactic acid
produced, and also moderate somewhat many of the effects which throw off
our BS.  Remember too that body tissue becomes much more sensitive to
insulin as you attain a fitness level - eventually exercise temp basal &
temp post basals may need readjustment.

	:)  See what I meant by "remarkable" and "amazing"??  I suppose I'll
understand if not everyone is an enthused as me.  Geeez - where's the fuel
cell professor when you need him!  <big grin!!>  ;-)

Delaine M. Wright, MS
Clinical exercise physiologist; CDE candidate (exam is SATURDAY!!) & I am
M507 Humalog since 11/97; Type 1 since 1983

Insulin-Pumpers website http://www.bizsystems.com/Diabetes/
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