Re: New study shows leg flexion less efficient than extensio
Been there, done that.JamesCun said:
Re: New study shows leg flexion less efficient than extensio
So, you are saying that with powercranks one leg pushing down can lift the other leg up. That is amazing and total BS. You haven't been anywhere or done anything. You just duck and weave and change the subject. Somehow you are now demanding that a researcher come here and waste his time explaining grade school concepts to a total snake oil salesman with a chip on his shoulder.FrankDay said:
Re: New study shows leg flexion less efficient than extensio
agree
Hopefully useful 'power data' (and other) was collected and can be used as the basis for a detailed analysis of other topics in a follow-on study.
If you're going thru the trouble of using test subjects, it can be worthwhile to collect as much data as possible during the session for use as input to multiple individual studies.
I think it is ok to not include portions of the data that is collected unless that data invalidates conclusions
that are drawn in the earlier use of the study data.
Jay Kosta
Endwell NY USA
----------------------acoggan said:
agree
Hopefully useful 'power data' (and other) was collected and can be used as the basis for a detailed analysis of other topics in a follow-on study.
If you're going thru the trouble of using test subjects, it can be worthwhile to collect as much data as possible during the session for use as input to multiple individual studies.
I think it is ok to not include portions of the data that is collected unless that data invalidates conclusions
that are drawn in the earlier use of the study data.
Jay Kosta
Endwell NY USA
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Re: Re:
I don't do opinions, will leave that to Frank.
Don't follow your first question.
The data would suggest that using a counterweight allowed the rider to use a mashing technique.
Before they could use a prosthesis. The favoured those with lower upper leg amputations as they could weight the prosthesis to match the other leg.
The change meant they had to use a pod that the stump rested in as some athletes in the category had higher upper leg amputation or no leg at all.
JayKosta said:
I don't do opinions, will leave that to Frank.
Don't follow your first question.
The data would suggest that using a counterweight allowed the rider to use a mashing technique.
Before they could use a prosthesis. The favoured those with lower upper leg amputations as they could weight the prosthesis to match the other leg.
The change meant they had to use a pod that the stump rested in as some athletes in the category had higher upper leg amputation or no leg at all.
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Re: New study shows leg flexion less efficient than extensio
Probably talking to Jim Martin like I did.
FrankDay said:
Probably talking to Jim Martin like I did.
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Re: New study shows leg flexion less efficient than extensio
Do you not see that the data presented already tells us a huge amount. You are being fooled by Frank's smoke and mirrors.
A rider with 7 years of immersion training in circular pedalling improved efficiency and lowered metabolic cost by changed to riding with a counter weight that allowed the subject to pedal more like most two leg riders.
Don't you think that is pretty cool?
Analysis around the stroke will only show what is rather obvious. Would just be confirming that the original stroke requires the rider to lift the leg up, you can test this doing a one leg pedal yourself, and that with the counterweight that the rider pedals more like two legged riders.
JayKosta said:
Do you not see that the data presented already tells us a huge amount. You are being fooled by Frank's smoke and mirrors.
A rider with 7 years of immersion training in circular pedalling improved efficiency and lowered metabolic cost by changed to riding with a counter weight that allowed the subject to pedal more like most two leg riders.
Don't you think that is pretty cool?
Analysis around the stroke will only show what is rather obvious. Would just be confirming that the original stroke requires the rider to lift the leg up, you can test this doing a one leg pedal yourself, and that with the counterweight that the rider pedals more like two legged riders.
Re: New study shows leg flexion less efficient than extensio
agree
But I suspect that most two legged riders have a technique that is more 'pedal in circles' than 'mash'.
So adding the counterweight assists the 'pedal in circles' technique, similar to two legged pedaling on a stationary bike that has a heavy flywheel.
Jay Kosta
Endwell NY USA
---------------CoachFergie said:
agree
But I suspect that most two legged riders have a technique that is more 'pedal in circles' than 'mash'.
So adding the counterweight assists the 'pedal in circles' technique, similar to two legged pedaling on a stationary bike that has a heavy flywheel.
Jay Kosta
Endwell NY USA
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Why suspect when you can read the research. Coyle showed this in 1991 that Cat 1 TT riders mashed more than Cat 2 TT riders.
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Re: New study shows leg flexion less efficient than extensio
Similarly, pedalling backwards does not provide a braking force to the bike (aside from a tiny bit of freewheel friction).
