The Powercrank Thread

[sciguy]

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I don't see the tie-in to PowerCrank usage, if there is one please elaborate.
If hematocrit level is what is imparing performance gains, the type of training wouldn't make a difference, would it?

I AM interested in non-doping methods that increase hematocrit levels, but that deserves its own thread.

Jay Kosta
Endwell NY USA

Jay,

The crux of the discussion/argument between Frank and most of the rest of the world is the question "what limits one's ability to do aerobic work?". Most exercise physiologists contend that the limit lies within the supply side of the equation with the cardiovascular system. Frank appears to feel it lies in the demand side of the equation. Use more muscles and you body will somehow find O2 to supply them.

Powercranks come to play in the discussion because if one uses them they are forced to use muscles with a less efficient fiber composition and less effective angles of attachment to do work that would be more efficiently done by the anti-gravity muscles which we all have in sufficient abundance. My continued question to Frank is " Why use what's less efficient to do a job that's already well handled by the muscles we train for hours every day and have since?

 

[JamesCun]

let me try to put in a visual format. Let's assume there are 10 pedaling sectors. In each sector there is a different muscle or combination of muscles working to provide power. Unfortunately, gravity also provides some force to the pedals and this can distort our understanding of what the muscles are actually doing. Because gravity is always pulling down this distortion tends to increase the impression of muscle work being done on the down stroke and decrease the impression of muscle work being done on the up stroke.
...

Why have you equalized the power output at each of the 10 sections of the pedal stroke? How does the graph have anything to do with gravity? Why are you suggesting that the upstroke can produce as much power as the downstroke? Would a recumbent bike have the same graph, or a bike that you ride sitting upside down?

Can you do the graphs for improving the riders to pro tour levels? How would it look if he needed to increase to 1000w in a sprint?

 

[JamesCun]

Jay,

The crux of the discussion/argument between Frank and most of the rest of the world is the question "what limits one's ability to do aerobic work?". Most exercise physiologists contend that the limit lies within the supply side of the equation with the cardiovascular system. Frank appears to feel it lies in the demand side of the equation. Use more muscles and you body will somehow find O2 to supply them.

Powercranks come to play in the discussion because if one uses them they are forced to use muscles with a less efficient fiber composition and less effective angles of attachment to do work that would be more efficiently done by the anti-gravity muscles which we all have in sufficient abundance. My continued question to Frank is " Why use what's less efficient to do a job that's already well handled by the muscles we train for hours every day and have since?

+1

The physiologists that I work with are currently focusing on stroke volume and hemoglobin mass as the primary predictors of performance in endurance sports.

 

[FrankDay]

Jay,

The crux of the discussion/argument between Frank and most of the rest of the world is the question "what limits one's ability to do aerobic work?". Most exercise physiologists contend that the limit lies within the supply side of the equation with the cardiovascular system. Frank appears to feel it lies in the demand side of the equation. Use more muscles and you body will somehow find O2 to supply them.

When the first exercise physiologist shows me that the arterial side desaturates at VO2max I might be persuaded. I have yet to see a healthy person desaturate at VO2 max (or at any other time when exercising). Hence, the supply of oxygen has to be adequate. What else could possibly be going on? It is actually quite simple if you understand all of the physiology involved, which most exercise physiologists don't. I am a trained anesthesiologist. If there is one thing anesthesiologists understand it is the physiology of oxygen delivery to the tissues.

"Use more muscles and you body will somehow find O2 to supply them." True, true, and related. Can you explain to me why the same person can test two different VO2max numbers just based upon how they are tested (cycling, running for instance). Or why athletes that use both their upper and lower body have higher VO2max on average (rowers, XC skiers) than those that don't (cyclists, runners)? The CV system adapting to increasing stress and increasing oxygen delivery ability has a lay term to explain what is going on. That term is "training".

Powercranks come to play in the discussion because if one uses them they are forced to use muscles with a less efficient fiber composition and less effective angles of attachment to do work that would be more efficiently done by the anti-gravity muscles which we all have in sufficient abundance. My continued question to Frank is " Why use what's less efficient to do a job that's already well handled by the muscles we train for hours every day and have since?

Wait, wait, where is your authority that these other muscles have less efficient fiber composition or less effective angles of attachment? How on earth do you explain the findings of Luttrell if this were the case?

What you don't understand is that all of these muscles you are so quick to denigrate are used by everyone anyhow. All the PC's force the rider to do is to use them a little more than they do now. You guys have essentially no real world understanding of where the pedal forces are coming form or how muscles work or how oxygen gets to the muscles yet you are willing to tell me I don't know what I am talking about.

