Exercise and Blood Sugar
When you exercise does that increase
your blood sugar levels or decrease them?
Great question - and the answer is both, actually. The
situation is basically like this . . .
When you exercise, or even think about going to exercise
(mentally get ready) your body responds be increasing your
blood glucose (sugar) levels. This occurs through so
called "glucose-sparing pathways" (gluconeogenesis,
glycogensis, etc) that occur in the liver and other tissues
in the body (your liver is the main organ that stores and
Okay, so there you are getting ready to work out, or
starting to do so, and your body has released all these
hormones to cause your liver to increase your blood glucose
levels - now what?
Basically, your muscles use glucose as a primary fuel
source during exercise - so your blood sugar levels are
maintained at a higher level while you are working out
until you use up all the stores your liver had available.
It is at this point that your body starts burning fats and
other fuel sources to keep it going.
That is the cut and dry answer to your question - although
really you could sit down and take entire biochemistry
courses on carbohydrate metabolism and still not get
through it all!!
I hope that helps
Susannah Sample, BSBME
Department of Surgical Sciences
School of Veterinary Medicine
University of Wisconsin, Madison
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Update: June 2012