Distance per stroke

Distance per stroke

Post by Iron » Tue, 14 May 1996 04:00:00


Hello all

Over the last week, I have started for the first time in my swimming
carreer (USS, NCAA Div I, and a couple of months of masters) to count my
strokes.  I have found that when I average 12 strokes per length, I can
average between a 1:10 and a 1:12 for a 100 yards, while if I take just
two stroke more, I can decrease that time to 1:08-1:10.

My question is this:

1)Do any of you count your stokes for freeestyle (I have done it for years
for ***, but never for free.)
2)Is 12 strokes per 25 about average?
3)What drills can I do to increase my speed, while retaining my stroke
efficincy.  Meaning, I want to be able to go 1:08 while only taking the
ususal 12 strokes.

Any suggestions?

 
 
 

Distance per stroke

Post by Edward M. Powe » Tue, 14 May 1996 04:00:00


Quote:

>Hello all

>Over the last week, I have started for the first time in my swimming
>carreer (USS, NCAA Div I, and a couple of months of masters) to count
my
>strokes.  I have found that when I average 12 strokes per length, I
can
>average between a 1:10 and a 1:12 for a 100 yards, while if I take
just
>two stroke more, I can decrease that time to 1:08-1:10.

>My question is this:

>1)Do any of you count your stokes for freeestyle (I have done it for
years
>for ***, but never for free.)
>2)Is 12 strokes per 25 about average?
>3)What drills can I do to increase my speed, while retaining my stroke
>efficincy.  Meaning, I want to be able to go 1:08 while only taking
the
>ususal 12 strokes.

>Any suggestions?

I've found that people's stroke count varies all over the place.
Generally, fewer seems to be better (ask Terry Lauglin or Emmett
Hines!).  One of my team's best drills to show the relationship and
"feel" of stroke efficiency and kick in relation to speed is "swim
golf."  We swim a series of 50s on a fixed sendoff (usually one
minute), adding the stroke count and the time for each swim.  The sum
is your "score."  You try to drop the score with each subsequent swim
by attacking the different variables that affect the score (kick,
perceived effort, distance per stroke, streamlining, etc.).  This is
incredibly helpful in showing how speed isn't always directly
proportional to effort.  Sometimes you can achieve a lower score by
concentrating on streamlining while reducing perceived effort!  Play
with it, you'll learn a lot!
Good luck!
Ed

 
 
 

Distance per stroke

Post by jopp.. » Tue, 14 May 1996 04:00:00

|>

|>>
|>>I have found that when I average 12 strokes per length, I can
|>>average between a 1:10 and a 1:12 for a 100 yards, while if I take
|>just
|>>two stroke more, I can decrease that time to 1:08-1:10.

|>>2)Is 12 strokes per 25 about average?

        Is that 12 strokes each arm (total 24) or 12 strokes total?

        I've been reading some things that suggest (for a masters
        fitness swimmer) under 20 total is beginning to get good,
        and that (as an example) Tom Dolan did/does 59 strokes per
        100 meters.  (I think that is for his 500m or 1500m, I can't
        recall...)  If Tom reads this, perhaps he can clarify or
        confirm this figure.

        Also, is your count for 25 yards or meters?  

        And for someone else who reads this, consider too that stroke
        counts will be quite a bit higher in a 50 meter pool over 25,
        because it seems clear that the flip turn and push off will
        cut a few strokes from the count.  If you end your glide at
        the flags, then your count is really over 20 yards/meters and
        not 25.

        Also, are we counting the first stroke that we might take
        underwater before breaking the surface?

|>>3)What drills can I do to increase my speed, while retaining my stroke
|>>efficincy.  Meaning, I want to be able to go 1:08 while only taking
|>the
|>>ususal 12 strokes.

        I got ahold of a book that (Rodale Press?) put out called 101
        Swimming Tips for Fitness Swimmers (or something like that.)
        They are of the Total Immersion school of thought in that "longer
        is better".  One interesting thing they pointed out is that as
        we first put our hand into the water on the stroke, we should
        not immediately start the pull, but rather reach out a bit more.
        As we do so the flow of water under the arm into the armpit actually
        gives the upper body a little lift if done properly.  I never
        noticed it before, and since then I have been conscious of it
        and (whether it is merely psychological or not) I feel faster
        and sleeker in the water and quite aware of this little lift.

--

        Joe Oppelt

        *************

        The opinion of my employer should not be inferred from my posting.

