Beware of PowerCranks

[Curtis L. Russell]

"Michael Press" <[email protected]> wrote in message
news:[email protected]...
....
> Looks like Jobst has another stocker.
>
> --
> Michael Press

OK, sure, but back to Don Giovanni. Maybe it is just operatic irony that he
gets pulled down to hell for maybe the one thing he really isn't guilty. I
can't grok irony in Italian very well.


--
Curtis L. Russell
Odenton, MD (USA)
Just someone on two wheels...

 

[Michael Press]

In article
<[email protected]>,
"Curtis L. Russell" <[email protected]>
wrote:

> "Michael Press" <[email protected]> wrote in message
> news:[email protected]...
> ...
> > Looks like Jobst has another stocker.
>
> OK, sure, but back to Don Giovanni. Maybe it is just operatic irony that he
> gets pulled down to hell for maybe the one thing he really isn't guilty. I
> can't grok irony in Italian very well.

Oh, I get it now. It's cycling irony that
Ivan Basso never tested positive.
Now lets settle the matter of
Greg "I am not a doper" Lemond's 1989 irony shots.

--
Michael Press

 

[Tom Kunich]

"Doug Taylor" <[email protected]> wrote in message
news:[email protected]...
>
> I have a problem with the logic and procedure - whether coming from a
> renowned authority, like Jobst, or by just another usenet hack, like
> you or me - of dismissing research which reaches conclusion A by
> attacking the author and not the research, and then asserting the
> truth of conclusion B, without citing evidence for the conclusion.

So you assume that a study noting bone loss with age - which happens ACROSS
THE BOARD - isn't suggesting that the bone loss should be mitigated by cross
training?

>>Unless you have an unusually weak musclature, you cannot improve your
>>strength by weight training enough to make anywhere as much difference as
>>riding your bike. That's why more and more training regimes are dropping
>>weight training and "cross training" programs for professional cyclists
>>save
>>to prevent training boredom.
>
> Again, your evidence for this assertion is?

I love you guys and your assertion that somehow a printed article (most of
which are written by students) indicates authority.

Here's a clue - you don't have one.

 

[Tim McNamara]

In article <[email protected]>,
Doug Taylor <[email protected]> wrote:

> On Tue, 12 Jun 2007 08:17:52 -0500, Tim McNamara
> <[email protected]> wrote:
> >
> >Jeez Louise. It was an obvious bit of sarcastic humor! Are you all
> >humor deficient?
>
> No, Tim. If it was funny, I would have laughed. Apparently Kunick
> didn't "get it" either.

Ah, well, I laughed.

> To me it was actually smug and condescending hyperbole, and didn't
> contribute to the subject under discussion - strength training and
> cross training.

Ah, well, as I said, I laughed. My goodness but this newsgroup is
populated by people who take themselves and cycling far too seriously.
I mean, really, unless you are paid to ride or aspire to be paid to ride
(or you cycle as a necessity of life), it's all about fun and enjoyment.
But some folks can suck the fun right out of it with deadly earnestness
and PowerTaps and PowerCranks and HRMs and what have you.

> Don't we have some reasonable expectation that people who come to
> usenet of the stature of a Jobst Brandt ought to play along and
> actually give evidence for their claims that: a) strength training is
> irrelevant to bicycle efficiency and b) there is zero risk of bone
> loss for avid cyclists?

You're a bit confused about how science works. Regarding (a), those who
claim that strength training provides a benefit for cycling have to show
that the benefit exists. Somebody might have done some good research on
this- I'd be astonished if there hasn't been quite a bit of it- showing
whether people climb faster, sprint faster, can exercise to exhaustion
over longer durations, etc. If the research shows no measurable
improvement then the thesis is not supported.

Regarding (b), well, that's not what Jobst said.

> They may be true, and if so, I would love to know the facts, cancel
> my expensive gym membership, and put my Powercranks up for sale on
> e-bay.

So? Do the literature review. Google is your friend.

 

[Doug Taylor]

On Tue, 12 Jun 2007 17:55:33 -0500, Tim McNamara
<[email protected]> wrote:

>
>So? Do the literature review. Google is your friend.

