Re: pedaling tricks: Coyle + Kautz studies show ...

Ken Roberts said:

Quoted message said:

a pro racer uses some power to raise his legs on the backstroke
wrote

Quoted message said:

Quoted message said:

If he does so, he has used power that could otherwise have
been used to push down faster.

Quoted message said:

That's just the kind of claim I want to learn about.

It takes no power to raise the backstroke as mentioned. It is a false
visualization that even considers that concept. Unless the man is an
amputee, his legs are balanced and rotate effortlessly minus viscous
losses in the muscles and joints (which must be overcome anyway).

Quoted message said:

What I was asking for was more recent studies that might support
that sort of claim. So please post references to a well-designed
study in a respected journal in which compares:

Quoted message said:

(a) well-trained racers who allow the force from the other pedal (and
kinetic energy) to do over 85% of the work of raising the leg; versus

Quoted message said:

(b) well-trained racers who use the leg's own muscles to do over 85% of the
work of raising the weight of the leg.

Wake up! You don't have to "raise" the leg! Any study of that is off
in never land in the first place.

Quoted message said:

Quoted message said:

Using muscles to pull up on pedals is wasteful ...

Quoted message said:

My observation about the 1991 study was not about pulling up on the
_pedal_, it was about using the leg's own muscles to pull up some
percentage of the leg's own _weight_.

Quoted message said:

I'm pretty sure most riders most of the time use the leg's own
muscles to pull up much less than 100% of the leg's weight -- and
force from the other pedal does the remainder of the work.

Quoted message said:

Only if the leg muscles' upward force exceeds 100% of the leg's
weight is there any upward pull on the _pedal_. What surprised me
in that oft-cited Kautz + Coyle 1991 study was that almost all those
elite racers trying their best in a 40km simulated time-trial were
getting into the 85-100% range, and none were below 60%.

Quoted message said:

So if it's true that they easily could have achieved the same 40km
endurance power output by using self-lifting of the leg's weight in
the 0-15% range, then how come none of them did that?

I don't think you'll get anywhere with all this if you cannot see that
it is all hocus pocus. If you cannot see the folly of the concept,
reading more about it won't get you any answers.

Jobst Brandt

Jobst Brandt wrote

Quoted message said:

I don't think you'll get anywhere with all this
if you cannot see that it is all hocus pocus.

I don't think we're going to get anywhere until some smart people take the
time to find the Kautz + Coyle 1991 study and actually _read_ it, then
carefully think through the physics.

Those guys did a lot of work to carefully describe their method and
measurements. Their work has been cited several times on this newsgroup by
highly respected posters. I don't think it's fair to just wave away their
results with some theoretical pronouncement.

Quoted message said:

You don't have to "raise" the leg! Any study of that
is off in never land in the first place.

Somebody please take the time to look at Table 2b on page 37 of the Kautz
1991 article. Note particularly the column labeled "-W SL (J)". I think the
numbers in the column are for each of the sixteen elite racers, how much
work (in Joules) the pedal did in pushing the weight of the leg upward to
get it into position for its next down-push. Some of those numbers seem
rather low to me, pretty close to 0 (for three riders, exactly 0).

So if their pedal didn't push the mass of their leg up, then how did it get
there? If something didn't "raise the leg" then how could it have made a
downward push in their next stroke?

Or maybe I'm all wrong because I misunderstood the article. Or maybe the
authors made a mistake somewhere. Anyway the authors do describe how they
calculated the number -- so this could all be checked by someone with a
sound understanding of physics or mechanical engineering. And then I could
get straightened out.

Ken

source:
Kautz SA, Feltner ME, Coyle EF, Baylor AM: "The pedaling technique of elite
endurance cyclists: changes with increasing workload at constant cadence".
International Journal of Sport Biomechanics 7:29-53, 1991.

linked from:
http://www.edb.utexas.edu/coyle/publications.php

Ken Roberts said:

Quoted message said:

I don't think you'll get anywhere with all this if you cannot see
that it is all hocus pocus.

