Ridecamp: Re: [RC] carbohydrate fuel

IN addition to Ray Geor's work their is an abundance of  good work coming
from Ken Hincliff's lab at OSU.  Ken was Ray's mentor at OSU.  A relatively
recent artilce out of Ken's lab, by current grad student/vet Eduard
Jose-Cunilleras, (Glycemic index of a meal fed before exercise alters
substrate use and glucose flux in exercising horses. Journal of Applied
Physiology 92: 117-128, 2002), indicates that horse insulin response is
virtaully identical to that of all mammals.  High glycemic index meals
(cracked corn) leads to very large insulin spikes, just as human athletes
incur when ingesting relatively simple sugars.  Exercise blunts, but does
not prevent this response.  The advice for smaller meals minimizes this
effect, as does the increase in fat, or the use of lower glycemic foods
such as hay.  Minimizing the insulin spikes is essential for manitaining
stable blood glucose.

Thank you also for pointing out that activity increase lactate clearance.
George Brooks from UC Berkeley has been demonstrating the dynamics of
lactate since the mid-70's, but most texts still indicate that this is is a
dead end metabolite indicative of a lack of oxygen, an understanding that
has been rendered archaic w/the use of tracers since the 70's.  Lacate is
produced and cleared constantly, even at rest.  A lacate molecule is an
energy dense 3 carbon molecule that can be converted to glucose (6
carbons), stored as glycogen in muscle and liver, and used directly as a
fuel by the myocardium (heart muscle) and very oxidative, aerobic,
slow-twitch fibers.  High lacate levels are indicative of intense exercise
and can be used to monitor intensity.  Moderate activity increases
circulation which speeds blood flow to the heart and liver and will
increase the clearance of lactate thru a variety of pathways.  Hand walking
interspersed with eating and sponging would help cooling, and lacate
clearance.



Jon K. Linderman, Ph.D., FACSM
Assistant Professor of Health and Sport Science
University of Dayton
300 College Park
Dayton, OH 45469-1210
Voice:(937) 229-4207
FAX: (937) 229-4244
jonlinderman@xxxxxxxxxxx
http://www.udayton.edu/~linderma




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