I did and came up with the cited articles supporting strength
training. If Jobst and Kunich want to dispute those, the burden is on
them, not me.

 

[Doug Taylor]

On Tue, 12 Jun 2007 15:31:18 -0700, Michael Press <[email protected]>
wrote:

>What do you mean `we', round eyes?

We the nerds of rbt.

rbr has an implicit requirements for credibility: you need to have
followed bike racing before the LANCE bandwagon; you should have
entered enough bike races to at least to point out of Cat 5. If you
want to get to the next level of respect, spelling and grammar help.

Your only cred is supporting dopers. Nice try, but no cigar. Sorry.

 

[Doug Taylor]

On Tue, 12 Jun 2007 22:45:48 GMT, "Tom Kunich" <cyclintom@yahoo. com>
wrote:

>> I have a problem with the logic and procedure - whether coming from a
>> renowned authority, like Jobst, or by just another usenet hack, like
>> you or me - of dismissing research which reaches conclusion A by
>> attacking the author and not the research, and then asserting the
>> truth of conclusion B, without citing evidence for the conclusion.
>
>So you assume that a study noting bone loss with age - which happens ACROSS
>THE BOARD - isn't suggesting that the bone loss should be mitigated by cross
>training?

Reading comprehension 101: we're talking about strength training.

>>>Unless you have an unusually weak musclature, you cannot improve your
>>>strength by weight training enough to make anywhere as much difference as
>>>riding your bike. That's why more and more training regimes are dropping
>>>weight training and "cross training" programs for professional cyclists
>>>save
>>>to prevent training boredom.
>>
>> Again, your evidence for this assertion is?
>
>I love you guys and your assertion that somehow a printed article (most of
>which are written by students) indicates authority.
>
>Here's a clue - you don't have one.

Did a google search and came up with all kinds of articles supporting
strength training for cycling. Cited two of them in a post in this
thread, with a legit question as to whether they held up.

In the other corner, we have engineering legend Jobst Brandt telling
us it's al b.s. - but citing no evidence. Holding Jobst's towel is
Tom Kunick, fawning all over Jobst like a loyal butt-boy, yes-manning
the strength is overrated mantra - but again, no evidence other than
if Jobst says it, it must be true.

Run that clue thing by me again?

 

[[email protected]]

Please tell me this wide ranging (it did start as a discussion of
powercranks, correct?) argument is not dead. I am not even a cyclist,
just a runner and rower who stumbled onto this thread by complete
accident, kept reading because I have always believed in a scientific
(to the extent it is even possible) approach to training and find such
discussions interesting regardless of the sport they are being applied
to, and am now rather enjoying this refresher of the 6 weeks we spent
on logic in my Philosophy 101 lecture in college. Perhaps I can stir
the pot a bit (without injecting any venom into the conversation by
either reacting to, nor taking, any personal potshots) by pointing out
that from where I am standing it looks like the current argument pits
Mr. Brandt's personal anecdotal evidence refuting the need for non-
cycling strength training against Mr. Taylor's citations to studies
ostensibly showing the benefits of non-cycling strength training to
cycling performance. Now, from what I gather Mr. Brandt's anecdotal
evidence is compelling because of his high level of achievement in the
sport (I apologize if I am understating this, again, I am not a
cyclist and must admit that I do not know the name) but, never-the-
less, it refelects the experience of one individual. As I write this
it occurs to me that he can probably cite other individuals whith a
similar training philosophy who have achieved equally high levels of
performance, but even so I believe that the argument is that non-
cycling strength training can improve on-the-bike performance, not
that high levels of achievement cannot be obtained without it, so that
simply pointing out really good cyclists who do not strength train
does not really prove that much of a point. On the other side we have
Mr. Taylor's assertion, in support of which he has cited a few
articles/studies. Now, I have not even followed the links and read any
of these, and I have no opinion whatsoever as to their scientific
validity. However, it does not seem that so far any of these have been
refuted beyond vague and generalized assertions about the validity of
exercise physiology studies in general (what I believe was being
refered to as "being written by students"). So, it seems that the
progression of the argument stands as such:

