I was not going to get into this debate, and I will not as far as powercranks go, until there is enough data on the subject gathered specifically from the use of powercranks. Otherwise, we are simply making educated (or not so educated guesses) about why they work or do not work. Standard physiology thinking says no, Frank says yes, but until there is more experiment all of us must agree that there is no *specific* data and we are all just blowing smoke.

However, I will say that Frank has missed the boat on this one. Brodsky's post about cardiac output being the limiter was right on. You and I both learned this in physiology in med school, Frank. I'd be interested to know where you got any idea otherwise. (Seriously, I'm not trolling here I am wondering if there was some work I am not aware of).

Philbert

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Dr. Philip Skiba
Scientific Training for Endurance Athletes now available on Amazon!

All excellent points, Brodsky. Welcome to the group.

Philbert

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Dr. Philip Skiba
Scientific Training for Endurance Athletes now available on Amazon!

The fact that one can force more blood through a small exercising muscle mass than through a very large exercising muscle mass, because BP can be kept higher with lower CO is not proof that the limiter to oxygen delivery is the heart or crdiac output. Your "suddenly increased blood flow perfused all muscle mass you would be on the floor" explanation does not work either as such is not possible in healthy individuals (or give me an instance of where this has occurred in the absence of a pathological condition like shock).

As with most pumps, output pressure will drop some as pumped volume increases. Since the distribution through the muscle is purely passive, this will affect the amount of blood that can get through the existing capillary bed. However, the heart is not the limiter unless it cannot respond to increased demand. To increase the demand and to improve oxygen delivery all one needs to do is to train more to develop a more dense capillary bed. This both increases the caapillary cross section but also decreases the mean diffusion distance, making delivery of oxygen more efficient. This new improved muscle can therefore pass more blood and deliver more oxygen even though there may be a nominally lower blodd pressure. The question is, is the heart the limiter? In the absence of cardiac disease, it is not. It is simply a matter of interpretation of the data and the basic understanding of how oxygen is delivered to the tissue. You and your friend have got it wrong.

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Frank,
An original Ironman and the Inventor of PowerCranks

RIP wrote: "Brodsky is correct, and you are wrong. The evidence is as follows:

1) there is very little O2 left in venous blood draining muscle during exercise at/near VO2max,

2) increasing O2 delivery to muscle results in an increase in VO2max.

The capacity of muscle to utilize O2 is therefore clearly not limiting, at least during exercise engaging more than a small fraction of the total muscle mass.

Being generous, I assume that the reason he understands this simple fact and you do not is just because he has studied exercise physiology, and you have not. "

Little oxygen in the veous blood at VO2 max is evidence the muscle has extracted all it is capable of, not that the heart cannot increase cardiac output if the muscle could take more.

Misinterpretation of the data is misinterpretation of the data regardless of what he has studied. Perhaps I understand this and he doesn't is because I had many years training as an MD anesthesiologist where delivery of oxygen to the tissues under all sorts of awful circumstances is the number one job. Understanding what is really going on and what makes it easier and harder helps in this job.

It is a relatively easy job to increase cardiac output without changing oxygen consumption.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

Philbert wrote: "You and I both learned this in physiology in med school, Frank. I'd be interested to know where you got any idea otherwise. (Seriously, I'm not trolling here I am wondering if there was some work I am not aware of). "

I didn't learn that in medical school and i doubt you did either. What I learned was that CO simply responded to peripheral demands. The main determinant of CO response to exercise is venous return which is determined by peripheral demands. To say otherwise requires there to be an active control of the heart to provide cardiac output primarily in anticipation of peripheral demands. It don't work that way. If the heart were the limiter we would all stop exercising in response to chest pain.

Even if we were taught that in medical school, one of the things I was taught in medical school was: "50% of what we are teaching you will be deemed wrong in 10 years, only problem is we don't know which 50%" If we were taught that, it was part of the wrong 50%.

Fran

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Frank,
An original Ironman and the Inventor of PowerCranks

alright. you fellers can talk that o2 stuff all day, but this is more to me:

"As any experienced skier will tell you, the skate technique is actually quite easy to master. If, however, you try it with old-fashioned wooden skis (remember those?) or the early fiberglass ones (waxed or waxless), you won't find yourself going any faster. This is why no one, including myself, ever used it except in certain situations. Again, it wasn't until much stiffer fiberglass skis that kept the kick wax from dragging on the ground all the time came along that people realized the potential. The skate technique in skiing is therefore much more akin to clapskates than it is to, say, the Fosbury flop. "



blah blah. how intriguing. i really do think rip should run for office - just blather on in a pedantic tone about complete rubbish and it MUST be right. in this case, tho, as in most of his drivel, nothing actually is with the key point being he would actually know that already if he had actually DONE it. same as it ever was, with rip.

