Technique: Efficiency vs Turnover

Technique: Efficiency vs Turnover

Post by BOBSOM » Mon, 30 Dec 1996 04:00:00


Stroke efficiency has nothing to do with strength or size but rather with
the timing of hip rotation.  I was recently in Australia to give a talk on
hip rotation to an international coaches conference.  After the
conference, I was invited to give a shorter version of the talk to the
swimmers training at the Australian Institute of Sport.  Popov, who had
just gotten back in the water, was training at 22 strokes on 50 meters.
Sarah Ryan, who has been training since the Olympics, was taking 38.  I
had them both stand in front of the group and go through their stroke as
if they were swimming up toward the ceiling.  Sarah rotated her hips when
her hand was down by her stomach.  Alex rotated his hips before he began
his pull.
Swimmers we have trained to advance the timing of their hip rotation
typically cut their stroke count by 30% or more.  All the graduates of our
camps take 10 single arm pulls or less on 25 yards.  One of our graduates
is now racing 1500 meters in less than 17 minutes with only 27 strokes on
50 meters, and he is only 16 years old.
Unfortunately, you can only see the timing of hip rotation from underwater
so it has been ignored in favor of more readily visible variables such as
height, strength and sex. But research has shown that swimmers do not
develop any appreciable force against the water until after they have
rotated their hips.  Thus swimming is like land sports such as golf,
tennis and baseball where hand speed is generated by the rotation of the
hips.

Bob Prichard

 
 
 

Technique: Efficiency vs Turnover

Post by runns.. » Tue, 31 Dec 1996 04:00:00


Quote:

>Stroke efficiency has nothing to do with strength or size but rather with
>the timing of hip rotation...<snip>... Popov, who had

just gotten back in the water, was training at 22 strokes on 50 meters.
Sarah Ryan, who has been training since the Olympics, was taking 38. <<

While hip rotation no doubt has important influences on streamlining and
power, and, therefore, "efficiency," other factors clearly influence
stroke count as well...lower body propulsion (kicking), for one.

Rather than to begin by arguing, I'd like to ask a question:

If the average kicking velocity of elite swimmers is compared, is there a
relationship between kick-related propulsion and overall performance, as
there is between stroke length and overall performance? Are Olympic "A"
freestyle finalists (on average) better kickers than Olympic "B" freestyle
finalists, and are the "B" finalists better kickers than the
non-qualifiers?  How much of stroke length in elite freestyle swimmers is
related to kicking, as opposed to being related to streamlining and upper
body efficiency?

-Larry Weisenthal

 
 
 

Technique: Efficiency vs Turnover

Post by dkolto » Wed, 01 Jan 1997 04:00:00

John,

this is the 3rd or fourth reply bi have read by you tonite, and you
definitely have an attack dog mentality for anything anyone says about
stroke efficiency, or similar subjects.  I am curious what your
background is as regards swimming.

As to your answer to the original post, i might add that at 6'4" 235lbs,
i can assure you with no uncertainty that when i stroke (with minimal
kick mind you) in a fst hip change, elongated fashion, my stroke cound
decreased by 2-4 strokes per length.  after the post you lambasted, i
took the time to try a few laps with the fastest hip rotation i could
attain at my rather large size.  stroke count went down.  Bob has
something here...

dan

 
 
 

Technique: Efficiency vs Turnover

Post by John Heen » Thu, 02 Jan 1997 04:00:00

Point of clarification: Effective propulsive energy generated, over a
given distance, can be simplistically equated to resistive force by
overall distance travelled.  Assuming resistance and rate of effective
propulsive energy (or propulsive power) does not change in example
below then the distance travelled per unit time, or pace, will not
change.

Resistance probably varies proportionally but crudely, over a narrow
change of velocity range, according to k times v to the power of a,
where k is a constant of proportionality that varies according to
resistance profile, v is velocity and a lies between 2 and 3.