Whole bike inertia (or via a heavy/fast spinning flywheel on a trainer) doesn't provide any propulsive force to the cranks. It's a freewheel. Stop pedalling and you coast, the bike's (or freewheel's) inertia doesn't move the cranks around for you. If it does, there's something wrong with your drivetrain or you are riding a fixed gear bike.JayKosta said:
Similarly, pedalling backwards does not provide a braking force to the bike (aside from a tiny bit of freewheel friction).
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Re: Re:
A counterweight means the weights are in a connected system. Your cranks are not a connected system, that's their raison d'être. Regular cranks are a connected system.
Because around 11kg reasonably approximates the amount of leg mass that moves up, down and around while pedalling. 5kg, 25kg or 100kg does not. Obviously the precise mass will vary depending on the individual rider, but for a typical male cyclist, ~11kg is about right.FrankDay said:
A counterweight means the weights are in a connected system. Your cranks are not a connected system, that's their raison d'être. Regular cranks are a connected system.
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Re: Re:
But probably more importantly, the duration of such minor crank velocity variations are 1-2 orders of magnitude less than metabolic response times, so I doubt there is much of an efficiency gain because of this factor. It's far more probable that the shift of placing more demand on leg extensors from leg flexors has resulted in improved efficiency. IOW better bang for your O2 buck when using the best muscles for the job of cycling.
Crank velocity variation during a crank revolution while riding steady state is pretty small. It does vary depending on the bike/rider's inertia and gear/cadence. The variability would be larger for a single legged rider but still relatively small.JayKosta said:
But probably more importantly, the duration of such minor crank velocity variations are 1-2 orders of magnitude less than metabolic response times, so I doubt there is much of an efficiency gain because of this factor. It's far more probable that the shift of placing more demand on leg extensors from leg flexors has resulted in improved efficiency. IOW better bang for your O2 buck when using the best muscles for the job of cycling.
Re:
But did they accomplish that by intentionally reducing their level of pedal-in-circles?
I haven't re-read the entire 1991 study -
Physiological and biomechanical factors associated with elite endurance cycling performance
But I think this portion of the abstract is significant - note that it doesn't mention anything about intentional pedaling technique differences. Nor does the article mention intentional technique differences.
"The higher performance power output
of group I was produced primarily by generating higher peak torques
about the center of the crank by applying larger vertical forces to the
crank arm during the cycling downstroke. Compared with group 2,
group I also produced higher peak torques and vertical forces during
the downstroke even when cycling at the same absolute work rate as
group 2. Factors possibly contributing to the ability of group I to
produce higher "downstroke power" are a greater percentage of Type
I muscle fibers (P < 0.05) and a 23% greater (P < 0.05) muscle
capillary density compared with group 2. We have also observed a
strong relationship between years of endurance training and percent
Type I muscle fibers (r = 0.75; P < 0.001). It appears that "elitenational
class" cyclists have the ability to generate higher "downstroke
power", possibly as a result of muscular adaptations stimulated by
more years of endurance training."
Figure 5 of the article does show that the stronger group 1 did not completely unweight the pedal on the upstroke, but the amount of negative torque is very small. The group 2 did completely unweight and did produce a small amount of positive torque on the upstroke. But I don't think either group could be considered as 'mashers' who intend for the upstroke foot and leg be pushed upward by the force of the downstroke.
Jay Kosta
Endwell NY USA
-----CoachFergie said:
But did they accomplish that by intentionally reducing their level of pedal-in-circles?
I haven't re-read the entire 1991 study -
Physiological and biomechanical factors associated with elite endurance cycling performance
But I think this portion of the abstract is significant - note that it doesn't mention anything about intentional pedaling technique differences. Nor does the article mention intentional technique differences.
"The higher performance power output
of group I was produced primarily by generating higher peak torques
about the center of the crank by applying larger vertical forces to the
crank arm during the cycling downstroke. Compared with group 2,
group I also produced higher peak torques and vertical forces during
the downstroke even when cycling at the same absolute work rate as
group 2. Factors possibly contributing to the ability of group I to
produce higher "downstroke power" are a greater percentage of Type
I muscle fibers (P < 0.05) and a 23% greater (P < 0.05) muscle
capillary density compared with group 2. We have also observed a
strong relationship between years of endurance training and percent
Type I muscle fibers (r = 0.75; P < 0.001). It appears that "elitenational
class" cyclists have the ability to generate higher "downstroke
power", possibly as a result of muscular adaptations stimulated by
more years of endurance training."
Figure 5 of the article does show that the stronger group 1 did not completely unweight the pedal on the upstroke, but the amount of negative torque is very small. The group 2 did completely unweight and did produce a small amount of positive torque on the upstroke. But I don't think either group could be considered as 'mashers' who intend for the upstroke foot and leg be pushed upward by the force of the downstroke.
