The Powermeter Thread

[acoggan]

That, my friend, in not a mechanism.

Yes, it is.

Besides, in general, HR doesn't change much at VO2 max hence filling time should not change to explain the drop in output.LOL. Filling time decreases as HR increases at all heart rates. What "pushes" the heart beyond its maximum pumping capacity?

Despite ever-increasing filling pressure, reduced filling time starts to limit ESV even at submaximal heart rates, but SV doesn't initially decrease because EDV progressively falls. You can only squeeze so much blood out of the heart, however, so eventually SV, and hence Q, also decrease.

Why does the "maximum pumping capacity" of the heart depend upon how it is measured (running, cycling, rowing, etc)?

Unless you are specifically trained in, e.g., cycling, you can't push the heart to its maximum pumping capacity because you don't vasodilate enough. That's why the highest VO2 measured in such cases is referred to as VO2peak, not VO2max.

When you explain it to the real experts in cardiac physiology, the cardiac anesthesiologists,

<snort>

I doubt the cardiologists will buy your explanation either because there is no data to support what you say.

http://www.ncbi.nlm.nih.gov/pubmed/12591751

 

[FrankDay]

Yes, it is.



Despite ever-increasing filling pressure, reduced filling time starts to limit ESV even at submaximal heart rates, but SV doesn't initially decrease because EDV progressively falls. You can only squeeze so much blood out of the heart, however, so eventually SV, and hence Q, also decrease.

Phooey. Well, I guess it could be a mechanism if it actually explained the data but there is zero quantitative data to support this speculation, especially to explain the drop in CO as one exercises beyond VO2max. Your explanation should result in a leveling of CO at VO2max but cannot explain the drop.

Unless you are specifically trained in, e.g., cycling, you can't push the heart to its maximum pumping capacity because you don't vasodilate enough. That's why the highest VO2 measured in such cases is referred to as VO2peak, not VO2max.

But, the heart behaves the same at VO2peak as it does at VO2max, with CO dropping. This is a BS argument because the only way we know that something isn't VO2max is because later we come along and test another way and get a higher number. One can never be certain that any given test actually tests an athletes VO2max.

http://www.ncbi.nlm.nih.gov/pubmed/12591751

You don't seem to understand that I agree that it appears that the heart (or the CV system, if you insist) is the limiter to athletic performance (or VO2max) if one has an incomplete understanding of the underlying physiology. However, such a simplistic view of the data doesn't address the mechanism to explain this limitation. How, exactly, can we explain the way CO drops off after VO2max is reached (or, even before it is reached if we look at VO2peak or even lesser workloads continued for longer periods)? Are there any other things going on at the same time that might explain this phenomenon? How does one explain the heart seemingly adapting to training such that it is possible for the sedentary to increase VO2max with training or the drop in VO2max as one stops training? What specific change (or changes) in the heart explains these changes that are seen? But, these changes are only the final common pathway that are the result of many systemic changes. Without understanding these underlying issues one doesn't really understand what is going on.

Your problem is you are looking at the end result and not trying to look at the nuances involved in the physiology associated with the factors associated that determine cardiac output, stroke volume and HR.

Rather than snickering at the knowledge of your average (cardiac) anesthesiologist I would suggest you would be better off getting to know one and having a heart to heart (so to speak) conversation with one. How can we explain stroke volume going up in athletes for the same filling pressure despite, sometimes, thickened myocardium which should, one would think, reduce stroke volume? Perhaps you might learn something about underlying cardiac physiology by looking at how the CV system responds and is limited in other conditions associated with high oxygen consumption from muscle activation, such as malignant hyperthermia, or conditions that affect the hearts ability to respond to stress in the operating room and how to treat them.

 

[acoggan]

Phooey. Well, I guess it could be a mechanism if it actually explained the data but there is zero quantitative data to support this speculation, especially to explain the drop in CO as one exercises beyond VO2max. Your explanation should result in a leveling of CO at VO2max but cannot explain the drop.

Phooey yourself. Not only does it explain both the leveling and the drop, but as I just showed you there are data to support this conclusion.

