New study shows leg flexion less efficient than extension.

[backdoor]

Re:

And the Performance Artist nicely distracts people from the OP study that showed a cyclist pedalling more like a Gimmickcranker for seven years is more efficient when he changes to a system that allows him to pedal more like a masher. Lets not lose sight of that!

As a coach, this type of research is Gold as it shows me that what I am teaching my riders and most importantly what I am not wasting their time on is good evidence based data.

is this how you do your mashing 12 to 6 o'clock ?

According to Dr Broker, pulling up on the pedal does not increase maximal power output, and in fact it can cause injury. Pulling the pedal up puts a lot of pressure on the hamstrings and the hip flexors. These muscles are designed to lift the weight of the leg against gravity whilst running or walking and struggle to cope with the demand of contracting repeatedly against the resistance of the pedal. As the muscle fatigues, this increases tightness, which can contribute to lower back and hip pain. In addition to this, at recommended cadences of 80-90rpm, the muscular system cannot contract and relax quick enough to deactivate one group of muscles and contract another. In other words, as the left leg pushes down, the right leg cannot get out of the way quick enough to create negative pressure on the pedal, let alone generate force in an upwards direction.

In short, pulling on the upstroke does not work. So what is the correct pedal technique? Dr Broker advocates directing all your power into the downward stroke, starting the stroke at 12 o’clock, and ending it at 6 o’clock. This is termed the ‘drive phase’. As the drive phase is coming to an end on one leg, it should be beginning on the other leg, while the first leg relaxes. Peak torque during the drive phase should occur around the 3 o’clock position.

 

[CoachFergie]

Re: Re:

...
is more efficient when he changes to a system that allows him to pedal more like a masher.
...

----
Yes, the counter-weight 'could' allow him to pedal more like a masher, and it just as well 'could' allow him to pedal more like 'circular pedaling', or more like un-coupled crank pedaling (which doesn't require strong positive torque on the upstroke).

What do you see in the OP abstract/article that suggests that his style with counter-weight was 'mashing'?

Jay Kosta
Endwell NY USA

Guess you could look at the other research in the area as well, you would ask the question why efficiency is improved, and you could have experience of working with para riders with amputation above the knee and see the differences in how they have to ride when they can use a prosthesis (which acts as a counterweight) or have to ride with their stump in a pod as per Paralympic regulations. Could also talk with guys like Jim Martin and read all the research in the area not just cherry pick those abstracts that confirm your particular bias.

 

[CoachFergie]

Re: Re:

Dr Broker advocates directing all your power into the downward stroke, starting the stroke at 12 o’clock, and ending it at 6 o’clock. This is termed the ‘drive phase’. As the drive phase is coming to an end on one leg, it should be beginning on the other leg, while the first leg relaxes. Peak torque during the drive phase should occur around the 3 o’clock position.

Did Broker say that or is that what Jacques voice in your head is telling you?

In his chapter in High-Tech Cycling (2nd ed.) he doesn't mention this in his review of forces around the pedal stroke.

 

[Alex Simmons/RST]

Re: Re:

I didn't say you mentioned the null hypothesis but you don't have to as you are attempting to assign a percentage to the chance of differences being real based on a p-value.
You keep making this false statement that I have bolded, it does nothing of the kind and this has been pointed out to you over and over. Yet more trolling.

Frank is a lost cause when it comes to discussion free of logical fallacies.

Indeed I play a game of logical fallacy bingo when Frank posts. It can be quite entertaining.

 

[CoachFergie]

Now if you said drinking game I would book the next flight to Sydney!

 

[backdoor]

Re: Re:

Dr Broker advocates directing all your power into the downward stroke, starting the stroke at 12 o’clock, and ending it at 6 o’clock. This is termed the ‘drive phase’. As the drive phase is coming to an end on one leg, it should be beginning on the other leg, while the first leg relaxes. Peak torque during the drive phase should occur around the 3 o’clock position.

Did Broker say that or is that what Jacques voice in your head is telling you?

In his chapter in High-Tech Cycling (2nd ed.) he doesn't mention this in his review of forces around the pedal stroke.

If that is how he pedals, his pedalling effectiveness is at a minimum wasting energy in the 12-1 and 5-6 o'clock sectors.
http://www.telegraph.co.uk/men/active/recreational-cycling/10840824/How-to-cycle-with-the-technique-of-a-pro.html

 

[acoggan]

Re: New study shows leg flexion less efficient than extensio

[quote="FrankDayUncoupled cranks is nothing like one-legged pedaling (because there is a counterweight on the other side making it unnecessary to unweight with additional force)[/quote]

<sarcasm mode on>

Yes, that's precisely why they are so easy to use from the git-go, making no adaptation period necessary.