Jay Kosta
Endwell NY USA
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Re: Re:
Most people don't think about pedalling at all. Based on the volumes of research on the matter and especially this latest study, they don't need to.
Just keep training as experience counts and choose your parents wisely as fibre type distribution counts.
JayKosta said:
Most people don't think about pedalling at all. Based on the volumes of research on the matter and especially this latest study, they don't need to.
Just keep training as experience counts and choose your parents wisely as fibre type distribution counts.
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I tried to think about pedalling on the club run last night, just pushing is pedalling in circles.
Re: Re:
The toughest part of any research study is the interpretation. This has to be one of the most misinterpreted papers ever. Just because somebody (even the author sometimes also) says it shows something doesn't mean it really does. While the faster group did, on average, push down harder than the slower group, the faster group also had 4 more years of endurance training under their belt and from table 4 burned more oxygen, rode closer to their maximum, and put out 35 watts more power. But, looking at individual riders (figure 4) how fast they were had no relationship to how hard they pushed or anything else pedaling technique-wise that I can see. The two hardest pushers were only the 4th and 10th fastest of the 15 person group and were 3 and 6 minutes slower than the fastest rider. The one putting out the most power and by far the fastest of the fast was only the 4th hardest pusher and he also did substantial work on the upstroke. With 1 or 2 exceptions the force pattern of the fastest group was essentially the same as the slower group, the difference being hardly more than noise (figure 5). To conclude that faster riders "just push harder" and don't pull up compared to slower riders from this data simply means one has not examined the data closely. All one can really conclude from this study is that more experienced endurance athletes tend to perform better than the less experienced.JayKosta said:
Frank, are those your visual statistics or did you recalculate all the statistics from the raw data?
Re:
There is no need to recalculate. They did not find a statistical significant difference in pedaling style. The faster group was more powerful. Wow, there is a finding to take to the bank. The more powerful group pushed against the pedals harder. Wow, another finding to take to the bank. The question is whether there is a cause and effect. Does training oneself to push harder result in more power than other training methods. A cursory examination (as noted above) definitely says NO! To say otherwise simply does not fit this data esp comparing rider A to riders D and J.JamesCun said:
Re: Re:
1. It isn't clear how they got to Figure 7. What should be normalized are the muscle forces, not the total forces. Remember, the total forces graph increase the apparent pushing forces and decrease the apparent pulling forces.
While group 2 may be pulling more than group 1, it is by a tiny amount when one is considering the muscle forces. Any analysis that isn't looking at the muscle forces is sort of a waste of time don't you think?
2. Even though it appears there is a difference I don't think the difference reached statistical significance. If it didn't then there is no difference.
3. If the real outlier in group 2 were removed (suject k) there would probably be no difference between groups. I am really interested in knowing what the story is for subject K. That is the most bizarre pedaling pattern. It is how I would expect an amputee to pedal. The next most bizarre is subject N. Of all the people I have measured technique on essentially everyone is stronger across the bottom than the top. N is doing nothing across the bottom and quite strong across the top. One thing I wonder about is whether the subjects knew when their technique was being recorded. Is it possible that these "weaker" subjects were modifying their stroke trying to look as "good" as what they expected the better cyclists to look like?
4. But, most importantly, and what you ignored, is explaining the difference between the form of the absolute best cyclist in this cohort by far and subject D and J. That difference alone gives lie to the thought that "pushing harder" is the key to increasing power.
Just a few problems here.acoggan said:Differences between groups were evident even when they were compared at the same power:
1. It isn't clear how they got to Figure 7. What should be normalized are the muscle forces, not the total forces. Remember, the total forces graph increase the apparent pushing forces and decrease the apparent pulling forces.
While group 2 may be pulling more than group 1, it is by a tiny amount when one is considering the muscle forces. Any analysis that isn't looking at the muscle forces is sort of a waste of time don't you think?
2. Even though it appears there is a difference I don't think the difference reached statistical significance. If it didn't then there is no difference.
3. If the real outlier in group 2 were removed (suject k) there would probably be no difference between groups. I am really interested in knowing what the story is for subject K. That is the most bizarre pedaling pattern. It is how I would expect an amputee to pedal. The next most bizarre is subject N. Of all the people I have measured technique on essentially everyone is stronger across the bottom than the top. N is doing nothing across the bottom and quite strong across the top. One thing I wonder about is whether the subjects knew when their technique was being recorded. Is it possible that these "weaker" subjects were modifying their stroke trying to look as "good" as what they expected the better cyclists to look like?
