The Powercrank Thread

[FrankDay]

We can see what Frank would like us to believe but fortunately good people like Dr Martin have armed us with quality data that would suggest it is just marketing smoke and mirrors.

LOL. What Frank would like you to believe is that everyone (even those who have never heard of PowerCranks) use all of the muscles of the legs to generate power around the entire pedaling circle. Now, thanks to the wonderful data of Dr. Martin, that is, finally, easily demonstrated to the "just push harder" crowd. It simply makes sense to me that if one is interested in increasing power that it would be better to try to better train all those muscles (and, perhaps, a little more) than to concentrate on a few of them involving only a small part of the circle. PowerCranks simply make that "train them all" choice "easily" possible while also, hopefully, doing a little something for technique too.

 

[MarkvW]

It isn't a matter of "fixing" anything. It is a matter of gaining power. A watt on the "pulling" side is just as valuable as a watt on the pushing side. Just as a watt over the top is just as valuable as a watt anywhere else. Look at how weak those riders were going over the top, a part of the pedal stroke that you claim you are just as strong as their pushing. There is lots to be gained, if not "fixed", in what those people were doing.

Thanks for the great example of an ipse dixit. You are a wonderful source of them.

 

[Alex Simmons/RST]

LOL. What Frank would like you to believe is that everyone (even those who have never heard of PowerCranks) use all of the muscles of the legs to generate power around the entire pedaling circle. Now, thanks to the wonderful data of Dr. Martin, that is, finally, easily demonstrated to the "just push harder" crowd. It simply makes sense to me that if one is interested in increasing power that it would be better to try to better train all those muscles (and, perhaps, a little more) than to concentrate on a few of them involving only a small part of the circle. PowerCranks simply make that "train them all" choice "easily" possible while also, hopefully, doing a little something for technique too.

And yet training with Powercranks does not result in performance improvements over and above those attainable with regular cranks.

 

[FrankDay]

Thanks for the great example of an ipse dixit. You are a wonderful source of them.

Huh? If anything is an example of an Ipse Dixit

Ipse dixit, Latin for "He, himself, said it," is a term used to identify and describe a sort of arbitrary dogmatic statement which the speaker expects the listener to accept as valid.[1]

it would be the post From Dr Martin declaring simply what was measured as not needing fixing. What the heck does "doesn't need fixing" mean if the athlete wants to increase power? He can't because there is nothing to "fix". The pattern is perfect as it is? Or, what? A truly stupid conclusion from such a paucity of data. The data was very pertinent to this discussion but that statement regarding its meaning was truly bizarre coming from such a learned person.

 

[FrankDay]

And yet training with Powercranks does not result in performance improvements over and above those attainable with regular cranks.

unless you believe the Dixon study but let's not do that back and forth again.

 

[M Sport]

It isn't a matter of "fixing" anything. It is a matter of gaining power. A watt on the "pulling" side is just as valuable as a watt on the pushing side.

Do you have any evidence available that shows there is no loss in total power being generated by chasing additional watts in pulling up? i.e. what is being lost in the downstroke?

Would one be better off just training smarter to increase total watts?

 

[CoachFergie]

And yet training with Powercranks does not result in performance improvements over and above those attainable with regular cranks.

Don't forget Dixon!!!

Oh wait yes that proves powercranks work as much as my study disproves the utility of the performance manager in WKO+

Although have to say my study is a sensation on Twitter and Slowtwitch from various sources.

Only one person touting Dixon and it's not one of the authors, bwah ha ha ha ha!!! One of the Dixon authors wrote a couple of paragraphs in Cutting Edge Cycling about powercranks and didn't even mention the study!!!

 

[elapid]

Rarely, am I shown to be in error.

LOL. Rarely do you recognize you are in error and you never admit you are in error. However, your errors are numerous. Recent examples of your errors include not knowing the difference between a reflex and a learned behaviour (another thread), ignoring the role of the lower leg muscles and ankle in power and efficiency, and stating that the gluteal muscles are involved in action on the stifle (and perhaps that the knee is not a joint). I am not an engineer, MD or exercise physiologist, but I can still pick your errors pretty easily.