<sarcasm mode off>

Fact: as far as the physics of leg motion are concerned, there is absolutely no difference between uncoupled cranks and one-legged pedaling without a counterweight.

 

[JamesCun]

Re: New study shows leg flexion less efficient than extensio

Uncoupled cranks is nothing like one-legged pedaling (because there is a counterweight on the other side making it unnecessary to unweight with additional force)

<sarcasm mode on>

Yes, that's precisely why they are so easy to use from the git-go, making no adaptation period necessary.

<sarcasm mode off>

Fact: as far as the physics of leg motion are concerned, there is absolutely no difference between uncoupled cranks and one-legged pedaling without a counterweight.

I missed that one. Frank is back to saying that uncoupled cranks act as a counterweight and transfer energy from one leg to the other. What a farce.

 

[FrankDay]

Re: Re:

...
It is not a reasonable use of the statistic, the statistic cannot be used to assign a probability of the null hypothesis being true or false, this has been pointed out several times and is in the article you have quoted. You CANNOT use a p-value in this way,
...

-------------------------------------------
From the wiki article - https://en.wikipedia.org/wiki/P-value -
An equivalent interpretation is that p-value is the probability of obtaining the observed sample results, or "more extreme" results, when the null hypothesis is actually true (here, "more extreme" is dependent on the way the hypothesis is tested).[2]

I think the article says that
IF the null hypothesis is TRUE.
THEN the p-value is the probability of getting the observed results

similaraly,
If the results are due to chance
then the probability of getting the observed results is the p-value.

Jay Kosta
Endwell NY USA

This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false, but it is not what Frank is trying to do. It is this rubbish that started this conversation:

Many of you will note that they show "no difference". Of course, there are differences but they just don't reach the P<.05 level of significance.
For instance: Gross efficiency in the PC group improved from 19.7 to 20.9 (a 6% improvement) while the control group improved from 19.8 to 20.3 (a 2.5% improvement). This difference only reached the 0.25 level of significance. So, there is a 1 in 4 chance this difference is due to chance or a 3 in 4 chance (75%) the differences are real.

Then, time-trial power. The PC group improved from 284 to 298 watts (5%) while the control group improved from 274 to 281 watts (2.5%). This difference only reached the 0.125 level of significance. So, there is a 1 in 8 chance this difference is due to chance or a 7 in 8 chance (87.5%) the differences are real.

He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong.

Where on earth do you see me saying that???!!! Where do I mention null hypothesis? What I say is that the p sets the probability that this data is true. Nothing more, nothing less.

I didn't say you mentioned the null hypothesis but you don't have to as you are attempting to assign a percentage to the chance of differences being real based on a p-value.
You keep making this false statement that I have bolded, it does nothing of the kind and this has been pointed out to you over and over. Yet more trolling.

Huh? Just what is a p-value in your mind? If the p-value is the probability of whatever is being measured not being due to chance what is the reciprocal of the p-value equal?

 

[FrankDay]

Re:

...
This is true Jay, notice it only refers to the result under a certain condition, it does not refer to the likelihood of a hypothesis being true or false,
...
He was attempting to use the p-value to assign a probability that the hypothesis is true. This is categorically wrong. This statistic cannot attach probabilities to hypotheses. This is clearly stated in the article:

--------------------------------------------------
I agree, it's a complex and subtle difference (well to me anyhow...) that the
p-value indicates the likelihood of the TEST DATA being obtained WHEN the null hypothesis is TRUE.
And NOT that the p-value (from the test data) indicates the likeliness of the null hypothesis BEING true.

Jay Kosta
Endwell NY USA

We all agree with this although I think you should substitute IF for WHEN.

 

[CoachFergie]

Re: Re:

Dr Broker advocates directing all your power into the downward stroke, starting the stroke at 12 o’clock, and ending it at 6 o’clock. This is termed the ‘drive phase’. As the drive phase is coming to an end on one leg, it should be beginning on the other leg, while the first leg relaxes. Peak torque during the drive phase should occur around the 3 o’clock position.

Did Broker say that or is that what Jacques voice in your head is telling you?

In his chapter in High-Tech Cycling (2nd ed.) he doesn't mention this in his review of forces around the pedal stroke.

