Dr. Jeff Broker on pedaling

Congratulations Dr. Coggan,

Of all the people who have ever gotten on the cranks (I believe you have been on them once) you are the only one who has ever presumed that training with Powercranks wouldn’t change the way someone pedals a bicycle into a more “circular” pattern. So, let’s presume you are correct (you could be because Luttrell didn’t “measure the pattern of force application” so who knows what changes the PC’s caused.) So, then, how would you explain the Luttrell results? Are you proposing that six weeks of PowerCranks changed the muscle fibre type in these subjects, since we “know” this could improve efficiency (that is what Coyle presumed in his “study” of Lance Armstrong so it isn’t that far fetched, although that study went on for 6 years, not 6 weeks). Or, is there another explanation.

However, I am aware of people who have looked at EMG changes associated with PC use so people have demonstrated that PC’s do change the lower extremity coordination, from which we might be able to infer this changes force application but, of course, it isn’t proof to types like you. Dixon gathered this data but we won’t actually see it for awhile in a paper I am told. There is at least on other study just underway (and maybe another just finishing) in which EMG data is also being collected along with the metabolic and power data so we will see what this shows. Once one or two researchers show PowerCranks change pedaling style occurs will you accept that this is one of the things that PC’s actually do without each reasearcher reproducing this each study?

I must say, I think everyone who has ever trained with this device must be snickering at your objection here. Thanks for the chuckle.

Oh, and I am glad you can think of several studies that “addressed this very question”. Name one that measured pedaling style (or presumed a pedaling style, a la Luttrell) and efficiency, and then effectively caused the athlete to change pedaling style and then remeasured efficiency. I look forward to your reply.

I think it would be more productive if we all got together and fought to the death. Last man standing gets to proclaim what is the “truth”, and the rules are that he’s not allowed to get into a circular discussion with himself.

Is this “Testa” the doctor of the BMC team? Did he say anything of interest?

Frank, do you believe there is one and only one correct way to power the pedals ?
No
.

Uhh, that would be me. I don’t recall being angry, but I’m sorry I made a two day conference seem like a week to you.
For the record, I thought Jeff Broker’s presentation (along with Dan Heil and Rick Neptune) was one of the best of the
symposium.

After Jeff’s presentation what do you now know about pedaling that you did not know before ?

Well there’s what you know and what you have proven through research.

The most interesting presentations were the ones that elicited more questions, rather then providing answers. In Jeff Broker’s case, I found the decomposition of pedaling forces (muscular, gravitational, inertial) interesting. I always new this was the case but had never seen it quantified before. I am not ready to concede the point that technique is worthless (or next to worthless, as one attendee who I had dinner with both nights suggested) but being able to get a true picture of the muscular input to pedal forces was very interesting.

I also thought Jeff’s brief comment on variability in skilled tasks was interesting. The idea being that some variation in pedaling technique is worthwhile in that it can produce changes in muscle recruitment and provide a degree of rest to the “primary” muscles recruited in pedaling.

Rick Neptune’s modeling of muscle recruit was also a highlight for me.

Jeff’s “bottom line,” if you can call it that, is that pedaling technique can be changed through feedback and practice but to what end is not clear as “a masher can still be world road race champion” (with a photo of Lance Armstrong). It is interesting to note that since Lance won worlds he had changed his technique, at least visually, although he has not been back to Jeff’s lab to measure any changes in pedal forces.

As with all good conferences, there was plenty of food for thought and plenty of questions still to be answered.

As I think about this again, I think I know where the “angry redhead” comment stems from. One of the most frustrating aspects of the SICI conference for me was the return of KOPS (knee over pedal spindle). I thought this idea was long dead among any one who has ever turned a critical eye to bicycle positioning.

KOPS is at best a happy coincidence and at worst completely arbitrary bike fit folklore. At one point I polled the panel as to who believed in KOPS and was dismayed at how many of these experts still use KOPS (even some who conceded that it is an arbitrary measure).

The other frustrating aspect of the conference is that most of the questions that I had when I first became interested in the science of bike fit (at the Texas A&M wind tunnel in '97 – when I met the likes of Andy Coggan, Jim Martin, Doug Milliken and Dave Kennedy) are still unanswered and for the most part unstudied TEN YEARS LATER! However, I think some of the discussions I had with the presenters and over dinner show that conferences like this can help focus the discussion and even get us to agree at least what terms like “hip angle” really mean!

By the way, we didn’t end the conference with any consensus on how to measure “hip angle.” :slight_smile:

To me the uncrossable gulf seems to be that the folks who don’t really put any faith in pedaling circles feel that way because they think it isn’t worth it to try and train new muscles to do new things. They would rather just use big muscles to do more of what they already do.