It does seem to make sense to use those anti-gravity muscles to their fullest but they really aren't optimized for pedaling, they are optimized for cycling and running. Walking and running involve very little contraction of the Quads, they rather mostly contract isometrically to support the knee and hold the body weight. The knee bends a lot but only when the foot is off the ground and so there is no resistance to movement beyond the mass of the limb. There is no resemblance to cycling per se other than a superficial one.

If you want to examine cycling you should be looking at the specific demands cycling puts on the joints and muscles and the opportunities provided by the motion and constraints and see what might be exploited. Power can be applied anywhere around the circle by any muscle and not just when the foot is on the ground by the antigravity muscles. If you choose to limit your cycling experience to the muscles that serve the runner that is your choice. I just don't think that a very smart choice if one is serious about optimizing performance.

 

[JamesCun]

When the first exercise physiologist shows me that the arterial side desaturates at VO2max I might be persuaded. I have yet to see a healthy person desaturate at VO2 max (or at any other time when exercising). Hence, the supply of oxygen has to be adequate. What else could possibly be going on? It is actually quite simple if you understand all of the physiology involved, which most exercise physiologists don't. I am a trained anesthesiologist. If there is one thing anesthesiologists understand it is the physiology of oxygen delivery to the tissues.

How does blood doping work if people already have enough O2 in the blood to more than satisfy any need...

 

[FrankDay]

+1

The physiologists that I work with are currently focusing on stroke volume and hemoglobin mass as the primary predictors of performance in endurance sports.

I think they will find that the primary predictor is how well trained they are. In equally trained individuals such things may start to make a difference but that is hardly anything important to the average athlete. Anyhow, this is off topic and further discussions along this line should probably go into the physiology thread.

 

[JamesCun]

I think they will find that the primary predictor is how well trained they are. In equally trained individuals such things may start to make a difference but that is hardly anything important to the average athlete. Anyhow, this is off topic and further discussions along this line should probably go into the physiology thread.

It is fundamental to the discussion of what is limiting performance and how PC's would impact that performance. You have made some claims that the limiter is muscle recruitment (since the 'key' muscles are already working as hard as possible).

Can you respond to my other questions about your graphs, and bring it back on topic...

 

[FrankDay]

Why have you equalized the power output at each of the 10 sections of the pedal stroke?

Because you have to break the stroke into segments to analyze it. 10 was a convenient number.

How does the graph have anything to do with gravity?

Because gravity has an awful lot to do with the forces the pedals see.

Why are you suggesting that the upstroke can produce as much power as the downstroke?

Because putting potential energy in the leg on the upstroke returns kinetic energy on the downstroke in a gravitational field such as we find ourselves in on earth.

Would a recumbent bike have the same graph, or a bike that you ride sitting upside down?

No, because "down" (the direction of gravity) is in different parts of the stroke in different cycling positions

Can you do the graphs for improving the riders to pro tour levels? How would it look if he needed to increase to 1000w in a sprint?

In anyone person the basic pedal dynamic usually remains about the same regardless of power (most riders will tend to unweight more at higher powers), all that is increased is the magnitude of the forces.

 

[FrankDay]

How does blood doping work if people already have enough O2 in the blood to more than satisfy any need...

Blood doesn't carry enough oxygen to satisfy every need. Doping (increasing the HCT) increases the amount of oxygen carried by the blood such that it can satisfy more needs before being "exhausted". Luckily for us when the blood cannot deliver anymore oxygen to the muscles it still has plenty for the heart and brain. Here is a link to some reading that might help you understand what is going on. I especially like this quote from the second page. "the circulation of blood in man and other animals is regulated peripherally" … "in human circulation the heart functions as a demand pump." Guess this author isn't one of those esteemed exercise physiologists who say otherwise.

 

[FrankDay]

Here is a link to a pdf on bicycle pedaling that discusses this issue of gravity affecting pedal forces. Discusses just about everything else also. Too bad the average cycling researcher doesn't have his understanding of the problem
Forces in bicycle Pedaling by Papadapalous

 

[coapman]

Because you have to break the stroke into segments to analyze it. 10 was a convenient number.

Does not answer the question which was, why have you equalized the power at each of the 10 sections.

 

[FrankDay]

Does not answer the question which was, why have you equalized the power at each of the 10 sections.

