Glycogenolysis in non active muscle during exercise? What could be the reason???

[President Wilson]

Fellow colleagues,

The question is in regards to glycogenolysis, or the breakdown of glycogen to form either pyruvate or lactic acid. We of course discuss this in the following article

http://www.abcbodybuilding.com/energetic2.pdf

Glycogenolysis is critical to exercise performance, and as exercise intensity increases we become more and more reliant on this energy pathway. Further, depletion of glycogen levels leads to fatigue, and decreased performance. In fact, in individuals with Mccardles disease, who cannot break down glycogen, they only attain 50 % of the maximal values during exercise as compared to normal individuals. But this is because glycogen powers contraction in 'active muscle tissue'


Question
here is an interesting finding. While this does not occur all the time, during some prolonged exercise, such as one leg cycling, there has been doccumented as much as a 20 % decrease in muscle glycogen in the non active leg. But why is this the case?

Thats what I would like to hear your insights on!

[Hells Fire]

That is intriguing. It appears that muscular glycogen in one area is being used to fuel contraction in another.

I'm not sure if it's possible, but maybe there are transport mechanisms that can move glycogen from inactive areas to where they are needed. This is sort of how fat utilization works. For example, you can burn fat from your glutes while using an arm ergometer.

[President Wilson]

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I'm not sure if it's possible, but maybe there are transport mechanisms that can move glycogen from inactive areas to where they are needed. This is sort of how fat utilization works. For example, you can burn fat from your glutes while using an arm ergometer.

[/ QUOTE ]

Great points!

By what mechanisms do you guys think glucose is leaving the cell then, since glucose itself once phosphorylated is stuck (if it remains as glucose that is!)

[dashforce]

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there has been doccumented as much as a 20 % decrease in muscle glycogen in the non active leg

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Is there any indication of a decrease of muscle glycogen in other areas (like the arms, abs, back, etc)?

[President Wilson]

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there has been doccumented as much as a 20 % decrease in muscle glycogen in the non active leg

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Is there any indication of a decrease of muscle glycogen in other areas (like the arms, abs, back, etc)?

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Yes,

the studies I have seen indicate that when training the legs, the forearm had depletion of glycogen, though this did not occur in the reverse situation.

[kokokolo]

is this one of those where after we try our best, the teacher just tells us the answer ?

[Venom]

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is this one of those where after we try our best, the etacher just tells us the answer ?

[/ QUOTE ]

President will definitely be able to add a lot to this. But there are several unanswered questions in practically any area of research. So the more ideas and contributions (especially for future research), the better.

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Is there any indication of a decrease of muscle glycogen in other areas (like the arms, abs, back, etc)?



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This is exactly what I was going to ask!

The first thing that comes to mind is a whole body increase in glycolysis and lypolysis, due to increased catabolic hormones such as catecholamines.

[dashforce]

That's exactly what I was thinking -- perhaps the "reverse is not true" (forearm training doesn't produce the same) is because it just doesn't register as a sufficiently significant stressor to really get those hormones flowin'.

Although maybe not related, this post definitely got me to revisit the "transfer of strength in the arms" post (training one arm = stronger opposite arm).