 

[elapid]

All I meant to imply is that when the femur moves the anatomical part of the body generally referred to as "the knee" moves with it.

The knee is not a passive joint. If the only musculature in the leg was the gluteals, then this assumption would be true. However, with large muscle groups responsible for flexion and extension of the knee (quads, hamstrings, gastrocnemius, etc), the gluteals have no direct or passive affect on knee action. If you make such basic assumptions which are plainly erroneous, then the basis of any of your other arguments are immediately weakened.

 

[elapid]

unless you believe the Dixon study but let's not do that back and forth again.

Then why mention it when you know you will be shot down by the weight of the evidence against you and PCs?

 

[sciguy]

Jim,

Thanks so much for stopping by and providing us with a very thought provoking piece regarding the forces seen throughout the pedaling cycle. Teasing out the net muscular power from the pedal power really makes the whole issue easier to think about. That fact that the information is derived directly from actual data collected during research allows one to have a much greater level of trust in the implications compared to just randomly hypothesizing about the issue involved.

I greatly look forward to any future installments on the topic of pedaling biomechanics that you may make.

Hope the courses and grant writing don't keep you too busy to stop by on occasion. We can really use your research/data based inputs.

Hugh

 

[JamesCun]

The knee is not a passive joint. If the only musculature in the leg was the gluteals, then this assumption would be true. However, with large muscle groups responsible for flexion and extension of the knee (quads, hamstrings, gastrocnemius, etc), the gluteals have no direct or passive affect on knee action. If you make such basic assumptions which are plainly erroneous, then the basis of any of your other arguments are immediately weakened.

Rarely would I agree with frank. But, the knee joint can move in space without the knee angle changing. Sure would be easier to talk about the upper leg/thigh/femur moving, but I think most understand that the knee moves up and down when you pedal a bike.

 

[FrankDay]

Jim,

Thanks so much for stopping by and providing us with a very thought provoking piece regarding the forces seen throughout the pedaling cycle. Teasing out the net muscular power from the pedal power really makes the whole issue easier to think about. That fact that the information is derived directly from actual data collected during research allows one to have a much greater level of trust in the implications compared to just randomly hypothesizing about the issue involved.

I think you will find that his data doesn't reflect directly measured values but rather reflects reverse engineered calculated values from a model. The only directly measured data, I am sure, is the total pedal force data and some rider biometric measurements (to help calculate leg mass and moments). This type of data has been widely available for years even though anyone experienced in this area would have known that muscle work and power had to be generated on the backstroke this is the first time I have seen someone develop a model and publish this breakdown so that those not experienced in this area can look beyond pedal forces and better understand what is really going on.

If it isn't clear that the entire circle is used in generating power (whether the rider fully unweights or not) after seeing this data something is seriously wrong with your analytical ability. The only question should be now is what use do you want to make of this information.

 

[coapman]

The only question should be now is what use do you want to make of this information.

I could ask CoachF the same question when he sees the verification graph of my maximal torque through 12, 1 and 2 technique.

 

[FrankDay]

Do you have any evidence available that shows there is no loss in total power being generated by chasing additional watts in pulling up? i.e. what is being lost in the downstroke?

Sure, but is is mostly anecdotal evidence as few here believe the Dixon study.

Would one be better off just training smarter to increase total watts?

Just what does "training smarter" mean to you? Ignoring 2/3 of the circle because the power generated there is smaller than that seen on the downstroke. As a general rule, isn't it easier to train up under trained muscles than well-trained muscles? If I wanted to "train smart" I think I might want to look for any under trained muscles I might have rather than ignoring them because they are weak and concentrate on the well trained muscles I have. But, I look forward to hearing your definition of "training smart."

 

[FrankDay]

I could ask CoachF the same question when he sees the verification graph of my maximal torque through 12, 1 and 2 technique.

We are all waiting.

 

[FrankDay]

LOL. Rarely do you recognize you are in error and you never admit you are in error.

Sure I do, check out post 882 in this very thread.

However, your errors are numerous. Recent examples of your errors include not knowing the difference between a reflex and a learned behaviour (another thread), ignoring the role of the lower leg muscles and ankle in power and efficiency, and stating that the gluteal muscles are involved in action on the stifle (and perhaps that the knee is not a joint). I am not an engineer, MD or exercise physiologist, but I can still pick your errors pretty easily.

