pedaling tricks: Coyle + Kautz studies show ...

I've been having lots of my ideas about pedaling technique busted by reading
the archives of this newsgroup, and smart people would cite the 1991 studies
by Coyle and Kautz and others, so I tracked them down -- but when I read the
two articles I was surprised . . .
both 1991 papers show that:
(a) elite racers do _not_ pedal like casual riders.
(b) elite racers _do_ generate positive power in the upward phase of the
stroke cycle, in a 40km performance.

So before I go along with the principle that "technique is irrelevant", I'd
like to hear an explanation of some of the results in those articles -- or
else references to more recent studies that show something different.

The papers also demonstrated things I expected, like no evidence that
"ankling" increases power in endurance performance, and that elite racers
apply little or no upward force to the pedal during the upward phase. So I'm
glad I read the articles, I just want to get a more careful analysis of two
implications from them. Below is my attempt.

Ken
________________________________________
details . . .
(a) elite racers do _not_ pedal like most riders.
I think that most casual riders in a one-hour endurance performance do not
use each leg to lift its own weight during its upward phase (though perhaps
they will do it in a short acceleration or hill-climb). The skilled racers
in their "high workload" 40km time-trial effort were making each leg lift
most of its own weight. That's what Table 2b on page 37 of the Kautz article
shows.

The average "negative work" per stroke cycle for the racers was 3 Joules. If
the mass of the "lifted portion" of the leg is 10% of the body mass of a 75
kg cyclist, and the leg is lifted 0.34 meters in the upward phase, that's 25
Joules of work. If only 3 Joules are being done "negatively" by getting
pushed up by the pedal, then the racer's leg itself is doing 88% of the
lifting. They kept on doing that 90 times a minute for almost an hour.
Rather different from casual riders.

(b) elite racers _do_ generate positive power in the upward phase of the
stroke cycle, in a 40km performance.

Because in the physics of pedaling the reduction of negative work _is_
positive work.
If the work of lifting the weight of one leg is 25 Joules, at 90rpm that's a
power rate of 37 Watts (for each leg). If each leg generates positive power
at a rate of 196 Watts, but the other leg is permitted to just ride up on
its pedal, then 37 Watts go into lifting the other leg, instead of
propelling the rider forward, so the power applied to speed is only 159
Watts per leg.

But if the racer uses each leg's own muscles to actively lift 90% of its
weight at 90rpm, then only 4 Watts is subtracted from the propulsive work,
and the power applied for forward speed is 192 Watts.

That's 20% more Watts. Positive power from lifting the weight of leg in the
upward phase. By real racers in an endurance performance.
________________________________________
sources:

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.

Coyle EF, Feltner ME, Kautz SA, Hamilton MT, Montain SJ, Baylor AM, Abrahams
LD, Petrek GW: "Physiological and biochemical determinants of elite
endurance cycling performance". Medicine and Science in Sports and Exercise
23:93-107, 1991.

I found copies of these articles linked from:
http://www.edb.utexas.edu/coyle/publications.php

In article
,
"Ken Roberts" wrote:

I've been having lots of my ideas about pedaling technique busted by reading
the archives of this newsgroup, and smart people would cite the 1991 studies
by Coyle and Kautz and others, so I tracked them down -- but when I read the
two articles I was surprised . . .
both 1991 papers show that:
(a) elite racers do _not_ pedal like casual riders.
(b) elite racers _do_ generate positive power in the upward phase of the
stroke cycle, in a 40km performance.

snip

The papers also demonstrated things I expected, like no evidence that
"ankling" increases power in endurance performance, and that elite racers
apply little or no upward force to the pedal during the upward phase.

snip

The statement following (b) and the second half of the second paragraph
appear to contradict each other.

On Thu, 19 Oct 2006 04:02:54 GMT, "Ken Roberts"
wrote:

I've been having lots of my ideas about pedaling technique busted by reading
the archives of this newsgroup, and smart people would cite the 1991 studies
by Coyle and Kautz and others, so I tracked them down -- but when I read the
two articles I was surprised . . .
both 1991 papers show that:
(a) elite racers do _not_ pedal like casual riders.
(b) elite racers _do_ generate positive power in the upward phase of the
stroke cycle, in a 40km performance.