If that is how he pedals, his pedalling effectiveness is at a minimum wasting energy in the 12-1 and 5-6 o'clock sectors.
http://www.telegraph.co.uk/men/active/recreational-cycling/10840824/How-to-cycle-with-the-technique-of-a-pro.html

Well I guess a newspaper article is better than the voice of Jacques in your head but still not a peer review article or text where Broker gives a specific recommendation.

 

[acoggan]

Re: Re:

If the p-value is the probability of whatever is being measured not being due to chance what is the reciprocal of the p-value equal?

First, it's not the reciprocal of alpha (i.e., 1/alpha) you've been touting, it's 1-alpha.

Second, 1-alpha != beta.

 

[PhitBoy]

Re: New study shows leg flexion less efficient than extensio

Nothing has really changed in the hundred plus posts since I wrote:

I love these science denier threads! They remind me of "Merchants of Doubt". FD is particularly good at denial because he actually does understand at least some of the science and mixes accurate facts with propaganda. Very effective technique to manipulate the weak minded; essentially what conservative talk show hosts do. Just enough fact to confuse the fiction. Coapman/Backdoor/Perfection claims to have the most perfect pedaling technique on the face of the earth but has refused repeated invitations to have his technique analyzed at British Cycling in Manchester or at Brunel University in London. I would assume that means he doesn't want his fantastic pedaling technique exposed as fantasy.
Anyway, I believe the salient bits of the debate in this thread as well as the pedaling technique thread are:
1. Two studies in the peer reviewed literature have shown that cyclists are less efficient when they follow instructions to pull up more (Korff et al 2007 and Mornieux et al 2008)
2. Another paper shows that pedaling with one leg is less efficient that pedaling with two legs or than pedaling with a counterweight (Burns et a., 2014)
3. FD argues that these are acute interventions and those tested did not have the proper technique that they would get from prolonged training with decoupled cranks. Uncoupled cranks force the rider to pedal as if he was doing single leg cycling with no counterweight.
4. The study mentioned by the OP is a case study of a hip level amputee who has done nothing but single leg non counterweighted cycling for seven years. This should be very nearly the equivalent of long term training with decoupled powercranks. This four time US Paralympic National Champion was more efficient with a counterweight.
5. We know from the abstract by Elmer et al 2015 that cyclists pull up less when doing single leg pedaling with a counterweight (the full paper is in revision and should be accepted soon). Taken together these research findings strongly suggest that pulling up compromises efficiency even when the cyclist is well practiced.
I can't really follow FD's current argument about why this doesn't close the book on the notion of pulling up being more efficient.
So, CoachFergie, SciGuy, AndyCoggan, FD, and Coapman, thanks so much for the entertainment! Better than a reality show!
Yours Truly,
PhitBoy

 

[CoachFergie]

Yes, we should not be distracted from the original study which disproves the claim that immersion training in circular pedalling, in this case 7 years worth, is less efficient than riding with a counterweight, a pedalling technique that is more like mashing. Look forward to the full paper.

 

[JayKosta]

Re: New study shows leg flexion less efficient than extensio

Nothing has really changed in the hundred plus posts since I wrote:
...

---------------------------------
Quite true, and I really don't expect much to change in the near future from academic research.

What I do think will happen is that the manufacturers of of the new generation power meters (that measure left-right pedal power and force vectors) will start to provide some detailed information about how those features of the PMs can be used to improve performance. I expect it to be mostly anecdotal, or perhaps based on measurements of name-brand PROs that could be used as 'guidance' or 'suggestions' about what type of pedaling technique they use.

I did a brief google-search for info from mfg's about using their new PMs, and didn't find anything more than typical ideas about having L/R power output 'balanced', and advocating a circular-pedaling style. The info that I did find was mostly from Pioneer and iNewton.

With a large company such as Pioneer selling these PMs, I expect they will soon see a need to provide some specific info about how their products can be used.

Jay Kosta
Endwell NY USA

 

[Alex Simmons/RST]

Re: New study shows leg flexion less efficient than extensio

Nothing has really changed in the hundred plus posts since I wrote:
...

---------------------------------
Quite true, and I really don't expect much to change in the near future from academic research.

What I do think will happen is that the manufacturers of of the new generation power meters (that measure left-right pedal power and force vectors) will start to provide some detailed information about how those features of the PMs can be used to improve performance. I expect it to be mostly anecdotal, or perhaps based on measurements of name-brand PROs that could be used as 'guidance' or 'suggestions' about what type of pedaling technique they use.

I did a brief google-search for info from mfg's about using their new PMs, and didn't find anything more than typical ideas about having L/R power output 'balanced', and advocating a circular-pedaling style. The info that I did find was mostly from Pioneer and iNewton.