John Heenan

: Suppose a swimmer swims a 1500 meters aerobically in 1,000 seconds
: using 10,000 arbitrary units of metabolic energy (as measurable
: through oxygen consumption) using a late hip rotation against a
: constant average resistance of 100 arbitrary force units with a
: metabolic energy to effective mechanical propulsive energy efficiency
: conversion factor of 10%.  Ignore energy effects of dives and turns.
: Suppose his optimal metabolic energy consumption is at this rate (that
: is 10,000/1,000 = 10 metabolic energy units per second).  Suppose
: changes in style have no effect on his capacity to convert the
: metabolic energy into effective propulsive energy at the same
: efficiency. (It may even be more efficient for a swimmer to shorten
: their stroke as stretching out stroke can result in utilising energy
: less efficiently, early hip rotation or not). Suppose he takes 1000
: complete stokes in the 1500 metres. That is one complete stroke per
: second.  Hence 10 metabolic energy units are being consumed in each
: stroke cycle.  Suppose, for simplicity, he stretches out his stroke
: and times hip rotation earlier to obtain a more 'effective catch'
: earlier. Suppose he expends 20 arbitrary units of energy per stoke
: cycle. He is still consuming 10 metabolic units of energy per second.
: Since energy conversion efficiency is the same and resistive force is
: the same and he now completes the distance in the same time of 1000
: seconds.  But what is his stoke rate?  He takes 20/10 = 2 seconds to
: complete stoke.  So nothing has changed in terms of time to complete
: the distance.  Although he generates more propulsuive energy per stoke
: and slows stroke down, his overall swimming efficiency has remain
: unchanged.  However the liklihood of the following six factors
: remaining the same is nil:

: 1. Rate of metabolic energy consumed

: 2. Metabolic to bodily mecahnical energy conversion efficiency

: 3. Bodily meachanical energy to effective propulsive energy efficiency

: 4. Metabolic to effective propulsive energy efficiency (involves both
: of above)

: 5. Resistive force

: 6. Effective propulsive energy generated per stoke inversely
: proportional to time to complete the stoke

: While effective propulsive energy or metabolic to effective propulsive
: efficiency energy may increase, it may be offset by an increase in
: resistive force.
--
John Heenan    Tel:(+612 or 02) 9580 3027    Fax:(+612 or 02) 9383 8064

 
 
 

Technique: Efficiency vs Turnover

Post by BDHindso » Thu, 02 Jan 1997 04:00:00

I don't proclaim to be any sort of expert,
I'm just a good 'ol boy from Indiana.

But, Sam Freas, who has coached a LOT of good sprinters[not in theory,
but in reality!!], says basically, [and I don't paraphrase here, I just
use my own words to say what he says], to stay flat in the water when
sprinting!!  

And one other observation:  Janet Evans had a terrible stroke!!  

And yet another comment:  Janet got beat by Brooke because Brooke smoked
her on turns at the Trials, every single one by a margin of 18" - 12".
Janet would start to make up ground and then a turn.  Hmm???  Leg
strength from Brooke better then Janet?  I then believe that once she
got beat, she kinda said, "oh well, I'll have fun!!"  

Just my two ears of corn worth....
BDH

 
 
 

Technique: Efficiency vs Turnover

Post by SBRMJ » Thu, 02 Jan 1997 04:00:00

Resistance profile? Rate of Propulsive energy? K times?
Gee, I just put on my goggles and swim.

 
 
 

Technique: Efficiency vs Turnover

Post by Anton Lio » Fri, 03 Jan 1997 04:00:00

Quote:

> Resistance profile? Rate of Propulsive energy? K times?
> Gee, I just put on my goggles and swim.

I agree!

There has to be a line drawn between information that is designed to
help athletes; ie try rotating your hips earlier/faster and SEE if it
works for YOU?!!

AND information that is designed for lengthy arguments between coaches
and sports scientists.

It's ridiculous to simply assume that a particular post is in the latter
category, and thus 'needs' to be attacked or argued against...

Anton.

 
 
 

Technique: Efficiency vs Turnover

Post by John Heen » Fri, 03 Jan 1997 04:00:00

Some may notice there has been mention of the Bernoulli Principle in
my postings in this thread.  It has no relevance to the main
principles.  There is a discussion of this in section of my web pages
entitled 'What are the biomechanics of swimming?' at URL
http://www.ozemail.com.au/~ohn/swim/2.html#1

John

: Point of clarification: Effective propulsive energy generated, over a
: given distance, can be simplistically equated to resistive force by
: overall distance travelled.  Assuming resistance and rate of effective
: propulsive energy (or propulsive power) does not change in example
: below then the distance travelled per unit time, or pace, will not
: change.

: Resistance probably varies proportionally but crudely, over a narrow
: change of velocity range, according to k times v to the power of a,
: where k is a constant of proportionality that varies according to
: resistance profile, v is velocity and a lies between 2 and 3.

