Re: [Paddlewise] A new way to teach the forward stroke?

rebyl_kayak_at_energysustained.com wrote:

> The figures [for estimating the power output at 100 watts]
> come from two sources. i) The NASA research quoted in chapter 2 of the
> classic text 'Bicycling Science' by Wilson, which includes rowing and
> cycling and shows them to be similar in power production. The NASA
> graphs suggest that 200 Watts is near the upper end of cycling power an
> average man might sustain for an hour or more, so 100W is quite
> conservative. ii) the other source is my personal experience in using a
> moderately loaded 200W electric bike to go to work each day through a
> traffic free park, and the same bike with the motor switched off to
> return from work. There seems to be little difference in my average
> speed in either case. The effort I put into cycling seems about
> comparable to the effort I put into seakayaking with a speed of 7km/hr
> in a moderately loaded kayak in 1m waves and headwinds less tan 10knots.

I find it hard to believe that the power output of cycling or rowing can 
be matched by kayaking. Cycling uses the biggest, strongest muscles you 
have. Rowing (at least in a sliding chair) uses those same muscles and 
adds the muscles that stretch the back, which are again quite big.
Kayaking, compared to that, is little more than squirming your torso and 
flailing your arms.

But that's just belief, and we shouldn't talk about beliefs. For now, I 
accept that you output 100W of useful energy. The storage and usage of 
potential energy might be up to 1/3 of that output.

> PeterO response - I think blade turbulance leading to thermal losses
> could also be a factor but don't know to what extent.

There will _absolutely_ be losses in blade turbulance. But those losses 
are AFTER the conversion of potential energy to force and motion of the 
paddle blade. Those losses will exist in any stroke.

> The point I'm getting to re muscle tension is that its always there in a
> typical paddling stroke and I doubt its completely absent even in a limb
> that falls free, unless its anaesthetised perhaps.

As far as I know, only trained dancers can really let a limb drop 
freely. In the vertical-rest though, the arms do not fall free: Their 
speed is kept in check by the blade in the water. Even the arm of a 
non-dancer should have time to relax.

> But then I paddle at sea and it may be different on rivers.

My usual training sessions are in a pond, with mostly flat water. I'm 
sure that at sea you'll use much more muscles, to keep yourself balanced 
and keep your blade in the water. The excitement of being on waves will 
probably cause a lot of tension too - but all those tensions will be 
there whatever stroke you use.

> Response - There are detailed tables for oxygen and energy use at rest
> and in different activities in the 'Bicycling Science text but they
> don't include static tension - I'll have to look that up, unless someone
> has these figures already.

I've studied one of those tables - but it indicated that, at rest, a man 
consumes 750 watts of energy. All other sites claim it to be about 100W, 
so I don't trust the table I used.

I might find time tonight to do some heartrate measurements on myself: 
at rest, at light exercise and at holding a paddle in front of me. It 
might give _some_ insight in what's going on. I don't make a promise 
though: There might be a good movie on TV.

> Thanks for your patient responses Niels I've got a better uunderstanding
> of your ideas and techniques and though they may not be applicable to my
> circumstances they've improved my understanding of paddle strokes and
> been most interesting.

You're welcome. Your questions are friendly and curious; It's a pleasure 
to answer them.

Niels
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