Isn't "Event Specificity" More Important Than "VO2max" And "LT" Zones And All That?

BOulderite,

I think the problem with your analysis is that you are comparing averages (over the marathon) to a single heart rate value (heart rate at threshold attained during at test). Because of cardiac drift during the marathon you will have a higher average heart rate at the end then you will probably ever see during a training run. I just completed a long marathon session this morning which included (note that my max heart rate of 183 and my threshold of 169 are close to some of the figures you posted):

15 minutes at 130-145 bpm, 30 minutes at 145-150 bpm, 30 minutes at 150-155 bpm, 30 minutes at 155-160 bpm, 23 minutes at 160-163 bpm, 7 minutes uphill at 163-172 bpm (2:15:00 total).

From treadmill tests my estimated heart rate at marathon pace is between 159 and 164 (R value between .92 and .95). This is the goal heart rate range that I try to reach by the end of these long runs and this heart rate "feels" like marathon effort to me. However, if I had "raced" this run today and started the first 30 minutes at 160-163 bpm I would expect that my heart rate at the same pace would gradually climb throughout the workout and would likely reach the low 170s or higher by the end. This wouldn't be the result of having gone over threshold but, rather, would be the result of the muscle and heat stress that has built up in my body over the distance covered. So, at the end of a marathon my average heart rate might be equal to my threshold heart rate (169) but the 2 values represent 2 entirely different things.

Also, a lot of the fatigue at the end of a marathon doesn't even have to do with glycogen depletion but simple muscle fatigue (mechanical fatigue). Cross bridges can only activate so many times before they begin to fail to do so effeciently. The fatigue and cramping has a lot to do with a lack of hydration and the lowering of the action potential threshold. Also, the more you contract the muscle fiber over and over and over again the easier it is going to be to contract it again and so you reach a point where basically the signal to the muscle is overwhelming and you cramp up. So, not only do you need to load up on glycogen but water as well. Those out there for 3, 4, 5 hours will also need to take salt as well.

Alan

Thanks, Alan. I'm curious why one rarely reads about mechanical fatigue. It seems like the vast majority of the literature is focused on aerobic systems. Perhaps I should be going back to look at Bompa and other non-running specific, strength-training researchers.

Interesting thread! On another current thread about Japanese marathoners it was mentioned several times they sometimes wear up to three sweat suits. Benji Durden and Marty Liqouri are of the opinion there is a similar to altitude but different effect. They seem to feel training in moderate heat at sea level increases the total volume of blood versus the increase in hemoglobin gained at altitude. What are your thoughts on this? Ron Daws did this as well training for some of his marathons. Any credence to this? Could this be helpful for one who is unable to train at altitude when used judiciously?

800 dude wrote:

Thanks, Alan. I'm curious why one rarely reads about mechanical fatigue. It seems like the vast majority of the literature is focused on aerobic systems. Perhaps I should be going back to look at Bompa and other non-running specific, strength-training researchers.

Posture posture posture!!! There is a lot of room for improvement with many runners if they correct imbalances and weaknesses, improve posture....hey...that can be another thread entirely! :)

Runningart2004 wrote:

Cross bridges can only activate so many times before they begin to fail to do so effeciently. ... Also, the more you contract the muscle fiber over and over and over again the easier it is going to be to contract it again .

Isn't that a contradiction?

Tinman wrote:

All good and well but.... wrote:

Marathon lactate is 2.3

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Blood plasma lactate (average) relates to intensity of exercise, so a faster runner can, theoretically, run at a higher concentration than a slower one. A 2:10 marathoner might run a full millimole higher than a 4:20 marathoner.

Regards,

Tinman

This is wrong.

I agree that cardiac drift needs to be factored in. But if your heart rate drifts beyond your normal LT rate, aren't you still going to accumulate too much lactate? It's not like you can tell your legs, "Oh it's just cardiac drift -- don't slow down."

The relevant point for this discussion is that we've now thoroughly outlined why training at threshold or even higher intensities plays an important role in marathon training.

This may not sit well with the Lets Run crowd that preaches miles, miles, miles and sometimes scolds coaches like jtupper for suggesting less mileage and more intensity can benefit distance runners.

Your making the wrong assumption that Heart Rate causes lactate to increase or that they are directly related.

There is NO true Threshold Heart Rate. It will vary based on the day, shape, any other factor.

To give you an example, my threshold at the beginning of the season could occur around 165bpm, while 2 months later it could occur at 185bpm.

So even as your heart rate drifts up because of cardiac drift, if you are running at or around threshold the lactate levels will stay relatively the same, even if the HR increases.

and to add to the discussion. There is some "danger" in doing too much threshold type stuff at the wrong time when training for a marathon. If you continually try and increase the threshold, while neglecting the aerobic threshold (or marathon pace) then the gap between aerobic thresh and lactate thresh can be too large. The goal (for most runners) towards the end of the marathon training is to close the gap between aerobic (marathon pace) threshold and LT until there's something like a 5% difference (percentage could be off, it's too early and I'm at school so don't have notes).

I think everyone agrees that "threshold" is best though of as a metabolic range. It's not defined by a precise heart rate, or any other highly specific measurement.

Yes, too much threshold training can be counterproductive. So can too little.

I kind of like the advice to run long once a week, run hard once a week, and to do them together a few times per month while preparing for a marathon. I think you could get to a pretty high level without a lot more guidance than that.

