The Powercrank Thread

[elapid]

i don't say that because you are not an engineer, I say that because you don't understand it. It is just if you were an engineer you would.

Well, I understand plenty well enough both the topic and that bullying habits like that will not have an effect on me.

nothing.

That's what I thought. If it has absolutely nothing to do with this topic then you are trolling.

The only reason to mention this is to illustrate how little actual power these muscles provide.

I know you do not have very good comprehension skills, but hadn't I already started with this and then repeated it at least twice now? ...

I agree that they don't provide much power compared to the hip flexors and the quads. Stated very plainly in at least two previous posts.

When are you starting those classes again? Perhaps a grasp of English will help you understand some of the more basic concepts that you still cannot comprehend.

actually, the ankle joint can be fixed externally, that is what a cast or splint can do.

How many cyclists do you see cycling with casts or splints? :roll eyes:

My simplification, which ignored the ankle joint, of course requires the assumption that the lower leg muscles function to stabilize the ankle joint to maintain efficiency. That is a reasonable assumption and I would have thought went without saying until running into a nit-picker such as you. Simplifications are supposed to be simple to help make the point one is trying to make more easily understandable. This approach obviously failed with you.

We know you are simple, Frank. Simple is as simple does. Seems preposterous to be talking about fusing ankles or cycling with casts or splints to try and prove a point when the ankle joint is not immobile during pedalling. Seems even sillier when others have shown the importance of the ankle joint and lower leg muscles for cycling efficiency and you continue to disregard their importance. Oh wait, is that because they're not engineers and hence couldn't possibly understand what they are talking about?

 

[FrankDay]

Well, I understand plenty well enough ... Blah blah blah

If you understood this you would have no trouble coming here explaining to the world exactly how and where I am wrong. Show a vector diagram of the forces caused by the various muscles and explain which ones are doing work and which aren't as the foot moves around the circle. Instead all you do is declare yourself knowledgeable and call me names. But, it is the internet. I would hope for more but it is obvious I am not gonna get it.

 

[elapid]

If you understood this you would have no trouble coming here explaining to the world exactly how and where I am wrong. Show a vector diagram of the forces caused by the various muscles and explain which ones are doing work and which aren't as the foot moves around the circle. Instead all you do is declare yourself knowledgeable and call me names. But, it is the internet. I would hope for more but it is obvious I am not gonna get it.

Do not misquote me. The "blah blah blah" is your addition and you should have made that obvious.

What names have I called you?

Diagrams and references have been provided. This would be at least the fifth time that I have stated that the gastrocnemius has a relatively minor role in the generation of power during pedalling compared to the hip flexors and quads. Do I really need to repeat myself again and again? Or are you really that simple?

However, you continue to ignore the importance of the lower leg muscles and ankle for efficiency. Instead you obfuscate by wanting us to assume that cyclists are cycling with casts or splints or surgically fused ankles to make some bizarre point.

 

[JayKosta]

...
However, you continue to ignore the importance of the lower leg muscles and ankle for efficiency. Instead you obfuscate by wanting us to assume that cyclists are cycling with casts or splints or surgically fused ankles to make some bizarre point.

===========================================

I think that all of us AGREE that the lower leg muscles play an important role in the pedaling motion - without them the angle joint would flop around in a very unproductive manner. So YES, they are important for effective pedaling. And of course efficiency depends on effectiveness.

Can we move on?
For lower leg muscles, is there any need to be concerned about the muscular strength, endurance, efficiency, or technique?

Jay Kosta
Endwell NY USA

 

[JayKosta]

That would be explained if the peak force from the glutes occurred after 3. How the torque is distributed depend on the weight of the various leg parts (gravity) and the force and timing of the various muscles.

==========================
I don't understand the mention of
"peak force from the glutes occured after 3"
- I thought your view is that the glutes can't produce much (any?) useful power after 3.

The inclusion of gravity contributing to high force after 3 seems reasonable.

Jay Kosta
Endwell NY USA

 

[elapid]

For lower leg muscles, is there any need to be concerned about the muscular strength, endurance, efficiency, or technique?

Perhaps not revelant to this thread, but there are a variety of factors which may affect all of the factors you have mentioned.

Sciguy has previously mentioned the position of the cleat between mid-foot and the more traditional fore position. The mid-foot cleat position has been championed by Steve Hogg and more on this topic can be seen here.