Quoted message said:

I don't think we're going to get anywhere until some smart people
take the time to find the Kautz + Coyle 1991 study and actually
_read_ it, then carefully think through the physics.

Quoted message said:

Those guys did a lot of work to carefully describe their method and
measurements. Their work has been cited several times on this
newsgroup by highly respected posters. I don't think it's fair to
just wave away their results with some theoretical pronouncement.

Quoted message said:

Quoted message said:

You don't have to "raise" the leg! Any study of that is off in
never land in the first place.

Quoted message said:

Somebody please take the time to look at Table 2b on page 37 of the
Kautz 1991 article. Note particularly the column labeled "-W SL
(J)". I think the numbers in the column are for each of the sixteen
elite racers, how much work (in Joules) the pedal did in pushing the
weight of the leg upward to get it into position for its next
down-push. Some of those numbers seem rather low to me, pretty close
to 0 (for three riders, exactly 0).

Quoted message said:

So if their pedal didn't push the mass of their leg up, then how did
it get there? If something didn't "raise the leg" then how could it
have made a downward push in their next stroke?

The question is what force does the other leg exert on the downward
pedal when no muscular activity is involved. Just look at a pair of
pedals on a bicycle, spinning on a chainless set of cranks and compute
the energy used to raise the upward crank while ignoring the same force
times distance effect of the downward crank. The system does not spin
from external input once set in motion. Only bearing drag and windage
slows it down. Both of these losses are mainly independent of
whether there are feet and legs on those pedals.

Quoted message said:

Or maybe I'm all wrong because I misunderstood the article. Or
maybe the authors made a mistake somewhere. Anyway the authors do
describe how they calculated the number -- so this could all be
checked by someone with a sound understanding of physics or
mechanical engineering. And then I could get straightened out.

This is similar to the article written about gyroscopic forces in
bicycle wheels that make bicycling possible. The whole concept is
easily disproven by toy scooters with 3-inch diameter wheels, roller
blades and ultimately ice skates, but this man published an entire
paper in his refutation of the concept (published in Physics Today),
thereby dignifying the proposition. The work you cite about energy
loss in a crankshaft does likewise because, for example, automotive
engine pistons only push downward.

I wonder whether these men believe that gravity has an effect on
pedaling efficiency. Do recumbents with BB's above the elevation of
the hips generate power by themselves? Is horizontal pedaling
similarly affected to vertical pedaling? ...and other such problems.

Quoted message said:

source:

Quoted message said:

Kautz SA, Feltner ME, Coyle EF, Baylor AM: "The pedaling technique
of elite endurance cyclists: changes with increasing workload at
constant cadence". International Journal of Sport Biomechanics
7:29-53, 1991.

Quoted message said:

linked from:

http://www.edb.utexas.edu/coyle/publications.php

Jobst Brandt

email hidden said:

Ken Roberts said:

Quoted message said:

a pro racer uses some power to raise his legs on the backstroke
wrote

Quoted message said:

Quoted message said:

If he does so, he has used power that could otherwise have
been used to push down faster.

Quoted message said:

That's just the kind of claim I want to learn about.

It takes no power to raise the backstroke as mentioned.

This is true.

Quoted message said:

It is a false visualization that even considers that concept. Unless
the man is an amputee, his legs are balanced and rotate effortlessly
minus viscous losses in the muscles and joints (which must be overcome
anyway).

But I don't believe it's a false visualization.

If the right foot is pushing down, the weight of the right leg raises
the left leg anyway. But if you raise the left leg with its muscles, so
it's hovering above the left pedal as it goes up, not being pushed by
it, the weight of the left leg will be added to the total force on the
right pedal.

If you're sitting on a seesaw, going down, and the person on the other
end jumps off suddenly, or is winched upwards by some additional force,
you go down a lot faster. You apply the same force as before, but the
counterweight has gone, and the torque at the fulcrum is greater.

Some diagrams, although I think this is fairly obvious really:

Let's say our legs weigh 5kg each and we push with 10kg force on the
downstroke.

