New study shows leg flexion less efficient than extension.

[CoachFergie]

Re: Re:

You have definitive answers. There is actually a ton of research showing that pulling up, unweighting and uncoupled cranks don't matter. Why are you not listening to the sport scientists here who are actually doing research on these things, or the sport scientists and exercise scientists who have an understanding of the science that has gone into answering these questions?

Yes all negative research, why not search for what does matter and could improve natural pedalling performance. Can you provide a study on unweighting that does not include pulling up the pedal and crank.

You really don't get it Noel. The worst thing in the world is that much negative research never gets published. The reason that no one has published any positive results on changes in pedalling technique is that no one has found any data. It's actually pretty cool that a lot of the research on things like crank length or uncoupled cranks has actually been published showing that there are no significant or meaningful gains to be made.

 

[CoachFergie]

Re: New study shows leg flexion less efficient than extensio

...
What are you trying to achieve here, you are clearly out of your depth?! What are you wanting to come away with from participating in this discussion? If you want a seat at the adult table then you need to lift your game!

-------------------------------------
Hamish (CoachFergie),

I'm trying to get a better understanding of the physiological aspects of pedaling - e.g. power generation, efficiency, and endurance. My interest is primarily intellectual - just wanting to know and understand the details.

As I said in an earlier post, I think that 'everything makes a difference' - or perhaps I should have said 'everything has an effect'.
Saying that something 'makes a difference' might be construed as it being 'important' - that's not what I mean. Just that it has some effect (perhaps tiny) on the final result.

So, I'm trying to understand the 'costs' and 'benefits' of doing those things (e.g. mashing, circular pedaling, pulling up, etc.). Knowing these things might not have much practical value - but it is of interest to me.

Jay Kosta
Endwell NY USA

That is why we use statistics, to determine what is significant or what is a meaningful effect.

 

[JamesCun]

Re: New study shows leg flexion less efficient than extensio

...
Nothing you wrote here makes any sense or has any relevance to my question. Are you trying to say that training the upstroke might increase max power output over short durations but will also reduce efficiency and limit power output over longer durations? If that is your point, I agree with you.

---------------------------------------------------------
If we are not already talking about it - please give me more info about your question regarding my mention of 'blend of power and endurance'.
ref - viewtopic.php?p=1738369#p1738369

Concerning your question above - close, but not quite - Yes training the upstroke can increase max short duration power, but probably at reduced efficiency for that short duration. Whether it will reduce overall longterm efficiency and limit longterm power COMPARED to those values BEFORE training the upstroke is unknown. It would depend on how well the person's body has responded to the upstroke training.

Jay Kosta
Endwell NY USA

Why do you think training upstroke power would lead to lower efficiency in short duration efforts but not long duration efforts?

You are consistently mixing random terms in your posts and it isnt at all clear what you are trying to say. A blend of power and endurance is a meaningless statement without some explanation or qualifiers.

 

[backdoor]

Re: Re:

You have definitive answers. There is actually a ton of research showing that pulling up, unweighting and uncoupled cranks don't matter. Why are you not listening to the sport scientists here who are actually doing research on these things, or the sport scientists and exercise scientists who have an understanding of the science that has gone into answering these questions?

Yes all negative research, why not search for what does matter and could improve natural pedalling performance. Can you provide a study on unweighting that does not include pulling up the pedal and crank.

You really don't get it Noel. The worst thing in the world is that much negative research never gets published. The reason that no one has published any positive results on changes in pedalling technique is that no one has found any data. It's actually pretty cool that a lot of the research on things like crank length or uncoupled cranks has actually been published showing that there are no significant or meaningful gains to be made.

So there is no published research on isolated unweighting ?

 

[JamesCun]

Re: Re:

You have definitive answers. There is actually a ton of research showing that pulling up, unweighting and uncoupled cranks don't matter. Why are you not listening to the sport scientists here who are actually doing research on these things, or the sport scientists and exercise scientists who have an understanding of the science that has gone into answering these questions?

Yes all negative research, why not search for what does matter and could improve natural pedalling performance. Can you provide a study on unweighting that does not include pulling up the pedal and crank.

You really don't get it Noel. The worst thing in the world is that much negative research never gets published. The reason that no one has published any positive results on changes in pedalling technique is that no one has found any data. It's actually pretty cool that a lot of the research on things like crank length or uncoupled cranks has actually been published showing that there are no significant or meaningful gains to be made.

So there is no published research on isolated unweighting ?

What is isolated unweighting?

 

[CoachFergie]

Something else he imagines when he watches a video of Jacques Anquetil.

