Body Rotation

On 24 Mar 2004 22:41:48 GMT, [email hidden]

(Skipthomp48) said:

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Does the entire body tilt in the rotation or just lower,
that is does the head stay straight looking down (or
slightly ahead) while body rotates at waist?

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In TI drills, usually the head is either facing down, or
up to breathe. I'm not sure what you mean by "body
rotates at waist," but the entire body rolls as a unit,
except for the head.

Donal Fagan AIA Donal@DonalO'Fagan.com (Anglicise the name
to reply by e-mail)

"Skipthomp48" <[email hidden]> wrote in message
"]news:[email hidden]...

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Been working on this very hard, and I do agree that fish
like swimming is working for me! One question: Does the
entire body tilt in the rotation

or

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just lower, that is does the head stay straight looking
down (or slightly ahead) while body rotates at waist?

I have been told have belly button face side of pool
during rotation, but

what

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about the head? Someone posted pictures in the body
position post (i

think)

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relative to hip out of water on rotation. That picture
showed full body rotation, head turned, facing pool side,
not down. In classes I have done

a

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drill where we do that. Help/advice please.

Head stays pretty much fixed (except to breathe) the rest of
the body, from shoulders down rotates together. Don't wanna
twist at the waist. That will often cause you to weave and
slow down.

rotates together? i don't know of many swimmers who have the
same degree of rotation at the hip as they do at the
shoulder...

"DaKitty" <[email hidden]> wrote in message
news:l6u8c.5222$1I5.141@fed1read01...

Quoted message said:

"Skipthomp48" <[email hidden]> wrote in message news:20040324174148.18837.00000020@mb-
m20.aol.com...

Quoted message said:

Been working on this very hard, and I do agree that fish
like swimming

is

Quoted message said:

Quoted message said:

working for me! One question: Does the entire body tilt
in the rotation

or

Quoted message said:

just lower, that is does the head stay straight looking
down (or

slightly

Quoted message said:

Quoted message said:

ahead) while body rotates at waist?

I have been told have belly button face side of pool
during rotation,

but

Quoted message said:

what

Quoted message said:

about the head? Someone posted pictures in the body
position post (i

think)

Quoted message said:

relative to hip out of water on rotation. That picture
showed full body rotation, head turned, facing pool
side, not down. In classes I have

done

Quoted message said:

a

Quoted message said:

drill where we do that. Help/advice please.

Head stays pretty much fixed (except to breathe) the rest
of the body,

from

Quoted message said:

shoulders down rotates together. Don't wanna twist at the
waist. That will often cause you to weave and slow down.

thank you...that answered my question. I was doing it
correctly...skip

"Larry Weisenthal" <[email hidden]> wrote in message
"]news:[email hidden]...

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rotates together? i don't know of many swimmers who have
the same degree

of

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rotation at the hip as they do at the shoulder... <<

This was actually the subject of a peer review study which
we discussed

maybe a

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year ago. As elite swimmer increase their speed, their hip
rotation

decreases

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and their shoulder rotation increases, but the decrease in
hip rotation is greater than the increase in shoulder
rotation, so that the total

amplitude of

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shoulder rotation (relative to the bottom of the pool, not
relative to the hips) decreases.

I'm working on my next controversy in swimming technique.
Calling it "dry armpits/wet hips." Working on nuances and
how to teach it.

you mean riding high up on the water when sprinting?

<<This was actually the subject of a peer review study which
we discussed maybe a year ago.>>

Hi Larry. Could you tell me who was involved in that study?
I either missed it somehow or my memory is poor (every once
in a while I find myself focused on coaching issues on my
deck to the exclusion of all other decks for months and
months at a time. Especially in pre-Olympic years).

Thanks.

Regards,

Scott

[email hidden] (Scott Lemley) wrote in message news:<[email hidden]>...

Quoted message said:

<<This was actually the subject of a peer review study
which we discussed maybe a year ago.>>

Hi Larry. Could you tell me who was involved in that
study? I either missed it somehow or my memory is poor
(every once in a while I find myself focused on coaching
issues on my deck to the exclusion of all other decks
for months and months at a time. Especially in pre-
Olympic years).

Thanks.

Regards,

Scott

1: J Biomech 2003 Jan;36(1):53-62

Stroke frequency in front crawl: its mechanical link to the
fluid forces required in non-propulsive directions.

Yanai T.