The mid-foot cleat position is also related to a pedalling technique called ankling which has been proposed by some to be more efficient, particularly at lower cadences as explained here.

 

[FrankDay]

===========================================

I think that all of us AGREE that the lower leg muscles play an important role in the pedaling motion - without them the angle joint would flop around in a very unproductive manner. So YES, they are important for effective pedaling. And of course efficiency depends on effectiveness.

There is a difference between needing the muscles to be effective and whether they actually produce power. Without the lower leg muscles stabilizing the ankle joint the upper leg muscles cannot produce much, if any, power. I think that is pretty obvious. It is like in rowing, the back and shoulder muscles stabilize the back so the large leg muscles can put force into and move the oar. Only after the large leg muscles are through with their work does the back, then the arms continue the stroke to get more work done from these much smaller but not totally ineffective muscles.

Can we move on?
For lower leg muscles, is there any need to be concerned about the muscular strength, endurance, efficiency, or technique?

Jay Kosta
Endwell NY USA

Of course there is, at least regarding strength and endurance because if they are not strong enough they cannot support the ankle for hip power efforts and if they don't have enough endurance they cannot last an entire race. If one wants to talk about efficiency or technique then one is getting into whether ankling is effective or useful, which is not clear to anyone although many have strong opinions about it. I simply, for the purposes of this discussion, think that should be ignored because it is, IMHO, small potatoes regarding the big picture for power production and efficiency.

 

[elapid]

because it is, IMHO, small potatoes regarding the big picture for power production and efficiency.

Well, your opinion is at odds with all the published information regarding the role of the lower leg muscles and ankle in pedalling efficiency. Other than your opinion, which you know how highly most of us regard , where are your analyses and published reports to counter the information that has been published and presented to date?

 

[FrankDay]

==========================
I don't understand the mention of
"peak force from the glutes occured after 3"
- I thought your view is that the glutes can't produce much (any?) useful power after 3.

The glutes move the knee. Depending upon how one is fitted on the bike the direction of the knee changes and pretty much follows the direction of the pedal as one moves from 2-6, reaching maximum effectiveness at around 4:30. I have attached 3 pictures that illustrates what I think should be and what probably is going on here.

The glutes should be able to apply very high forces in the near optimum direction anywhere between these two points so what actually happens depends upon what effort the rider is doing in using this muscle.

The inclusion of gravity contributing to high force after 3 seems reasonable.

The gravity torque component should be highest at 3 but it will remain quite high until about 4, when the direction of pedal motion has changed enough to be a significant factor in reducing its torque producing effect.

 

[elapid]

The glutes move the knee.

The gluteals are hip flexors (as well as abductors and internal rotators). They have nothing to do with the action of the knee. That's the quads.

 

[FrankDay]

The gluteals are hip flexors (as well as abductors and internal rotators). They have nothing to do with the action of the knee. That's the quads.

LOL. Last time I looked the gluteals acted at the hip joint on the femur as a hip extender (the iliopsoas is the hip flexor). Also, last time I looked, the knee was at the end of the femur. Hence, I think it is reasonable to say that the gluteals move the knee. Back to anatomy and english comprehension class for you I am afraid.

 

[elapid]

LOL. Last time I looked the gluteals acted at the hip joint on the femur as a hip extender (the iliopsoas is the hip flexor). Also, last time I looked, the knee was at the end of the femur. Hence, I think it is reasonable to say that the gluteals move the knee. Back to anatomy and english comprehension class for you I am afraid.

Where did you get your medical degree? Look at the origin and insertion of the gluteal muscles. All originate from the pelvis and insert on the femur, and hence their function has everything to do with the hip joint. None insert on the tibia and hence they do not have an action on the knee joint.

Not only do you ignore the lower leg muscles and ankle in power and efficiency, but you have no idea of the action of the gluteal muscles. Talk about someone having to go back to their anatomy books. No wonder your opinion carries such little weight when you cannot even get basic anatomy right.

 

[JayKosta]

...
I have attached 3 pictures that illustrates what I think should be and what probably is going on here.
...

========================
Thanks for the illustrations.
My confusion was that I was thinking about your comments regarding QUADS, while the issue was the GLUTES ....

Jay Kosta
Endwell NY USA

 

[FrankDay]

Where did you get your medical degree? Look at the origin and insertion of the gluteal muscles. All originate from the pelvis and insert on the femur, and hence their function has everything to do with the hip joint. None insert on the tibia and hence they do not have an action on the knee joint.