 

[PhitBoy]

Re: Re:

It's actually pretty cool that a lot of the research on things like crank length

Several papers show that crank length does not directly influence max power, metabolic cost, or relative contributions of the various power producing actions. I did not set out to show things DIDN'T matter. I, like some of you, was keenly interested in how to optimize performance. When I was in grad school I was coaching two very good sprinters. One 5'8" with extremely long torso/ short legs and the other 6'5" with longer legs. Naturally the shorter rider chose 165mm cranks and the taller one rode "longer" 167.5's. That didn't seem like it could possibly optimal and I was keen to help them both. While the crank length study within my dissertation was framed within the context of growth, development, and aging, my original interest was in how to optimize these two guys.
While findings are negative in the sense that they show crank length doesn't matter they are very positive in that they show what does matter. Namely that maximum muscular power is interactively constrained by muscle shortening velocity and the frequency with which the muscle is excited and relaxed. See Martin et al., 2000 J Biomechanics and give it a read. Not only are those two factors determinant of cycling power, they are also determinant of power produced by isolated muscle undergoing cyclical contraction. So I guess calling these findings negative is all in the eye of the reader.
The data on pedaling technique and metabolic cost are also very exciting because they show that one's intuitive pedaling action is excellent. The whole-leg (hip, knee, and ankle) extension and flexion action used in cycling is possibly simply a spinal cord level program evolved for gait. Very little thought goes into the pedaling action (or needs to) because one simply activates that program and dials up or down the intensity as the task requires. Even children pedal with similar biomechanics as adult cyclists (Korff et al JEB). Pulling up more than what comes naturally would require that one use that synergy less on the extension phase and more on the flexion phase. This would get very complicated during double leg cycling because extension and flexion are going on simultaneously in the two legs.
I share some of the forum members' dream of finding a way to improve efficiency and improve performance with simple changes. I'll let you know when we find some.
PhitBoy

 

[CoachFergie]

Cheers PhitBoy

As good a example as any to publish studies that don't find a positive result. In my research that didn't find that measures of fitness, fatigue and freshness could predict max mean powers on race day I did happen to notice that 20/25 subjects were at a level of non functional overreaching and 1 was definitely overtrained.

Some good people doing some excellent work in the area of biomechanics. Even if it doesn't meet the standards of the Gimmickcranks Inc Marketing Plan.

 

[JayKosta]

Re: New study shows leg flexion less efficient than extensio

...
Nothing you wrote here makes any sense or has any relevance to my question. Are you trying to say that training the upstroke might increase max power output over short durations but will also reduce efficiency and limit power output over longer durations? If that is your point, I agree with you.

---------------------------------------------------------
...
Concerning your question above - close, but not quite - Yes training the upstroke can increase max short duration power, but probably at reduced efficiency for that short duration. Whether it will reduce overall longterm efficiency and limit longterm power COMPARED to those values BEFORE training the upstroke is unknown. It would depend on how well the person's body has responded to the upstroke training.

Jay Kosta
Endwell NY USA

Why do you think training upstroke power would lead to lower efficiency in short duration efforts but not long duration efforts?
...

---------------------------------------------------------
I think that efficiency would be lower in max power output short duration efforts because:
1) It is generally accepted that efficiency goes down during maximum effort situations.
2) Effective upstroke training would result in more muscles being used during the max power duration. So the total amount of muscles that are being used less-efficiently is a larger percentage of body weight.

For long duration efforts, as I said earlier, "unknown" - but these are things I consider:
1) Typically the efficiency of doing a task, such as using upstroke muscles, becomes better after effective training.
2) During long duration efforts there might not be any need to use the 'upstroke muscles' more vigorously than they were used prior to training. So, to the extent that the upstroke muscles are being used, they are doing so more efficiently than prior to training.

I consider 'training upstroke muscles' to be similar to training 'climbing muscles', or 'sprinting muscles' - they all have the potential to be used in a way that gives better results.

Jay Kosta
Endwell NY USA

 

[CoachFergie]

Re: New study shows leg flexion less efficient than extensio

...
Nothing you wrote here makes any sense or has any relevance to my question. Are you trying to say that training the upstroke might increase max power output over short durations but will also reduce efficiency and limit power output over longer durations? If that is your point, I agree with you.

---------------------------------------------------------
...
Concerning your question above - close, but not quite - Yes training the upstroke can increase max short duration power, but probably at reduced efficiency for that short duration. Whether it will reduce overall longterm efficiency and limit longterm power COMPARED to those values BEFORE training the upstroke is unknown. It would depend on how well the person's body has responded to the upstroke training.

