Arthritis, advice please...

[Nick Maclaren]

In article <[email protected]>, Nick <[email protected]> writes:
|>
|> What about the mass of the leg, the friction etc, chemical efficiency of
|> the muscles. Law of physics indeed!

Negligible. Look it up. Most of those would (and do) militate against
a high cadence, anyway.

|> > It's not just the frequent flexing, but the associated crouch and
|> > always-bent knees. Almost all the problems that cyclists have with
|> > direct strain on the knee joint are caused by the position in which
|> > they do it.
|>
|> I would like to see a ref for this. I believe a lot of knee problems are
|> caused by tracking problems caused by muscle imbalance. I don't believe
|> this can be entirely avoided by any normal riding position.

I never said that they could be. And tracking problems ARE a position
problem, just as much as the ones that have been mentioned!

Do you have a proper PHYSIOLOGICAL reference for "muscle imbalance"?
My understanding is that it is an invention of pseudo-scientific
psychling writers, though I could be wrong.


Regards,
Nick Maclaren.

 

[Nick Maclaren]

In article <[email protected]>,
Peter Clinch <[email protected]> writes:
|> Nick Maclaren wrote:
|>
|> > Eh? Surely YOU aren't one of the psychlists who believe that the laws
|> > of phsyics don't apply! X pounds at a cadence of 100 and 2X at a cadence
|> > of 50 produce exactly the same power, and therefore have exactly the same
|> > effect on the aerobic threshold. End of story.
|>
|> I believe in empirical evidence. That tells me that if I go for a long
|> ride at speed mashing all the way then my legs stop working well quite
|> dramatically, where if I spin lower gears then I can come back with much
|> more speed and much less pain.

Fine. So? You may be unusual. For the evidence that low cadences are
generally more efficient, see Whitt "Bicycling Science".

|> It's the laws of physics as applied at molecular chemistry level in the
|> way muscles work, not a very plain force times distance. Otherwise, why
|> exactly do we need gears at all?

Yes. And, given that, you would expect that the more natural a motion,
the more efficient it would be. That might not be so, but it the way
that the smart people guess.

|> But where did I say anything about being in a semi-crouch? I just said
|> I prefer higher cadences even when in a relatively upright position, as
|> on my Brompton.

The normal reason that people use them is because they are in a
semi-crouch. You may be an exception.

|> > However, you are right that it may not help, and might even make things
|> > worse. But, IF it does, THEN the person will ALSO have trouble walking
|> > up hills and stairs.
|>
|> Sorry to break natural laws again on your watch, but I have no trouble
|> walking up hills and stairs (quite the opposite, I'm remarkably good at
|> both), but dislike and find uncomfortable low cadences with big effort
|> on bikes, even with upright pedalling positions. Perhaps my nerve
|> endings need better education?

Perhaps your position isn't as appropriate for low cadence cycling as
you think that it is?

|> > If the person DOESN'T have trouble doing those
|> > but DOES on a bicycle, then their position is wrong for the technique.
|>
|> Yet if I adopt a different technique and that gets me about fine and
|> doesn't hurt, then I'm still "wrong"?

Don't be silly. I said that it indicates that your position is wrong
for the technique. If you can pedal efficiently at 200 RPM, or using
just one leg, then bully for you - and you aren't wrong to do so.


Regards,
Nick Maclaren.

 

[Nick]

Nick Maclaren wrote:
> In article <[email protected]>, Nick <[email protected]> writes:
> |>
> |> What about the mass of the leg, the friction etc, chemical efficiency of
> |> the muscles. Law of physics indeed!
>
> Negligible. Look it up. Most of those would (and do) militate against
> a high cadence, anyway.
>

But Peter was saying the high cadence kept the aerobic threshold up.
i.e. more work. If you have tried spinning really fast you will have
practical experience that the effects are not negligible.

> |> > It's not just the frequent flexing, but the associated crouch and
> |> > always-bent knees. Almost all the problems that cyclists have with
> |> > direct strain on the knee joint are caused by the position in which
> |> > they do it.
> |>
> |> I would like to see a ref for this. I believe a lot of knee problems are
> |> caused by tracking problems caused by muscle imbalance. I don't believe
> |> this can be entirely avoided by any normal riding position.
>
> I never said that they could be. And tracking problems ARE a position
> problem, just as much as the ones that have been mentioned!
>
> Do you have a proper PHYSIOLOGICAL reference for "muscle imbalance"?
> My understanding is that it is an invention of pseudo-scientific
> psychling writers, though I could be wrong.
>

Iliotibial band syndrome. It's real.