But, the heart behaves the same at VO2peak as it does at VO2max

No, it does not. As an example, even most lay individuals involved in endurance sports are aware that you cant achieve the same heart rate when cycling as when running (unless, of course, you are a trained cyclist).

, with CO dropping.This is a BS argument because the only way we know that something isn't VO2max is because later we come along and test another way and get a higher number. One can never be certain that any given test actually tests an athletes VO2max.

The fact that the integrative physiology of exercising humans is difficult to safely dissect in no way means that the conclusions of such research isn't true.

You don't seem to understand that I agree that it appears that the heart (or the CV system, if you insist) is the limiter to athletic performance (or VO2max) if one has an incomplete understanding of the underlying physiology. However, such a simplistic view of the data doesn't address the mechanism to explain this limitation.

Yes, it does: with ever-increasing sympathetic stimulation, the heart is pushed beyond it's optimal frequency of contraction (a simplistic analogy is the way that an internal combustion engine reaches maximum horsepower at an rpm less than maxium).

How, exactly, can we explain the way CO drops off after VO2max is reached (or, even before it is reached if we look at VO2peak or even lesser workloads continued for longer periods)?

I already told you: the heart keeps beating faster and faster, but with less blood pumped with each beat, so that cardiac output and, hence, convective O2 delivery, actually fall, leading to a plateau (and sometimes even a "peaking over") in whole-body VO2.

Are there any other things going on at the same time that might explain this phenomenon?

LOTS of things are going on under such an extreme emergency situation for the body. The fact remains, however, that VO2max is not limited by, e.g., some "central governor" as wrongly believed by Noakes or by peripheral O2 utiliation, but the cardiovascular system's ability to deliver said O2.

How does one explain the heart seemingly adapting to training such that it is possible for the sedentary to increase VO2max with training or the drop in VO2max as one stops training? What specific change (or changes) in the heart explains these changes that are seen?

I know it's hard for you, Frank, but I think (or at least hope) you'll be less confused if you first focus on understanding the responses to acute exercise, rather than worrying about chronic adaptations.

Rather than snickering at the knowledge of your average (cardiac) anesthesiologist

Don't worry, Frank, I'm not - I only snicker at you.

How can we explain stroke volume going up in athletes for the same filling pressure despite, sometimes, thickened myocardium which should, one would think, reduce stroke volume?

What did I just tell you about not confusing the acute responses and chronic adaptations to training?

Anyway, it is well-established that endurance training increases ventricular compliance (and that the increase in wall thickness in endurance-trained individuals is merely proportional to the increased EDV...Laplace's Law and all that).

Perhaps you might learn something about underlying cardiac physiology by looking at how the CV system responds and is limited in other conditions associated with high oxygen consumption from muscle activation, such as malignant hyperthermia, or conditions that affect the hearts ability to respond to stress in the operating room and how to treat them.

Malignant hyperthermia is not exercise (though they have similarities).

 

[FrankDay]

LOTS of things are going on under such an extreme emergency situation for the body. The fact remains, however, that VO2max is not limited by, e.g., some "central governor" as wrongly believed by Noakes or by peripheral O2 utiliation, but the cardiovascular system's ability to deliver said O2.

I agree that there is no central governor as described by Noakes. Where we disagree is the physiological mechanism behind VO2max. You might want to look at what is going on with cardiac pH as one approaches VO2max and how both the ability of the muscle to contract and relax changes with altered pH.

As I said, your approach is simplistic. But, continue to pretend that no one else could possibly know anything more about anything related to physiology than you.

 

[FrankDay]

Anyway, it is well-established that endurance training increases ventricular compliance

Why? Do you understand the mechanism?

 

[hiero2]

The years drag on and you guys continue to bicker on this forum using nothing but anecdotal reports to support your ideas.

Meanwhile others are out there doing real science and applying it successfully in World Class competition.

This thread should just be a copy & paste of your last dozen efforts to undermine each other with low blows and hypocritical comments backed by nothing but hot air.

