Anaerobic vs. aerobic

[BulldogMomma]

Today when I was working out at a fitness center (I only go because I need to finish my one year contract) I was reading some information on the wall regarding anaerobic and aerobic workouts. They said that when you are in your aerobic zone, you are burning fat (I'm okay with that.) but when you are in the anaerobic zone you are burning muscle. Is this true? I had always thought that you were burning glygocen, the fuel for muscle, but not necessarily the muscle itself?

Can someone clear this up for me? Thanks!

 

[Connie1]

There has to be more to it...
(bumping)

 

[Bernard]

Burning muscle - that sounds odd ? :-hmmm
BUMPING !!!!!!!!

Anna

 

[lwseymour]

I'm not sure if this will answer your question or not but check out the "Glycogen, Maribeth" thread posted by Jillybean on 10-9-02 under the Open discussion forum. Maribeth is great at explaining things and is very knowledgeable about glycogen. Again, I'm not sure if this is exactly what you need or not. Hopefully it will help.
Lisa

 

[Debra]

Glycogen is stored in the liver & muscles. But the fueling for exercise is a bit more complex than fat vs glycogen. You start out burning mostly glycogen, as you warm up & get into your aerobic zone (you need oxygen to burn fat), there's a transition to a fat/glycogen mix. Mostly fat at the low end, more glycogen at the high end. At a true anaerobic level (sprinting), you use pure glycogen.

This is a simplistic generalization. Females may be more efficient at using fat for fuel. You can also train your body to be a more efficient fat burner to conserve glycogen (base training by endurance athletes).

There are benefits to high intensity exercise, you burn a lot of calories & strengthen the cardiovascular system. There are benefits to moderate intensity exercise, using fat while still strengthening the cardiovascular system. Unless your fitness goals are very basic, you want a mix of both.

A sports nutrition book can provide a more detailed explanation. Author's I can recommend are Nancy Clark, Ellen Coleman & Ed Burke.

Hope this helps.
Debra

 

[BulldogMomma]

[font size="1" color="#FF0000"]LAST EDITED ON Nov-07-02 AT 12:54PM (Est)[/font][p]My biggest concern is that this fitness center is leading its members to believe that if they work outside their aerobic zone (into the anaerobic zone) that they are burning muscle tissue. I think that's wrong and so I plan on posting a sheet with references to show otherwise.

Thank you Debra for the author's you listed and I will also go back and look at Maribeth's glycogen thread.

Hmmm....if I keep arguing with them about their fitness information - maybe they'll boot me out and I won't have to fulfill my contract obligations and I can do Cathe all the time!!!

Margie

 

[Maribeth]

The idea that training at higher intensities than the "aerobic zone" burns muscle is erroneous--unless you become glycogen depleted. Granted, the more intensely you exercise, the quicker you become glycogen depleted, but to make an absolute statement that training above your aerobic zone burns muscle protein is just plain wrong.

In healthy people, burning protein to supply energy for exercise doesn't happen unless their supply of glycogen drops below a critical level. So, as long as you keep your glycogen stores adequately stoked, you can train as intensely as you want without worries about burning muscle.

This is yet another factoid--someone took a factual piece of information out of context and tried to make a hard and fast rule of it without providing all the vitals.
Maribeth

 

[naughtoj]

And glycogen runs out approximately when?? I know there is not an exact answer on this one, but say I eat a very high carbohydrate diet and I am planning to do IMAX.....glycogen has not run out yet, right?? But if I did IMAX twice it would?? I wonder because on Saturdays I often go for long run/hikes that can last 2 hours and don't eat anything along the way. Should I be packing gatorade or something for the 2nd hour, to spare muscle loss???

Thanks Maribeth..

Janice

 

[Maribeth]

Janice,
As you mentioned, there's no exact answer on this one because everyone is different. If your glycogen supplies are well stocked, in general they will be depleted after about 75-90 minutes of fairly intense exercise, so on your two hour hikes, I would take something to replenish along the way.
Maribeth

 

[naughtoj]

Thank you..

Janice

 

[JenniferAnn]

My understanding is that the leading promoters of the 'fat burning zone' are the manufacturers of cardio machines so it stands to reason that a gym would promote the 'fat burning zone' too since they usually have so many machines.