>
> Regards,
> Nick Maclaren.

 

[Nick Maclaren]

In article <[email protected]>, Nick <[email protected]> writes:
|>
|> But Peter was saying the high cadence kept the aerobic threshold up.
|> i.e. more work. If you have tried spinning really fast you will have
|> practical experience that the effects are not negligible.

So you are saying that it's less efficient? All right, I can believe
that, if you say so.

|> > Do you have a proper PHYSIOLOGICAL reference for "muscle imbalance"?
|> > My understanding is that it is an invention of pseudo-scientific
|> > psychling writers, though I could be wrong.
|>
|> Iliotibial band syndrome. It's real.

Oh, yes, that's real all right - I get it myself. But calling it
"muscle imbalance" is pseudo-scientific at best.


Regards,
Nick Maclaren.

 

[Nick]

Nick Maclaren wrote:
> In article <[email protected]>, Nick <[email protected]> writes:
> |>
> |> But Peter was saying the high cadence kept the aerobic threshold up.
> |> i.e. more work. If you have tried spinning really fast you will have
> |> practical experience that the effects are not negligible.
>
> So you are saying that it's less efficient? All right, I can believe
> that, if you say so.
>
> |> > Do you have a proper PHYSIOLOGICAL reference for "muscle imbalance"?
> |> > My understanding is that it is an invention of pseudo-scientific
> |> > psychling writers, though I could be wrong.
> |>
> |> Iliotibial band syndrome. It's real.
>
> Oh, yes, that's real all right - I get it myself. But calling it
> "muscle imbalance" is pseudo-scientific at best.
>

I called it muscle imbalance because Iliotibial band syndrome is just a
specific example of many conditions that can occur when muscles become
too tight or too week. My sports physio gives me a whole range of
stretches and exercises.

I am not a doctor so forgive me if I use non scientific terms.

>
> Regards,
> Nick Maclaren.

 

[Nick Maclaren]

In article <[email protected]>, Nick <[email protected]> writes:
|>
|> I called it muscle imbalance because Iliotibial band syndrome is just a
|> specific example of many conditions that can occur when muscles become
|> too tight or too week. My sports physio gives me a whole range of
|> stretches and exercises.

Yes, but that isn't normally the cause! Strengthening some other
muscles may often help, but that doesn't mean that imbalance was the
cause. Exactly the same applies to lower back pain, which is very
often helped by strengthening the abdominal muscles. Though lower
back pain is far MORE likely to be caused by imbalanced muscles than
iliotibial band syndrome is.

My understanding is that most of the causes are due to problems with
foot positioning, in many different ways. As you can't change the
way your bones fit together, a physiotherapist has to recommend
cures that may have little to do with the cause.

|> I am not a doctor so forgive me if I use non scientific terms.

No, it's not YOUR use I was referring to! I have read it before,
and didn't know what the author was rabbitting on about.

My objection to such terms is that they mislead people into thinking
that the cause is something other than what it is, and sometimes even
into doing themselves harm trying to cure it.


Regards,
Nick Maclaren.

 

[Peter Clinch]

Nick Maclaren wrote:

> Fine. So? You may be unusual.

But I may not be, and IME people who mash hard suffer over
distances much more than spinners, with spectacular performance
drop-offs caused by muscles that just *stop*. Only at the
anecdotal level, but very visibly so to me at that level.

> For the evidence that low cadences are
> generally more efficient, see Whitt "Bicycling Science".

For evidence the other way, see which technique has been on the
increase due to sporting success. However, we digress from the
OP's knee problems. All I was really trying to raise is that an
upright position and low cadence are not necessarily things that
need to be adopted together, and indeed can act independently for
or against his problem.

> Yes. And, given that, you would expect that the more natural a motion,
> the more efficient it would be. That might not be so, but it the way
> that the smart people guess.