Normal pedalling:

L ---------- + ---------- R
| |
v weight 5kg v weight 5kg + 10kg push

In this system, torque at the fulcrum (marked with a +) is 15r - 5r =
10r where r is crank length. So we get a full 10kg push, not 5kg, in
spite of having to "lift" the left leg. So far so good.

Now with 1kg of leg-lift on the up pedal:

L ---------- + ---------- R
| |
v 5kg - 1kg lift v weight 5kg + 10kg push

torque is increased to 15r - 4r = 11r.

If you just lift the up-leg a little bit, reducing the force between
pedal and foot, you're already adding to the total torque on the crank
(assuming the right leg muscles are pushing down as much as they were
before). You can lift more and more until the point at which the up-leg
is "hovering", and beyond that point, until it's actually pulling up on
the cleat.

Actually pulling up, as opposed to just "leg-lifting":

^
| weight 5kg - 6kg leg-lift
L ---------- + ---------- R
|
v weight 5kg + 10kg push

Torque is 16r.

The point that you don't have to be pulling up on the cleat for the
up-leg to be contributing to the crank torque is a good point I think,
that hadn't occurred to me before.

I think the distinction between leg-raising and pulling up makes sense.

"Ken Roberts" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Jobst Brandt, in response to

Quoted message said:

a pro racer uses some power to raise his legs on the backstroke

wrote

Quoted message said:

If he does so, he has used power that could otherwise
have been used to push down faster.

That's just the kind of claim I want to learn about.

What I was asking for was more recent studies that might support
that sort of claim. So please post references to a well-designed study
in a respected journal in which compares
(a) well-trained racers who allow the force from the other pedal (and
kinetic energy) to do over 85% of the work of raising the leg; versus
(b) well-trained racers who use the leg's own muscles to do over 85%
of the work of raising the weight of the leg.

Quoted message said:

Using muscles to pull up on pedals is wasteful ...

My observation about the 1991 study was not about pulling up on the
_pedal_, it was about using the leg's own muscles to pull up some
percentage of the leg's own _weight_.

I'm pretty sure most riders most of the time use the leg's own muscles
to pull up much less than 100% of the leg's weight -- and force from
the other pedal does the remainder of the work.

Only if the leg muscles' upward force exceeds 100% of the leg's weight
is there any upward pull on the _pedal_. What surprised me in that
oft-cited Kautz + Coyle 1991 study was that almost all those elite
racers trying their best in a 40km simulated time-trial were getting
into the 85-100% range, and none were below 60%.

So if it's true that they easily could have achieved the same 40km
endurance power output by using self-lifting of the leg's weight in
the 0-15% range, then how come none of them did that?

Read the study on Powercranks. These train the cyclist to pull up on the
backstroke.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?CMD=search&DB=pubmed

Many here, as well as many sports scientists, do not believe in the
effect. I personally believe in this effect having trained with them for
several thousand miles and subsequently improved my racing performance
(at age 50).

Phil H

Ben C Eggs said:

Quoted message said:

Quoted message said:

> If a pro able to put out 400 watts uses some of that power to
> raise his legs on the backstroke, that's nice, but the question
> is whether he can put out more power steadily.

Quoted message said:

Quoted message said:

Quoted message said:

> The usual debate is over whether using different muscles more
> heavily will end up being overall more efficient, not a perpetual
> motion scheme.

Quoted message said:

Quoted message said:

Quoted message said:

That's just the kind of claim I want to learn about.

Quoted message said:

Quoted message said:

It takes no power to raise the backstroke as mentioned.

Quoted message said:

This is true.

Quoted message said:

Quoted message said:

It is a false visualization that even considers that concept. Unless
the man is an amputee, his legs are balanced and rotate effortlessly
minus viscous losses in the muscles and joints (which must be overcome
anyway).

Quoted message said:

But I don't believe it's a false visualization.

It is false in that it implies that action costs power or for that
matter work, because it doesn't.

Quoted message said:

If the right foot is pushing down, the weight of the right leg
raises the left leg anyway. But if you raise the left leg with its
muscles, so it's hovering above the left pedal as it goes up, not
being pushed by it, the weight of the left leg will be added to the
total force on the right pedal.