School of Physical Education, University of Otago, PO Box
56, Dunedin, New Zealand. [email hidden]

Two hypotheses were tested: (a) stroke frequency is
predictable from the amplitudes of bodyroll and the turning
effect around the body's long-axis generated by the non-
propulsive fluid forces (that is, the torque driving
bodyroll), and (b) swimmers exhibit at least one alteration
in the factors influencing the bodyroll cycle as they
increase the stroke frequency for faster swimming, so that
they can reduce the fluid forces "wasted" in non-propulsive
directions. The mechanical formula that links stroke
frequency and the kinetics of bodyroll was derived on the
basis of Euler's equation of motion. Experimental data were
collected from competitive swimmers to validate the derived
mechanical relations and to examine the strategy that
skilled swimmers would use to change the stroke frequency
as they swam faster. A strong correlation (slow: r = 0.70
and fast: r = 0.85) and a non-significant difference
between the observed stroke frequency and the formula-based
estimates supported the first hypothesis. As the subjects
increased stroke frequency (38%) for faster swimming,
bodyroll decreased (19%) and the trunk twist increased
(40%). The combined alterations resulted in a small
reduction in the shoulder roll (12%), enabling the swimmers
to gain the benefits associated with a large rolling action
of the upper trunk, while limiting the amount of increase
in the turning effect of fluid forces in non-propulsive
directions (40%). The second hypothesis was, therefore,
supported. The derived mechanical formula provides a
theoretical basis to explore mechanisms underlying the
interrelations among stroke frequency, stroke length and
swimming speed, and sheds light on a possible reason that
swimmers generally adopt six-beat kicks.

"Larry Weisenthal" <[email hidden]> wrote in message
"]news:[email hidden]...

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you mean riding high up on the water when sprinting?<<

No, refers to body rotation. Don't want to re-start an old
Larry vs TI controversy, but it has to do with what type
of rotation to use. Rotate

the

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body as a log, or coil and uncoil. If you go to swim meets
and watch real

good

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sprinters and middle distance swimmers, you will note that
their hips are relatively flat in the water...they bob
back and forth (the "cheek to

cheek"

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thing)...usually staying within +/- 45 degrees (or less),
while the

shoulders

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often rotate to very nearly 180 degrees (certainly
exposing the armpits to

the

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air with each stroke). The back and forth hip rolling is
non-propulsive

and

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probably increases drag (don't yell at me; I first read
this from Cecil Colwin). As I noted previously, research
shows that as expert competitive swimmers increase their
velocity in the water, their hip rotation

decreases and

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their shoulder rotation increases (hips travel a smaller
arc; shoulders

travel

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a larger arc), but the magnitude of decrease of hip
rotation is greater

than

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the magnitude of increase of shoulder rotation, so that
the total

magnitude of

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body rotation (relative to the bottom of the pool) is
decreasing with increasing velocity. So the way to swim
faster is not to rotate your hips more, but to rotate your
hips less and rotate your shoulders more. It's a coiling
and uncoiling motion, rather than a log rolling motion.
I'm trying

to

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figure out the best way to learn it, train it, and teach
it. Thus far, focusing on making sure that both armpits
get nice and dry, while

initiating

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rotation with my hips but limiting hip rotation so that
I'm NOT "skating

on my

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side" seems to be taking me in the general direction of
where I'm trying

to go,

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but I'm not quite there yet. What I'm trying to achieve is
a fluid coil/uncoil, as I see in my hero, Andy Miller-Bray
(46 y.o. who made the

US

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national team which swam in the world champs in Barcelona
last summer).

Andy

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makes it look so easy.

I hear what you're saying. What I've learned over the last
months is that there is really two different styles of
stroke, one used for sprinting, another for distance. In
sprinting, to get the explosive power many swimmers tend to
flatten out because it becomes near impossible to rotate
their entire body at the same rate their stroke turns over,
so the amplitude of the body rotation lessens to keep up the
pace. When swimming longer distances, with a lower stroke
speed, the rotation is much more prominent.

Perhaps some day, we'll ruin into an extraordinary swimmer
that will be able to rotate his whole body at the same rate
they can turn their arms in the sprint (extra core
strength?), and he'll smoke all the records.

I think the flattening out is not due to the speed being
higher if you're flatter, I think it's due to body's
physical limitation. I think they go faster because in a
sprint, their stroke rate and power moves them faster... but
longer distances they are probably unable to maintain the
'sprint and the push' so they relax into more of a body
rotate/glide position.

knowing that, if I was looking for a perfect body position,
I'd first separate the sprinting style from distance style,
and analyze them on their own.

Even at my relatively slow rate, I tend to flatten out when
I try to sprint, but if I try swimming at the same flatter
body position, and a pace that I would use for a 1000 or a
1650, I'm much slower in a flatter position, then fully
rotating... And in a flatter position, I do tend to strain
my shoulders, since in a 1000 there are a lot more strokes
than in a 100 or a
50. Swimming flatter in a 100 you won't get as much of an
injury from improper shoulder position, as you would
swimming a 1650. I noticed it making a 3-4 seconds
difference in my 200 free (faster with full rotation)...
and even in a sprint on occasion, if I stay too flat, I
tend to choke out the sprint. If I relax a bit, and
remember to rotate more, I usually swim my PB's.