The natural motion is for maximum efficiency at a low,
hunting/gathering sort of speed, and is a very different mechanical
motion to pedalling a bike. It is not necessarily anything to do
with maximum efficiency in pedalling a bike at a given rate, where
you have far more felxibility in tuning your speed/output
compromise than if you're on foot because all you do is speed up,
rather than change the whole motion.
"Natural motion" on a bike is a faintly ridiculous notion, as it's
completely artificial: nature doesn't really do wheels...
"Natural" is what you'd have got used to. I was a masher not
because it was natural, but when I got my first "racer" I figured
that since top gear was "fastest" anything else made me a wuss, so
I went everywhere (even up hills from standing starts) in top gear.
Dumb, but true. On my walk to work I'm occasionally passed by a
cycle commuting girl, who'd finish on the hill up to the hospital
at continental drift cadence, going very slowly in absolute speed
too. I asked her why whe didn't use lower gears one day after
watching her for months, she said it looked stupid. I let it
drop... Last time I saw her she was zooming up at high cadence.
Was that "natural", or learned? The latter method was visibly more
efficient.

> The normal reason that people use them is because they are in a
> semi-crouch.

No shortage of mashers in a crouch position...
I suspect the reason people use low cadences is that was what they
got used to on the single-speed they learned to ride a bike on. I
think most people tend to use higher cadences because they're told
they can keep going for longer if they do. They perpetuate such
advice because they find it to be true!

> Perhaps your position isn't as appropriate for low cadence cycling as
> you think that it is?

Or perhaps I'm just physiologically suited to higher cadence
cycling at present, whether or not I'm upright, lying back on my
recumbent, or crouching. I don't think the answers are nearly as
black and white universal as you seem to think, and I still see no
obvious reason why cadence needs to be hardwired to riding position.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Andy Leighton]

On 2 Aug 2007 08:59:51 GMT, Nick Maclaren <[email protected]> wrote:
>
> In article <[email protected]>,
> Colin McKenzie <[email protected]> writes:
>|>
>|> > You could try a traditional upright position, with a much lower
>|> > cadency, and see if that helps. Alternatively, you could see if
>|> > walking UP a steepish hill (1:5 to 1:3) causes the problem, because
>|> > it is essentially equivalent; if that doesn't cause the pain, then
>|> > a traditional position and cadency (30-50) may help.
>|>
>|> Not sure about your cadence figures. A brisk walk covers 100m in 1
>|> minute. A double stride might be 1.7 metres. Divide one by the other
>|> and you get a cadence of about 59, or about 62 with a 1.6m double
>|> stride. That's slower than generally recommended for cycling, but well
>|> above your 30-50.
>
> At that speed, a double stride might also be 2 metres! Mine is, and
> I am only 6'2".

Only 6'2", only 6'2". Some of us are a lot shorter than that and have
correspondingly short legs. A single stride of 1 metre is stretching
rather a bit more than is comfortable for me.

--
Andy Leighton => [email protected]
"The Lord is my shepherd, but we still lost the sheep dog trials"
- Robert Rankin, _They Came And Ate Us_

 

[Peter Clinch]

Nick Maclaren wrote:

> So you are saying that it's less efficient? All right, I can believe
> that, if you say so.

Efficient in what sense though? Total energy used to go x meters,
quite possiibly, but since the fuel isn't likely to be a problem
then the degree to which a useful output can be sustained may be
far more important in a cycling context. It certainly is to me,
especially if I've got a big day (or series of days) ahead of me.

However, we were on pain caused by arthritis, which I suspect isn't
/necessarily/ an article of maximising efficiency. More what sort
of motion and forces can be best accommodated by the body in
question. And I don't think it's helpful to say "if upright you
*must* be using a low cadence". It might work best... but it's not
a given. High cadences are possible in such a position, and may
work well for some.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Colin McKenzie]

Peter Clinch wrote:
> The natural motion is for maximum efficiency at a low, hunting/gathering
> sort of speed, and is a very different mechanical motion to pedalling a
> bike. It is not necessarily anything to do with maximum efficiency in
> pedalling a bike at a given rate, where you have far more felxibility in
> tuning your speed/output compromise than if you're on foot because all
> you do is speed up, rather than change the whole motion.
> "Natural motion" on a bike is a faintly ridiculous notion, as it's
> completely artificial: nature doesn't really do wheels...

But the way hunter/gatherers cover the miles is at a jog-trot. I tried
to time a jogger in the park today, and I think he did about 7 double
steps in 5 seconds. That's a cadence of 80-90, though I'd want to see
a bigger sample to confirm the figure. Coincidentally or not, this is
what I feel comfortable at on the bike. My riding position is more
upright than average, but not bolt upright.