Sure, just try climbing a grade by just pulling up on pedals and
you'll see how ineffective those muscles are at doing significant
work. Nature makes these muscles to operate in walking at best and
even then, stepping over a low fence is not easy, although pushing
down by putting one foot on the top of that obstacle is not.

Just because you have such leg retracting muscles doesn't mean they
are effective in propelling you. Pulling up is best done with the leg
extended as in sprinting and climbing when standing. In those
exercises the leg doesn't so much as pull up as giving anchor to the
force of the descending leg, the big force being achieved when the
pedals are horizontal. That is not the same as puling up in seated
pedaling.

Quoted message said:

If you're sitting on a seesaw, going down, and the person on the
other end jumps off suddenly, or is winched upward by some
additional force, you go down a lot faster. You apply the same
force as before, but the counterweight has gone, and the torque at
the fulcrum is greater.

Well, then you better get that other leg amputated to give more down
force.

Jobst Brandt

[email hidden] aka Jobst Brandt rhetorically asked:

Quoted message said:

...Do recumbents with BB's above the elevation of the hips generate power by
themselves?...

In my considerable experience, no. 🙁

--
Tom Sherman - Here, not there.

Ben C said:

email hidden said:

Ken Roberts said:

> a pro racer uses some power to raise his legs on the backstroke
> wrote

Quoted message said:

> If he does so, he has used power that could otherwise have
> been used to push down faster.

Quoted message said:

That's just the kind of claim I want to learn about.

It takes no power to raise the backstroke as mentioned.

This is true.

Quoted message said:

It is a false visualization that even considers that concept. Unless
the man is an amputee, his legs are balanced and rotate effortlessly
minus viscous losses in the muscles and joints (which must be overcome
anyway).

But I don't believe it's a false visualization.

If the right foot is pushing down, the weight of the right leg raises
the left leg anyway. But if you raise the left leg with its muscles, so
it's hovering above the left pedal as it goes up, not being pushed by
it, the weight of the left leg will be added to the total force on the
right pedal.

If you're sitting on a seesaw, going down, and the person on the other
end jumps off suddenly, or is winched upwards by some additional force,
you go down a lot faster. You apply the same force as before, but the
counterweight has gone, and the torque at the fulcrum is greater.

Some diagrams, although I think this is fairly obvious really:

Let's say our legs weigh 5kg each and we push with 10kg force on the
downstroke.

Normal pedalling:

L ---------- + ---------- R
| |
v weight 5kg v weight 5kg + 10kg push

In this system, torque at the fulcrum (marked with a +) is 15r - 5r =
10r where r is crank length. So we get a full 10kg push, not 5kg, in
spite of having to "lift" the left leg. So far so good.

Now with 1kg of leg-lift on the up pedal:

L ---------- + ---------- R
| |
v 5kg - 1kg lift v weight 5kg + 10kg push

torque is increased to 15r - 4r = 11r.

If you just lift the up-leg a little bit, reducing the force between
pedal and foot, you're already adding to the total torque on the crank
(assuming the right leg muscles are pushing down as much as they were
before). You can lift more and more until the point at which the up-leg
is "hovering", and beyond that point, until it's actually pulling up on
the cleat.

Actually pulling up, as opposed to just "leg-lifting":

^
| weight 5kg - 6kg leg-lift
L ---------- + ---------- R
|
v weight 5kg + 10kg push

Torque is 16r.

The point that you don't have to be pulling up on the cleat for the
up-leg to be contributing to the crank torque is a good point I think,
that hadn't occurred to me before.

I think the distinction between leg-raising and pulling up makes sense.

Or

L ---------- + ---------- R
| |
v weight 5kg v weight 5kg + 10kg push
+ 1kg push

Torque is 9r.

Some contend this is common among cyclists who learned to ride without
foot retention, since some pressure is required to keep one's feet on
the pedal.

Obviously, pushing with the up-leg is counterproductive.

--
Tom Sherman - Here, not there.

Phil Holman wrote

Quoted message said:

Read the study on Powercranks.