4. But, most importantly, and what you ignored, is explaining the difference between the form of the absolute best cyclist in this cohort by far and subject D and J. That difference alone gives lie to the thought that "pushing harder" is the key to increasing power.
Re: Re:
It's pretty obvious that you are guilty of-
Cherry picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position, while ignoring a significant portion of related cases or data that may contradict that position. It is a kind of fallacy of selective attention, the most common example of which is the confirmation bias.[1][2] Cherry picking may be committed intentionally or unintentionally. This fallacy is a major problem in public debate.[3]
but then again it's not a big surprise given your track record.
Hugh
FrankDay said:
It's pretty obvious that you are guilty of-
Cherry picking, suppressing evidence, or the fallacy of incomplete evidence is the act of pointing to individual cases or data that seem to confirm a particular position, while ignoring a significant portion of related cases or data that may contradict that position. It is a kind of fallacy of selective attention, the most common example of which is the confirmation bias.[1][2] Cherry picking may be committed intentionally or unintentionally. This fallacy is a major problem in public debate.[3]
but then again it's not a big surprise given your track record.
Hugh
Re: Re:
edit: regarding "cherry picking" one has to wonder how it was that the two groups ended up with 9 in one and 6 in the other? Cherry picking perhaps to get the result they wanted? There is no natural break. Yes, 1 minute difference between 9 and 10 but there is a 1.5 minute difference between 6 and 7 so why not two groups of 6 and 9?
Another issue I have with this paper is they are looking at total pedal forces but there is no way of even hoping to guess what the non-muscular forces and muscular forces were since they do not give us the cadence the riders were at when the measurements were taken. Cadence is a huge contributor to non-muscular vertical forces and vertical forces was one of the key things they looked at.
Cherry picking??? LOL. It is not cherry picking to point out that there was no significant difference found between the two groups in pedaling style even when the outliers, that intrigued me, were included. And, it is not cherry picking to ask how subjects A, D, and J support the notion that learning how to "just push harder" makes one faster. The cherry pickers are those who have misinterpreted this data and point to it as supporting that "pushing harder" is the key to getting faster.sciguy said:
edit: regarding "cherry picking" one has to wonder how it was that the two groups ended up with 9 in one and 6 in the other? Cherry picking perhaps to get the result they wanted? There is no natural break. Yes, 1 minute difference between 9 and 10 but there is a 1.5 minute difference between 6 and 7 so why not two groups of 6 and 9?
Another issue I have with this paper is they are looking at total pedal forces but there is no way of even hoping to guess what the non-muscular forces and muscular forces were since they do not give us the cadence the riders were at when the measurements were taken. Cadence is a huge contributor to non-muscular vertical forces and vertical forces was one of the key things they looked at.
Re: Re:
A was both the most powerful and had the fastest 40 km TT of the entire group with 376 watts and 51 minutes but but had only the 4th strongest push (table 6 and figure 4). D and J were the two strongest pushers but didn't look very good in comparison. D had the 5th highest power (357 watts, 19 watts lower) and 4th fastest time trial, 54 minutes, 3 minutes slower while J had the 9th highest power (335 watts, 41 watts lower) and the 10th fastest time trial, 57 minutes, 6 minutes slower). If pushing harder is so important to power generation explain these quite large discrepancies.
You really couldn't figure this out for yourself? Does anyone other than myself ever really look at this stuff? OKJamesCun said:
A was both the most powerful and had the fastest 40 km TT of the entire group with 376 watts and 51 minutes but but had only the 4th strongest push (table 6 and figure 4). D and J were the two strongest pushers but didn't look very good in comparison. D had the 5th highest power (357 watts, 19 watts lower) and 4th fastest time trial, 54 minutes, 3 minutes slower while J had the 9th highest power (335 watts, 41 watts lower) and the 10th fastest time trial, 57 minutes, 6 minutes slower). If pushing harder is so important to power generation explain these quite large discrepancies.
Frank, just giving you a chance to feel superior in your own mind.
Now, back to reality. They look at the overall grouping to avoid the cherry picking that you are doing. They do the stats to see if they can find a difference that can't be explained by random chance. They use actual numbers instead of ranked order, saying 1st and 4th is totally meaningless.
Any other sideshows here???
Now, back to reality. They look at the overall grouping to avoid the cherry picking that you are doing. They do the stats to see if they can find a difference that can't be explained by random chance. They use actual numbers instead of ranked order, saying 1st and 4th is totally meaningless.
Any other sideshows here???
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