Colin McKenzie

--
No-one has ever proved that cycle helmets make cycling any safer at
the population level, and anyway cycling is about as safe per mile as
walking.
Make an informed choice - visit www.cyclehelmets.org.

 

[Membrane]

Peter Clinch <[email protected]> wrote:

> IME people who mash hard suffer over
>distances much more than spinners, with spectacular performance
>drop-offs caused by muscles that just *stop*.

I've had that problem for as long as I can remember. Having recently
gotten more serious about cycling I began to look for answers, I tried
drinking more and more regularly, drinking energy drinks instead of
water, eating moire and more regularly, eating energy bars instead of
sandwiches. I also changed my climbing method from low cadence climbing
(primarily standing) to seated higher cadence climbing. The latter has
had the most noticeable effect on my ability to do longer distances.

My ability over longer distances still tapers off too much for my
liking, which may be because of years of low cadence cycling resulting
in muscles characterized by lots of explosive ability, but not enough
staying power.

All my life I've skipped a step when going up stairs. This requires
explosive muscle ability. Recently I've noticed that I'm no longer able
to do that with the ease that I was used to. Maybe my changed climbing
practice is beginning to pay off and my muscles are slowly changing, or
maybe it is just the result of getting older

>I
>think most people tend to use higher cadences because they're told
>they can keep going for longer if they do. They perpetuate such
>advice because they find it to be true!

+1

--
Membrane

 

[Tony Raven]

Colin McKenzie wrote:
> Peter Clinch wrote:
>> The natural motion is for maximum efficiency at a low,
>> hunting/gathering sort of speed, and is a very different mechanical
>> motion to pedalling a bike. It is not necessarily anything to do with
>> maximum efficiency in pedalling a bike at a given rate, where you have
>> far more felxibility in tuning your speed/output compromise than if
>> you're on foot because all you do is speed up, rather than change the
>> whole motion.
>> "Natural motion" on a bike is a faintly ridiculous notion, as it's
>> completely artificial: nature doesn't really do wheels...
>
> But the way hunter/gatherers cover the miles is at a jog-trot. I tried
> to time a jogger in the park today, and I think he did about 7 double
> steps in 5 seconds. That's a cadence of 80-90, though I'd want to see a
> bigger sample to confirm the figure. Coincidentally or not, this is what
> I feel comfortable at on the bike. My riding position is more upright
> than average, but not bolt upright.
>

An interesting article on stride rate and length would indicate your
estimate is about right.
http://www.thefinalsprint.com/2006/09/tall-vs-short-runners/
The jogger's "gears" are their stride length, not rate it would seem.

Interesting that the optimum stride rate for runners is the same as the
optimum cadence for cyclists. Must be a message there somewhere
assuming an "efficient competition" theory that if it was better at a
different cadence someone would have found that competitive advantage
and exploited it.

Tony

 

[Ace]

On 2 Aug 2007 18:30:15 GMT, [email protected] (Nick Maclaren) wrote:

>
>In article <[email protected]>,
>Peter Clinch <[email protected]> writes:
>|> Nick Maclaren wrote:
>|>
>|> > Eh? Surely YOU aren't one of the psychlists who believe that the laws
>|> > of phsyics don't apply! X pounds at a cadence of 100 and 2X at a cadence
>|> > of 50 produce exactly the same power, and therefore have exactly the same
>|> > effect on the aerobic threshold. End of story.
>|>
>|> I believe in empirical evidence. That tells me that if I go for a long
>|> ride at speed mashing all the way then my legs stop working well quite
>|> dramatically, where if I spin lower gears then I can come back with much
>|> more speed and much less pain.
>
>Fine. So? You may be unusual. For the evidence that low cadences are
>generally more efficient, see Whitt "Bicycling Science".

You (both) seem to have moved away from the point of the questio,
which is trying to work out what's best for minimising joint pain.
Pure efficiency is hardly relevant to that at all.

My take on this high/low cadence in that context is that the best
approach is the one that minimises pressure on the joint itself, so
heavy pushing, or mashing, is definitely a bad thing. I know several
people with knee problems, including myself, but my wife is a more
extreme example, having virtually no meniscus in her left knee.