I was speaking of VO2 max when I used the 80-85%. I am not a big fan of heartrate percentages because of the large standard deviations in max hearrate results. It is somewhat difficult to figure your exact max anyway. This 220 minus your age is inaccurate for over 1/3 of people. Another problem that I have with only using heartrate is that it does not take into account stroke volume. I feel that percentage of cardiac output might be better. Again you run into the same problems for the average runner.

actually, i believe that a threshold HR does exist, to an extent. while it is true that this can vary on any given day for a myriad of variables stated above, there is no real explanation why it would vary 20 bpm from the start to the end of the season if you are relatively trained. HR may not cause lactate accumulation but it is a measure of how hard the body is working and what metabolic pathways the body is deriving energy from. Pace on the other hand is not. so sjm, while you may have a HR of 165 and a pace of 5:15/mile at the start of the season i would venture to say that if you ran the same pace and your HR was 185 then on that day (for whatever reason) you are not doing a true threshold workout but something more intense. the only true way of knowing if you are working at the proper intensity is to take lactate measurements during a workout (marius would certainly endorse this) HR while pretty accurate varies and pace is certainly not as valuable because it is not mearuring what the body is doing at all.

Although I don't agree with everything in his post, but Runningart2004 has brought something else important to marathon running. This mechanical fatigue also called muscle fatigue can also be taken into account. The powerful contractions that muscles can produce before you begin running are counteracted by the high mileage. On multiple occassions. I have found that my verticle increses 2-3 inches after I have stopped aerobic training for 2-3 weeks. And once I pick back up my training the verticle goes back. After a long run or a marathon you can take rest completly restore your ATP and your muscles will not contract as they would have before the run. It has been found that muscles are working much harder to contract at mile 16 than mile 4 even at the submaximal levels. The better marathon runners may have a better muscle/mechanical fatigue resistance.

Vigil is also a believer in some plyo training in distance runners. Here is an article related to 5k running and power.

http://jap.physiology.org/cgi/content/full/86/5/1527

That makes sense but what I was getting at is that the effort late in the marathon is 'at the edge', neither T nor M, just as hard as you can without tearing a calf or cramping or losing the bowels.

VO2 has its associated headaches too, of course.

I've had it measered three times by three different labs. Scores were 71, 62 and 65. Seemed to have more to do with how much I weighed than how fit I was. Plus, different testing protocols affect the measurement.

Heartrate, while not perfect, is really the only accessible tool for most of us.

Jack Daniels V-DOT is useful too ... but it's tricky if you train at altitude (here in Bould) but race frequently at sea level, as the scoreshave to be converted back and forth. I get as much or more good feedback from my heartrate monitor than any other measurement.

Max heartrate is easy to figure out if you don't mind wearing a monitor during a 5k race or mile repeats, in my experience. I'd never consider using the antiquated 220-age formula.

Actually, the HR that LT occurs at will vary based on a number of variables and it can in fact vary by a significant amount from one training period to another.

HR isn't a measure of what metabolic pathways are used. It can not tell you that in any way shape or form. We can only infer what is used from HR. It's no better than inferring what you use based on the speed of the run.

I assure you that HR at LT can vary by that much depending on what point in the training period you are in. I've checked it on myself using lactate measurments every 5-6 weeks over a year. The HR at LT changes, sometimes dramatically.

It's the same as % of VO2 that LT occurs at. There is no exact percentage. The percentage of VO2 that LT occurs at will increase as you go through a certain type of training. SO just like HR, it's not too unusual to see the percent jump several percentage points throughout a year.

You mention marius, so you should go look at his data and it will confirm the wide variance in HR at LT over a training period/season.

I agree, the late stages of the marathon you are also on the edge of tearing something or cramping up. You are deydtrated, your stomach/intestines are protesting, it feels like tendonitis is occuring or you might pull something. But I think a lot of the muscle fatigue is due to the glycogen depletion and dehydration. If you've put in the high mileage for many years your muscle fibers can hold up- whereas if you go through the half way too fast you might feel some lactate build up, cross your venilatory threshold and start to slow before those final stages even occur. Futhermore, if you carbo load properly, train your liver properly, and pace yourself optimally I think you can make it to the finish without running out of glycogen....so in that less common case, your limiting factor would probably be only stomach/intestine problems or a stiffness in the legs like you can't get them to move any faster. I'd also like to think that there is a "mental toughness" involved that seems very important around the 22-23 mile mark.

Also, I'd add that I think HR is going to very day to day and it depends on many variables such as hydration level, etc (as stated above). Like V02max, your LT isn't really very constant and the only way to accurately measure it is to take blood samples to measure and plot a deflection in lactate values in a very controlled workout of something like "cruise intervals." HR or percentages are not accurate enough to work with when it comes to determining pace- I think.

So the only good way to determine pace is blood sampling for lactate values?

Not very encouraging news for most of us!

HR can be useful, but also misleading. On a hot day for example HR is not accurately reflecting how hard you are working. Under these conditions, more blood is being diverted to the periphery in hopes of cooling the core and this means to maintain the same blood flow to the exercising muscles, total cardiac output must increase. Of course, if you adjust pace to accommodate HR, then you are at the desired HR but certainly not at the same intensity of running -- the running muscles are under-achieving. Same would be true if dehydrated -- less blood volume and usually less stroke volume, which, again means increasig HR to keep up the desired cardiac output