1) Baseline assumption: The best way to train for cycling is by
cycling (to the exclusion on non-cycling strength training)
2) Anecdotal evidence in support of baseline assumption (a rather
compelling case, but anecdotal all the same): Mr. Brandt has achieved
very high levels of cycling achievement by following our baseline
assumption
3) Assertion of an alternative hypothesis: Non-cycling strength
training can improve cycling performance more than cycling exclusively
4) Citation of "authority" is support of the alternative hypothesis

Now, I put "authority" in quotation marks not as a dig at its
reliability (of which I express no opinion whatsoever, I am neither
scientist nor engineer), but rather to highlight what appears to me as
one of the two ways forward (at least, if the goal is to progress the
argument rather than to respond to personal affronts with personal
counter-attacks).

a) Specifically discredit all of the "authorities" cited by pointing
out specific and significant flaws (which will spawn side arguments, I
know, but leaving that issue aside for the present) thereby leaving
our alternative hypothesis as an unsupported claim, at least and until
other authorities can be found to support it (which has not been done
yet, beyond the vague generalities mentioned above)

-or-

b) Cite some actual authorities in support of the baseline assumption
(and when I say "authorities" I am not talking just about people [in
which case I would use the word "experts"] I mean any verifiable
evidence). For example "more and more training regimes are dropping
weight training and "cross training" programs for professional
cyclists" - which/whose training regimes? How about some numbers on
this?

Now, it is late, I am tired, and my train of thought has completely
derailed so I will leave my synopsis at that. Thanks for humoring me,
I hope this thread remains a lively debate, and I apologize for my
prodigious use of punctuation in place of properly constructed
senetences (I know my copy of Strunk and White is in this desk
somewhere...). If nothing else perhaps someone will at least find it
worthwhile/compelling/amusing to poke holes in my thought process. I
look forward to it.

Jason

 

[[email protected]]

On Jun 20, 9:30 am, [email protected] wrote:
[snip]

http://home.earthlink.net/~acoggan/setraining/

 

[Tom Kunich]

<[email protected]> wrote in message
news:[email protected]...
>
> a) Specifically discredit all of the "authorities" cited by pointing
> out specific and significant flaws (which will spawn side arguments, I
> know, but leaving that issue aside for the present) thereby leaving
> our alternative hypothesis as an unsupported claim, at least and until
> other authorities can be found to support it (which has not been done
> yet, beyond the vague generalities mentioned above)

You don't need to discredit these studies. You only need to discredit their
findings which are usually based on preconcieved notions. Remember, it isn't
unusual for 10 studies on a subject to be done and half find opposite the
other half. This doesn't make the studies wrong, it makes the interpretation
of them quesitonable.

As I pointed out in an earlier posting, most of these studies are done by
Master's and PhD candidates who are simply doing work for their degrees.
Most of them couldn't care less about the subject or the result and are only
in it for the publication credit towards their degrees. They are judged more
on not making experiment design errors more than on the experiment itself.

Think about this - claiming that doing arm curls with heavy weights will
make your legs work better.

 

[Bill]

Tom Kunich wrote:
> <[email protected]> wrote in message
> news:[email protected]...
>> a) Specifically discredit all of the "authorities" cited by pointing
>> out specific and significant flaws (which will spawn side arguments, I
>> know, but leaving that issue aside for the present) thereby leaving
>> our alternative hypothesis as an unsupported claim, at least and until
>> other authorities can be found to support it (which has not been done
>> yet, beyond the vague generalities mentioned above)
>
> You don't need to discredit these studies. You only need to discredit their
> findings which are usually based on preconcieved notions. Remember, it isn't
> unusual for 10 studies on a subject to be done and half find opposite the
> other half. This doesn't make the studies wrong, it makes the interpretation
> of them quesitonable.
>
> As I pointed out in an earlier posting, most of these studies are done by
> Master's and PhD candidates who are simply doing work for their degrees.
> Most of them couldn't care less about the subject or the result and are only
> in it for the publication credit towards their degrees. They are judged more
> on not making experiment design errors more than on the experiment itself.
>
> Think about this - claiming that doing arm curls with heavy weights will
> make your legs work better.
>
>
Maybe if you were doing squats while doing the curls???
Sorry, couldn't resist.
Bill Baka

 

[Doug Taylor]

On Thu, 21 Jun 2007 15:47:56 -0400, Doug Taylor
<[email protected]> wrote:


>As everybody in this forum knows or should know, it is hard to think
>of any sport which hurts as much and can elevate your heart rate as
>high as skate skiing, where, for example, you find yourself gliding up
>the same hills in winter that you have to dismount your mtn. bike to
>get over in summer. The muscular effects no doubt are pretty much
>non-specific or even irrelevant to cycling, but the cardiovascular
>benefits certainly carry over. Same with classic skiing.