The effect of this is that heavy loads on the knee, such as squatting
or trying to push a high gear uphill, cause a lot of pain, and here as
in general pain is a sign of potential damage and is best avoided.
Changing to a middling-low gear for the same hill reduces the maximum
force being exerted on the knee joint and therefore minimises pain.

Of course, take it too far to the other extreme, and start spinning at
100+, and the smaller force is exerted at a much higher speed, which
is itself a factor in potentially damaging the joint.

So my advice, based on practical experience, is that keeping to a
_comfortable_ medium cadence, using the gears to minimise the pressure
you're exerting per stroke while also avoiding doing more strokes than
needed, is probably the bext approach you can take.

As for position, I find it hard to understand why anyone would choose
the low saddle, knees nowhere near straight, seating position if they
have such problems - to my mind its patently obvious that this
significantly increases both the stresses on the knees and the
efficiency of the operation. On occasion I borrow a work bike[1] to
cycle between campuses, and if the large-framed ones are all out I
_really_ notice the difference in both those respects.

[1] They're dreadful things, with yank cruiser-style frame and bars,
twistgrip-operated 2 1/2 speed[2] and a back-pedal brake that makes
mounting a real challenge. I hates them.
[2] i.e. they're supposed to be 3, but usually so badly adjusted that
there's only 2 available
--
Ace in Alsace - brucedotrogers a.t rochedotcom

 

[Ace]

On 02 Aug 2007 19:47:26 GMT, Andy Leighton <[email protected]>
wrote:

>On 2 Aug 2007 08:59:51 GMT, Nick Maclaren <[email protected]> wrote:
>>
>> In article <[email protected]>,
>> Colin McKenzie <[email protected]> writes:

>>|> Not sure about your cadence figures. A brisk walk covers 100m in 1
>>|> minute. A double stride might be 1.7 metres. Divide one by the other
>>|> and you get a cadence of about 59, or about 62 with a 1.6m double
>>|> stride. That's slower than generally recommended for cycling, but well
>>|> above your 30-50.
>>
>> At that speed, a double stride might also be 2 metres! Mine is, and
>> I am only 6'2".
>
>Only 6'2", only 6'2". Some of us are a lot shorter than that and have
>correspondingly short legs. A single stride of 1 metre is stretching
>rather a bit more than is comfortable for me.

It's much more than those of us of normal height (i.e. 6'2") can
manage too. My legs are in proportion (34" IL) and can only manage a
1m stride if my front leg is bent when it touches down, a bit like a
comic Marty Feldman walk - not a comfortable gait, nor one that I'd
like to keep up for more than a short time. A more normal stride for
me is about 80cm.

--
Ace in Alsace - brucedotrogers a.t rochedotcom

 

[Tony Raven]

Ace wrote:

> You (both) seem to have moved away from the point of the questio,
> which is trying to work out what's best for minimising joint pain.
> Pure efficiency is hardly relevant to that at all.
>

http://www.sportsinjurybulletin.com/archive/1044-cyclists-knee-injuries.htm

There is nothing definitive I could find in the arthritis literature in
a quick search but what there is certainly seemed to support a high
cadence over a low cadence

Tony

 

[Peter Clinch]

Membrane wrote:

> My ability over longer distances still tapers off too much for my
> liking, which may be because of years of low cadence cycling resulting
> in muscles characterized by lots of explosive ability, but not enough
> staying power.

We are one another, and presumably share the £5! ;-)

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/

 

[Nick Maclaren]

In article <[email protected]>,
Ace <[email protected]> writes:
|>
|> You (both) seem to have moved away from the point of the questio,
|> which is trying to work out what's best for minimising joint pain.
|> Pure efficiency is hardly relevant to that at all.

Yup.

|> My take on this high/low cadence in that context is that the best
|> approach is the one that minimises pressure on the joint itself, so
|> heavy pushing, or mashing, is definitely a bad thing. I know several
|> people with knee problems, including myself, but my wife is a more
|> extreme example, having virtually no meniscus in her left knee.

No, that's wrong, in the simplistic form that you have stated. Any
person who walks or runs will put their whole weight on each knee
once every stroke. Pressure itself is not harmful, in a person who
isn't already disabled.