The spinning circles folks say just the opposite, you CAN train the newm muscles to do new things.

I don’t see how those two positions are affected by these data.

Read the last sentence of the quote I posted: it isn’t about training “new” muscles to do “new things” (or just read this: http://www.me.utexas.edu/...Papers/essr30(4).pdf).

Dr. Coggan, here is the last sentence you posted: “Indeed, the effort to eliminate them can actually cost a rider energy and efficiency.”

and here is part of the summary of the paper you referred to: “. . . also, as noted above, the counter-torque need not be the result of negative work performed by muscles. If, for the sake of theoretical argument, we assume that the muscle coordination can be timed perfectly so that the negative work done by individual muscles is negligible, then the total mechanical work done by all muscles must be exactly equal to the total external workload (assuming no transmission losses in the drive system). Because it is impossible to get more work out of the system than is put into it, a pedal-crank mechanism could not result in more work from the same pedal (or muscle) forces in this case. To do so would mean a perpetual motion machine, with energy created by the mechanism… Thus, a pedal-crank mechanism design should be based on the force-length-velocity-activation relationships of skeletal muscle and their influence on the cost of generating muscle force, not only on the mechanical work performed.”

As I have read this paper again I think it makes a good argument for pedaling in circles. They make the argument that internal work is pretty much the same regardless of pedaling style as long as no active muscle force is used in applying the counter torque, something we can all agree probably doesn’t exist except in riders less than 5 years old where the “optimum” coordination is still being learned and those with neurologic diseases such as cerebral palsey where relaxation does not occur easily.

So, it concludes that if the counter torque is caused by gravity it has no detrimental effect on overall efficiency. From this analysis it concludes that overall power is mainly influenced by how much muscle is used during the stroke. (“the total mechanical work done by all muscles must be exactly equal to the total external workload”) From this, one can conclude (as you and others have) that the best way of increasing muscle mass is to “just push harder”. But, others (a larger number of people, amongst coaches anyhow) have concluded that increasing “the total mechanical work done by all the muscles” is more efficiently done by invoking more muscles into the equation, by pedaling in circles, rather than trying to use the same pushing muscles more, which will necessarily invoke more of the less metabolically efficient fast twitch fibres in those muscles. Of course, it would also be compatible with both solutions together, pushing harder and pedaling in circles. This paper is compatible with all arguments and does not prove or disprove any of the above arguments.

Even though I still take issue with some of what they say I think this paper agrees with my summary above.

Comments?

To me the uncrossable gulf seems to be that the folks who don’t really put any faith in pedaling circles feel that way because they think it isn’t worth it to try and train new muscles to do new things. They would rather just use big muscles to do more of what they already do.
The spinning circles folks say just the opposite, you CAN train the newm muscles to do new things.
I don’t see how those two positions are affected by these data.
Read the last sentence of the quote I posted: it isn’t about training “new” muscles to do “new things” (or just read this: http://www.me.utexas.edu/...Papers/essr30(4).pdf).
Dr. Coggan, here is the last sentence you posted: “Indeed, the effort to eliminate them can actually cost a rider energy and efficiency.”
and here is part of the summary of the paper you referred to: “. . . also, as noted above, the counter-torque need not be the result of negative work performed by muscles. If, for the sake of theoretical argument, we assume that the muscle coordination can be timed perfectly so that the negative work done by individual muscles is negligible, then the total mechanical work done by all muscles must be exactly equal to the total external workload (assuming no transmission losses in the drive system). Because it is impossible to get more work out of the system than is put into it, a pedal-crank mechanism could not result in more work from the same pedal (or muscle) forces in this case. To do so would mean a perpetual motion machine, with energy created by the mechanism… Thus, a pedal-crank mechanism design should be based on the force-length-velocity-activation relationships of skeletal muscle and their influence on the cost of generating muscle force, not only on the mechanical work performed.”
As I have read this paper again I think it makes a good argument for pedaling in circles. They make the argument that internal work is pretty much the same regardless of pedaling style as long as no active muscle force is used in applying the counter torque, something we can all agree probably doesn’t exist except in riders less than 5 years old where the “optimum” coordination is still being learned and those with neurologic diseases such as cerebral palsey where relaxation does not occur easily.
So, it concludes that if the counter torque is caused by gravity it has no detrimental effect on overall efficiency. From this analysis it concludes that overall power is mainly influenced by how much muscle is used during the stroke. (“the total mechanical work done by all muscles must be exactly equal to the total external workload”) From this, one can conclude (as you and others have) that the best way of increasing muscle mass is to “just push harder”. But, others (a larger number of people, amongst coaches anyhow) have concluded that increasing “the total mechanical work done by all the muscles” is more efficiently done by invoking more muscles into the equation, by pedaling in circles, rather than trying to use the same pushing muscles more, which will necessarily invoke more of the less metabolically efficient fast twitch fibres in those muscles. Of course, it would also be compatible with both solutions together, pushing harder and pedaling in circles. This paper is compatible with all arguments and does not prove or disprove any of the above arguments.
Even though I still take issue with some of what they say I think this paper agrees with my summary above.
Comments?