Your weak knowledge base in certain areas or lack of reading comprehension is not particularly good evidence I have made errors. But, it is the internet so you are, of course, welcome to state your opinion.

 

[coapman]

We are all waiting.

Then maybe you can answer the question.

 

[sciguy]

I think you will find that his data doesn't reflect directly measured values but rather reflects reverse engineered calculated values from a model.

Hence my use of the term derived.

Originally Posted by sciguy

That fact that the information is derived directly from actual data collected during research allows one to have a much greater level of trust in the implications compared to just randomly hypothesizing about the issue involved.

 

[FrankDay]

Hence my use of the term derived.

Cool, missed that. Of course, anyone the least bit practiced here would have known these two types of forces were present and that it was likely that positive muscular forces existed around the entire circle. What had not been done before was even an attempt to quantify these forces. I have been saying that for years to the derision of those who look at those negative forces and thought no work was being done on the upstroke. What Martin's data does is, by using his model, puts a magnitude to these various forces and documents that the muscles do actual work around the entire circle and that the entire circle is involved in power production (the total power being the average produced by the muscles around the entire circle. Of course, his model has yet to be verified but it looks to give reasonable results and is a lot better than nothing.

 

[Bio_McGeek]

Okay, I am just looking over comments that have been made since my post. Goodness, this is a congenial group!
One of the points of contention seems to be related to my use of the word fix. My point was that since there is rarely negative muscular power there is nothing inherently wrong with typical pedaling. Others seem to thing that fixing should include improving. Specifically making greater use of flexion actions. Of course, anyone can increase power during flexion when cycling at 250w. Its submaximal so the cyclist is free to choose the extent to which each joint contributes. In a recent paper by Elmer we looked at biomechanics across a range of net powers at 90 rpm. Below you will see a figure I made from that data. Its shows the relative contribution of each work or power producing joint action to overall crank work for a cycle. Keep in mind this is relative contribution so work is increasing with each increment in net power. Also, I used work in this figure because using power gets complicated. By far, the most work is done with hip extension across all powers. The contributions of knee extension and flexion as well as ankle extension vary with power. The cyclists in this study tended to increase the relative contribution of work done by knee flexion and decreased the relative contribution of knee extension.
These data make it clear that cyclists can use knee extension to a greater extent than they typically do but choose not to. Why would they choose not to? One explanation would be that its less efficient. The studies that I know of in which cyclists have been instructed to increase pulling have all shown that it is less metabolically efficient even though it is more mechanically effective. A limitation of those studies is that they were acute changes and so more practice might have shown different results. I recently had a paralympic cyclist in my lab and the data will put this argument to rest. Its not published yet so I can't disclose it yet. Maybe a year or so from now I can reveal.
Edit: I have just added a figure of absolute rather than relative work by each joint action. This may give a much better impression of how each joint action increases with power.
Cheers,
Jim
[URL=http://s1035.photobucket.com/user/jimmartin4/media/AbsoluteJointwork_zpsf75f9a9b.jpg.html][/URL]

 

[FrankDay]

Then maybe you can answer the question.

you said you could ask the question after you showed the verification graph.

I could ask CoachF the same question when he sees the verification graph of my maximal torque through 12, 1 and 2 technique.

I would be happy to answer the question after you show the verification graph. As I said, we are still waiting for that.

 

[sciguy]

Jim.

What great food for thought and discussion.

Much appreciated

Hugh

 

[CoachFergie]

Yes, thanks Jim, that is really great insight into what is really happening. Some very cool science coming from your lab!

 

[FrankDay]

Okay, I am just looking over comments that have been made since my post. Goodness, this is a congenial group!
One of the points of contention seems to be related to my use of the word fix. My point was that since there is rarely negative muscular power there is nothing inherently wrong with typical pedaling. Others seem to thing that fixing should include improving. Specifically making greater use of flexion actions.

