Glycogen stores

what causes muscle glycogen stores to be depleted more w/o too much catabolism? low intensity cardio (65-70% MHR) for 30 mins or low weight high rep weight lifting for 30 mins?

Aerobic exercise is fuelled by glucose in the blood rather than glycogen in the muscles. When this glucose level is low in the blood, the liver will secrete glucagon (a hormone) which will cause glycogen stored in the liver to be broken down into glucose again by the process of glycogenolysis. The glucose will flow into the blood for aerobic use.

High rep weight training will expend glycogen stores in the muscles, not glucose. This is because glucose cannot be stored within body cells because it is soluble among many other reasons, whereas glycogen is insoluble like starch. During exercise that relies heavily on the muscles, glycogen in the muscle is hydrolysed (broken down by water) to glucose. The glucose is then used in respiration.

Therefore the answer to your question is, glycogen stores will be lower after the weight training because stores will have been depleted in the muscle. After the low intensity cardio, glucose levels will be lower in the blood and glycogen stores will be lower in the liver. However, the glycogen stores in the muscle will remain untouched.

Hope that answers your q.

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Originally Posted by Flexor

Aerobic exercise is fuelled by glucose in the blood rather than glycogen in the muscles. When this glucose level is low in the blood, the liver will secrete glucagon (a hormone) which will cause glycogen stored in the liver to be broken down into glucose again by the process of glycogenolysis. The glucose will flow into the blood for aerobic use.

High rep weight training will expend glycogen stores in the muscles, not glucose. This is because glucose cannot be stored within body cells because it is soluble among many other reasons, whereas glycogen is insoluble like starch. During exercise that relies heavily on the muscles, glycogen in the muscle is hydrolysed (broken down by water) to glucose. The glucose is then used in respiration.

Therefore the answer to your question is, glycogen stores will be lower after the weight training because stores will have been depleted in the muscle. After the low intensity cardio, glucose levels will be lower in the blood and glycogen stores will be lower in the liver. However, the glycogen stores in the muscle will remain untouched.

Hope that answers your q.

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Good explaination. Best way to lower glycogen stores is to carb deplete or high rep weight training as lifting that exceeds the 30 sec mark becomes mianly relient on muscle glycogen. Low intensity cardio will not utilize glycogen as Flexor mentioned. You will burn through blood sugar, which is estimated to take apporx 20min and then you will tap into fat as long as oxygen is present. Whenever in an oxygen debt glycogen will be your primary fuel.

wow! thats awesome! thanks guys...how do you know all this stuff?

BTW giantz...I might have a $100 riding on the giants, depending on the point spread for this weekends game. they better not dissapoint! ;)

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Originally Posted by xtinaunasty

wow! thats awesome! thanks guys...how do you know all this stuff?

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Studying, intelligence, desire to learn.

That type of thing :)

Quote:

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Originally Posted by xtinaunasty

wow! thats awesome! thanks guys...how do you know all this stuff?

BTW giantz...I might have a $100 riding on the giants, depending on the point spread for this weekends game. they better not dissapoint! ;)

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They are 2.5 point Favs. I dunno Christina, I wouldn't bet my money on them, I hate to say it but the Panthers are nasty and we're banged up.

2.5 points?? thats it? hmmm...yeah im not so sure anymore either. i dunno, i have faith