> And certainly, if I were a professional or highly
>competitive Cat 1, 2 or even 3 or 4 cyclist, I'm sure the vast
>majority of my training would be cycling specific and that cross
>training would be largely for mental health purposes.
>beneficial, and beats the hell out of cycling 24-7-365, and certainly
>slaving on the basement trainer.

Well maybe not.

Jason McCartney, after finishing 3rd in the TOC Stage 5 23.5k ITT on
February 23, 2007:

"You know it is interesting because I haven’t been riding my bike
much," said McCartney about his time since camp, spent at his home in
Iowa. "I have just been skiing a lot. We had a real bad cold snap
where it was zero degrees and so I haven’t been able to ride my bike
since camp. But I ski between 2 and 4 hours. I wasn’t sure how my form
was going to be here but I think skiing helped me stay fit."

 

[[email protected]]

On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
> On Jun 5, 11:04 pm, "Phil Holman" <piholmanc@yourservice> wrote:
>
> > <[email protected]> wrote in message
> > > In recent times, steam RR locomotives, although not rated in Horse
> > > Power (but rather "tractive effort", the pull at which the wheels
> > > would spin) had a conversion chart to HP based on grate area in the
> > > fire box which governs how much heat can be transferred to steam in
> > > the boiler. Grate area is closely similar to lung displacement for
> > > physically fit racers. That is what limits climbing or TT ability,
> > > not ankling, pedaling style or other external means.
>
> > You continue to repeat this misconception. Lung displacement or lung
> > capacity is not the limiting factor in climbing or TTing or cycling in
> > general. If you understood the cause and effect elements you would
> > understand that extreme "out of breath" is caused by excess CO2 in the
> > blood stream as a result of lactic buffering.
>
> Great! Now we have one engineer feeding misconceptions about how
> physiology functions to another engineer...

No, now we have an exercise physiologist trying to correct someone
with a correct understanding of the limiter. I am truly amazed that
you haven't figured out what is going on here yet.

>
> Fact: CO2 plays only a very limited role in regulating ventilation
> during exercise.

Fact: There are two main drivers for ventilation. CO2 and O2. The main
one is CO2. The body adjusts ventilation to maintain the arterial
partial pressure of CO2 at 40torr. CO2 is the prime determiner of
ventilatory function at all times except during extreme hypoxia, which
never occurs during normal exercise.

>
> > That is, the limits of
> > aerobic capacity were reached upstream (cardiac output, blood muscle
> > interface limitations etc) and no further limitations are imposed by the
> > lungs. It wouldn't matter if you doubled lung capacity, blood lactate
> > concentrations wouldn't change and this is the culminating event in
> > limiting aerobic performance. Heavy breathing is an effect not a cause.
>
> In fact, mild-to-moderate arterial desaturation tends to occur during
> maximal exercise in a significant portion of the population (at least
> discounting young, healthy, untrained men!), indicating that, at least
> to some extent, aerobic capacity (i.e., VO2max) is limited, in part,
> by pulmonary function.
>
> Andy Coggan

Phoeey. A small arterial desaturation is most likely explained by
increased left to right shunting and ventilation perfusion mismatch at
the extremes and is probably has no effect on performance because of
the oxyhemoglobin saturation curve. There could be other explanations
also such as a shift in the curve due to changes in pH. Small levels
of desaturation have almost no effect on oxygen carrying capacity to
the tissues.