Not only do you ignore the lower leg muscles and ankle in power and efficiency, but you have no idea of the action of the gluteal muscles. Talk about someone having to go back to their anatomy books. No wonder your opinion carries such little weight when you cannot even get basic anatomy right.

Could you please show me where I said the glutes act on the knee JOINT? Moving the knee is not the same as acting on the knee joint. The knee rotates around the hip. Acting on the hip joint moves the knee. Oh, and in case you missed it, the glutes are not hip flexors as you said, they extend the hip.

 

[sciguy]

Frank,

It seems that your contention that the use of the one's quads from 3 o'clock towards 6 o'clock in the pedaling cycle is is not only useless but also detrimental to performance is not shared by all.

I put the question to Jim Martin.

Jim,

Frank Day made the following statement a few days ago and it just doesn't sit square with my intuition on the topic.

"What most seem to be missing is PowerCranks improve power by improving the effectiveness of the muscles contractions, including the pushing muscles. For instance, most people think of pushing down the same as maybe a weight lifter would do which involves both the glutes and the quads. The problem is that below 3 o'clock on the pedal stroke if one is using the quads the quads would drive the foot forward in relation to the knee when, the pedal is moving backwards. Contracting the quads past 3 o'clock is a complete waste of energy. "

Frank feels that beyond the 3 o'clock position the lower leg should be passively extended using only the force of gravity rather than any activation of the quads. I'm in the camp that feels that the glutes work in concert with the quads even from 3 until 6 o'clock. Frank is caught up working about the extended lower leg going in the wrong direction without considering the effect of the lower leg also being extended at the same time offsetting said motion.

So what are your thoughts on the matter? Have you folks done any emg studies on the subject?

Thanks for any insights you're willing to share.

His response to me:

No, your intuition is fine. The reason Frank's assertion is invalid is because he doesn't account for inter segmental energy transfer aka segmental power balance. Knee extension power can and is still effective. The path that knee power takes, however, is unexpected. It will be delivered first the thigh segment. It will then leave the thigh by crossing the knee as a joint reaction force power term. That takes it down to the lower leg and eventually it will cross the ankle. Sounds crazy or at least unintuitive but I can show you cycling data to support. I recommend David Winter's biomechanics text. When I first found it, I read it like a novel. You might like it as well.
Cheers,
Jim

Before you dismiss any of this out of hand you might want to do a bit of background research regarding David Winter. Seems he was a navy man like you but went on to do some rather significant work of biomechanics.

http://en.wikipedia.org/wiki/David_A._Winter

I expect Jim Martin to be stopping in to add to the discussion of this topic.

Learning is always fun

Hugh

 

[FrankDay]

========================
Thanks for the illustrations.
My confusion was that I was thinking about your comments regarding QUADS, while the issue was the GLUTES ....

Jay Kosta
Endwell NY USA

There is a lot going on and things are constantly changing so it can get confusing. People think pedaling is simple, it is not. It is a complicated sequence requiring the highly coordinated contraction of a large number of muscles. Understanding what the optimum coordination pattern should be is hard enough. Achieving it is even harder.

 

[elapid]

Could you please show me where I said the glutes act on the knee JOINT? Moving the knee is not the same as acting on the knee joint. The knee rotates around the hip. Acting on the hip joint moves the knee.

The glutes move the knee.

What is the knee if it is not a joint? There is no other definition for a knee. Just another pathetic attempt to squirm out of the fact that you have no idea of what you are talking about. The gluteals do NOT move the knee, not passively and not actively. The gluteal muscles do not insert on the tibia and hence do not act on the knee. Acting on the hip joint does not mean they move the knee. The hamstring muscles, which originate on the pelvis and insert on the tibia, and are hence biarticular, act on both the hip and knee joints. Again, go back to your anatomy books, look at the insertions and origins of the gluteal muscles, and their functions and tell me if there is any textbook out there that states that the gluteal muscles have an action on the knee joint.

[I am back home for 4 weeks - I'll check in occasionally when time permits, but I hope someone here will continue to make sure that you do not continue spouting posts full of errors and unsubstantiated opinions]

 

[FrankDay]

Frank,

It seems that your contention that the use of the one's quads from 3 o'clock towards 6 o'clock in the pedaling cycle is is not only useless but also detrimental to performance is not shared by all.

I put the question to Jim Martin.