Fergie, I spotted your picture recently. It was in the dictionary under the word "windbag"

Jeroen - since you are "new", to me, and I to you, I am leaving your post, intact, as a learning object.
I do not find it odd that you mention anecdotal reportage. It has been previously noted, and warned against, in this section of the forums. However, I do find it odd that, following a number of posts by CoachFergie with valid links to "real science", and a number of quotations of abstracts, from which it should be possible to locate the research, that you single out CoachFergie for a personal attack.

This is not an area (of the forums) particularly attended to by most moderators, but it is one that I visit on occassion. I miss most of the byplay, and don't really have time to babysit through all the threads. So, if you see something egregious - please report it. It will get reviewed. If you make a note in the report "attention: Hiero", I will take a look. Sometimes it is a few days between my visits, so be patient.

Back to your post. With the exception of the last paragraph, it is a, more or less, a valid complaint, I suppose. Others have noted the same things. The last paragraph, though, is a personal attack, and "NO PERSONAL ATTACKS" is part of the forum rules.

I believe that is sufficient clarity.

 

[hiero2]

What was it about "science isn't always the best way of answering some questions" (http://forum.cyclingnews.com/showpost.php?p=1156563&postcount=66) that you didn't understand?

P.S. Even the phrasing of your question demonstrates that you don't "get it" - that is, you're asking about the same strawman argument that was the premise for Swart et al.'s paper.

Coggan, Ph.D.: Given your experience and acknowledging your work in the field, I have left your original post claiming the study you mentioned used a straw man argument. However, you have failed to establish why or how the study fails by relying on straw man logic. You have neither been specific, nor clear enough to do this.

Please remember that your audience here is not an audience of your peers. We are perhaps less lettered, but we are, nonetheless, sometimes intelligent and intellectual, and can often understand plain English. Therefore, your responses here should be tailored to an audience that would be reading CN, or Velonews, rather than the NEJN.

If you can not validate your argument, it becomes a personal attack, and thus, against forum rules.

 

[hiero2]

One more warning:

To every poster who has posted in this thread, or similar ones in this sub-forum. Re-examine every sentence you have, that used the pronoun "you". Most of these ARE personal attacks. For posts that also added to a legitimate conversation, and were not just a snipe, I have left them, mostly as-is. I do not have the time to generously edit your post for you, unless you want to start signing the back of a $20 bill*, and forwarding same to me for each post! Either start editing your own posts more rigorously, or when I find such examples, they will be unceremoniously deleted.

Oh, and don't fash me for not catching everything. Too bad, so sad, but I'm not here every day. What I catch, will go. If it continues, at some point, in spite of your proven positions and expertise in the field, it will warrant forced vacations.

*(For those who do not know this, the "sign a $20 bill" is a standing joke on a US radio show on NPR - "Car Talk". You can find it on the internet, I think they do some streaming of recent shows.)

 

[CoachFergie]

However, you have failed to establish why or how the study fails by relying on straw man logic. You have neither been specific, nor clear enough to do this.

Both the Swart and Robinson papers make a straw man argument because they make the assumption that both a Heart Rate monitor and Power meter are used to improve performance and use a performance test to compare the same training stimulus using either a HRM or a PM.

While some people may believe that this is the case that is not what either product is designed to do. A heart rate monitor measures heart rate and a power meter measures power. End of story.

Although I haven't been called on it I feel justified calling Frank Day's posts in this thread trolling unless someone can make the argument that a former Doctor and Engineer is seriously confused by something that measures something and a method or tool that improves something.

In 13 years of using power as a measurement of cycling fitness I have never seen anyone improve (or get worse) from just having measured their power.

 

[FrankDay]

In 13 years of using power as a measurement of cycling fitness I have never seen anyone improve (or get worse) from just having measured their power.

Or, I suspect, not having measured their power.