Once again you appear to be forgetting about unweighting. Pedaling in circles is a weak pedaling style and this is caused by pulling up more than is necessary for total unweighting of idling leg because this extra pulling up power is power lost to main down power leg. In addition attempting to apply insignificant power in the 12 and 6 o’c areas is a distraction which delays and also weakens the main down stroke. Attempting to apply max power to the downstroke while using the total unweighting technique will give best results.

Keep bumping this thread, Frank’s sales are almost back to normal. Football season is always a tough time.

To me the uncrossable gulf seems to be that the folks who don’t really put any faith in pedaling circles feel that way because they think it isn’t worth it to try and train new muscles to do new things. They would rather just use big muscles to do more of what they already do.
The spinning circles folks say just the opposite, you CAN train the newm muscles to do new things.
I don’t see how those two positions are affected by these data.
Read the last sentence of the quote I posted: it isn’t about training “new” muscles to do “new things” (or just read this: http://www.me.utexas.edu/...Papers/essr30(4).pdf).
Dr. Coggan, here is the last sentence you posted: “Indeed, the effort to eliminate them can actually cost a rider energy and efficiency.”
and here is part of the summary of the paper you referred to: “. . . also, as noted above, the counter-torque need not be the result of negative work performed by muscles. If, for the sake of theoretical argument, we assume that the muscle coordination can be timed perfectly so that the negative work done by individual muscles is negligible, then the total mechanical work done by all muscles must be exactly equal to the total external workload (assuming no transmission losses in the drive system). Because it is impossible to get more work out of the system than is put into it, a pedal-crank mechanism could not result in more work from the same pedal (or muscle) forces in this case. To do so would mean a perpetual motion machine, with energy created by the mechanism… Thus, a pedal-crank mechanism design should be based on the force-length-velocity-activation relationships of skeletal muscle and their influence on the cost of generating muscle force, not only on the mechanical work performed.”
As I have read this paper again I think it makes a good argument for pedaling in circles. They make the argument that internal work is pretty much the same regardless of pedaling style as long as no active muscle force is used in applying the counter torque, something we can all agree probably doesn’t exist except in riders less than 5 years old where the “optimum” coordination is still being learned and those with neurologic diseases such as cerebral palsey where relaxation does not occur easily.
So, it concludes that if the counter torque is caused by gravity it has no detrimental effect on overall efficiency. From this analysis it concludes that overall power is mainly influenced by how much muscle is used during the stroke. (“the total mechanical work done by all muscles must be exactly equal to the total external workload”) From this, one can conclude (as you and others have) that the best way of increasing muscle mass is to “just push harder”. But, others (a larger number of people, amongst coaches anyhow) have concluded that increasing “the total mechanical work done by all the muscles” is more efficiently done by invoking more muscles into the equation, by pedaling in circles, rather than trying to use the same pushing muscles more, which will necessarily invoke more of the less metabolically efficient fast twitch fibres in those muscles. Of course, it would also be compatible with both solutions together, pushing harder and pedaling in circles. This paper is compatible with all arguments and does not prove or disprove any of the above arguments.
Even though I still take issue with some of what they say I think this paper agrees with my summary above.
Comments?

Once again you appear to be forgetting about unweighting. Pedaling in circles is a weak pedaling style and this is caused by pulling up more than is necessary for total unweighting of idling leg because this extra pulling up power is power lost to main down power leg. In addition attempting to apply insignificant power in the 12 and 6 o’c areas is a distraction which delays and also weakens the main down stroke. Attempting to apply max power to the downstroke while using the total unweighting technique will give best results.
I guess it depends upon how one defines pedaling in circles. To me “pedaling in circles” doesn’t involve any “unnecessary” pulling up but simply complete unweighting. It requires active movement of the foot around the entire circle and nothing more. It does not require equal pedal force around the entire circle, something that is essentially impossible at any kind of power output. One may be applying “insignificant power” to the pedal during this time but one is not doing insignificant work because one is increasing the potential energy of that “recovery” leg which one converts back into kinetic energy on the down stroke. That is what I refer to as pedaling in circles. It seems to be what you also regard as optimum technique ("Attempting to apply max power to the downstroke while using the total unweighting technique will give best results. ").