: John Heenan


: : Suppose a swimmer swims a 1500 meters aerobically in 1,000 seconds
: : using 10,000 arbitrary units of metabolic energy (as measurable
: : through oxygen consumption) using a late hip rotation against a
: : constant average resistance of 100 arbitrary force units with a
: : metabolic energy to effective mechanical propulsive energy efficiency
: : conversion factor of 10%.  Ignore energy effects of dives and turns.
: : Suppose his optimal metabolic energy consumption is at this rate (that
: : is 10,000/1,000 = 10 metabolic energy units per second).  Suppose
: : changes in style have no effect on his capacity to convert the
: : metabolic energy into effective propulsive energy at the same
: : efficiency. (It may even be more efficient for a swimmer to shorten
: : their stroke as stretching out stroke can result in utilising energy
: : less efficiently, early hip rotation or not). Suppose he takes 1000
: : complete stokes in the 1500 metres. That is one complete stroke per
: : second.  Hence 10 metabolic energy units are being consumed in each
: : stroke cycle.  Suppose, for simplicity, he stretches out his stroke
: : and times hip rotation earlier to obtain a more 'effective catch'
: : earlier. Suppose he expends 20 arbitrary units of energy per stoke
: : cycle. He is still consuming 10 metabolic units of energy per second.
: : Since energy conversion efficiency is the same and resistive force is
: : the same and he now completes the distance in the same time of 1000
: : seconds.  But what is his stoke rate?  He takes 20/10 = 2 seconds to
: : complete stoke.  So nothing has changed in terms of time to complete
: : the distance.  Although he generates more propulsuive energy per stoke
: : and slows stroke down, his overall swimming efficiency has remain
: : unchanged.  However the liklihood of the following six factors
: : remaining the same is nil:

: : 1. Rate of metabolic energy consumed

: : 2. Metabolic to bodily mecahnical energy conversion efficiency

: : 3. Bodily meachanical energy to effective propulsive energy efficiency

: : 4. Metabolic to effective propulsive energy efficiency (involves both
: : of above)

: : 5. Resistive force

: : 6. Effective propulsive energy generated per stoke inversely
: : proportional to time to complete the stoke

: : While effective propulsive energy or metabolic to effective propulsive
: : efficiency energy may increase, it may be offset by an increase in
: : resistive force.
--
John Heenan    Tel:(+612 or 02) 9580 3027    Fax:(+612 or 02) 9383 8064

 
 
 

Technique: Efficiency vs Turnover

Post by John Heen » Fri, 03 Jan 1997 04:00:00

: John,

: this is the 3rd or fourth reply bi have read by you tonite, and you
: definitely have an attack dog mentality for anything anyone says about
: stroke efficiency, or similar subjects.  I am curious what your
: background is as regards swimming.

: As to your answer to the original post, i might add that at 6'4" 235lbs,
: i can assure you with no uncertainty that when i stroke (with minimal
: kick mind you) in a fst hip change, elongated fashion, my stroke cound
: decreased by 2-4 strokes per length.  after the post you lambasted, i
: took the time to try a few laps with the fastest hip rotation i could
: attain at my rather large size.  stroke count went down.  Bob has
: something here...

: dan

Dan

Lowering your stroke count may, but does not necessasrily, make you a
faster or more efficient swimmer.  I went to elabourate length to
demonstrate this.

Bob Pritchard may have a lot to offer through his stroke clinics.  On
an analytical level his statements are too simplistic.  I am not
denying earlier hip rotation, for some, might be more beneficial.
However later or reduced hip rotation might be more beneficial for
others.  For some, changes in style may make no significant difference
in the long term.  No amount of stroke work will compensate if you
cannot generate sufficient sustained power.

My background in swimming?  I am on the periphary (Masters swimming
etc).  My background with regard to the technical?  University degree
in mecahnical engineering.  While raising the conceptual level, I have
kept the technical detail level of my discussions at a very basic
level.  I dabble in the scientific sphere.  I have made contributions
to rec.sport.swimming on the biomechanics of swimming.  They can be
viewed on web URL http://www.ozemail.com.au/~ohn/swim/2.html#1 .
However contributions I have made in this thread are a significant
addition.

John Heenan
--
John Heenan    Tel:(+612 or 02) 9580 3027    Fax:(+612 or 02) 9383 8064

 
 
 

Technique: Efficiency vs Turnover

Post by John Heen » Tue, 14 Jan 1997 04:00:00

Quote:

> John,

> Just curious, are you a coach, master swimmer or what?  I have seen you on
> this newsgroup and have never heard of you before.  Just need a little bio
> on you to figure where you are coming from

This is an extract from a posting already made to this thread:

My background in swimming?  I am on the periphary (Masters swimming
etc).  My background with regard to the technical?  University degree
in mecahnical engineering.  While raising the conceptual level, I have
kept the technical detail level of my discussions at a very basic
level.  I dabble in the scientific sphere.  I have made contributions
to rec.sport.swimming on the biomechanics of swimming.  They can be
viewed on web URL http://www.ozemail.com.au/~ohn/swim/2.html#1 .
However contributions I have made in this thread are a significant
addition

John Heenan
--
John Heenan    Tel:(+612 or 02) 9580 3027    Fax:(+612 or 02) 9383 8064