So before I go along with the principle that "technique is irrelevant", I'd
like to hear an explanation of some of the results in those articles -- or
else references to more recent studies that show something different.

The papers also demonstrated things I expected, like no evidence that
"ankling" increases power in endurance performance, and that elite racers
apply little or no upward force to the pedal during the upward phase. So I'm
glad I read the articles, I just want to get a more careful analysis of two
implications from them. Below is my attempt.

Ken
________________________________________
details . . .
(a) elite racers do _not_ pedal like most riders.
I think that most casual riders in a one-hour endurance performance do not
use each leg to lift its own weight during its upward phase (though perhaps
they will do it in a short acceleration or hill-climb). The skilled racers
in their "high workload" 40km time-trial effort were making each leg lift
most of its own weight. That's what Table 2b on page 37 of the Kautz article
shows.

The average "negative work" per stroke cycle for the racers was 3 Joules. If
the mass of the "lifted portion" of the leg is 10% of the body mass of a 75
kg cyclist, and the leg is lifted 0.34 meters in the upward phase, that's 25
Joules of work. If only 3 Joules are being done "negatively" by getting
pushed up by the pedal, then the racer's leg itself is doing 88% of the
lifting. They kept on doing that 90 times a minute for almost an hour.
Rather different from casual riders.

(b) elite racers _do_ generate positive power in the upward phase of the
stroke cycle, in a 40km performance.

Because in the physics of pedaling the reduction of negative work _is_
positive work.
If the work of lifting the weight of one leg is 25 Joules, at 90rpm that's a
power rate of 37 Watts (for each leg). If each leg generates positive power
at a rate of 196 Watts, but the other leg is permitted to just ride up on
its pedal, then 37 Watts go into lifting the other leg, instead of
propelling the rider forward, so the power applied to speed is only 159
Watts per leg.

But if the racer uses each leg's own muscles to actively lift 90% of its
weight at 90rpm, then only 4 Watts is subtracted from the propulsive work,
and the power applied for forward speed is 192 Watts.

That's 20% more Watts. Positive power from lifting the weight of leg in the
upward phase. By real racers in an endurance performance.
________________________________________
sources:

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.

Coyle EF, Feltner ME, Kautz SA, Hamilton MT, Montain SJ, Baylor AM, Abrahams
LD, Petrek GW: "Physiological and biochemical determinants of elite
endurance cycling performance". Medicine and Science in Sports and Exercise
23:93-107, 1991.

I found copies of these articles linked from:
http://www.edb.utexas.edu/coyle/publications.php

Dear Ken,

Regardless of whether you raise your leg using its own muscles or by
pushing harder with the other leg, you have to supply the power
through your cardio-pulmonary system.

Your left leg can indeed put more power into the pedal if your right
leg is lifting itself and offering no resistance--but your right leg
is obliged to supply the extra power to raise itself.

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.

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

Cheers,

Carl Fogel

Tim McNamara wrote
The statement following (b) and the second half of the second paragraph
appear to contradict each other.

One statement is about effective propulsive Power produced by the whole
system during the upward phase. The other is about a specific kind of Force
during the upward phase.

Power (measured in Watts) versus Force (in Newtons).
Total system versus one part.

In a complicated system like two separate multi-line-segment legs
constrained to a circular-motion, there can be multiple ways to perform
effective Work. Immediately and Directly pushing on the pedals is only one.
(I can think of two others for seated pedaling on a flat road. For standing
pedaling on an undulating road, the range of possibilities gets wilder.)

Still one or both of the statements might be _wrong_ -- so let's talk about
that.

Ken

Carl Fogel wrote
If a pro able to put out 400 watts uses some of that \
power to raise his legs on the backstroke, that's nice ...

It's worse than nice -- I just noticed another surprise in the articles:

(c) elite racers lift their upper leg higher than necessary.

This can be seen in the graph of "Pedal Angle" (in Coyle 1991 it's Figure 6a
on page 103, and in Kautz 1991 it's Figure 3a on page 39 and Figure 4a on
page 43). The angle is more downward at the finish of the upward phase (360
or 0 degrees) than it is at the start of the upward phase (180 degrees).
With a 170mm crank, the ball of the foot must rise 0.34 meters during the
upward phase of the stroke cycle.