Jay Kosta
Endwell NY USA

Why do you think training upstroke power would lead to lower efficiency in short duration efforts but not long duration efforts?
...

---------------------------------------------------------
I think that efficiency would be lower in max power output short duration efforts because:
1) It is generally accepted that efficiency goes down during maximum effort situations.
2) Effective upstroke training would result in more muscles being used during the max power duration. So the total amount of muscles that are being used less-efficiently is a larger percentage of body weight.

For long duration efforts, as I said earlier, "unknown" - but these are things I consider:
1) Typically the efficiency of doing a task, such as using upstroke muscles, becomes better after effective training.
2) During long duration efforts there might not be any need to use the 'upstroke muscles' more vigorously than they were used prior to training. So, to the extent that the upstroke muscles are being used, they are doing so more efficiently than prior to training.

I consider 'training upstroke muscles' to be similar to training 'climbing muscles', or 'sprinting muscles' - they all have the potential to be used in a way that gives better results.

Good grief...

Short duration power doesn't need to be efficient as it is not an issue.

Training the upstroke muscles is a waste of time. Several studies showing a sufficient training period of 6-10 weeks, where any coach worth his paycheck can easily get huge results, has found that training with an uncoupled crank has led to no improvement in performance.

No, training the upstroke does not improve efficiency, it decreases it. One poorly performed study by Luttrell, that was published in JSCR, and was laughed off the stage when presented at ACSM because they couldn't show they had calibrated the gas analysis equipment properly, and several subsequent studies (Burns, and Williams studies for a start) showed no improvement in efficiency.

Your considerations are s**t, you are an idiot who I now place on the same level as Noel. No reasonable evidence seems to sway your opinion. Sadly, there are too many of your kind!

Sad when people like Jim Martin and Andy Coggan share their evidence based knowledge that absolute morons like you feel obliged to waste everyones time with your stupid crackpot theories!

 

[JamesCun]

Re: New study shows leg flexion less efficient than extensio

I think that efficiency would be lower in max power output short duration efforts because:
1) It is generally accepted that efficiency goes down during maximum effort situations.
2) Effective upstroke training would result in more muscles being used during the max power duration. So the total amount of muscles that are being used less-efficiently is a larger percentage of body weight.
...

Point 1 is irrelevant.
Point 2 is incoherent.

 

[backdoor]

Re: New study shows leg flexion less efficient than extensio

...
Nothing you wrote here makes any sense or has any relevance to my question. Are you trying to say that training the upstroke might increase max power output over short durations but will also reduce efficiency and limit power output over longer durations? If that is your point, I agree with you.

---------------------------------------------------------
...
Concerning your question above - close, but not quite - Yes training the upstroke can increase max short duration power, but probably at reduced efficiency for that short duration. Whether it will reduce overall longterm efficiency and limit longterm power COMPARED to those values BEFORE training the upstroke is unknown. It would depend on how well the person's body has responded to the upstroke training.

Jay Kosta
Endwell NY USA

Why do you think training upstroke power would lead to lower efficiency in short duration efforts but not long duration efforts?
...

---------------------------------------------------------
I think that efficiency would be lower in max power output short duration efforts because:
1) It is generally accepted that efficiency goes down during maximum effort situations.
2) Effective upstroke training would result in more muscles being used during the max power duration. So the total amount of muscles that are being used less-efficiently is a larger percentage of body weight.

For long duration efforts, as I said earlier, "unknown" - but these are things I consider:
1) Typically the efficiency of doing a task, such as using upstroke muscles, becomes better after effective training.
2) During long duration efforts there might not be any need to use the 'upstroke muscles' more vigorously than they were used prior to training. So, to the extent that the upstroke muscles are being used, they are doing so more efficiently than prior to training.

I consider 'training upstroke muscles' to be similar to training 'climbing muscles', or 'sprinting muscles' - they all have the potential to be used in a way that gives better results.

Good grief...

Short duration power doesn't need to be efficient as it is not an issue.

Training the upstroke muscles is a waste of time. Several studies showing a sufficient training period of 6-10 weeks, where any coach worth his paycheck can easily get huge results, has found that training with an uncoupled crank has led to no improvement in performance.

No, training the upstroke does not improve efficiency, it decreases it. One poorly performed study by Luttrell, that was published in JSCR, and was laughed off the stage when presented at ACSM because they couldn't show they had calibrated the gas analysis equipment properly, and several subsequent studies (Burns, and Williams studies for a start) showed no improvement in efficiency.

Your considerations are s**t, you are an idiot who I now place on the same level as Noel. No reasonable evidence seems to sway your opinion. Sadly, there are too many of your kind!