His response to me:



Before you dismiss any of this out of hand you might want to do a bit of background research regarding David Winter. Seems he was a navy man like you but went on to do some rather significant work of biomechanics.

http://en.wikipedia.org/wiki/David_A._Winter

I expect Jim Martin to be stopping in to add to the discussion of this topic.

Learning is always fun

Hugh

cool but it would be even better if winter showed up as I doubt Martin truly understands this stuff. It is mechanics. If he hasn't taken a statics or dynamics course in engineering school he may not get it. The forces will always balance. The question is whether contracting a muscle at any particular point helps or hurts what one is trying to accomplish.

 

[sciguy]

cool but it would be even better if winter showed up as I doubt Martin truly understands this stuff. It is mechanics. If he hasn't taken a statics or dynamics course in engineering school he may not get it. The forces will always balance. The question is whether contracting a muscle at any particular point helps or hurts what one is trying to accomplish.

Frank, you are one egocentric peace of work. It will be tough to get Dr. Winter on the forum since he passed away in 2012 but if you'll read chapter 7 of his text you might just begin to get a clue.

Hugh

 

[JayKosta]

...
I put the question to Jim Martin.
...

============================
Perhaps Jim Martin can present his views about which muscles produce movement of the pedals at various points around the circle.

Also, I think it is important to differentiate between direct muscle action which exerts immediate force, and muscle action which generates momentum that will continue even after the muscle action stops.
For example, if the downward force from the quads is stopped at 3 o'clock, the momentum of the leg will continue to exert downward force much further.

Jay Kosta
Endwell NY USA

 

[FrankDay]

Before you dismiss any of this out of hand you might want to do a bit of background research regarding David Winter. Seems he was a navy man like you but went on to do some rather significant work of biomechanics.

http://en.wikipedia.org/wiki/David_A._Winter

I expect Jim Martin to be stopping in to add to the discussion of this topic.

Learning is always fun

Hugh

Actually, this got me to thinking. Because of the reactive forces extending the knee after 3 is not a complete waste of energy because the reactive forces would tend to increase the downward pressure on the knee and so would still add some driving force to that provided by the glutes. However this benefit would soon be lost as the pedal starts moving more and more backwards. Further, the question has to be asked if this is the best use of this muscle. Wouldn't it be better starting to rest so it can contract forcefully over the top where the muscle action directly translates to power?

 

[FrankDay]

What is the knee if it is not a joint?

An anatomical feature?

There is no other definition for a knee. Just another pathetic attempt to squirm out of the fact that you have no idea of what you are talking about. The gluteals do NOT move the knee, not passively and not actively. The gluteal muscles do not insert on the tibia and hence do not act on the knee. Acting on the hip joint does not mean they move the knee. The hamstring muscles, which originate on the pelvis and insert on the tibia, and are hence biarticular, act on both the hip and knee joints. Again, go back to your anatomy books, look at the insertions and origins of the gluteal muscles, and their functions and tell me if there is any textbook out there that states that the gluteal muscles have an action on the knee joint.

nor did I state that they did. 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. Sheeese!

[I am back home for 4 weeks - I'll check in occasionally when time permits, but I hope someone here will continue to make sure that you do not continue spouting posts full of errors and unsubstantiated opinions]

LOL. You do such a good job of it.

 

[sciguy]

Actually, this got me to thinking. Because of the reactive forces extending the knee after 3 is not a complete waste of energy because the reactive forces would tend to increase the downward pressure on the knee and so would still add some driving force to that provided by the glutes.

So can I take that as an official apology?

 

[FrankDay]

============================
Perhaps Jim Martin can present his views about which muscles produce movement of the pedals at various points around the circle.

Also, I think it is important to differentiate between direct muscle action which exerts immediate force, and muscle action which generates momentum that will continue even after the muscle action stops.
For example, if the downward force from the quads is stopped at 3 o'clock, the momentum of the leg will continue to exert downward force much further.

Jay Kosta
Endwell NY USA

momentum is a product of pedal speed. Muscle contraction has no influence on momentum except how it influences pedal speed, which for a single rotation at power is a tiny one.

 

[FrankDay]

So can I take that as an official apology?

It goes to the usefulness of discussions such as this as it can help people see errors in their thinking by hearing alternative views, at least to those willing to look introspectively and admit they made an error, which I like to think describes me but doesn't seem to describe everyone here. Anyhow, the question remains as to whether it is smart to be contracting the quad beyond 3. I still hold it is not. But, it you can make a cogent argument my mind can be changed.