But if the pedal is angled 10-15 degrees more downward at the top, that
implies that the heel must have risen 0.37 meters. If the mass of the upper
leg is 10% of a 75kg cyclist, that 0.03 meter is an extra 2 Joules of work.
Using two legs at 90rpm, it adds 6 Watts. (other things being equal which
they usually aren't)

... but the question is whether he can put out more power steadily.

Whether those racers _could_ sustain a higher power rate for a longer time
by using some different mix of muscle moves is interesting for theory. The
point of the articles was about what real racers actually _do_ without being
told to test some theory.

"Steadily"? To me sustaining it for a simulated 40km / 25 mile distance
qualifies as "steadily".

The racer in the study who did like 488 Watts (including both legs) made
each leg fully lift its own weight 4500 times without resting. Amazing, and
completely unimaginable for a casual rider -- or even for me who's been
practicing it.

The usual debate is over whether using different muscles
more heavily will end up being overall more efficient ...

"Efficient" is a tricky concept which is undeniably valuable for "debate".
But for _riding_? Efficiency must be very carefully defined if it's going
to be helpful for improving technique and speed of real riders.

Cars are much less "efficient" than cyclists by almost any measure of
efficiency, but cars go much faster. What I'm looking for in my pedaling is
not "efficiency" but sustainable Power (the kind that's measured in Watts).

Ken

Ken Roberts wrote:
Carl Fogel wrote
If a pro able to put out 400 watts uses some of that \
power to raise his legs on the backstroke, that's nice ...

It's worse than nice -- I just noticed another surprise in the articles:

(c) elite racers lift their upper leg higher than necessary.

This can be seen in the graph of "Pedal Angle" (in Coyle 1991 it's Figure 6a
on page 103, and in Kautz 1991 it's Figure 3a on page 39 and Figure 4a on
page 43). The angle is more downward at the finish of the upward phase (360
or 0 degrees) than it is at the start of the upward phase (180 degrees).
With a 170mm crank, the ball of the foot must rise 0.34 meters during the
upward phase of the stroke cycle.

But if the pedal is angled 10-15 degrees more downward at the top, that
implies that the heel must have risen 0.37 meters. If the mass of the upper
leg is 10% of a 75kg cyclist, that 0.03 meter is an extra 2 Joules of work.
Using two legs at 90rpm, it adds 6 Watts. (other things being equal which
they usually aren't)

... but the question is whether he can put out more power steadily.

Whether those racers _could_ sustain a higher power rate for a longer time
by using some different mix of muscle moves is interesting for theory. The
point of the articles was about what real racers actually _do_ without being
told to test some theory.

"Steadily"? To me sustaining it for a simulated 40km / 25 mile distance
qualifies as "steadily".

The racer in the study who did like 488 Watts (including both legs) made
each leg fully lift its own weight 4500 times without resting. Amazing, and
completely unimaginable for a casual rider -- or even for me who's been
practicing it.

The usual debate is over whether using different muscles
more heavily will end up being overall more efficient ...

"Efficient" is a tricky concept which is undeniably valuable for "debate".
But for _riding_? Efficiency must be very carefully defined if it's going
to be helpful for improving technique and speed of real riders.

Cars are much less "efficient" than cyclists by almost any measure of
efficiency, but cars go much faster. What I'm looking for in my pedaling is
not "efficiency" but sustainable Power (the kind that's measured in Watts).

Ken

This is from my own expereince.
Because I read a lot about the idea of pedaling circles, I taught
myself, many years ago, to pull up. when I ride, I always concentrate
on pulling up, and my pushing down comes naturally. Recently, I have
read that pushing down may be more important, so i have tried to do so.
This is what I have found.

when i concentrate on pushing down and not pulling up, I generate more
power, my speedometer shows an slight increase in speed. however, I
cannot sustain it. I have to go bakc to pulling to keep a close speed.
I beleive that since I am used to pulling up, my cardio system is used
to do this. i guess that I can try to work on pushing down and my
cardio sytem will adapt to it to.

I find the ability to being able to do both important. soemtimes I am
working hard mostly focusing on pulling up. I get tired and I
momentarily switch to pushing down. That gives me a break.

I know that I am mostly pushing down and slightly pulling. However, I
can add something to the pull by conscioulsy thinking about it, or to
the push. Knowing how to do both cna have its advantages in my humble
unscientific opinion.