 
 
 

Distance per stroke

Post by jopp.. » Wed, 15 May 1996 04:00:00

|>
|>   One interesting thing they pointed out is that as
|>   we first put our hand into the water on the stroke, we should
|>   not immediately start the pull, but rather reach out a bit more.
|>   As we do so the flow of water under the arm into the armpit actually
|>   gives the upper body a little lift if done properly.  

        After writing this yesterday, I concentrated a bit more on this
        in my workout this morning.

        I realized that in concentrating on reaching out with my front
        hand, I forced myself to make the end of my other arm's stroke
        just a little bit longer.
--

        Joe Oppelt

        *************

        The opinion of my employer should not be inferred from my posting.

 
 
 

Distance per stroke

Post by Ben Keye » Wed, 15 May 1996 04:00:00

1) I did when I started swimming again my Junior year in College, but I'm
not sure how wide-spread this is.

2) 12 per 25 yards is not many at all.  I'm just under 6'2" with relatively long
arms and a "long" stroke according to coaches and I usually counted 13-14 /length.
I'd bet if you counted other swimmers that you swim with you'd see a wide range of
stroke length to speed ratios.  Some folks get a lot out of their stroke while others
go with turnover.  Taller swimmers don't necessarily have longer strokes either - a
6' 5" sprinter in our conference took something like 25 strokes/length and was quite
quick (20.5ish) for 50.

3) I would think you would want to focus on making sure you get a full pull from the
top and push all the way through at the bottom of your stroke.  (Standard coaching
line).  Sculling drills are probably good for the general stroke efficiency, but it's
been a while since I've been in the water.

Quote:

> Hello all

> Over the last week, I have started for the first time in my swimming
> carreer (USS, NCAA Div I, and a couple of months of masters) to count my
> strokes.  I have found that when I average 12 strokes per length, I can
> average between a 1:10 and a 1:12 for a 100 yards, while if I take just
> two stroke more, I can decrease that time to 1:08-1:10.

> My question is this:

> 1)Do any of you count your stokes for freeestyle (I have done it for years
> for ***, but never for free.)
> 2)Is 12 strokes per 25 about average?
> 3)What drills can I do to increase my speed, while retaining my stroke
> efficincy.  Meaning, I want to be able to go 1:08 while only taking the
> ususal 12 strokes.

> Any suggestions?

 
 
 

Distance per stroke

Post by RunnSw » Thu, 16 May 1996 04:00:00

Terry Laughlin states that an advantage to "reaching out" and keeping the
arm extended as long as possible is that it increases one's effective
waterline length.

In sailing or in any racing of a boat which displaces (rather than rides
over) water, there is a bow wave and a stern wave.  As the velocity
increases, the boat is effectively pressed down into the trough between
these two waves.  The longer the boat, the faster the maximum hull speed.
Everything being equal, a longer boat will always beat a shorter boat,
because of this.

Now, I don't really see how this applies to swimming, at all.  Even when
the master himself (Terry) does this, the lead arm is way below the
waterline.  Unless the lead arm is literally half above and half under the
water, the waterline length is not increased by this.  So I doubt that a
swimmer's "hull speed" is increased by the extended arm.

I am not disputing that the extended arm helps.  Terry correctly observes
that the fastest swimmers tend to do this, so it obviously does something
positive to improve speed.

Question:  Any other explanations of why the extended arm and forearm
should help a swimmer go faster (compared to, for example, driving the
hand, forearm, and arm through the same "hole" in the water at a 45 degree
angle, until one attains the high elbow position?

Larry Weisenthal

 
 
 

Distance per stroke

Post by Frazer Middleto » Thu, 16 May 1996 04:00:00

<snip...

Quote:
> Now, I don't really see how this applies to swimming, at all.  Even when
> the master himself (Terry) does this, the lead arm is way below the
> waterline.  Unless the lead arm is literally half above and half under the
> water, the waterline length is not increased by this.  So I doubt that a
> swimmer's "hull speed" is increased by the extended arm.

...>
Do you not by extending your arm also stretch your body somewhat?
I certainly feel "longer" when stretching out than when not.  The
difference in length may be small, but at least its a positive
increase...Of course your body is "half above half below" the water,
so this is where the hull concept comes in.

Regards,
-Frazer-

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Distance per stroke

Post by Larry Joh » Fri, 17 May 1996 04:00:00

Quote:

>Terry Laughlin states that an advantage to "reaching out" and keeping the
>arm extended as long as possible is that it increases one's effective
>waterline length.