What is harmful is pressure while the knee is bent through an acute
(or even right) angle. That is the origin of the rule that you should
never put weight on a knee when it is bent though more than a right
angle - though that rule is much denied in this group.

|> The effect of this is that heavy loads on the knee, such as squatting
|> or trying to push a high gear uphill, cause a lot of pain, and here as
|> in general pain is a sign of potential damage and is best avoided.
|> Changing to a middling-low gear for the same hill reduces the maximum
|> force being exerted on the knee joint and therefore minimises pain.

However, standing on the pedals with a relatively straight leg does
NOT cause the same pain, and that is how people use high gears uphill.
The point about a traditional upright position is that it is a very
comparable motion to walking up a steepish hill.

Now, whether or not that is going to cause trouble will depend on the
person, but the fact remains that it is a very natural movement, and
is therefore less likely to. And that is confirmed by evidence on
casual and tyro cyclists.


Regards,
Nick Maclaren.

 

[Sandy Morton]

In article <[email protected]>,
[email protected] <[email protected]> wrote:
> I'm desperate to get back on board, any ideas? (Any!)

uk.people.support.arthritis is a very helpful nesgroup

--
A T (Sandy) Morton
on the Bicycle Island
In the Global Village
http://www.millport.net

 

[Chris Malcolm]

Nick Maclaren <[email protected]> wrote:

> In article <[email protected]>,
> "[email protected]" <[email protected]> writes:
> |>
> |> Well, for the past 6 weeks I've been off my bike because of knee pain.
> |> I went to the doc. who diagnosed osteo-arthritis (SP?). I've been for
> |> an Xray, and have a future appointment with the physio. I've also
> |> started to take a vaiety of supplements (cod liver oil, glucosamine,
> |> green lipped muscle).
> |>
> |> I'm desperate to get back on board, any ideas? (Any!)

> I shall now get flamed

> If it really is osteo-arthritis, none of that flummery will help.

That may well be true, but it's not necessarily that after a
*diagnosis* of arthritis it's not possible to recover. I knew a
lunatic marathon runner who ended up finding even walking painful
because according to the docs he consulted he'd worn out his knees
with too much running, irreversible arthritic damage, never be able to
run again. But being a lunatic he was both very determined and
unwilling to accept diagnoses he didn't like, and five years later he
successfully completed a Himalayan marathon with no pain at all.

His regime was complete rest until no pain at all, adoption of a
joint-healthy diet, then very lightly loaded knee exercises graduating
to walking when that was possible with no pain. He avoided highly
repetitive exercises, e.g. preferred walking and running on uneven
ground.

Over the years I've read complaints on this newsgroup of people who
got knee problems when using cleats which fixed their feet in
position, whose problems went away when switching to cleats which
allowed some foot rotation, so I suspect there may be something in his
idea of avoiding highly repetitive joint exercises.

--
Chris Malcolm [email protected] DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]

 

[Peter Clinch]

Nick Maclaren wrote:

> No, that's wrong, in the simplistic form that you have stated. Any
> person who walks or runs will put their whole weight on each knee
> once every stroke. Pressure itself is not harmful, in a person who
> isn't already disabled.
>
> What is harmful is pressure while the knee is bent through an acute
> (or even right) angle. That is the origin of the rule that you should
> never put weight on a knee when it is bent though more than a right
> angle - though that rule is much denied in this group.

You'll also find it much denied by telemark skiers, who routinely bounce
down ski runs with both knees bent to right angles and find that since
the muscles can take a share in the impact absorption their knees come
out of it considerably less buffeted than if they'd done the same run
skiing with classic parallel technique, with much straighter legs.
Their /thighs/ will be on fire, but *not* their knees. I know this
from doing it, and no, I don't think I can break the laws of physics.

And how do we take the pressure on a jump? Is it by bending the knees
as much as possible? Is that really harmful?

Furthermore, the above is completely irrelevant to cadence. I don't
know where you got the idea that high cadence goes with low seat
heights: I set mine as I as I can get it and still be able to pedal at all.

> However, standing on the pedals with a relatively straight leg does
> NOT cause the same pain, and that is how people use high gears uphill.
> The point about a traditional upright position is that it is a very
> comparable motion to walking up a steepish hill.

People don't walk up steep hills or stairs with straight legs. They
raise their forward leg to a sharp bend and then straighten it. The
maximum effort is on the push off, when the knee is maximally bent.

Again, this is not clearly dependant upon cadence.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email protected] http://www.dundee.ac.uk/~pjclinch/