Sad when people like Jim Martin and Andy Coggan share their evidence based knowledge that absolute morons like you feel obliged to waste everyones time with your stupid crackpot theories!

Empty vessels make the most noise. Why not explain why training upstroke muscles is a waste of time, I can. Do you believe training upstroke muscles is a waste of time for one legged riders ?

 

[CoachFergie]

Having coached a few one legged riders I can suggest it depends on their classification. If amputee above the knee they are not allowed to use a prosthetic so adopting a more circular approach to pedalling is necessary. Although as the op study shows is not the most efficient option available to them.

 

[FrankDay]

Re: New study shows leg flexion less efficient than extensio

This discussion reminds me of a story. When I was a beginner I happened to do rather well in a straight line sprint competition (3rd behind Les Barczewski and Jeff Fields). Afterward they invited me to train with them. One day I was riding with Jeff and asking him a bunch of these kind of questions; When he was sprinting did he pull up? Did he scrape the mud? Did he push over the top? Finally he came right over to me and leaned on me with his shoulder while we were riding (totally intimidating to me as a Cat 4). He put his face about 6" away from mine and said in a low voice "I'm trying to shove the pedals into the f*cking asphalt". Fifty research papers later and I can say he was pretty much right. Pedaling is overwhelmingly a leg extension task with a little leg flexion tacked on.
Keep it simple and it will all be fine.

So, let me get this straight. You hold yourself out as doing cycling research. You post studies and personal experience regarding what happens on the upstroke

In all the data I've seen, muscular power (the sum of ankle, knee, hip, and hip transfer power) is positive during almost of all the leg flexion phase. Most of that power comes from knee flexion (hamstrings and gastroc). The power during submaximal cycling is not as great as the power required to lift the leg so negative power is still observed at the pedal (gasp!). This would be in the category that I think you would call "unweighting".
With increases in power (e.g. 250, 400, 550, 700, 850 (submax!), and maximal sprint; see Elmer et al. 2011 in MSSE) absolute power for each joint action increases and power during flexion will eventually be positive even at the pedal level meaning that power during flexion is greater than that required to lift the leg.
This data is highly relevant to the discussion of pedaling technique and motor skill acquisition because it shows that all the cyclists we have tested (from recreational to elite) CAN pull up enough to produce positive pedal power during flexion but they CHOOSE not too do so when pedaling at endurance level powers. Repeat, everyone already knows how to pull up with power.

And then, when the argument doesn't go quite the way you expect it to you resort to arguing anecdotes that when you were a beginner that someone better than you told you he didn't think about pedaling technique and only "pushed harder" which goes against all that science you posted earlier. It would seem to me that based upon your scientific knowledge you should realize that what he thought he was doing probably bore no resemblance to what he was actually doing. You are, presumably, a scientist. One wouldn't know it from this post.

 

[FrankDay]

Re: Re:

but I haven't seen any definitive answers about what the difference is, and whether, or how, it can be used to give better results.

Jay Kosta
Endwell NY USA

Yep, the scientific research in this area is abysmal.

 

[FrankDay]

Re: Re:

Here is another way to think about unweighting. Coast alone on your bike out of the saddle, one foot at 3 and one foot a 9 o'clock. You are coasting so the pedals are not turning so 50% of your weight has to be on the 3 o'clock pedal and 50% on the 9 o'clock pedal. The pedal forces are equal and opposite. Now, what do you have to do if you want to start pedaling? There is only one way, you have to have an unbalanced force with more force on the forward pedal than the backwards pedal.

Yes.

The only way to do this is to unweight the back pedal.

No.

Even if my back pedal has weight, I can turn the crank. Even if I actively push down with my back leg, but I just push down less than my front pedal, I can turn the crank.

Unweight implies "reduce weight". Either lift completely or lift partially to overcome gravity. From "weight", which comes from mass and gravity. It is not necessary to unweight to start pedalling.

If it was necessary to unweight it would not be possible to pedal single-legged with a counterweight.

Unweighting doesn't mean pulling up with force. Unweighting simply means reducing the weight some. What Phitboy posted and is pretty well established is that EVERYONE does this. The degree to which they do this varies with how hard they are pedaling with higher degrees of unweighting the closer they are to full effort (even to the point of pulling up with force at near max efforts). These lesser degrees of unweighting mean the unweighting muscles are doing work to drive the bicycle (even when the force on the pedal is negative) because they are putting potential energy into the leg that is returned on the downstroke. Even the one-legged rider pedaling with a counterweight is unweighting on the upstroke, he is just doing less of it more like what someone pedaling with both legs does. The problem with the counterweight is it forces the rider to push harder than the two legged rider does because there is no unweighting. The unweighting work increases the power of the rider because it adds to what is done on the downstroke. It is simple physics.