In my case, I rotate shoulders, and hips need to follow, but
the shoulders are leading the rotation. I think there is so
much emphasis on hip rotation because a lot of people tend
to rotate their shoulders a fair amount, and tend to leave
the hips behind. Also, the way out bodies work, there is
always going to be some coiling and uncoiling with
shoulder/hip rotation. To me, feel for what seems to fall
into the 'rhythm' of swimming, getting the feel for the path
of least resistance in the water. I think those may vary to
a degree for different body styles and different
musculoskeletal build and strength. Anyway, that's at least
the way it's been working out for me.

"Larry Weisenthal" <[email hidden]> wrote in message
"]news:[email hidden]...

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I think another reason why sprinters don't "log roll" so
much is that the

kick

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is more efficient when the back and forth rolling is more
limited. I've commented before how flat Thorpe's hips seem
to be, so that his feet look

like

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they are kicking the way a snorkler on the surface would
kick, with a predominately vertical, rather than sideways
motion. I'm curious about

the

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difference between a flutter kick and a dolphin kick with
regard to being vertical vs horizontal. It's now popular
to do breakouts with an

underwater,

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"sideways" dolphin. But when the whole body isn't
undulating,

dolphin-style, I

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wonder if a flutter kick is more effective on the surface
vertically

rather

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than on the side. And then there is Yanai's research
(abstract quoted by Eric). In the full text version of
this paper, Yanai measures 6 different body-rotating
torques produced by the upper body during the stroke cycle

and

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Yanai further notes that each kick in a 6 beat kick
cycle exactly

coincides

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with and counterbalances a body-rotating torque of the
upper body. Yanai theorizes that the reason sprinters
naturally develop 6 beat kicks is to prevent their bodies
from engaging in resistive and non-propulsive side to

side

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rotations during the stroke cycle.

- Larry

Interesting observations. I'm not sure whish way works
better. I did notice one thing, in my own case, rotation
helps, but only when done in proper rhythm. That rhythm, for
one, a person needs to gain a feel for it, and the other
thing is, it takes a fair amount of strength and energy to
do it right. As the energy runs out, I get flatter. I can
still go decent speed, but nowhere near what I can do with
proper rotation... So yet again, running into my own body
physical limitations of the moment, rather than what may be
optimal technique.... in my case.

"Richard Cant" <[email hidden]> wrote in message
"]news:[email hidden]...

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In message <0r8ac.64768$1I5.31606@fed1read01>, DaKitty
<[email hidden]> writes

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What I've learned over the last months is that there is
really two different styles of stroke, one used for
sprinting, another for distance. In sprinting, to get the
explosive power many swimmers tend to flatten out because
it becomes near impossible to rotate their entire body at
the same rate their stroke turns over, so the amplitude
of the body rotation lessens to keep up the pace. When
swimming longer distances, with a lower stroke speed, the
rotation is much more

prominent.

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OK my two pence worth..

Firstly the flatter body position is higher drag than the
side on position because it cuts a bigger footprint in the
surface.

However the on the side position requires rotations which
are in themselves wasted effort. Clearly at slower speeds
the stroke count will be lower and hence this energy loss
is less and will be more than compensated by the gain from
the slippery on the side position.

So there will be a natural transition from rolling to a
flatter position as you go quicker. The exact range of the
changeover depends on the swimmer - all other things being
equal the better swimmers will have lower stroke count and
so the transition to the flatter sprinting position should
happen at a higher speed.

A couple of other factors will produce the same effect.

The are action will produce a torque in the opposite
direction which will sink the legs and create drag. Better
swimmers will move their arms in ways that minimise this
effect (high elbow pull) but some effect is unavoidable
from the upper arms.

To counterbalance this there are a number of possible
things that could help.

(a) Gliding with the arm angled down at the start of the
stroke.

(b) Holding the head low so water flows over it when not
breathing (a la Popov).

(c) Kicking - but only if the hips are near horizontal.

Now (a) becomes less and less usable as the stroke rate
increases because the glide is unaffordable. whilst (b)
can only provide a limited effect because the head is not
as far in front of the body as the leading arm. This
leaves (c) as a major option when sprinting. I can't see
why the kick should be less propulsive on the side - but I
can see why it should be less effective at lifting the
legs so I guess this is the real reason why sprinters do
it. In any case it is known from Doc Counsilman's
experiments (where he towed swimmers with a line whilst
kicking and measured the drag) that the kick becomes less
propulsive at higher speeds and can even produce more
drag. So why sprinters do it more than distance swimmers
can only be explained by some other factor like the above.

--
Richard Cant

That's a very nice explanation of what I've come to
understand and believe, for the most part.