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Glucose measuring.

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Joined: 31 Jan 2005
Posts: 216
Location: Austin

PostPosted: Mon Feb 13, 2006 11:30 am GMT +0000    Post subject: Glucose measuring. Reply with quote


I am not a fan of consuming enormous amounts of's and stuff like that. It actually seems to hurt my performance, particularly my legs.

Is there a correlation between glucose utilization in the body for fuel and the level of lactate produced in the blood stream? If so can I assume that by using a glucose meter it's possible to get an estimate of lactate levels in the blood stream? Can an excess amount of sugar in the blood stream be detrimental to performance? I'm not looking for a "black box," but it does seem like there are many sugar types and concoctions that go way overboard and the usage rate by racers is higher than seems reasonable. Last, if I were to measure my glucose levels before and after a ride will there be a direct correlation between my starting levels and how much i burn based on my levels after a ride? One more, at the end of the day is it just the type of sugar and it's assimilation by the body?

WOW seems like I'm a bit confused.
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The Bike Doc

Joined: 08 May 2003
Posts: 1371
Location: Corpus Christi and Warda, Texas

PostPosted: Mon Feb 13, 2006 2:57 pm GMT +0000    Post subject: Reply with quote


I am going to have to restrict you to one question a month after that fusillade! Wink

The short answers to your rapid fire questions:


The long answer for the inquisitor that is in all of us:

Carbohydrates (sugars and starches) that are consumed are converted to simple sugars (one sugar molicule or two sugar molecules linked together) during digestion. The non-glucose sugars are then converted to glucose. In an individual who has a normally functioning pancreas and no insulin resistance (no diabetes) the body maintains a fairly tight range of blood sugar from 60 to 120 mg/deciliter even after meals. The body will produce glucose from either converting stored glucose in glycogen (a starch stored in the muscles and liver), from fat stores or from muscle. Your muscles and brain require glucose to operate so your body will make glucose from whatever source is available. The later two forms of glucose production occur when the glycogen stores have been depleted and the intake of carbohydrates (the primary source of glucose) is less than the ongoing metabolism of glucose.

Lactic acid production is the byproduct of anaerobic metabolism, the burning of glucose at a rate that exceeds oxygen delivery. So lactic acid production is not a byproduct of the source of the glucose utilized but of the oxygen state in which the glucose is burned. Some of your confusion regarding lactic acid and glucose may come from the fact that when glucose is produced by processing stored fats, there is a byproduct called acetoacetic acid which is an acid that increases the acid level in the body.

Measurements of pre- and post- work out glucose levels will not reflect how many calories you have burned since a normally functioning body maintains tight control of the glucose levels. A glucose meter cannot be used to indirectly measure lactic acid levels. Blood sugar levels that are too high which will occur in someone who has diabetes and will affect performance due to causing excess dehydration (too high a blood sugar acts as a diuretic). What matters at the end of the day is how many calories that you burned. When calories burned exceed calories consumed, weight goes down.

Thanks, (whew!)
Paul K. Nolan, MD
AKA: The Bike Doc
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