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
>
> > In fact, mild-to-moderate arterial desaturation tends to occur
> > during maximal exercise in a significant portion of the population
> > (at least discounting young, healthy, untrained men!), indicating
> > that, at least to some extent, aerobic capacity (i.e., VO2max) is
> > limited, in part, by pulmonary function.
>
> Phoeey. A small arterial desaturation is most likely explained by
> increased left to right shunting

Left to right shunting from where to where through what? This term is
usually used to indicate left to right shunting through an atrial septal
defect or cases of tricuspid atresia. There should be little or no left
to right shunting through a patent foramen ovale and should be no
shunting at all in a normal heart. So I am not clear to what you refer.
Thanks.

 

[[email protected]]

On Jul 30, 2:53 pm, Tim McNamara <[email protected]> wrote:
> In article <[email protected]>,
>
> [email protected] wrote:
> > On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
>
> > > In fact, mild-to-moderate arterial desaturation tends to occur
> > > during maximal exercise in a significant portion of the population
> > > (at least discounting young, healthy, untrained men!), indicating
> > > that, at least to some extent, aerobic capacity (i.e., VO2max) is
> > > limited, in part, by pulmonary function.
>
> > Phoeey. A small arterial desaturation is most likely explained by
> > increased left to right shunting
>
> Left to right shunting from where to where through what? This term is
> usually used to indicate left to right shunting through an atrial septal
> defect or cases of tricuspid atresia. There should be little or no left
> to right shunting through a patent foramen ovale and should be no
> shunting at all in a normal heart. So I am not clear to what you refer.
> Thanks.

My bad, I should have said increased right to left shunting although
this is not so much as a physiological shunt but as a ventilation
perfusion defect behaving as a shunt.

 

[Tim McNamara]

In article <[email protected]>,
[email protected] wrote:

> On Jul 30, 2:53 pm, Tim McNamara <[email protected]> wrote:
> > In article <[email protected]>,
> >
> > [email protected] wrote:
> > > On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
> >
> > > > In fact, mild-to-moderate arterial desaturation tends to occur
> > > > during maximal exercise in a significant portion of the
> > > > population (at least discounting young, healthy, untrained
> > > > men!), indicating that, at least to some extent, aerobic
> > > > capacity (i.e., VO2max) is limited, in part, by pulmonary
> > > > function.
> >
> > > Phoeey. A small arterial desaturation is most likely explained by
> > > increased left to right shunting
> >
> > Left to right shunting from where to where through what? This term
> > is usually used to indicate left to right shunting through an
> > atrial septal defect or cases of tricuspid atresia. There should
> > be little or no left to right shunting through a patent foramen
> > ovale and should be no shunting at all in a normal heart. So I am
> > not clear to what you refer. Thanks.
>
> My bad, I should have said increased right to left shunting although
> this is not so much as a physiological shunt but as a ventilation
> perfusion defect behaving as a shunt.

That didn't really clarify. Ventilation defects are generally caused by
obstructions somewhere in the airway; perfusion defects are generally
caused by emboli in the pulmonary vasculature. What is the cause of the
"ventilation perfusion defect" you are pointing towards? Does this
occur in non-pathological individuals?

I trimmed the rest of your previous post in an over-zealous fit of good
netiquette, unfortunately. It would appear that Nielsen (2003) found
that arterial desaturation during exercise is multifactoral and that
large lung capacity does offer some protection from this. Perhaps this
link offers some light on the subject:

http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids
=14617055&dopt=AbstractPlus

 

[[email protected]]

