MUSCLE CATABOLISM

A

anoopbal

New Member
I was curious to know what is the time limit when the body starts eating away muscles for energy.Does it depends on intensity, duration or the availability of protein.Why doesthe body have to go for your muscles if there is still glycogen and fat left to be tapped? Is there any difference in time when protein catabolism starts for aerobic and anaerobic exercise?I know our on board nutrition will help me out (:-?
:) Anoop
 
For the slower, more fibrous protein sources, probably something like 6-8hrs max. Carbs (elevating blood glucose) would prevent protein breakdown to some extent.
 
[b said:
Quote[/b] (anoopbal @ Sep. 07 2003,1:25)]I was curious to know what is the time limit when the body starts eating away muscles for energy.Does it depends on intensity, duration or the availability of protein.Why doesthe body have to go for your muscles if there is still glycogen and fat left to be tapped? Is there any difference in time when protein catabolism starts for aerobic and anaerobic exercise?
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It depends on what hormones are released. Whever catabolic hormones are released such as epinephrine, norepinephrine, cortisol, etc. there will be catabolism of proteins, glycogen, and lipids. Some of the catabolic effect of these hormones can be modulated by insulin. So drinking an MRP during training can and does offset the catabolism that arizes from these hormones.

Also, the long term nutrative state of the body will also have an effect. If you have been starving for some time, the body will make an attempt to protect proteins from catabolism. If on the other hand you have been eating to gain bodyweight, you will have an abundance of labile proteins floating around for catabolism. The impact of this is minimal.

So, the type of exercise is less of an indicator of what kind of anabolic/catabolic environment will be induced than is the hormones which are greatly modulated by the diet.
 
Are you meaning how long before the body starts to eat itself when starved?
Because it happens relatively quickly, when the body first gets no protein/energy sources liver glycogen will be used quickly. This will stimulate ketogensis, but until the body adapts, glucose formed from protein will be larger. Once ketones are high enough, glucose production decreases, but there is still a constant supply of protien dissapearing.
The fatty acids cant really be used to make glucose (to any great extent, ie glycerol) so they dont stop muscle loss.
If the muscles are still full of glycogen, this makes no difference either as this glycogen cant get back into systemic circulation.

In a more long term look, dieting will cause a similar loss of muscle, but thats controlled by the hormonal state due to low bodyfat and lack of dietary energy.
 
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