That link didn't work for me -- maybe because I'm not a subscriber to
PubMed?

Interesting that the Coyle and Kautz 1991 studies did figure into the
(giant) (sometimes fascinating) "Powercranks" thread on this newsgroup back
in 2004. I've only recently been involved with this group, but I read it in
the archives.

I recall that at least one highly-regarded participant who did _not_
advocate using Powercranks clearly understood that the 1991 Kautz and Coyle
studies showed that the elite racers were leg-self-lifting close to 100% of
leg-weight.

And I recall one prominent Powercranks advocate wondered how that result
could have been possible without training with Powercranks.

Ken

"Ken Roberts" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Phil Holman wrote

Quoted message said:

Read the study on Powercranks.

That link didn't work for me -- maybe because I'm not a subscriber to
PubMed?

a.. Luttrell MD,
b.. Potteiger JA.
Department of Health, Sport and Exercise Science, University of Kansas,
Lawrence 66045, USA.

Powercranks use a specially designed clutch to promote independent pedal
work by each leg during cycling. We examined the effects of 6 wk of
training on cyclists using Powercranks (n=6) or normal cranks (n=6) on
maximal oxygen consumption (VO2max) and anaerobic threshold (AT) during
a graded exercise test (GXT), and heart rate (HR), oxygen consumption
(VO2), respiratory exchange ration (RER), and gross efficiency (GE)
during a 1-hour submaximal ride at a constant load. Subjects trained at
70% of VO2max for 1 h.d(-1), 3 d.wk(-1), for 6 weeks. The GXT and 1-hour
submaximal ride were performed using normal cranks pretraining and
posttraining. The 1-hour submaximal ride was performed at an intensity
equal to approximately 69% of pretraining VO2max with VO2, RER, GE, and
HR determined at 15-minute intervals during the ride. No differences
were observed between or within groups for VO2max or AT during the GXT.
The Powercranks group had significantly higher GE values than the normal
cranks group (23.6 +/- 1.3% versus 21.3 +/- 1.7%, and 23.9 +/- 1.4%
versus 21.0 +/- 1.9% at 45 and 60 min, respectively), and significantly
lower HR at 30, 45, and 60 minutes and VO2 at 45 and 60 minutes during
the 1-hour submaximal ride posttraining. It appears that 6 weeks of
training with Powercranks induced physiological adaptations that reduced
energy expenditure during a 1-hour submaximal ride.

PMID: 14666944 [PubMed - indexed for MEDLINE]

Quoted message said:

Interesting that the Coyle and Kautz 1991 studies did figure into the
(giant) (sometimes fascinating) "Powercranks" thread on this newsgroup
back in 2004. I've only recently been involved with this group, but I
read it in the archives.

I recall that at least one highly-regarded participant who did _not_
advocate using Powercranks clearly understood that the 1991 Kautz and
Coyle studies showed that the elite racers were leg-self-lifting close
to 100% of leg-weight.

Probably Andy Coggan

Quoted message said:

And I recall one prominent Powercranks advocate wondered how that
result could have been possible without training with Powercranks.

Probably Frank Day, the Powercranks inventor.

I tested and reported on them back in 2000/2001. For my n =1 study I
increased power output by approx 10% which gave me just over a 1mph
increase in TT speed and also put me in the medals at US and World
Masters Track.

Phil H

On 2006-10-21, Johnny Sunset aka Tom Sherman <[email hidden]> wrote:
[snip]

Quoted message said:

Or

L ---------- + ---------- R
| |
v weight 5kg v weight 5kg + 10kg push
+ 1kg push

Torque is 9r.

Some contend this is common among cyclists who learned to ride without
foot retention, since some pressure is required to keep one's feet on
the pedal.

This sounds a plausible explanation actually of why cycling feels better
and seems to work better with clips, even though you don't feel like
you're pulling up significantly.

I believe Jobst when he says the muscles that lift up are much less
effective than the ones that push down. This sounds like why even pros
only lift 85% to 100% of leg weight (whereas they're pushing down
several hundred % of leg weight on the other side).