That question was answered when I did the graph the first time. To reiterate, this graph is an effort to demonstrate the work the muscles are actually doing around the pedaling circle because people get confused as to what the muscles are doing when they look at the pedal forces on the pedal thinking that is all coming from the muscles when a large portion of those forces are gravity driven. Read the Papadapalous paper I linked to above as it discusses pretty much everything that is going on and why analysis is so difficult.

 

[coapman]

That question was answered when I did the graph the first time. To reiterate, this graph is an effort to demonstrate the work the muscles are actually doing around the pedaling circle because people get confused as to what the muscles are doing when they look at the pedal forces on the pedal thinking that is all coming from the muscles when a large portion of those forces are gravity driven. Read the Papadapalous paper I linked to above as it discusses pretty much everything that is going on and why analysis is so difficult.

Nothing new or of any interest in that paper, where is the connection with PC's.

 

[FrankDay]

Nothing new or of any interest in that paper, where is the connection with PC's.

There may not be anything new or of interest to you but I thought there might be for others.

Anyhow, the paper simply goes to explaining why it is difficult to analyze muscle use when pedaling and "pedaling technique" by simple measuring of pedal forces. Since PowerCranks are all about changing technique and muscle use I thought it relevant. Sorry you didn't think it so.

 

[FrankDay]

OK, I did another test on another PowerCranker. This is a much more elite rider than Dave, Chris Hopkinson, who holds several worlds records for ultra endurance cycling. He was in San Diego and will be riding this years RAAM and has been on PowerCranks about 4 months. I took the opportunity to test him when he was in the area. I will post two representative pictures that are hard for me to explain. The screen shots are at about the same power (350 watts) and same time of the test 1+ minute into the test and he was on 170 mm cranks. The only difference between the tests was one was in PowerCranks (independent) mode and the other locked up like regular cranks. I cannot explain why the technique is so different (and worse, in my opinion) when the cranks are locked up. If he was not unweighting fully when locked up I could explain that but the changes are mostly across the top and bottom and a change in orientation. Not sure why that would be but it was quite obvious. I suspect this would correct itself as he had more time on the PC's. Too bad I didn't do this with Dave also.
Here is the screenshot of the regular cranks test.

and, the PowerCranks test.

I combined the two in Photoshop to make comparison easier.

 

[FrankDay]

One more combined screen shot, this time looking at an easy power for Chris, about 140 watts. When people lighten up they tend to lighten up everywhere, including the backstroke. This is obvious compared to the 350 watts screen shots shown above. In this case he actually went negative on the right leg (he always seemed to have more trouble with his right leg even though he thought that was his good one before all this testing). What this illustrates is how much going negative affects the rest of the stroke. On the left the difference between PC and regular mode is almost imperceptible. On the right though going negative means the shape of the entire curve is affected and elongated because the loss must be made up somewhere.

 

[coapman]

One more combined screen shot, this time looking at an easy power for Chris, about 140 watts. When people lighten up they tend to lighten up everywhere, including the backstroke. This is obvious compared to the 350 watts screen shots shown above. In this case he actually went negative on the right leg (he always seemed to have more trouble with his right leg even though he thought that was his good one before all this testing). What this illustrates is how much going negative affects the rest of the stroke. On the left the difference between PC and regular mode is almost imperceptible. On the right though going negative means the shape of the entire curve is affected and elongated because the loss must be made up somewhere.

This type of testing proves nothing. Why not do as I requested earlier, after initial acceleration is complete get him to ride at maximal power output for about 30 seconds using PC mode and locked mode for about three or four attempts at each separated mode.

 

[sciguy]

On the left the difference between PC and regular mode is almost imperceptible. On the right though going negative means the shape of the entire curve is affected and elongated because the loss must be made up somewhere.

Frank,

I'm not following why this must be so. edit - Oh to get the same total watts but they could be had from the other leg too??????

Can you explain what the tanish oblong line represents....not talking about the zero line?

Does the screen shot represent a single revolution? Is it possible to see the average of dozens or hundreds of revolutions?

You do of course realize that your presence next to Chris or Dave while testing might have just a tiny bit of influence on their technique as might a couple hours of additional duration.

Hugh

 

[JayKosta]

This type of testing proves nothing. Why not do as I requested earlier, after initial acceleration is complete get him to ride at maximal power output for about 30 seconds using PC mode and locked mode for about three or four attempts at each separated mode.

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Why do you think that a '30 second max output' test would be particularly useful for testing PowerCranks? My understanding is that PowerCranks are primarily for TRAINING aerobic endurance type pedaling - not that they are to be useful during short duration max effort situations.

