On Jul 31, 7:54 pm, Doug Taylor wrote:
On Tue, 31 Jul 2007 11:30:58 -0700, wrote:

In my opinion, the limiter is the ability to deliver oxygen to the
mitochondria so the mitochonria compensate by using another mechanism
with lactic acid as an end point. Once there are enough mitochondria
in this situation the amount of lactic acid being produced overwhelms
the bodies ability to compensate for this and the "failure cascade"
starts.

Pardon me if I switch topics, but now that Frank is posting I want to
get back to the subject ofPowercranksand strength training .

Jobst Brandt has opined - I hope I am not misconstruing him - that the
full circle muscular movement thatPowercrankstrain, is not really
used when pedaling a bicycle. Good old stomping is how regular cranks
work mechanically.

I'm still a beginner on myPowercranksand usually manage a low
cadence. I trained them on the basement trainer over the winter, and
now use them only about twice a month (hint: they are absolutely
perfect to use when taking a spin with your S.O. if she, or he, is a
less strong cyclist. They slow you, or at least me, down enough so
that we actually can ride together.)

Anecdote: I took out my single speed maintain bike this evening for
the first time this season and the first time ever after usingPowercranks. Anyone who climbs on single speeds knows that the
gearing is much higher than what would be used on a multi geared bike,
and that standing and grinding at a very low cadence, rather than
sitting and spinning, is what gets you up and over. I found that an
approximation of a circular pedaling motion works much more
efficiently than stomping in this venue, and that I was noticeably
stronger over terrain that in the past was much more difficult.

So, anecdotally and subjectively, I'm thinking these puppies have made
me stronger.

FWIW.

First, Jobst is wrong. Everyone pedals in circles to some degree, in
that they do some work on the back stroke, the only question is how
much do they do? People get confused when they look at measured pedal
forces and they see everyone with negative forces on the back stroke
and very large forces on the down stroke. They construe this to mean
that stomping is the way to go. What they forget is the effects of
gravity on those measured forces.

By way of example Let's say you measure your forces and find that you
are putting 50 lbs of force on the down stroke each revolution and a
negative 5 lbs on the up stroke. From this you think you are a masher.
However, If you consider that each leg weighs perhaps 25 lbs what
this really means is you are really pulling up with 20 lbs force when
you see those negative 5 lbs on the pedal and that 25 lbs of the
downward force is actually the weight of the leg such that you are
only actually pushing with 20 lbs of muscular force on the downward
portion. So you are actively pushing with 25 lbs force and pulling
with 20 lbs force, what almost anyone would call close to pedaling in
circles, even though the forces on the pedals do not look like that
at all. If all PowerCranks does is make the rider completely unweight
then they only have to pull up another 5 lbs and now they are pushing
with 25 lbs force and pulling with 25 lbs force, what anyone would
consider pedaling in circles I am sure, even though the forces on the
pedals would be 50 on the downstroke and 0 on the up.