A downwards push on the up-pedal doesn't in theory waste energy, just
reduces torque. But then this is something I've never been quite sure of
about the human body.

If you hold up a small weight for a short time, without moving it, your
arm gets very tired quite quickly, but you are only applying force not
doing work. But is your body burning calories just to keep those muscles
contracted? As though our internal construction resembled a system of
slipping belts?

Certainly pushing down on the up-pedal might make your legs feel more
tired after less effort, even if it doesn't actually consume energy.

As someone else pointed out, a cyclist isn't too bothered about
efficiency per se, more about how far and how fast he can go. Noone
minds if they have to eat twice as many cakes.

Phil Holman wrote

Quoted message said:

Read the study on Powercranks.

Quote from study's abstract:

Quoted message said:

. . . gross efficiency (GE) . . . The Powercranks group had significantly
higher GE values than the normal cranks group ...

I'm generally uninterested in improving "Efficiency". I confess I do not
know what the "Gross" kind is.

My goal is higher sustainable Power (the kind that's measured in Watts).

In the last couple of months, Sharon and I have been trying a new training
method.

I don't know any well-controlled comparative studies to support it, so I'm
sure I'm going to get skewered on this newsgroup for mentioning it, but . .
.. here goes . . .
getting out and riding up a big hill.

Sharon has already achieved a 10% gain in speed and power. And she says
making it all the way to the top of a big hill is intrinsically satisfying.

Ken

"Ken Roberts" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Phil Holman wrote

Quoted message said:

Read the study on Powercranks.

Quote from study's abstract:

Quoted message said:

. . . gross efficiency (GE) . . . The Powercranks group had
significantly higher GE values than the normal cranks group ...

I'm generally uninterested in improving "Efficiency". I confess I do
not know what the "Gross" kind is.

It is generally accepted in sports/cycling that GE is approximately 25%
+/- a few %. This means that if 1000 joules of energy are expended but
an athlete, only 250 will contribute to useful work (forward motion). If
you
improve GE, for the same 1000 joules, more energy can be utilized for
forward motion.

Quoted message said:

My goal is higher sustainable Power (the kind that's measured in
Watts).

If you want to talk in watts, 1000 joules per second (1000 watts) are
burned by the average rider to generate 250 watts measured at the wheel.
If this is their max sustainable output for a 40k TT, by improving GE by
3%, they will now potentially generate 280 watts (12% increase)

Quoted message said:

In the last couple of months, Sharon and I have been trying a new
training method.

I don't know any well-controlled comparative studies to support it, so
I'm sure I'm going to get skewered on this newsgroup for mentioning
it, but . . . here goes . . .
getting out and riding up a big hill.

Sharon has already achieved a 10% gain in speed and power. And she
says making it all the way to the top of a big hill is intrinsically
satisfying.

Well OK, all seasoned riders/racers already do this and more. Once you
have made all the training gains that can be made over several years,
where do you go from there?

Phil H

Phil Holman wrote

Quoted message said:

If you want to talk in watts, 1000 joules per second (1000 watts) are
burned by the average rider to generate 250 watts measured at the wheel.
If this is their max sustainable output for a 40k TT, by improving GE by
3%, they will now potentially generate 280 watts (12% increase)

OK, so what I want is Watts delivered thru the wheel to the road (not Watts
burned). I'm not getting why that study couldn't measure that (like the
Coyle Kautz 1991).

Quoted message said:

Quoted message said:

getting out and riding up a big hill.

Quoted message said:

Well OK, all seasoned riders/racers already do this and more.

"and more"? Not me.
I'm usually trying to play with how _little_ training I can get away with,
and how I can minimize its impact on the rest of my life -- and yet still
achieve my long-single-day and high-pass touring goals. Since I don't have
a hill close by where I live, I tried to see how training with no serious
hills would work -- but for my goals it didn't. So now I try to get some
serious hill work each week.

Quoted message said:

Once you have made all the training gains that can be made over several
years, where do you go from there?