And, I defy you to show me where it has ever been shown that any rider has ever been shown to actively push down on the backstroke while riding even though such is theoretically possible.

 

[FrankDay]

Re: Re:

Frank, if you want to make a point, make it and make it clear and make it stand on its own. Don't 'make a point' then as soon as its countered (very easily in this case) go back and say but but but look over here... What a waste of time. If the point is that people CAN unweight, fine. That doesn't mean they should unweight if they are looking for maximum efficiency.

You seem to be the one trying to argue whether they SHOULD unweight. Fact is everyone DOES UNWEIGHT.

I don't agree. Why do you state that as a fact?

Because it is a scientific "fact". Every study that has measured pedaling forces shows unweighting on the backstroke. It has never been shown that any rider with intact musculature pedals without unweighting. If you, or anyone else, can find such a study I will eat my words. Everyone unweights on the upstroke. The only variation is in the degree to which they do it.

 

[FrankDay]

Re: Re:

It's actually pretty cool that a lot of the research on things like crank length

Several papers show that crank length does not directly influence max power, metabolic cost, or relative contributions of the various power producing actions. I did not set out to show things DIDN'T matter. I, like some of you, was keenly interested in how to optimize performance. When I was in grad school I was coaching two very good sprinters. One 5'8" with extremely long torso/ short legs and the other 6'5" with longer legs. Naturally the shorter rider chose 165mm cranks and the taller one rode "longer" 167.5's. That didn't seem like it could possibly optimal and I was keen to help them both. While the crank length study within my dissertation was framed within the context of growth, development, and aging, my original interest was in how to optimize these two guys.
While findings are negative in the sense that they show crank length doesn't matter they are very positive in that they show what does matter. Namely that maximum muscular power is interactively constrained by muscle shortening velocity and the frequency with which the muscle is excited and relaxed. See Martin et al., 2000 J Biomechanics and give it a read. Not only are those two factors determinant of cycling power, they are also determinant of power produced by isolated muscle undergoing cyclical contraction. So I guess calling these findings negative is all in the eye of the reader.

Why you are bring this up here is not clear. Perhaps you might want to add this to the crank length thread. But since you did bring it up I have several issues with your implication, that crank length doesn't matter. I agree that the effects on crank length on power are small within a wide range and for most people if they see a big effect on power when they go shorter it is because shorter cranks slow their pedal speed to something better. However, that doesn't mean it is zero. I think it quite clear reasonable criticism of the Martin paper includes:
1. If his cohort would have been twice as large the difference between 145 and 170 would have reached statistical signficance. Would he have still concluded then that because the difference was small that it is ok to continue riding sub-optimal crank lengths?
2. The data was not obtained in the aero position. I believe crank length has a larger effect on power when riders are in the aero position and Martin's data would be shifted to the left under those conditions, especially if tested in shorter people, like women. Unfortunately, this data gets applied to all conditions as "proof" crank length doesn't matter when it doesn't apply to all conditions.
3. Wouldn't it have been better for Martin to have looked at that data and rather than concluding that crank length doesn't matter because the differences were small to have concluded that the data is interesting and bears further study? How many serious competitors would give up any power just because the difference was small?
4. Does this data apply to smaller people, like females?

The data on pedaling technique and metabolic cost are also very exciting because they show that one's intuitive pedaling action is excellent. The whole-leg (hip, knee, and ankle) extension and flexion action used in cycling is possibly simply a spinal cord level program evolved for gait. Very little thought goes into the pedaling action (or needs to) because one simply activates that program and dials up or down the intensity as the task requires. Even children pedal with similar biomechanics as adult cyclists (Korff et al JEB). Pulling up more than what comes naturally would require that one use that synergy less on the extension phase and more on the flexion phase. This would get very complicated during double leg cycling because extension and flexion are going on simultaneously in the two legs.

Pedaling is not intuitive, it is learned. We all learned on platform pedals.Yes, that technique is reasonably efficient and, as you say, "excellent" but that doesn't mean it cannot be improved upon. It would appear that pedaling technique does affect efficiency. The data suggests that one-legged pedaling is less efficient than counter balanced one-legged pedaling which is less efficient than two legged pedaling. And, there is some further data to suggest that enhancing the upstroke action in bilateral pedaling is more efficient still (Luttrell). If one claims to understand pedaling one needs to be able to explain the mechanism of these differences. What one finds instead is most simply ignoring these mechanisms.