On Jul 30, 9:56 pm, Tim McNamara <[email protected]> wrote:
> In article <[email protected]>,
>
>
>
> [email protected] wrote:
> > On Jul 30, 2:53 pm, Tim McNamara <[email protected]> wrote:
> > > In article <[email protected]>,
>
> > > [email protected] wrote:
> > > > On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
>
> > > > > In fact, mild-to-moderate arterial desaturation tends to occur
> > > > > during maximal exercise in a significant portion of the
> > > > > population (at least discounting young, healthy, untrained
> > > > > men!), indicating that, at least to some extent, aerobic
> > > > > capacity (i.e., VO2max) is limited, in part, by pulmonary
> > > > > function.
>
> > > > Phoeey. A small arterial desaturation is most likely explained by
> > > > increased left to right shunting
>
> > > Left to right shunting from where to where through what? This term
> > > is usually used to indicate left to right shunting through an
> > > atrial septal defect or cases of tricuspid atresia. There should
> > > be little or no left to right shunting through a patent foramen
> > > ovale and should be no shunting at all in a normal heart. So I am
> > > not clear to what you refer. Thanks.
>
> > My bad, I should have said increased right to left shunting although
> > this is not so much as a physiological shunt but as a ventilation
> > perfusion defect behaving as a shunt.
>
> That didn't really clarify. Ventilation defects are generally caused by
> obstructions somewhere in the airway; perfusion defects are generally
> caused by emboli in the pulmonary vasculature. What is the cause of the
> "ventilation perfusion defect" you are pointing towards? Does this
> occur in non-pathological individuals?
>
> I trimmed the rest of your previous post in an over-zealous fit of good
> netiquette, unfortunately. It would appear that Nielsen (2003) found
> that arterial desaturation during exercise is multifactoral and that
> large lung capacity does offer some protection from this. Perhaps this
> link offers some light on the subject:
>
> http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_...
> =14617055&dopt=AbstractPlus

You are right that ventilation perfusion "abnormalities" can be multi-
factorial. However, some differences are normal. Gravity has a huge
effect on blood flow distribution through the lungs and very little
effect on ventilation distribution. Luckily for us God designed us to
accomodate for this gravitational effect and we were designed to
maximize oxygen transfer in the upright position. Turns out that more
of our inspired air goes into the part of the lung near the diaphragm
and less near the apex (the top near the neck). Luckily, that is the
bottom of the lung where gravity makes it natural for more blood to
go, especially at lower flow rates. At rest and when upright this
distribution is very well balanced. However, as one exercises, more
blood flow "forces" a higher percentage of the blood volume to go
towards the apex where ventilation is less (this "forcing" occurs
because once the lower alveolar capillaries are "maxed out" any
additional flow must move further up the chain where there is room to
accomodaate it). This would change the ventilation perfusion
relationship tending to naturally lower arterial oxygen saturation at
higher efforts. Further, in cycling, one isn't necessarily in the
"optimum" upright position, which can change this relationship further.

 

[[email protected]]

On Jul 30, 9:56 pm, Tim McNamara <[email protected]> wrote:
> In article <[email protected]>,
>
>
>
> [email protected] wrote:
> > On Jul 30, 2:53 pm, Tim McNamara <[email protected]> wrote:
> > > In article <[email protected]>,
>
> > > [email protected] wrote:
> > > > On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
>
> > > > > In fact, mild-to-moderate arterial desaturation tends to occur
> > > > > during maximal exercise in a significant portion of the
> > > > > population (at least discounting young, healthy, untrained
> > > > > men!), indicating that, at least to some extent, aerobic
> > > > > capacity (i.e., VO2max) is limited, in part, by pulmonary
> > > > > function.
>
> > > > Phoeey. A small arterial desaturation is most likely explained by
> > > > increased left to right shunting
>
> > > Left to right shunting from where to where through what? This term
> > > is usually used to indicate left to right shunting through an
> > > atrial septal defect or cases of tricuspid atresia. There should
> > > be little or no left to right shunting through a patent foramen
> > > ovale and should be no shunting at all in a normal heart. So I am
> > > not clear to what you refer. Thanks.
>
> > My bad, I should have said increased right to left shunting although
> > this is not so much as a physiological shunt but as a ventilation
> > perfusion defect behaving as a shunt.
>
> That didn't really clarify. Ventilation defects are generally caused by
> obstructions somewhere in the airway; perfusion defects are generally
> caused by emboli in the pulmonary vasculature. What is the cause of the
> "ventilation perfusion defect" you are pointing towards? Does this
> occur in non-pathological individuals?
>
> I trimmed the rest of your previous post in an over-zealous fit of good
> netiquette, unfortunately. It would appear that Nielsen (2003) found
> that arterial desaturation during exercise is multifactoral and that
> large lung capacity does offer some protection from this. Perhaps this
> link offers some light on the subject:
>
> http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_...
> =14617055&dopt=AbstractPlus