Andres

On 2006-10-19, wrote:
Ken Roberts wrote:
Carl Fogel wrote
If a pro able to put out 400 watts uses some of that \
power to raise his legs on the backstroke, that's nice ...
[snip]
when i concentrate on pushing down and not pulling up, I generate more
power, my speedometer shows an slight increase in speed. however, I
cannot sustain it. I have to go bakc to pulling to keep a close speed.
I beleive that since I am used to pulling up, my cardio system is used
to do this. i guess that I can try to work on pushing down and my
cardio sytem will adapt to it to.

I find the ability to being able to do both important. soemtimes I am
working hard mostly focusing on pulling up. I get tired and I
momentarily switch to pushing down. That gives me a break.

I remember riding up a steep hill near the end of a long ride once and
getting to the point where I felt like I was almost unable to continue.
Then I started pulling up. It was like a whole new pair of legs. The
"new" legs lasted for only a couple of hundred metres however before
they felt about as shredded as the original pair. But they got me to the
top.

The thing with pros is that even when they're "spinning" at 90+ rpm
they're still applying a very high pedal force. They must be to be doing
the incredible speeds they do. Pulling up a bit would reduce the maximum
muscle strain in those circumstances, and take a bit of pressure of the
downwards foot. This effect is less significant for the 150 Watt mortal
whose maximum power at 90 rpm is quite gentle on the feet and legs.

Andres wrote
Knowing how to do both can have its advantages

Yes for sure -- and any cyclist who also can walk _already_ knows how to do
both pushing down and pulling up.

Pulling up on the weight of the leg by using the hip-flexion muscles is a
normal and necessary part of human walking. Even more so in running. Lots of
people walk at a 50rpm cadence, and run at 60rpm. And lots of casual riders
pedal a bicycle at 50-60rpm. So if they can jog for half an hour without
stopping, they should be able to use their hip-flexion muscles to pull up
some percentage of the weight of of each leg for pedaling half an hour.

One key difference with two-legged cycling is that there's no need to pull
up any of the weight of the leg. Because the weight of the leg on the
pedal in its upward stroke is exactly counter-balanced by the weight of the
other leg on the other pedal. With running, if you don't use your
hip-flexion muscles to pull up on the leg, it won't get there to make the
next stride. With bicycling, you could almost just let the kinetic energy of
the mass of the lower leg moving through the bottom segment of the pedal
circle to carry it to the top.

I'd be interested to know for casual riders what percentage of the work of
raising the weight of the leg gets done by that leg's own hip flexion
muscles. Is it 0% or 5% or what? I'd be surprised if it's more 10% is
sustainable for a half-hour pedaling session. It would also be interesting
to know if and when they instinctively do some self-lifting without having
it suggested to them, and whether they report being conscious of it.

Based on my experiences of (occasional) training in single-leg pedaling I'd
be surprised if currently I can pull up 100% of my leg weight for longer
than 5 minutes at 80rpm. For some reason 90rpm at 100% always feels real
hard -- another reason I'm so impressed with those racers in the 1991 Coyle
+ Kautz studies.

I'd guess that in pedaling continually for an hour I can average
leg-self-lifting something like 30-45% of leg-weight per pedal-stroke. Then
the "big question" of ...

Pulling up on the weight of the leg versus pulling up on the pedal. This
means pulling up more than 100% of leg weight. Seems unlikely I could
sustain 120% for more than a minute, but I've never measured. Of course even
at 120%, I'm still pulling up mostly on the weight of my leg.

I don't get why some people make a big deal about pulling up on leg versus
pedal, because most riders can't reliably feel the difference between 110%
and 90% -- and anyway most riders are incapable of pulling up more than 100%
for more than a few seconds -- so it's not like many of us are going to
mistake 110% as an endurance performance technique.

Ken

On Thu, 19 Oct 2006 19:27:41 GMT, "Ken Roberts"
wrote:

Andres wrote
Knowing how to do both can have its advantages

Yes for sure -- and any cyclist who also can walk _already_ knows how to do
both pushing down and pulling up.

Pulling up on the weight of the leg by using the hip-flexion muscles is a
normal and necessary part of human walking. Even more so in running. Lots of
people walk at a 50rpm cadence, and run at 60rpm. And lots of casual riders
pedal a bicycle at 50-60rpm. So if they can jog for half an hour without
stopping, they should be able to use their hip-flexion muscles to pull up
some percentage of the weight of of each leg for pedaling half an hour.