I share some of the forum members' dream of finding a way to improve efficiency and improve performance with simple changes. I'll let you know when we find some.
PhitBoy

Well, there are lots of places to look, just starting with trying to explain the efficiency differences we know about would be a good start from a research perspective I would think. Could you tell us where you are currently looking?

 

[FrankDay]

Re:

Having coached a few one legged riders I can suggest it depends on their classification. If amputee above the knee they are not allowed to use a prosthetic so adopting a more circular approach to pedalling is necessary. Although as the op study shows is not the most efficient option available to them.

Is it against the rules for one-legged riders to add counterweights to the unused crank?

 

[PhitBoy]

Re: New study shows leg flexion less efficient than extensio

One poorly performed study by Luttrell, that was published in JSCR, and was laughed off the stage when presented at ACSM because they couldn't show they had calibrated the gas analysis equipment properly, and several subsequent studies (Burns, and Williams studies for a start) showed no improvement in efficiency.

Ah Frank's beloved Luttrell and Potteiger study. I was there when it was presented at ACSM. There was a line at the mic with people waiting to ask questions. I didn't even get to ask a question before the moderator closed questions and moved on to the next speaker. One guy accused the speaker (I think Potteiger presented) of presenting a paid infomercial. I've never seen anything like the response to that presentation before or since.
As you mention there are likely a number of issues with that study. For me, the main issue is the use of the pan loaded Monark. Belts heat up and change friction over time. When we have used a pendulum loaded Monark we typically have a student designated to do nothing but keep an eye on the pendulum and constantly tweak it to hold it where we want it. With the pan load you have no idea what the resistance really is unless you have load cells on both ends of the belt. MacIntosh has a paper showing how inaccurate that system is.
Also, that 10% difference they report is so large that if it were real it would show up in other studies as you said. A single drop of lube (intentional or inadvertent) on the flywheel would go a long way to explain the results. When we lube the belts on our pendulum loaded ergs they require much more tension for the same load. Maybe the chain was making noise and the student running the study spayed lube on it and accidentally got some on the flywheel. And, as you mentioned there may have been met cart calibration issues. There are no doubt many reasons that paper only made it in to the lower tier JSCR.
Bad science gets published now and again but "truth will out" eventually.

 

[JamesCun]

Re: Re:

Here is another way to think about unweighting. Coast alone on your bike out of the saddle, one foot at 3 and one foot a 9 o'clock. You are coasting so the pedals are not turning so 50% of your weight has to be on the 3 o'clock pedal and 50% on the 9 o'clock pedal. The pedal forces are equal and opposite. Now, what do you have to do if you want to start pedaling? There is only one way, you have to have an unbalanced force with more force on the forward pedal than the backwards pedal.

Yes.

The only way to do this is to unweight the back pedal.

No.

Even if my back pedal has weight, I can turn the crank. Even if I actively push down with my back leg, but I just push down less than my front pedal, I can turn the crank.

Unweight implies "reduce weight". Either lift completely or lift partially to overcome gravity. From "weight", which comes from mass and gravity. It is not necessary to unweight to start pedalling.

If it was necessary to unweight it would not be possible to pedal single-legged with a counterweight.

Unweighting doesn't mean pulling up with force. Unweighting simply means reducing the weight some. What Phitboy posted and is pretty well established is that EVERYONE does this. The degree to which they do this varies with how hard they are pedaling with higher degrees of unweighting the closer they are to full effort (even to the point of pulling up with force at near max efforts). These lesser degrees of unweighting mean the unweighting muscles are doing work to drive the bicycle (even when the force on the pedal is negative) because they are putting potential energy into the leg that is returned on the downstroke. Even the one-legged rider pedaling with a counterweight is unweighting on the upstroke, he is just doing less of it more like what someone pedaling with both legs does. The problem with the counterweight is it forces the rider to push harder than the two legged rider does because there is no unweighting. The unweighting work increases the power of the rider because it adds to what is done on the downstroke. It is simple physics.

And, I defy you to show me where it has ever been shown that any rider has ever been shown to actively push down on the backstroke while riding even though such is theoretically possible.

Can you explain how someone unweights without pulling up?

As an aside, unweighting is a terrible term. Typically 'un' means 'no' or 'not'. So, not weighted or no weight. As you say, the degree of unweighting is the key here. I would think many on this thread take unweighting to mean no weight on the pedals as opposed to reduced weight on the pedals.

 

[FrankDay]

Re: New study shows leg flexion less efficient than extensio

...
Nothing you wrote here makes any sense or has any relevance to my question. Are you trying to say that training the upstroke might increase max power output over short durations but will also reduce efficiency and limit power output over longer durations? If that is your point, I agree with you.