>In sailing or in any racing of a boat which displaces (rather than rides
>over) water, there is a bow wave and a stern wave.  As the velocity
>increases, the boat is effectively pressed down into the trough between
>these two waves.  The longer the boat, the faster the maximum hull speed.
>Everything being equal, a longer boat will always beat a shorter boat,
>because of this.

>Now, I don't really see how this applies to swimming, at all.  Even when
>the master himself (Terry) does this, the lead arm is way below the
>waterline.  Unless the lead arm is literally half above and half under the
>water, the waterline length is not increased by this.  So I doubt that a
>swimmer's "hull speed" is increased by the extended arm.

>I am not disputing that the extended arm helps.  Terry correctly observes
>that the fastest swimmers tend to do this, so it obviously does something
>positive to improve speed.

>Question:  Any other explanations of why the extended arm and forearm
>should help a swimmer go faster (compared to, for example, driving the
>hand, forearm, and arm through the same "hole" in the water at a 45 degree
>angle, until one attains the high elbow position?

>Larry Weisenthal

I am not familiar with the intricacies of boat design, however, I do have a
degree in Aerospace engineering and work as an aerodynamicist.  I maybe able
to help clarify things.

Your concern about the waterline is incorrect.  I believe that the waterline
defines the amount of boat volume and surface area being influenced by the
water.  It is true that the waterline and near surface region, due to the
proximity of a lower viscosity fluid (air), is more turbulent, and thus
will impart greater drag on the swimmer or boat.  Regardless, I don't
believe that this is part of the theory.

I believe that when they say, 'everything being equal', they are referring
to total displacement and wetted surface area.  Just because one boat is
longer that the other, doesn't necessarily mean it's drag is less.  To fit
the theory and be valid for comparison, displacement and surface area must
be equal.  This isn't true for a swimmer, however it doesn't make the
analogy useless.  Ignoring the dynamic changes to displacement (or volume
of a swimmer in the water, due to waves,  etc.) a swimmers displacement
can be assumed to be constant.  This is can be assumed true since the body
will rise slightly out of the water as the arms enter, so that buoyancy
equals weight.  What isn't constant is the amount of surface area, as the
arms enter and leave the water, the amount of surface area in contact with
the water changes.  However, I don't believe that this is really significant,
either.  I don't have a feel for the amount of friction drag from a swimmers
body, but pressure drag must be the more significant contributor.

Having said all of that, I believe that there is another aspect to the theory
that is more important and may help to explain the longer boat-less drag
concept.  An important concept in determining the drag of an object is the
maximum cross-sectional area and the its distribution.  I believe that this
is the crux of the theory that Terry is referring to.  Basically, the larger
and blunter the object, the greater the drag.  To reduce drag (but keep the
same displacement and surface area) you can stretch, or elongate, the object.
For example, take two identical cubes, grab one of the cubes by any two
opposite corners and pull on it until you begin to approximate the shape of
a pencil.  If you now push both objects through the water, which one would
be easier to push.  Terry may say, see I told you, a longer boat has less
drag, and he would be correct.  But from an aerodynamic point of view, I
would say that it was the smaller maximum cross-sectional area and it's
smoother distribution.  The distribution, of course, is the cross-sectional
area transition from zero cross-sectional area (just upstream of the object)
to the max (on me it's my abdomen) to zero again (just downstream of the
object).

To sum up what could easily turn into a masters thesis, while the arm is in
the water and positioned out in front of the swimmers head, it is creating a
smoother transition of cross-sectional areas.  In other words, the flow
about a swimmers body is gradually and relatively smoothly being moved out
of the way when the arm is in this position.  As opposed to the head and
shoulders having to perform this operation alone.  This will seem obvious
if you compare the push off from the side of the pool with your body in a
streamlined position and with your arms at your sides.  The arms breakup
the flow gradually if they are out in front compared to your blunt head
and shoulders alone.  If you try this, you can actually feel a tremendous
increase in the pressure drag and subsequent loss of speed.  BTW, swimmers
legs automatically do this for the aft portion, unless the swimmer bends
the knees excessively or doesn't point the toes.

So, with this in mind, remember to roll your body so that you may stretch
out your arm as far as possible, making your body as long and as smooth
as possible.  But also shielding you head and shoulders from taking the
oncoming flow of the water.

