ridecamp@endurance.net: carbohydrate and insulin

carbohydrate and insulin

Beth Glace (lb@nismat.org)
Mon, 24 Mar 1997 12:30:33 +0000

You pose a good question Truman. Carbohydrate is THE most proven
nutritional aid in terms of its ability to extend performance, other
than fluids, that is. Timing is crucial. Let me qualify myself and
say that this is true in humans at least. When you exercise sugar is
utilized, as well as protein and fat, to produce energy. This
carbohydrate is coming from muscle stores [glycogen] and from
blood sugar. After a high carbohydrate meal your blood sugar rises,
and in response your body produces insulin which pumps the sugar from
the blood and into the tissues where it can be used or stored. So
your sugar goes up and then begins to fall again. If you at that
point begin to exercise you've added another drain on blood sugar so
it falls rapidly and you end up with abnormally low blood sugar or
"hypoglycemia". Performance at that point drops, the individual may
be somewhat lightheaded, weak, confused and HUNGRY. The liver then
responds by pumping out more sugar into the blood and you're
normalized. Until that happens your best bet is to sit down and wait
it out or eat something.
Luckily exercise suppresses insulin production. So, for
example, even if you drink a sports drink or eat a banana or Power
Bar DURING exercise or during a short break, your body won't produce
high amounts of insulin and your sugar won't drop precipitously.
Carbohydrates are routinely given during exercise and we see no big
swings in blood sugar. What you must be careful of is eating large
amounts of sugar 1/2 hour to 1 hour prior to beginning exercise
because that allows enough time for insulin to be stimulated. Eat
a few hours prior to exercise especially if you've ever noted these
symptoms, or at least avoid large amounts of simple sugars
just prior to exercise. On another issue,although chromium used
biochemically in the handling of energy substrates there is not one
good study that shows that it improves endurance performance and
there have been DOZENS that have looked at the question in humans.
There is some preliminary evidence that it might be useful in
male body builders, but that leaves most of us out.
Hope this was helpful in planning your eating/feeding schedule
although I don't know how tolerant horses are to large doses of
simple sugars.

Beth Glace, M.S.
Sports Nutritionist
lb@nismat.org

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