---------------------------------------------------------
...
Concerning your question above - close, but not quite - Yes training the upstroke can increase max short duration power, but probably at reduced efficiency for that short duration. Whether it will reduce overall longterm efficiency and limit longterm power COMPARED to those values BEFORE training the upstroke is unknown. It would depend on how well the person's body has responded to the upstroke training.

Jay Kosta
Endwell NY USA

Why do you think training upstroke power would lead to lower efficiency in short duration efforts but not long duration efforts?
...

---------------------------------------------------------
I think that efficiency would be lower in max power output short duration efforts because:
1) It is generally accepted that efficiency goes down during maximum effort situations.
2) Effective upstroke training would result in more muscles being used during the max power duration. So the total amount of muscles that are being used less-efficiently is a larger percentage of body weight.

For long duration efforts, as I said earlier, "unknown" - but these are things I consider:
1) Typically the efficiency of doing a task, such as using upstroke muscles, becomes better after effective training.
2) During long duration efforts there might not be any need to use the 'upstroke muscles' more vigorously than they were used prior to training. So, to the extent that the upstroke muscles are being used, they are doing so more efficiently than prior to training.

I consider 'training upstroke muscles' to be similar to training 'climbing muscles', or 'sprinting muscles' - they all have the potential to be used in a way that gives better results.

Good grief...

Short duration power doesn't need to be efficient as it is not an issue.

Sure it does or, at least, it could matter. If one is more efficient for a short high intensity effort one might be able to sustain it for 12 seconds vs 10 if they were 20% more efficient. Seems that could be a benefit to a sprinter.

...

Sad when people like Jim Martin and Andy Coggan share their evidence based knowledge that absolute morons like you feel obliged to waste everyones time with your stupid crackpot theories!

LOL. Yes they share their opinions then disappear when confronted to back them up with facts.

 

[FrankDay]

Re: New study shows leg flexion less efficient than extensio

One poorly performed study by Luttrell, that was published in JSCR, and was laughed off the stage when presented at ACSM because they couldn't show they had calibrated the gas analysis equipment properly, and several subsequent studies (Burns, and Williams studies for a start) showed no improvement in efficiency.

Ah Frank's beloved Luttrell and Potteiger study. I was there when it was presented at ACSM. There was a line at the mic with people waiting to ask questions. I didn't even get to ask a question before the moderator closed questions and moved on to the next speaker. One guy accused the speaker (I think Potteiger presented) of presenting a paid infomercial.

Wow. And what did Potteiger say or do? Did he laugh or seem offended at the insinuation. That says way more about the person making that unsubstantiated accusation than Potteiger.

I've never seen anything like the response to that presentation before or since.

Nor should you, bias entering into a scientific meeting. Shame on them.

As you mention there are likely a number of issues with that study. For me, the main issue is the use of the pan loaded Monark. Belts heat up and change friction over time. When we have used a pendulum loaded Monark we typically have a student designated to do nothing but keep an eye on the pendulum and constantly tweak it to hold it where we want it. With the pan load you have no idea what the resistance really is unless you have load cells on both ends of the belt. MacIntosh has a paper showing how inaccurate that system is.

Can you show me a study that doesn't have any potential problems? They simply don't exist. The thing a real scientist would do would be to replicate the study exactly but to correct the problems they see in their methods to see if the data is good or not. Instead, people see a result that doesn't conform with their bias and just discount it.

Also, that 10% difference they report is so large that if it were real it would show up in other studies as you said. A single drop of lube (intentional or inadvertent) on the flywheel would go a long way to explain the results.

Why is this result so large? Coyle demonstrated a similar efficiency improvement in a trained cyclist (the best in the world) albeit over a longer length of time. The fact that this result is so large should be a reason for other to try to replicate the study. No one has done that. Some have done similar studies but not the same study. Either doing less time, or using a more experienced cohort that could explain their failure and Luttrell's positive finding.

When we lube the belts on our pendulum loaded ergs they require much more tension for the same load. Maybe the chain was making noise and the student running the study spayed lube on it and accidentally got some on the flywheel. And, as you mentioned there may have been met cart calibration issues. There are no doubt many reasons that paper only made it in to the lower tier JSCR.
Bad science gets published now and again but "truth will out" eventually.

Yep, and until someone replicates that study and demonstrates the finding was the result of an error it remains a valid study. The problems you suggest could also easily occur in the opposite direction, hiding a positive change by making it look like there is no change. The problem is you guys are really up the creek without a paddle if someone replicates the study and gets the same or similar results. All your smartness will be shown for what it is, a bunch of bias. Replicate the study and see what happens (except, if you do, please also measure pedal forces so we can document whether and how pedal forces changed by the intervention).