I'm not sure if I have cleared things up or confused matters worse, so
if you have any questions or comments, I would be glad to here them.

Good Luck, Larry John

 
 
 

Distance per stroke

Post by Edward M. Powe » Sat, 18 May 1996 04:00:00


Quote:

>An important concept in determining the drag of an object is the
>maximum cross-sectional area and the its distribution.  I believe that
this
>is the crux of the theory that Terry is referring to.  Basically, the
larger
>and blunter the object, the greater the drag.  To reduce drag (but
keep the
>same displacement and surface area) you can stretch, or elongate, the
object.
>For example, take two identical cubes, grab one of the cubes by any
two
>opposite corners and pull on it until you begin to approximate the
shape of
>a pencil.  If you now push both objects through the water, which one
would
>be easier to push.  Terry may say, see I told you, a longer boat has
less
>drag, and he would be correct.  But from an aerodynamic point of view,
I
>would say that it was the smaller maximum cross-sectional area and
it's
>smoother distribution.  The distribution, of course, is the
cross-sectional
>area transition from zero cross-sectional area (just upstream of the
object)
>to the max (on me it's my abdomen) to zero again (just downstream of
the
>object).

>To sum up what could easily turn into a masters thesis, while the arm
is in
>the water and positioned out in front of the swimmers head, it is
creating a
>smoother transition of cross-sectional areas.  In other words, the
flow
>about a swimmers body is gradually and relatively smoothly being moved
out
>of the way when the arm is in this position.  As opposed to the head
and
>shoulders having to perform this operation alone.  This will seem
obvious
>if you compare the push off from the side of the pool with your body
in a
>streamlined position and with your arms at your sides.  The arms
breakup
>the flow gradually if they are out in front compared to your blunt
head
>and shoulders alone.  If you try this, you can actually feel a
tremendous
>increase in the pressure drag and subsequent loss of speed.  BTW,
swimmers
>legs automatically do this for the aft portion, unless the swimmer
bends
>the knees excessively or doesn't point the toes.

This might explain the training techniques reported on Popov and other
Russian swimmers out of their hard training phase.  I read somewhere
that they were in the US and did nothing but long, easy catch up
stroke.  It stands to reason (based on the explanation above), that
keeping a hand out front at all times will aid in reducing resistance,
if not keeping the maximum "length of boat" as well.

Thanks Mr. Science!

Ed

 
 
 

Distance per stroke

Post by John C. C. Whi » Sat, 18 May 1996 04:00:00


Quote:

>>Terry Laughlin states that an advantage to "reaching out" and keeping

the >>arm extended as long as possible is that it increases one's
effective >>waterline length. >> >>In sailing or in any racing of a
boat which displaces (rather than rides >>over) water, there is a bow
wave and a stern wave.  As the velocity >>increases, the boat is
effectively pressed down into the trough between >>these two waves.
The longer the boat, the faster the maximum hull speed. >>Everything
being equal, a longer boat will always beat a shorter boat, >>because
of this. >>
Quote:

>I am not familiar with the intricacies of boat design,

however, I do have a >degree in Aerospace engineering and work as an
aerodynamicist. I maybe able >to help clarify things. > >Your concern
about the waterline is incorrect.  I believe that the waterline
Quote:
>defines the amount of boat volume and surface area being influenced by

the >water.  It is true that the waterline and near surface region, due
to the >proximity of a lower viscosity fluid (air), is more turbulent,
and thus >will impart greater drag on the swimmer or boat.  Regardless,
I don't >believe that this is part of the theory. > >

Nope, the concern about waterline is correct. The maximum speed of a
displacement hull is approximately 1.4 times the square root of the
waterline length (speed in knots, length in feet - sorry about the
units, but that's what I learned long ago). After that, as Larry W.
wrote, you are climbing your bow wave, which requires a huge increase
in power. So you must then either plane, or stretch your waterline, if
you want to go faster. So a tall swimmer with a 9 foot waterline might
go 4.2 knots, = 25536 feet per hour, = 7.09 feet per second, = 2.16
meters per second, = 23.2 seconds for 50 meters. The fastest swimmers
are able to operate in just this area of speed, so it certainly seems
that you want to be the longest boat you can.

That said, I don't see why it works for swimmers either. Maybe that's
why I can't swim 2 meters per second.

