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Aerobic vs. Anaerobic(12 posts)

Aerobic vs. AnaerobicJohn R.
Aug 8, 2001 9:31 AM
Is there a sharp division between these two - or does exercise gradually get more anaerobic as intensity is increased?

For instance, in the mountain stages of the Tour, do the riders pop in and out of aerobic and anaerobic exercise or is it just a matter of degree?

John R.
re: Aerobic vs. AnaerobicLardog
Aug 8, 2001 9:40 AM
Generally speaking, above 75% of your max heart rate is considered anaerobic zone. Below that, aerobic. One of the main differences your body will experience is that while your in an anaerobic zone, you will tend to burn more and more sugars as you *go up the ladder* so to speak. You'll tend to burn less and less fat along the way as well. This is due to the exertion level your body is working at. The harder you go, the more easier burning, faster burning fuel you'll use.
re: Aerobic vs. AnaerobicUncleMoe
Aug 8, 2001 9:54 AM
I've always understood that your body will burn the same amount of fat along the way, but burn more sugars. In essence, the more anaerobic you become, the percentage of fat you burn decreases in relation to sugar, but you still burn the same amount of fat.

Anaerobic = burn same amount of fat, more sugars, thus, percentage of fat burned decreases. Percentage of sugars burned increases.
re: Aerobic vs. AnaerobicLardog
Aug 8, 2001 10:26 AM
Between Larry and Moe (LOL) you've pretty well got it covered. The human body is so full of variables that it's hard to be exact. We're both right, and you can have in betweens as well.

In regards to the climbing sections of the tour, they're certainly in their first zone. I saw Carmichael mentioning how Lance was well over 180 during Huez.

Man, I can't imagine how they can eat enough during July just to finish.
but..dont know much
Aug 8, 2001 11:29 AM
I think there is more to it than just what your body is burning. Here is a discussion on AT which also provides insight into aerobic and anaerobic defitions. It is written about running but applies to cycling or any other exercise. You can spend alot of time find info on this kind of stuff on the net.

Anaerobic threshold (AT) is a frequently used term that sometimes causes a little confusion. What is the AT and how can you use it to run faster? For starters, the AT is an extremely reliable and powerful predictor of performance in aerobic exercise. To explore further, I will begin with a brief, oversimplified, review of physiology. Muscles can "burn" glucose two ways, aerobically ("with oxygen") and anaerobically ("without oxygen"). Both systems generate a temporary energy store, called ATP, which in turn produces mechanical work. However, there are some major differences.

An all out sprint, which requires a great deal of power output in a short period of time, uses the anaerobic system. The energy is quickly available, but the anaerobic pathways are not very efficient ; short term energy stores are rapidly depleted, lactic acid builds up, and exercise soon comes to a halt. After a brief rest, the system is recharged and ready for the next sprint. Distance running, which requires a steady power output over a long period of time, uses the aerobic system. These pathways can't generate the speed of the anaerobic, but they do possess a great deal more efficiency and endurance. Depending upon the distance, and effort, the body can use different proportions of both of these systems. Those who have raced the 800 meter know it's too long to be a sprint, but too short to be distance. This is right at the cross-over between the aerobic and anaerobic systems.

While running at a comfortable pace you use both systems, but the anaerobic:aerobic ratio is low enough that the lactate generated is easily removed, and doesn't build up. As the pace is increased, eventually a point is reached where the production of lactate, by the anaerobic system, is greater than its removal. The AT, also known as the lactate threshold, is the point where lactate (lactic acid) begins to accumulate in the bloodstream.

The AT varies from person to person, and, within a given individual, sport to sport. Untrained individuals have a low AT (approximately 55 % of VO2 max), and elite endurance athletes, a high AT (approx. 80 - 90% of VO2 max). You can train your body to remove lactate better and to juice up the aerobic mitochondrial enzymes, thus raising the AT. Don't worry you still get to experience the joy of lactate-laden legs that won't move, but it will happen at a faster running speed. Applying the right types of workouts is the key to properly shape your AT.

Interval work consists of a repeated series of short, high intensity, runs alternating with rest periods. Regardless of the race distance you are training for, 5k or marathon, interval work will help you run faster. Intervals should be creative, fun, and definitely not done every day. Whether it's 10 x 800m, or a 200m, 400m, 800m 400m, 200m pyramid, continually pushing yourself into a lactate burdened state makes your body adapt. Your aerobic enzymes get supercharged, and you become better at processing lactate.