By the way, I found the Nielsen article (the link didn't work for me)
that I think you referred to. It supports what I said ("A widening of
the PAO2-PaO2 difference does indicate that a diffusion limitation, a
ventilation-perfusion mismatch and/or a shunt influence the transport
of O2 from alveoli to the pulmonary capillaries."), although I am not
sure the author fully understands all the variables contributing to
these possibilities. Further, I found this sentence very interesting:
"During maximal exercise, an extreme lactate spill-over to blood
allows pH decrease to below 7.1 and according to the O2 dissociation
curve this is critical for SaO2." This finding supports the view that
"exercise is limited by the periphery" over the "exercise is centrally
limited" argument. something I have always maintained to the constant
derision of some of the so-called "experts" here and elsewhere, like
Dr.Coggan. I will add it to my quiver. Thanks for the link

 

[Michael Press]

In article
<[email protected]>
,
[email protected] wrote:

> On Jun 7, 11:57 am, Andy Coggan <[email protected]> wrote:
> > On Jun 5, 11:04 pm, "Phil Holman" <piholmanc@yourservice> wrote:
> >
> > > <[email protected]> wrote in message
> > > > In recent times, steam RR locomotives, although not rated in Horse
> > > > Power (but rather "tractive effort", the pull at which the wheels
> > > > would spin) had a conversion chart to HP based on grate area in the
> > > > fire box which governs how much heat can be transferred to steam in
> > > > the boiler. Grate area is closely similar to lung displacement for
> > > > physically fit racers. That is what limits climbing or TT ability,
> > > > not ankling, pedaling style or other external means.
> >
> > > You continue to repeat this misconception. Lung displacement or lung
> > > capacity is not the limiting factor in climbing or TTing or cycling in
> > > general. If you understood the cause and effect elements you would
> > > understand that extreme "out of breath" is caused by excess CO2 in the
> > > blood stream as a result of lactic buffering.
> >
> > Great! Now we have one engineer feeding misconceptions about how
> > physiology functions to another engineer...
>
> No, now we have an exercise physiologist trying to correct someone
> with a correct understanding of the limiter. I am truly amazed that
> you haven't figured out what is going on here yet.
>
> >
> > Fact: CO2 plays only a very limited role in regulating ventilation
> > during exercise.
>
> Fact: There are two main drivers for ventilation. CO2 and O2. The main
> one is CO2. The body adjusts ventilation to maintain the arterial
> partial pressure of CO2 at 40torr. CO2 is the prime determiner of
> ventilatory function at all times except during extreme hypoxia, which
> never occurs during normal exercise.
>
> >
> > > That is, the limits of
> > > aerobic capacity were reached upstream (cardiac output, blood muscle
> > > interface limitations etc) and no further limitations are imposed by the
> > > lungs. It wouldn't matter if you doubled lung capacity, blood lactate
> > > concentrations wouldn't change and this is the culminating event in
> > > limiting aerobic performance. Heavy breathing is an effect not a cause.
> >
> > In fact, mild-to-moderate arterial desaturation tends to occur during
> > maximal exercise in a significant portion of the population (at least
> > discounting young, healthy, untrained men!), indicating that, at least
> > to some extent, aerobic capacity (i.e., VO2max) is limited, in part,
> > by pulmonary function.
>
> Phoeey. A small arterial desaturation is most likely explained by
> increased left to right shunting and ventilation perfusion mismatch at
> the extremes and is probably has no effect on performance because of
> the oxyhemoglobin saturation curve. There could be other explanations
> also such as a shift in the curve due to changes in pH. Small levels
> of desaturation have almost no effect on oxygen carrying capacity to
> the tissues.

I am incompetent to assess these matters. I have read
very little, but got the impression that the limiting
factor in aerobic work capacity is the mitochondria
themselves.

--
Michael Press

 

[Joe Riel]

Michael Press <[email protected]> writes:

> I am incompetent to assess these matters. I have read
> very little, but got the impression that the limiting
> factor in aerobic work capacity is the mitochondria
> themselves.

That's why I am desiging nanopowercranks;
they allow the mitochondria to train themselves!

--
Joe Riel