 

[FrankDay]

Both the Swart and Robinson papers make a straw man argument …

Swart and Robinson are not strawmen because they are testing the commonly held belief that the power meter is a better tool than the HRM for improving cycling power. They simply looked to see if it were possible to achieve equivalent training using the two tools. They could find no difference. My guess is that Dr. Coggan benefits from this misconception (even if it may be only his ego involved) so he chooses to call those studies "strawman studies" and continues to say "science isn't the best way" to study the instrument because he cannot come up with a better way of studying it than Swart and Robinson so he prefers the power meter remain the stuff of legend (and his book).

 

[CoachFergie]

Swart and Robinson are not strawmen because they are testing the commonly held belief that the power meter is a better tool than the HRM for improving cycling power.

What nonsense. They both tested a misconception.

They simply looked to see if it were possible to achieve equivalent training using the two tools. They could find no difference.

Really? Wow, what a surprise.

My guess is that Dr. Coggan benefits from this misconception (even if it may be only his ego involved) so he chooses to call those studies "strawman studies" and continues to say "science isn't the best way" to study the instrument because he cannot come up with a better way of studying it than Swart and Robinson so he prefers the power meter remain the stuff of legend (and his book).

They are Strawman studies. A similar study would be comparing weight loss using two different brands of scales. The scales have no influence whatsoever on how much weight is lost, only measure.

 

[FrankDay]

They are Strawman studies. A similar study would be comparing weight loss using two different brands of scales. The scales have no influence whatsoever on how much weight is lost, only measure.

There is no such thing as a straw man "study". A straw man is a type of argument (A straw man or straw person, also known in the UK as an Aunt Sally,[1][2] is a type of argument and is an informal fallacy based on misrepresentation of an opponent's position. link here) What they did was simply a study. Calling it a straw man study, in and of itself, a straw man. Since you have stated here a power meter can't make a person better then those studies do not misrepresent your position but, simply, confirmed your position. Something else must be going on if you are all hot and bothered by them.

 

[CoachFergie]

There is no such thing as a straw man "study". A straw man is a type of argument (A straw man or straw person, also known in the UK as an Aunt Sally,[1][2] is a type of argument and is an informal fallacy based on misrepresentation of an opponent's position. link here) What they did was simply a study. Calling it a straw man study, in and of itself, a straw man. Since you have stated here a power meter can't make a person better then those studies do not misrepresent your position but, simply, confirmed your position. Something else must be going on if you are all hot and bothered by them.

Two studies based on a misconception about what a power meter is designed to do. No wonder neither study was published in a quality journal.

Having read both Strawman studies I didn't see any mention of either me nor my position on power meters

 

[FrankDay]

Having read both Strawman studies I didn't see any mention of either me nor my position on power meters

LOL. I don't think they were trying to test your position but, rather, the commonly held belief that having a power meter makes a difference in outcome.

 

[CoachFergie]

LOL. I don't think they were trying to test your position but, rather, the commonly held belief that having a power meter makes a difference in outcome.

The misconception that a power meter will make a difference in outcome and I disagree that this is common. Don't see to many people on wattage complaining that their power meter alone, didn't make them a more powerful cyclist.

 

[elapid]

Frank and Fergie, get a room.

Fergie (and Andrew), Frank is correct in that Swart et al's study is not a strawman study. Fergie, we've had this argument before, but the paper has been published and regardless of the quality of the journal (an impact factor of 1.83 is not bad btw) this information is now in the literature. Live with it and move on.

Frank, Fergie is correct in that PMs and HRMs are just measuring devices, nothing more and nothing less. A PMs have advantages over HRMs because the measurement of work is independent of most other variables and PMs are more reliable in measuring improvements over periods of time.

Rather than personal attacks and constant bickering, can you please leave your bickering for the crank/pedalling threads, which most people have given up reading because of both of you, and leave this thread to develop into the potential it has and the interest it holds for many of us? Please, please, please?

 

[CoachFergie]

Sounds like a plan.

Half way coffee break on a ride with two power meters. Will report the data back.