With a large company such as Pioneer selling these PMs, I expect they will soon see a need to provide some specific info about how their products can be used.

Jay Kosta
Endwell NY USA

Having the skills to make a good power meter does not mean they also have the requisite bio-mechanical understanding of whether the data is useful or how it may be used effectively. Most of the quality information about use of power meter data has not emerged from producers of power meters.

 

[FrankDay]

Re:

And the Performance Artist nicely distracts people from the OP study that showed a cyclist pedalling more like a Gimmickcranker for seven years is more efficient when he changes to a system that allows him to pedal more like a masher. Lets not lose sight of that!

Actually, no such thing was shown. Everyone is forced to guess exactly how this rider actually was pedaling in the two instances because pedaling technique or forces wasn't measured. Further, everyone is forced to guess as to exactly how these two techniques differed from bilateral pedaling with and without coupled cranks.

As a coach, this type of research is Gold as it shows me that what I am teaching my riders and most importantly what I am not wasting their time on is good evidence based data.

If you say so.

 

[FrankDay]

Re: Re:

If the p-value is the probability of whatever is being measured not being due to chance what is the reciprocal of the p-value equal?

First, it's not the reciprocal of alpha (i.e., 1/alpha) you've been touting, it's 1-alpha.

Second, 1-alpha != beta.

And, in this instance would mean?

 

[FrankDay]

Re: New study shows leg flexion less efficient than extensio

Nothing has really changed in the hundred plus posts since I wrote:
...

---------------------------------
Quite true, and I really don't expect much to change in the near future from academic research.

What I do think will happen is that the manufacturers of of the new generation power meters (that measure left-right pedal power and force vectors) will start to provide some detailed information about how those features of the PMs can be used to improve performance. I expect it to be mostly anecdotal, or perhaps based on measurements of name-brand PROs that could be used as 'guidance' or 'suggestions' about what type of pedaling technique they use.

I did a brief google-search for info from mfg's about using their new PMs, and didn't find anything more than typical ideas about having L/R power output 'balanced', and advocating a circular-pedaling style. The info that I did find was mostly from Pioneer and iNewton.

With a large company such as Pioneer selling these PMs, I expect they will soon see a need to provide some specific info about how their products can be used.

Jay Kosta
Endwell NY USA

Having the skills to make a good power meter does not mean they also have the requisite bio-mechanical understanding of whether the data is useful or how it may be used effectively. Most of the quality information about use of power meter data has not emerged from producers of power meters.

I agree. Most of these manufacturers really don't have a clue as to what is going on. In part because I am unawere of any "quality information" emerging from anywhere about use of 1st gen power meters. Lots of guessing as to how to use but nothing documented that such use is of any more value than what was available before. If you know of any please point me to it.

 

[JamesCun]

Re: New study shows leg flexion less efficient than extensio

Nothing has really changed in the hundred plus posts since I wrote:

snip

Perhaps because you had little or nothing to add.

Pathetic Frank. You've never contributed anything and yet you sit around and put down others who actually have something useful.

Your product isn't beneficial and you just can't handle that. We all get that, but maybe it's time to save face and fade into the sunset.

 

[JamesCun]

Re: New study shows leg flexion less efficient than extensio

Uncoupled cranks is nothing like one-legged pedaling (because there is a counterweight on the other side making it unnecessary to unweight with additional force)

<sarcasm mode on>

Yes, that's precisely why they are so easy to use from the git-go, making no adaptation period necessary.

<sarcasm mode off>

Fact: as far as the physics of leg motion are concerned, there is absolutely no difference between uncoupled cranks and one-legged pedaling without a counterweight.

I missed that one. Frank is back to saying that uncoupled cranks act as a counterweight and transfer energy from one leg to the other. What a farce.

Frank, how can you still say these things and expect to be taken seriously. You have so many factual lapses here, it's hard to imagine that it's for any reason besides purposeful deception.

 

[FrankDay]

Re: New study shows leg flexion less efficient than extensio

[quote="FrankDayUncoupled cranks is nothing like one-legged pedaling (because there is a counterweight on the other side making it unnecessary to unweight with additional force)

<sarcasm mode on>

Yes, that's precisely why they are so easy to use from the git-go, making no adaptation period necessary.

<sarcasm mode off>

Fact: as far as the physics of leg motion are concerned, there is absolutely no difference between uncoupled cranks and one-legged pedaling without a counterweight.

