quote:<HR>Originally posted by fredurie:

Let's go back to whether training at 85% of maximum HR is aerobic or
non-aerobic.<HR>

Yes, many folks here will think it's a matter of terminology. Just to clear up how I am interpreting the terminology:

Respiratory Quotient (RQ) aka Respiratory Exchange Ratio (RER) : the ratio of VCO2/VO2 for the body's metabolism during exercise, which can be used to determine the percentages of energy derived from burning fats and carbohydrates (there's a web page which gives neat details with some chemical formulas, etc, if anyone wants us to post the URL again...) Pure carb burning would give an RQ of 1.0, and pure fat burning would give about 0.70 (the exact number could vary a small amount based on the type of fat being burned - usually 0.70 is used, and it is apparently pretty good for the slow-twitch endurance fibers and their fuel (triglycerides, IIRC.)) So it's clear how to interpret the RQ... 0.85 would be 50/50 carbs/fat, 0.775 would be 25/75, 0.94 would be 80/20, etc. Part of the output from a good VO2 test will be HR vs RQ data through your whole range of exercise exertion.

Anaerobic Threshold (AT) : the point (HR) at which essentially all energy for exercise is provided by carbohydrates (glycogen.) This would be at an RQ of 1.00 (or very close to it.) Right around this point is the Lactate Threshold (LT) where (correct me if I'm wrong folks) the body produces more lactic acid (&other "lactates") than it can take care of slowly builds up an excess. Some of y'all know the details on LT better than I do, so clue the rest of us in on it.

Aerobic Threshold (AeT) : this is the tricky one. Most people mean that up to this point one is fairly aerobic, and after this point one is "not so aerobic". This point can be defined a couple ways: by a particular RQ value, by a "deflection point" where the slope of a particular curve seems to change abruptly, etc. Someone could say it's the point at which you start to get more energy from carbs than from fat (RQ = 0.5.) Someone else could say that's the point up to which you are getting at least 75% of the energy used from fats (RQ = 0.77 to 0.78.) Someone else (Maffetone?) could say it's a particular deflection point where the body starts using fuel resources and oxygen differently.

Aerobic Range : Usually means some range related to the Aerobic Threshold. Sometimes taken to mean "no higher than the Aerobic Threshold." Some coaches/authors talk about multiple aerobic ranges, some used for slow recovery runs, some used for long endurance runs, some used for "cardiovascular system development", etc. Whatever. If someone tells me what at RQ they wnat me to run, then I know for sure what they want. If someone just says "run aerobically", that would need some interpretation. "Easy aerobic run" is easier to figure out... at least for me that means "run easy", so I just run easy...

Whew. Now back to this 85% thing. Here's my take - for some that's "aerobic" and for some it's not. Of course it depends on conditioning, training, genetics, etc. (I won't go off on a tangent about genetics, so we won't have to talk about Reinhold Messner right now...)

Here's what I base my opinion on, admittedly not "hard" scientific double-blind studies with many hundreds of test subjects. As previously posted, I got to look at some data extracted from a set of VO2 tests (age, AeT, AT, max measured HR and VO2.) for less than 100 people. Mostly runners, some walkers, cyclists, triathletes.. in all ranges of condition from not very fit to very very fit. I know the AT was defined as the point at which RQ = 1.0. I don't know the definition of AeT used by that equipment, but I suspect that it was either 50/50 (RQ = .85) or that deflection point mentioned above.

Those VO2 tests don't really try to measure MHR. However, they can come pretty close with the max measured HR, which is past the AT, and is where the tester thinks he doesn't want the subject to go on. In my case the max measured was about 3 bpm below my MHR which I got with 3x an all-out hill run of 1.5 -2 minutes.

Ok. Finally. I've calculated the percentage of "max measured HR" represented by the measured "Aerobic Threshold" and they vary a lot. They range from 60% to over 90%. About 8% of the test subjects have an AeT which is over 90% of their max measured HR. Even if their real MHR was 5-7 bpm above the max measured, they would be below their "Aerobic Threshold" at 85% MHR. Another 15% of the test subjects had their AeT at or above 85% of their max measured HR.