 

[sciguy]

For those who haven't seen Alex Simmons' Blog entry regarding how a power meter was used to look at the power saved by drafting at 12 meters this is a very nice quick read. Try doing that one with a stop watch

http://alex-cycle.blogspot.com/2013/02/pour-me-draft.html

 

[elapid]

I have ridden with a PowerTap SL+ on a Zipp 303 wheel since 2006. I recently purchased another road bike and rather than swap wheels between my road bikes, I decided to purchase a used set of Zipp 404s with PT Pro+. I didn't want to buy the new PT G3 because I have two of the old yellow CPUs and didn't want to have to buy another CPU for the G3. (I have a number of road bikes, so I would prefer to stay with a hub-based PM system rather than have multiple bikes with non-hub-based PMs).

In addition, this year I have been doing indoor training at one of my LBS's with a 300 Pro Indoor Cycle.

One of the things I have always enjoyed about training with a PM is being able to measure my improvement in FTP after specific training periods.

My main question is (providing I calibrate both my PT SL+ and PT Pro+) should the data from both PMs be equivalent within the stated 1.5% error range regardless of the bike I use?

I have been curious about aero frames for a while and am not sure how much of it is marketing and how much of it is real when the bike is taken out of the wind tunnel and when the bike is ridden solo or in a pack. So I would like to see, over some given flat and hilly courses, the difference between similarly setup Lynskey-Zipp 303 and Cervelo S2-Zipp 404 combinations. Very basic and rough, but any comments would be welcome without getting too scientific.

 

[CoachFergie]

Andy or Alex may be able to confirm but someone with a power meter found a discernible difference between two riders riding an indoor track at a given pace and one rider riding alone. Potentially a drafting effect 125m behind. May be important if there is an uneven field in a pursuit or Kilo competition and you are the first rider and start alone.

 

[CoachFergie]

My main question is (providing I calibrate both my PT SL+ and PT Pro+) should the data from both PMs be equivalent within the stated 1.5% error range regardless of the bike I use?

In theory, yes. I haven't seen any data or reports on Powertaps. You will can check them periodically, of course if they are out you can't change them, and see if they do change over time.

With a Garmin head unit...

http://www.cyclepowermeters.com/powertap-garmin-calibration-check-76-c.asp

With Powertap Head Unit

http://www.cyclingpowerlab.com/PowerMeterCalibration.aspx

I have been curious about aero frames for a while and am not sure how much of it is marketing and how much of it is real when the bike is taken out of the wind tunnel and when the bike is ridden solo or in a pack. So I would like to see, over some given flat and hilly courses, the difference between similarly setup Lynskey-Zipp 303 and Cervelo S2-Zipp 404 combinations. Very basic and rough, but any comments would be welcome without getting too scientific.

An indoor velodrome would be ideal. An outdoor velodrome at a given speed and trying to hold a similar position. In the wind tunnell we make a white line of a riders shadow to ensure they hold the same position for each test we make.

Alex, Ric Stern or Robert Chung could talk you through the procedure for doing a simple test. Think you would need a Garmin to perform the Chung test or use Aerolab in Golden Cheetah.

 

[FrankDay]

A PMs have advantages over HRMs because the measurement of work is independent of most other variables and PMs are more reliable in measuring improvements over periods of time.

Well, I guess that is true as as PMs do measure work and HRM's measure something completely different. However, you say that is an advantage. An advantage towards what end? I guess if one is interested in measuring changes in power over time a PM (or ergometer) is a necessity. But, to what end would someone be interested in knowing that information?

 

[FrankDay]

For those who haven't seen Alex Simmons' Blog entry regarding how a power meter was used to look at the power saved by drafting at 12 meters this is a very nice quick read. Try doing that one with a stop watch

http://alex-cycle.blogspot.com/2013/02/pour-me-draft.html

Are you trying to imply that cyclists were unaware of the advantages of drafting before the advent of the power meter? I mean that is interesting information but, again, to what end? Is the advantage any more or less to a rider who doesn't have a PM on his bike?

 

[FrankDay]

...My main question is (providing I calibrate both my PT SL+ and PT Pro+) should the data from both PMs be equivalent within the stated 1.5% error range regardless of the bike I use?...

Yes. The PT's accuracy cares not a whit about the bike or anything else.