aerobic vs anaerobic

[ReverseLunge]

Does anyone know what the difference is? Which burns more calories and why?

[Strytllr]

aerobic and anaerobic what?!?

I can tell you the difference, but not in relation to anything in particular.

Aerobic means that it requires oxygen.

Anaerobic means that it requires the absense of oxygen.

*shrug*

[Army Fencer]

Originally posted by ReverseLunge
Does anyone know what the difference is? Which burns more calories and why?

Anaerobic activity is physical activity that does not require oxygen. Weight lifting (high weight, low repetitions) commonly falls in this catagory.

Aerobic activity is physical activity that does require oxygen. Marathon running is an example.

Now for the why (and a little biochemistry):

You burn far more calories in aerobic activity than in anaerobic activity. In aerobic activity, you recruit your mitochondria (your cellular power plants) to break down glucose, pyruvate, and acetyl CoA. It converts sugar to carbon dioxide, water, and 32-34 molecules of ATP (cellular energy currency).

In anaerobic activity, you can only break down glucose (and other sugar) to pyruvate. Pyruvate is converted to lactic acid in your muscles, and you often feel cramps in your muscles as a result of anaerobic activity. The process only has a net production of 2 ATPs.

Believe me, I can get into a whole lot more detail if you'd like.

[frenzl]

aerobic burns fat and anerobic burns glucose (sugars).

[ReverseLunge]

Originally posted by Army Fencer

You burn far more calories in aerobic activity than in anaerobic activity. In aerobic activity, you recruit your mitochondria (your cellular power plants) to break down glucose, pyruvate, and acetyl CoA. It converts sugar to carbon dioxide, water, and 32-34 molecules of ATP (cellular energy currency).

So you are saying that if I run at a very fast pace for one hour where "m struggling for air I'm going to be burning less calories than if I were to run at a slow or moderate pace?

[whtouche]

Not less calories, I don't think.
But to burn fat it is better to elevate your heart rate slightly(there's a calculation for it that I can't dig out right now) within a certain range where your body burns fat for energy. Elevate it beyond that and you start burning carbohydrates. Of course when you burn all those you'll start burning the fat, but it's easier just to skip the middle man. I've found I can walk for alot longer than I can run for anyways.

[Army Fencer]

Originally posted by ReverseLunge
So you are saying that if I run at a very fast pace for one hour where "m struggling for air I'm going to be burning less calories than if I were to run at a slow or moderate pace?

The numbers listed are ATPs per molcule of glucose, not ATPs per time. Your mitochondria (aerobic) are much slower at metabolizing than the just the simple glycolysis pathway (anaerobic). Theoretically, you could burn just as many calories either way.

Concerning fat breakdown:
Fat ---> Acetyl CoA ---> Mitochondria

In other words, lipolysis requires oxygen.

[Masterurethane]

Hurrah! I study Pharmacology. What a great topic.

But from a physical point of view. The energy you use is directly related to how much work you do.

[FoilyGeezer]

Originally posted by ReverseLunge
So you are saying that if I run at a very fast pace for one hour where "m struggling for air I'm going to be burning less calories than if I were to run at a slow or moderate pace?

Well, one of the physical traits of aerobic activity is that you don't use oxygen faster than you can acquire it. That's why you can be out of breath after a 200m sprint, yet only be mildly winded after a mile jog. This is oxygen debt. A couple good examples of this are running a 400m race as fast as you can. At some point you're legs start to burn, feel very heavy, and slow down, and no amount of will power will make them go faster again. The muscle has depleted it's available engergy resources. Another one is lifting to failure. Your muscle isn't any weaker on those last few reps, but there is no available energy left for it to run on...thus 5 lbs feels like 50.

If you're running for an hour and you're struggling for air, you're probably right on the cusp of anaerobic activity, but since you've sustained that level for an hour it would still have to be aerobic. Assuming you've sustained the same pace for the whole hour, you'll naturally end up burning more calories than you would have at a slower pace.

[Louweasel]

...but it's a pet hate of mine:

Originally posted by whtouche
Not less calories, I don't think.

You're right, it's not "less calories" - it's "fewer calories".