I would agree that as far as the physics of leg motion are concerned there is absolutely no difference between any mode of pedaling, one-legged, counterbalanced one legged, bilateral coupled or uncoupled. Where the difference lies is in what the muscles do or are forced to do to accomplish the pedaling motion using these differing techniques. Assuming everything else is the same that is why efficiency changes with differing techniques. Understanding what all the variables are and what can be changed is what will lead to maximizing cycling efficiency.

 

[FrankDay]

Re: New study shows leg flexion less efficient than extensio

Uncoupled cranks is nothing like one-legged pedaling (because there is a counterweight on the other side making it unnecessary to unweight with additional force)

<sarcasm mode on>

Yes, that's precisely why they are so easy to use from the git-go, making no adaptation period necessary.

<sarcasm mode off>

Fact: as far as the physics of leg motion are concerned, there is absolutely no difference between uncoupled cranks and one-legged pedaling without a counterweight.

I missed that one. Frank is back to saying that uncoupled cranks act as a counterweight and transfer energy from one leg to the other. What a farce.

Frank, how can you still say these things and expect to be taken seriously. You have so many factual lapses here, it's hard to imagine that it's for any reason besides purposeful deception.

Well, I don't say those things. You folks simply don't understand what is going on. Because no energy can be transferred from one leg to another with uncoupled cranks in order to ride them the rider is forced to apply positive force on the upstroke to keep the cranks going. Because of this all of the weight of the counterbalance (the weight of the thigh and leg) on the other crank goes to driving the bicycle, none is transferred to the rising leg because no energy transfer is necessary to keep the crank moving.

 

[PhitBoy]

Re: New study shows leg flexion less efficient than extensio

maybe it's time to save face and fade into the sunset.

We can hope but it seems unlikely. According to Manta http://www.manta.com/c/mmcbsqx/powercranks, Powercranks has sales of $220k per year. Pretty good jack. Frank absolutely has to maintain the possibility, however slim, that his magic cranks make people fitter, stronger, healthier, faster, more efficient, and better looking. He does that by doing a really impressive job of obfuscation, misdirection, and denial. Just like Merchants of Doubt.

Tell you what Frank, pick up the tab and I'll find a student to do a training study with magiccranks. Grad students get around $20k per year. Training studies are hard and require a lot of participant payments, figure at least $1k per subject to get them to train for several months with uncoupled cranks. You'd also need to supply the cranks for maybe 20 participants. So, figure $40k for the student for two years, $20k for the participants, and whatever the cranks cost you. Our office of sponsored projects generally expects the lab director to get a cut so throw in around $12k per year for me. The University of Utah's indirect cost rate is a little over 50% so all totaled you'd be in for around $110k to find out whether or not magiccranks work. My lab reports exactly what the data show, no more, no less, and no marketing spin. Of course you would not be allowed to see any of the data till the study was done and you would not have any say so in what we published. Deal? Gee, now that I've made that offer I hope I can find a student who is willing to work his/her butt off for two years for a very likely negative finding.

 

[JamesCun]

Re: New study shows leg flexion less efficient than extensio

Uncoupled cranks is nothing like one-legged pedaling (because there is a counterweight on the other side making it unnecessary to unweight with additional force)

<sarcasm mode on>

Yes, that's precisely why they are so easy to use from the git-go, making no adaptation period necessary.

<sarcasm mode off>

Fact: as far as the physics of leg motion are concerned, there is absolutely no difference between uncoupled cranks and one-legged pedaling without a counterweight.

I missed that one. Frank is back to saying that uncoupled cranks act as a counterweight and transfer energy from one leg to the other. What a farce.

Frank, how can you still say these things and expect to be taken seriously. You have so many factual lapses here, it's hard to imagine that it's for any reason besides purposeful deception.

Well, I don't say those things. You folks simply don't understand what is going on. Because no energy can be transferred from one leg to another with uncoupled cranks in order to ride them the rider is forced to apply positive force on the upstroke to keep the cranks going. Because of this all of the weight of the counterbalance (the weight of the thigh and leg) on the other crank goes to driving the bicycle, none is transferred to the rising leg because no energy transfer is necessary to keep the crank moving.

In uncoupled cranks there is no counterbalance. Are you to dense to understand that? Stop using that term in relation to uncoupled cranks.

You must always apply positive force on the pedals. That is totally different from coupled cranks. That is totally different from a counter weighted single crank. Your comment about keeping the crank moving isn't what is happening. You mean the bike continues to move since the other leg is still applying force and the upstroke leg only needs to be a positive force, not a high force to drive the bike forward.