I think you're raising the right key issue, but I'm not in that situation.
I'm sure I've got lots of opportunities for performance gains if I put in
more hours per week, but I have no intention of doing that. Sounds like I
don't need to consider Powercranks.

Ken

"Ken Roberts" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Phil Holman wrote

Quoted message said:

If you want to talk in watts, 1000 joules per second (1000 watts) are
burned by the average rider to generate 250 watts measured at the
wheel. If this is their max sustainable output for a 40k TT, by
improving GE by 3%, they will now potentially generate 280 watts (12%
increase)

OK, so what I want is Watts delivered thru the wheel to the road (not
Watts burned). I'm not getting why that study couldn't measure that
(like the Coyle Kautz 1991).

It is less reliable. Max sustainable wattage output varies considerably
from day to day and would confound any meaningful result. On the other
hand, if valid, the result shows that a higher useful wattage can be
achieved with the same energy burn.
They could only run an experiment like you suggest if they had immediate
feedback on O2 uptake and could measure power output increases at a
fixed O2 uptake. I'm not sure they have this capability and as far as I
can see, there is no difference in the conclusion.

Quoted message said:

Quoted message said:

Quoted message said:

getting out and riding up a big hill.

Quoted message said:

Well OK, all seasoned riders/racers already do this and more.

"and more"? Not me.
I'm usually trying to play with how _little_ training I can get away
with, and how I can minimize its impact on the rest of my life --
and yet still achieve my long-single-day and high-pass touring goals.
Since I don't have a hill close by where I live, I tried to see how
training with no serious hills would work -- but for my goals it
didn't. So now I try to get some serious hill work each week.

Quoted message said:

Once you have made all the training gains that can be made over
several years, where do you go from there?

I think you're raising the right key issue, but I'm not in that
situation. I'm sure I've got lots of opportunities for performance
gains if I put in more hours per week, but I have no intention of
doing that. Sounds like I don't need to consider Powercranks.

I agree, Powercranks are no easy way to achieve performance improvement.
Sounds like you have plenty of lower hanging fruit to work with.

Phil H

Phil Holman wrote

Quoted message said:

It is generally accepted in sports/cycling that GE is approximately 25%
+/- a few %. This means that if 1000 joules of energy are expended but an
athlete, only 250 will contribute to useful work (forward motion). If you
improve GE, for the same 1000 joules, more energy can be utilized for
forward motion.
. . . The Powercranks group had significantly higher GE values than the
normal cranks group ...

This is confusing to me. I thought this 25% number was based on the
fundamental biochemistry of aerobic respiration.

Why would it have been expected that shifting the mix of muscle moves in
training workouts more toward "pulling up", would have changed biochemistry?
Is there supposed to be something different about the biochemistry of fibers
in the hip-flexion muscles from the fibers in the hip-extension and
knee-extension muscles used in the down-push?

If it means a change in the proportions of Type I versus Type II muscle
fibers, then OK -- but isn't that an expected result of a well-designed
training program for _any_ muscle group, not just hip-flexion / up-pulling
muscles?

Here's a speculation about how focusing training workouts more on
upward-pull muscles might improve performance, which _might_ make sense on
my current non-expert knowledge of physiology:
"Upward-pull hip-flexion muscles are well-positioned to deliver propulsive
work, but in most well-trained cyclists less fully developed for aerobic
work than the big down-push muscles. Therefore there's more "open territory"
available in the hip-flexion fibers for increasing capillary density and
mitochondria enzyme concentrations (etc.) at lower biological "cost". So
the same amount of training focused more on upward-pull can be expected to
result in a larger gain in local peripheral muscle aerobic capacity than if
it training were spread proportionally to the current local capacities. The
resulting larger total of peripheral aerobic capacity can then be used to
put a larger _training_ stress on Central cardio-vascular capacity than was
available before, which after adaptation results in a higher VO2max, and
thus a higher sustainable power output to the wheel."

But I'm not sure what that speculative theory has to do with changing "Gross
Efficiency" as defined above. And I'm not sure how it fits with this quote
from the abstract of the study:

Quoted message said:

"Subjects trained . . . for 6 weeks."

Ken