It's interesting to note the age distribution of this. 55% of the folks aged 26-35 calculated out at 85% or above, 22% of them were above 90%. For the folks age 45 or older, only 6% calculated above 85% max Measured HR, and only 3% above 90%. It would seem from this "anecdotal" evidence that it's more likely for younger runners to have an "aerobic threshold" which is a high percentage of their MHR.

In any case, it doesn't surprise me at all that some runners can be "aerobic" at 85% of MHR. It probably helps if you're an "elite", but I know the 68 year old guy whose test said his aerobic threshold was at 92% of his max measured HR sure wasn't. I'm not sure what this percentage really means to most of us, anyway. Who really uses MHR for anything, anyway? For myself, as long as I know my AT that's the highest number I'd ever be interested in.

Sorry this was so long... hope I didn't bore anyone or sound too stupid.

Gino

For a good threshold run (not too fast and not too slow) I take about 3 or 4 miles (30 to 40 min) to warm up and get up to my goal pace. During the portion of the run at threshold (usually about 30 min) my HR will slowly rise from about 155 to 163. With an observed max of 184 that corresponds to 84% to 89% of max.

Which brings me to my second point. If MHR isn't important then how can one calculate percent MHR?

posted Oct-30-2007 07:18 PM
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quote:
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Originally posted by teresaa spencer:
Oh...and congrats to you Jimmy on the Red Sox.
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You mean me, right?

I mean all "Jimmie's" that apply.

quote:<HR>Originally posted by fredurie:

Let's go back to whether training at 85% of maximum HR is aerobic or
non-aerobic.<HR>

Yes, this brings to mind the classic definition of "aerobic" as "with oxygen" and "anaerobic" as "without oxygen." Using these definitions, exercise which does not exceed our bodies ability to take in enough oxygen for our fat and carbohydrate metabolisms is aerobic. When the demand for oxygen exceeds the supply, then we need also to use an anaerobic mechanism (glycolysis ?) for the extra energy.

Based on this, one could call exercise below our Anaerobic Threshold (AT) aerobic - because we are still providing the body enough oxygen for its energy needs.

I have read that there is usually some anaerobic component before we actually get all the way to the AT, however. I don't know any percentages about that, though.

When we get to the point of talking about no oxygen to receive the electrons at the end of the Electron Transport System (ETS), causing a backup in the ETS and the Krebs cycle... the number of ATP molecules netted per glucose molecule in glycolysis... etc, etc... I kinda start to doze off, as in the old saying
"When I works, I works hard. When I rests, I rests easy. When I thinks, I goes to sleep..."

quote:<HR>Originally posted by jjwaverly42:
What is your response to my earlier response to your post? Make it a conversation, man.

I quoted Maffetone's definitions for aerobic and anaerobic and how it differs from popular definitions--they are fuel and fiber based. I also mentioned how no matter what you call them, the LT runs work and I do them in the anaerobic phase because they do. Also it should be mentioned that Maffetone (and I already quoted this) saw that whether endurance runners did all-out intervals at 95% and above, or runs at 85-90%, they produced the same results in terms of fast-twitch development. That is why he steers his runners towards the least stressful anaerobic work--basically LT runs and intervals not exceeding 90% MHR. He wants to keep his runners healthy as well as fit. It's one thing getting to a race fit and you're sick and you're aching everywhere and perhaps injured, and another when you get there fit, healthy, and intact.

Does it really matter whether or not you call an LT aerobic or anaerobic?

--Jimmy

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<HR>

I'm not so sure I can buy that running at <90% max heart rate can produce the same results as running at 98% max heart rate. Coach Jack Daniels sure explains the difference in his book. What science does Maff use to come to that comclusion?

I understand he is speaking of endurance events and for marathon and up 90% can be considered speed work but would never fit the bill if you are aiming to peak for 5k.

I am a firm believer that their should be 3 training....zones(I hate the confining term). 1) slower than race pace(supporting zone) 2) at race pace(specific zone and 3)faster than race pace(training zone). For specific data on that see Renato Canova's methods that offer more data than science. 90% max heart rate one could corelate with half marathon effort so even that distance you might want to train(harder?).

I agree with what you said for those distances. What is your opinion on the importance of Maffetone training for shorter race distances where RQ is 1 or greater?