So how do you know if your workouts are pushing your AT? After several track workouts, you'll notice the feeling when in the anaerobic zone. There are also exercise tests which can estimate your AT (e.g. Conconi test), and now, through the miracle of modern medical technology, a hand-held device for directly measuring lactate. A small pinprick, one drop of blood, and in less than a minute you know the exact blood lactate concentration. The corresponding heart rate at the AT gives you a convenient way of monitoring your workouts. Regardless, always pay attention to how running feels. Repeat testing several months later can show you how your trai
Thanks...exactly what I was looking for...(nt)John R.
Aug 9, 2001 4:29 AM
re: Aerobic vs. Anaerobicjayz
Aug 8, 2001 11:16 AM
yes, there is a distinct area in which you will move from working aerobically to going anaerobic. This threshold is usually refered to in terms of heart rate. Keep in mind that this number is a floating target, to some degree. The more you train at this zone or slightly above, the more it will increase, and thus become a higher percentage of your max heart rate and VO2max.

You can give yourself a really, really rough estimate of this number, by simply increasing your workload untill you hit a point where you start to breath heavy and your legs start to hurt.

Your anearobic threshold is also called your lactate threshold, because it is the point at which the body can no longer remove the lactate in your blood faster than you are making it. Its your body's way of telling you to slow down or you are gonna hurt!! (granted we usually try to ignore this warning during a race or hard traing:)

Can your work above your LT?? sure...but you will be limited to some degree. it its a short race, you will probably spend your entire time above your LT...but you will be hurting. can you do a 5 hour century anaerobically?? no way.

as far as what you are using for are always usuing a combination of fat and gycogen (carbs). obviosly, the harder you work, the more calories you burn. some people say to stay low intensity for long durations, because thats where all the fat is burned. true, a greater percentage of fat is burned at that level, compared to carbs...but you overall calories burned is alot lower.
when you are going all out, i would guess that the very high majority of what are you burning is glygogen (i cant back that by actually figures..just based on readings).

hope that adds to the confusion :)
re: Aerobic vs. AnaerobicJon Billheimer
Aug 8, 2001 2:47 PM
Just to add a couple more points to the two very good posts above: if one is functioning completely anaerobically (which rarely happens), work will only be produced for a maximum of about 40 seconds. After that available ATP energy sources are exhausted and the acidic pH within the cell shuts down further muscle contractions. Secondly, anaerobic energy production cannot draw on fat as a fuel source. On the other hand, all aerobic energy production depends on an intial contribution from glucose as an energy source. A glucose substrate then combines with fat to synthesize ATP.
define "completely"....jayz
Aug 9, 2001 4:39 AM
my LT is 172 (as tested in a lab)...i can race for an hour and have an average of 185-190. I had a 25 min time trial which my average was 195. It Never went below 190. i would say that i was COMPLETELY anaerobic.
define "completely"....Jon Billheimer
Aug 9, 2001 9:44 AM

I threw that comment in to highlight the idea that we almost never are producing energy completely anaerobically, or aerobically for that matter. It's just that the balance of energy production gets tipped one way or the other, depending on the intensity of the effort. The technical definition of anaerobic threshold is when your blood would show a concentration of 4mmol of lactic acid per litre (?) of blood. However, even this is a somewhat arbitrary definition.

Total anaerobic energy production would exist when the ONLY source of ATP synthesis would be the CP and glycolytic systems, and in reality our bodies virtually never function that way. The best approximation of this is an all-out sprint at peak power or a 30 second Wingate test in a lab. Even then, peak power is only maintained for a few seconds, then begins to decline as fast twitch fibres begin to shut down and energy demands begin to be taken over by slow twitch fibres not quite yet exhausted. But you get the idea. When you're functioning over your LT, as in a race or short time trial, there is enough anaerobic energy production going on to produce continually increasing levels of lactic acid, faster than your cells and bloodstream can clear, so that eventually your power output will decline and eventually you must rest. However, your aerobic system is still functioning but making a smaller relative contribution to your energy needs. So this stuff is all relative.
PS.Jon Billheimer
Aug 9, 2001 9:54 AM
I reread your post, and I would seriously question the lab's results. Generally, your average heartrate over a 40k TT is considered to be right on your LT Heart Rate. And you're completely right about LT being a moving target. The lab could be off in the way they interpreted your data, or your LT could be at a higher concentration than 4mmol. Some studies have shown that certain athletes can tolerate 6 or even 8mmol lactate. The break point on Conconi tests also have been shown to be inaccurate for over 60% of athletes tested.
re: Aerobic vs. Anaerobicjtolleson
Aug 9, 2001 2:32 PM
My personal experience:

Anaerobic -- climbing uphill at a pace faster than my comfort zone, gasping quietly and trying not to barf.

Aerobic -- bailing on the climb and going downhill, having heartrate acceleration as I try to avoid deadly potholes.