Is there a rapid, practical test to assess overall muscle glycogen amounts and percentage of 'fullness' (versus depletion)?
Is a good question. I think the first part of exercise, the muscles cells use the glycogen of cells of muscle used and when this glycogen is deplete, use hepatic glycogen and other forms to obtain energy.
The second question, if other mates know a test will be interestin for me, too.
Thanks for participating! I may repost this question to a slightly wider audience, in the hopes of generating more interest.
Assessment of muscle glycogen can only be accurately determined via a muscle biopsy or by natural abundance 13C magnetic resonance spectroscopy. So to answer your question of "Is there a rapid, practical test to assess overall muscle glycogen amounts and percentage of 'fullness' (versus depletion)?" Not really no.
Muscles cannot exchange the glycgoen stores they have between one another. they lack an enzyme called glucose 6-phosphatase meaning once the glycogen is stored in the muscle, it cannot be removed again until it is used. The liver, however, does have this enzyme hence its key regulatory role in blood glucose maintenance.
The main question that comes back is why you would want to assess glycogen levels in the first place?
Knowing that individual muscles store glycogen and that glycogen stores don't "even out" through the body during activities such as glycogen-depleting resistance exercise is really interesting.
Why I'm asking: to have a better understanding of the variables that contribute to how we can make training and nutrition determinations for resistance-training athletes.
For a simple example, many talk of changed nutrition needs for athletes who are in a 'glycogen-depleted' state. Depending on the approach being used, more simple carbohydrates may be added at that time.
thoughts?
And thanks for your reply!
The only way to measure muscle glycogen content is by biopsy or magnetic resonance spectroscopy. There has been suggestion that glycogen may be transported via a lactate shuttle from non-exercising limb to an exercising limb (for example, see Bonen etal '91).
The previous answers are spot on. The only thing I can think of that may be rapid and practical (relatively speaking) is some sort of all-out anaerobic test and the analysis of work or oxygen debt. This article (http://www.ncbi.nlm.nih.gov/pubmed/8282617) may conjure some ideas.
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