 

[FrankDay]

Re: Re:

Here is another way to think about unweighting. Coast alone on your bike out of the saddle, one foot at 3 and one foot a 9 o'clock. You are coasting so the pedals are not turning so 50% of your weight has to be on the 3 o'clock pedal and 50% on the 9 o'clock pedal. The pedal forces are equal and opposite. Now, what do you have to do if you want to start pedaling? There is only one way, you have to have an unbalanced force with more force on the forward pedal than the backwards pedal.

Yes.

The only way to do this is to unweight the back pedal.

No.

Even if my back pedal has weight, I can turn the crank. Even if I actively push down with my back leg, but I just push down less than my front pedal, I can turn the crank.

Unweight implies "reduce weight". Either lift completely or lift partially to overcome gravity. From "weight", which comes from mass and gravity. It is not necessary to unweight to start pedalling.

If it was necessary to unweight it would not be possible to pedal single-legged with a counterweight.

Unweighting doesn't mean pulling up with force. Unweighting simply means reducing the weight some. What Phitboy posted and is pretty well established is that EVERYONE does this. The degree to which they do this varies with how hard they are pedaling with higher degrees of unweighting the closer they are to full effort (even to the point of pulling up with force at near max efforts). These lesser degrees of unweighting mean the unweighting muscles are doing work to drive the bicycle (even when the force on the pedal is negative) because they are putting potential energy into the leg that is returned on the downstroke. Even the one-legged rider pedaling with a counterweight is unweighting on the upstroke, he is just doing less of it more like what someone pedaling with both legs does. The problem with the counterweight is it forces the rider to push harder than the two legged rider does because there is no unweighting. The unweighting work increases the power of the rider because it adds to what is done on the downstroke. It is simple physics.

And, I defy you to show me where it has ever been shown that any rider has ever been shown to actively push down on the backstroke while riding even though such is theoretically possible.

Can you explain how someone unweights without pulling up?

Nope, at least on a bicycle. Unweighting is common in skiing without pulling up. It is why people turn at the top of the moguls, not the bottom. But, if you are skiing on a flat section and want to turn you unweight by pushing down then pulling up on the skis.

As an aside, unweighting is a terrible term. Typically 'un' means 'no' or 'not'. So, not weighted or no weight. As you say, the degree of unweighting is the key here. I would think many on this thread take unweighting to mean no weight on the pedals as opposed to reduced weight on the pedals.

Nope, unweighting is a great term in common use because it refers to reducing (not eliminating) the downward force. You simply haven't checked on the dictionary definition if you said that. http://dictionary.reference.com/browse/unweight?s=t

unweight
[uhn-weyt]

Word Origin

verb (used without object)
1.
Skiing. to lessen downward force and friction between the skis and the snow by a quick upward or downward shifting of the body or by using bumps in the terrain.

Either way, if you know of a better term I will be happy to use that for you (assuming I agree it is a better term).

 

[CoachFergie]

Re: New study shows leg flexion less efficient than extensio

One poorly performed study by Luttrell, that was published in JSCR, and was laughed off the stage when presented at ACSM because they couldn't show they had calibrated the gas analysis equipment properly, and several subsequent studies (Burns, and Williams studies for a start) showed no improvement in efficiency.

Ah Frank's beloved Luttrell and Potteiger study. I was there when it was presented at ACSM. There was a line at the mic with people waiting to ask questions. I didn't even get to ask a question before the moderator closed questions and moved on to the next speaker. One guy accused the speaker (I think Potteiger presented) of presenting a paid infomercial. I've never seen anything like the response to that presentation before or since.
As you mention there are likely a number of issues with that study. For me, the main issue is the use of the pan loaded Monark. Belts heat up and change friction over time. When we have used a pendulum loaded Monark we typically have a student designated to do nothing but keep an eye on the pendulum and constantly tweak it to hold it where we want it. With the pan load you have no idea what the resistance really is unless you have load cells on both ends of the belt. MacIntosh has a paper showing how inaccurate that system is.
Also, that 10% difference they report is so large that if it were real it would show up in other studies as you said. A single drop of lube (intentional or inadvertent) on the flywheel would go a long way to explain the results. When we lube the belts on our pendulum loaded ergs they require much more tension for the same load. Maybe the chain was making noise and the student running the study spayed lube on it and accidentally got some on the flywheel. And, as you mentioned there may have been met cart calibration issues. There are no doubt many reasons that paper only made it in to the lower tier JSCR.
Bad science gets published now and again but "truth will out" eventually.

Thanks, you're not the first to recall how badly received that paper was.