easy to master? uhhhh no. stand in wave 2 or 3 to wave 14 of the birkie and watch those people and tell me how easy it is to master - those enthusiats certainly haven't.

try it on older skiis and it isn't faster? uhhhh, no again. the technique was ALWAYS faster, how could it not be? maybe you just sucked at it, or maybe you were too stupid to scrape your kick wax off or maybe - more likely - you would rather write about something you don't know about because you were ( are) too lazy to bust your ass sufficiently to put yourself in an actual position of knowledge.

it wasn't till better eqipment came along that it was practical? uhhhhh, no again. where do you think that equipment CAME FROM? it came from people who . . . . . pay attention now rip . . . . . . had DONE IT making demands and requests for it. we knew it was there, we put in the time, and then we got ski makers to make it easier so lazy knowitalls like yourself could do it too. that is how it happened.

and, the analogy still holds. early skating was hard, it was not fully understood, and it was not for everybody, and idiot physiacally lazy knowitalls who couldn't do it with large vocabulary's always badmouthed it with various overworded and irrelevant faux-scientific jargon to stroke themselves. in the early days it took more out of you than it gave back. sound familiar?

you don't get it, and you are too freaking lazy to find out better for yourself - a pitiful state of being, to be sure. that you would take the next step and continue on prattling like you do given your lack of real experirence is so sad as to actually be maddening, from the sense of waste.

So, RIP, which would be the better oxygen delivery lottery to win? Increase CO capability lottery or the increased capillary density (increased ability of the muscle to pass blood and extract oxygen) lottery. I'll go for the second. You go for the first.

Actually, it isn't necessary to win the lottery for the less than elite as through training, one does develop the muscle capability and the CO capability follows. it is not the other way around.

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Frank,
An original Ironman and the Inventor of PowerCranks

Look RIP, you (all all the others) can claim that deliveryof oxygen during exercise is different than at other times if you want. Fine. Show me some data to indicate what has changed and I may believe it (depending upon the data, of course). I for one think I have a pretty good understanding of this stuff and until I have some data to indicate that my understanding is wrong I will continue to believe same. Your pronouncements that I am lacking don't bother me. Give me some data that means something.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

mr day. you are asking rip to produce data that means something, and i am asking him to obtain practical experience in the subjects he spouts off about. i guess your request counts double in the sense that you have experience in holding people's very lives in your hand based on your knowledge of the subject you are debating and he . . . . . . . . . . ho hum . . . . . . does not.

most people would, you know, find those request sorta reasonable.

i got a buck that sez rip will be undaunted by either request, however.

there you go mr day, you owe me a buck.

RIP, you ought to review what determines CO. Inthe absence of external cardiac stimulant drugs which can transiently affect CO, CO is determined mostly by venous return.

Epo works, not because it increases CO, but because it improves the amount of oxygen the muscle can extract using the existing capillary density and CO. The limiter is the local muscles ability to extract oxygen from the blood, not the ability of the heart to deliver oxygen to the muscle.

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Frank,
An original Ironman and the Inventor of PowerCranks

Don't worry, I am not going to take your word for it. Who is Michael Kjaer? Why isn't he here so we can ask him?

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Frank,
An original Ironman and the Inventor of PowerCranks

Tim,

the best scientists try to develop theories that support observation. In this instance, the PC opponents here will not even attempt to observe the devices, simply proclaiming they cannot work. You were an opponent once who was willing to let them speak to you themselves and you were converted. The PC's are so powerful they can overcome the strongest bias, if theyare given a chance. You are correct in pushing them to get some real experience.

In view of my academic arguments, I am simply someone with an appropriate background that refuses to be bullied by their "your not smart enough to understand this stuff so trust me" argument.

Frank

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Frank,
An original Ironman and the Inventor of PowerCranks

If you can show specific evidence to support this statement, we might be able to put this issue to bed once and for all.

Thanks again to all for the informative and entertaining debate.

RipVanNotAPCerChameleon,

Why don't you write up the difinitive paper on why PowerCranks can't work/don't work? Also, consider coming out from behind the shroud of you handles, step up and let us know who you are and why we should buy any of your arguments.

I'm pretty sure I know why you have not/will not do either of these things. I think you know too...

Cluck cluck...

I think you've got a slam dunk if you can show some evidence that say... during a repeated, sub max single leg knee extension (with similar forces and contraction frequencies that the quad group would see during cycling or running at VO2max) that O2 extraction is incomplete.

If during whole body exercise that extraction is complete, and if the muscle group is worked in isolation with similar forces and frequencies of contraction and the extraction is not complete; it seems to me your argument would be proven and even Frank would come around.