Since I was the one who was critical of that term I will address your point. To me, the phrase "no need to fix" implies some sort of perfection. You should know that one needs to choose ones words carefully or the meaning can be easily misconstrued. Nothing in that data suggests that there isn't substantial room for improvement in both technique and better use of different muscle groups. And, you misinterpret my seeming fixation on "flexion" action. While I do believe improvement can be achieved through better use of the hip flexors I believe that the biggest improvements come from better use of the extension muscles, specifically the knee extenders to use them earlier to improve forces over the top and to stop them sooner to avoid wasted efforts well beyond 3 o'clock. The point being that there seems to be plenty of room for improvement in both training underutilized muscles better and in changing technique to use what muscles we have more effectively.

Of course, anyone can increase power during flexion when cycling at 250w. Its submaximal so the cyclist is free to choose the extent to which each joint contributes. In a recent paper by Elmer we looked at biomechanics across a range of net powers at 90 rpm. Below you will see a figure I made from that data. Its shows the relative contribution of each work or power producing joint action to overall crank work for a cycle.

This chart raises more questions than it answers.

1. I would be especially interested in seeing your data that led you to conclude that the ankle extension (whatever that means, I presume you mean ankle plantarflexion) contributes 20% of the total work. I simply don't believe it. I don't see enough ankle motion to contribute that kind of work, especially ankle motion in the direction of pedal motion. Remember for a muscle to do any work it must shorten and to do any pedaling work that shortening must be directed to move the pedal forward. I simply don't see that occurring that allows the ankle to contribute as much power as the quads.
2. Oh, and what about ankle dorsiflexion, what does it contribute?
3. Most of the studies I have seen show that unweighting on the backstroke increases more (as a percentage) than pushing increases on the downstroke as the power increases. How does that jibe with reduced work being done by the hip flexors being reduced with increasing power?
4. And, the question you raised, Why is the work of the knee extensor falling off with increased power?

Keep in mind this is relative contribution so work is increasing with each increment in net power. Also, I used work in this figure because using power gets complicated. By far, the most work is done with hip extension across all powers.

That makes sense as that is the biggest muscle and the muscle whose timing is most effective and the muscle which is heavily trained compared to the others (excepting the quads, perhaps).

The contributions of knee extension and flexion as well as ankle extension vary with power. The cyclists in this study tended to increase the relative contribution of work done by knee flexion and decreased the relative contribution of knee extension.
These data make it clear that cyclists can use knee extension to a greater extent than they typically do but choose not to.

Choose? You are presuming the "choice" is a rational one because of some benefit? There might be other explanations. While you cn hypothesize all you can really say is you observed this and the reasons deserve further investigation.

Why would they choose not to? One explanation would be that its less efficient. The studies that I know of in which cyclists have been instructed to increase pulling have all shown that it is less metabolically efficient even though it is more mechanically effective.

Yes, and in those studies the cyclists never could quite do what they were asked to do. And, doesn't it make sense that asking someone to do something they are not used to doing but which could be more effective might give a negative result if they were not very good at the task?

A limitation of those studies is that they were acute changes and so more practice might have shown different results.

Indeed. Just how much practice is necessary is the question. I might suggest that you take this data and then recruit some extremely experienced PowerCrankers (several years of immersion training) and compare pedaling style. It seems that would give you a hint of the potential of the various muscle groups for improved training. Below I will add the measured pedaling technique of a pro triathlete with about 10 years of PowerCranks training behind him. Such a technique can only be accomplished with a pretty flat muscular work rate being observed around the entire circle.

I recently had a paralympic cyclist in my lab and the data will put this argument to rest. Its not published yet so I can't disclose it yet. Maybe a year or so from now I can reveal.
Cheers,
Jim

Thanks for getting back after my pretty critical remark. At least we can discuss the data that does exist and the potential that exists in that data. For instance, would you please confirm for the crowd here that a watt gained on the down stroke is not any more valuable than a watt gained on the backstroke or over the top. Whether it can be easier or harder to achieve in one place or another or not is a different discussion but the bicycle simply doesn't care where the watts are generated.

Note this athlete is actually doing positive work on the upstroke and about the same amount of work over the top as across the bottom. Compared to the work distribution of Dr. Martin's subjects this subject (pro triathlete Petr Vabrousek) has a very even work distribution.