Jay Kosta
Endwell NY USA

 

[coapman]

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Why do you think that a '30 second max output' test would be particularly useful for testing PowerCranks? My understanding is that PowerCranks are primarily for TRAINING aerobic endurance type pedaling - not that they are to be useful during short duration max effort situations.

Jay Kosta
Endwell NY USA

It's one way of discovering how effective this PC technique is at generating crank torque compared to the trained PC user's freestyle pedalling technique. This would be done at the same gearing of about 52/14. Frank has always claimed it is more powerful than the mashing technique and Coyle's research findings (circular v mashing) are incorrect.

 

[FrankDay]

This type of testing proves nothing. Why not do as I requested earlier, after initial acceleration is complete get him to ride at maximal power output for about 30 seconds using PC mode and locked mode for about three or four attempts at each separated mode.

This type of testing isn't trying to PROVE anything. All it is doing is measuring what each individual is doing under the conditions of the test. And, does demonstrate pedaling that involves zero negatives.

Actually, that is a pretty good suggestion but not for the reason you think. It is clear the PowerCranks have done their job on these folks in eliminating the negatives WHEN THEY ARE FRESH. The problem is testing them to see what they are doing when they are tired, how well is the new technique maintained. I had thought about putting them on the trainer for 2 hours and looking at them when they were fresh and then 2 hours later when they are, presumably, tired. But, a better way might be to simply put them on the trainer and have them ride somewhere between FTP and max and watch what happens as they tire then fail. Such a test wouldn't take more than 5-10 minutes but only one test could probably be run a day. See, there are things to be learned on the internet from people you would never expect to teach you anything. Thanks

 

[FrankDay]

Frank,

I'm not following why this must be so. edit - Oh to get the same total watts but they could be had from the other leg too??????

I tried to choose a representative section that demonstrated the difference between complete unweighting and partial unweighting for the same power in the same person.

Can you explain what the tanish oblong line represents....not talking about the zero line?

The tannish line is the power profile when riding PowerCranks at essentially the same power. So, no negatives allowed. We can see from the left leg that even though negatives are allowed he doesn't have any and the curves are almost identical. but, with the right leg he reverts much more when allowed and develops negative power the last half of the upstroke and then see how he compensates to maintain essentially the same power.

Does the screen shot represent a single revolution? Is it possible to see the average of dozens or hundreds of revolutions?

I am not sure. It is recording the session and I can't tell if it is averaging over a few seconds or giving each revolution. All I know for sure it is what the screen shows and when watching at real time it seems smooth.

You do of course realize that your presence next to Chris or Dave while testing might have just a tiny bit of influence on their technique as might a couple hours of additional duration.

Hugh

I never show the riders the screen when they are testing. They are simply riding their bikes. I am not sure I provide any greater influence on their pedaling technique that the knowledge they have PowerCranks on their bike and they want to work on their technique. When you are in town you can run some studies for me and we will see what influence you have.

I look forward when we have a head unit that will allow us to record what is going on during rides and races. That should eliminate any such bias. Unfortunately, that is not available right now so we are stuck with what we have. Isn't that always the case, the data is never perfect! Such is the life of a scientist.

 

[sciguy]

.I never show the riders the screen when they are testing. They are simply riding their bikes. I am not sure I provide any greater influence on their pedaling technique that the knowledge they have PowerCranks on their bike and they want to work on their technique.
.

And the policeman doesn't need to show me his radar gun for me to instantly take my foot off the pedal when I spy him by the side of the road Knowing that one's pedaling technique is being tested has got to influence it.

Hugh

 

[FrankDay]

And the policeman doesn't need to show me his radar gun for me to instantly take my foot off the pedal when I spy him by the side of the road Knowing that one's pedaling technique is being tested has got to influence it.

Hugh

But, it was being tested whether the cranks were locked or not. I can assure you these folks were just riding their bikes. Further, you criticism applies to all studies looking at pedaling technique. Ignore the data if you choose.

 

[sciguy]

But, it was being tested whether the cranks were locked or not. I can assure you these folks were just riding their bikes. Further, you criticism applies to all studies looking at pedaling technique. Ignore the data if you choose.

With other studies of pedaling technique there was no "agenda" as in "a more ideal way to pedal" that you espouse. That makes it a whole different ball of wax and if you can't see that you're too close.

I do look forward to seeing data for substantial periods of time as in hours taken with the cranks locked.

Hugh