One key difference with two-legged cycling is that there's no need to pull
up any of the weight of the leg. Because the weight of the leg on the
pedal in its upward stroke is exactly counter-balanced by the weight of the
other leg on the other pedal. With running, if you don't use your
hip-flexion muscles to pull up on the leg, it won't get there to make the
next stride. With bicycling, you could almost just let the kinetic energy of
the mass of the lower leg moving through the bottom segment of the pedal
circle to carry it to the top.

I'd be interested to know for casual riders what percentage of the work of
raising the weight of the leg gets done by that leg's own hip flexion
muscles. Is it 0% or 5% or what? I'd be surprised if it's more 10% is
sustainable for a half-hour pedaling session. It would also be interesting
to know if and when they instinctively do some self-lifting without having
it suggested to them, and whether they report being conscious of it.

Based on my experiences of (occasional) training in single-leg pedaling I'd
be surprised if currently I can pull up 100% of my leg weight for longer
than 5 minutes at 80rpm. For some reason 90rpm at 100% always feels real
hard -- another reason I'm so impressed with those racers in the 1991 Coyle
+ Kautz studies.

I'd guess that in pedaling continually for an hour I can average
leg-self-lifting something like 30-45% of leg-weight per pedal-stroke. Then
the "big question" of ...

Pulling up on the weight of the leg versus pulling up on the pedal. This
means pulling up more than 100% of leg weight. Seems unlikely I could
sustain 120% for more than a minute, but I've never measured. Of course even
at 120%, I'm still pulling up mostly on the weight of my leg.

I don't get why some people make a big deal about pulling up on leg versus
pedal, because most riders can't reliably feel the difference between 110%
and 90% -- and anyway most riders are incapable of pulling up more than 100%
for more than a few seconds -- so it's not like many of us are going to
mistake 110% as an endurance performance technique.

Ken

Dear Ken,

Walking or running involves pushing (hard) with one foot at roughly
the athlete's speed, and then whipping the unweighted foot forward
(lightly) at roughly twice that speed.

The muscles for pushing backward are enormously larger than the
muscles for pulling it forward again.

This is no surprise, since the pushing involves moving the whole body
forward, while the pulling involves only swinging one leg.

To get an idea of how large the difference is, stand up on the
pedals--it's quite easy to lift most of your body weight off the seat
with your pushing muscles.

Now hook your foot under some heavy object and try to lift it roughly
as high as the pedal stroke with the pulling muscles--darned hard,
isn't it?

Again, the question is whether an athlete using more muscles can put
out more total power steadily than he would using fewer muscles.

If his cardio-pulmonary system can put out 400 watts, then putting out
400 watts with pure pushing is the same as putting out 380 watts
pushing and 20 watts pulling.

The real debate is whether recruiting more muscles might raise the
total cardio-pulmonary limit, say to 420 watts.

Some studies mentioned on RBT suggest that there may be some gains in
total output with training, but they're small and open to question.
The usual experience is that you can go a little faster uphill by
pulling up, but that you'll be exhausted much sooner--your heart and
lungs are the limiting factor, not your leg muscles.

Cheers,

Carl Fogel

Ken Roberts wrote:
Andres wrote

Based on my experiences of (occasional) training in single-leg pedaling I'd
be surprised if currently I can pull up 100% of my leg weight for longer
than 5 minutes at 80rpm. For some reason 90rpm at 100% always feels real
hard -- another reason I'm so impressed with those racers in the 1991 Coyle
+ Kautz studies.

Ken:

I am not sure if I understand you correcly, but it is not hard to spin
one leg on a trainer or spin bike focusing on the pull alone. I can do
it for quite a while. I am sure that the pull will carry some momentum
into the push.

When I pull hard I end up with sore abductors, if I just push, I don't
feel my adductors at all. I agree with Carl that the total calorie
expenditure is ultimately the same at a certain effort if you are
pushing, pulling, or mixing it up. However, I still think that there
are advantages to pulling. One is that you have different muscle groups
to rely on, so once one muscle group is wasted, the other can come to
the aid. Also, you work different muscle groups and do not end up with
overdeveloped quads and weak hams. Again, these are unscientific
opinions.

Andres