-John White-

 
 
 

Distance per stroke

Post by OrcaVid » Sun, 19 May 1996 04:00:00

Larry,
I enjoyed your input to the hull line question. In our newsgroup we need
more qualified responses as opposed to opinion screaming.
On an additional note, could you expand on the turbulence model created at
the junction area between two different mediums (i.e. water and air). I
would like to understand this in lay physics in its application to
swimming. Underwater kicking as opposed to surface swimming and some of
the fluid dynamics working for and against us.
I would also be interested in hearing any relevant knowledge you might
consider sharing with us pertainiung to:
                        1) wave formation on bodies and laminar flow for
swimmers
                        2) changing body positions to take advantage of
this
                        3) oscillation of body/pool speed compared to
constant
                            body/water speed (and drag)

Mike Sharadin, coach

 
 
 

Distance per stroke

Post by RunnSw » Tue, 21 May 1996 04:00:00


Quote:

>The arms breakup
>the flow gradually if they are out in front compared to your blunt head
>and shoulders alone.

Excellent explanation, and one that rings true. Thank you very much for
taking the time to formulate and explain this idea.

However, it is a fact that the longer the hull length at the waterline,
the faster the maximum theoretical speed of the boat.  Any nautical
engineer or sailor can verify this, and it is supposed to be related to
the trough distance between bow and stern waves.

Larry Weisenthal

 
 
 

Distance per stroke

Post by Larry Joh » Tue, 21 May 1996 04:00:00

Quote:
>>I am not familiar with the intricacies of boat design,
>however, I do have a >degree in Aerospace engineering and work as an
>aerodynamicist. I maybe able >to help clarify things. > >Your concern
>about the waterline is incorrect.  I believe that the waterline
>>defines the amount of boat volume and surface area being influenced by
>the >water.  It is true that the waterline and near surface region, due
>to the >proximity of a lower viscosity fluid (air), is more turbulent,
>and thus >will impart greater drag on the swimmer or boat.  Regardless,
>I don't >believe that this is part of the theory. > >

>Nope, the concern about waterline is correct. The maximum speed of a
>displacement hull is approximately 1.4 times the square root of the
>waterline length (speed in knots, length in feet - sorry about the
>units, but that's what I learned long ago). After that, as Larry W.
>wrote, you are climbing your bow wave, which requires a huge increase
>in power. So you must then either plane, or stretch your waterline, if
>you want to go faster. So a tall swimmer with a 9 foot waterline might
>go 4.2 knots, = 25536 feet per hour, = 7.09 feet per second, = 2.16
>meters per second, = 23.2 seconds for 50 meters. The fastest swimmers
>are able to operate in just this area of speed, so it certainly seems
>that you want to be the longest boat you can.

>That said, I don't see why it works for swimmers either. Maybe that's
>why I can't swim 2 meters per second.

>-John White-

This is interesting, as I said, I am not familiar with the intracasies of
boat design.  However, I am still not convinced that these theories are
completely applicable to swimmers.  For one thing, when your arm is
stretched out in front, it is likely to be fully immersed, thus, no waterline.

It is very common in fluid dynamic circles to create general rules based on
emperical data.  This is because in the past, accurate application of the
Navier-Stokes equations to a particular design has been prohibitively expensive.
Wind tunnel or water tank experimants have also been expensive.  It is possible
that the "1.4 times the square root of the waterline length" formula is based on
a typical ship hull shape.

Other assumptions to boat design theory may also not be applicable to the swimmer.
This is not to say that Terry's advice is wrong, in fact I agree with the basic
concept.  However, I do disagree with the analogy to boat design for use with swimmers.
If we are to continue improving swimming technique, we need to determine if boat
design theory or other theories are applicable to swimmers.

Just to be sure I am not misunderstood, I agree that the arm stretched out in front
of the head has lower drag than if the arm isn't there.  However, I believe the lower
drag is due to the gradual transition of the water around the head and shoulders.
As opposed to the abrut transition if the arm isn't out front.

I would be interested in learning more about boat design and how some of these theories
were derived.  If you could send me some references I would appreciate it.

Thanks for your reply,
Larry John

 
 
 

Distance per stroke

Post by Larry Joh » Tue, 21 May 1996 04:00:00

Quote:



>>An important concept in determining the drag of an object is the
>>maximum cross-sectional area and the its distribution.  I believe that
>this
>>is the crux of the theory that Terry is referring to.  Basically, the
>larger
>>To sum up what could easily turn into a masters thesis, while the arm
>is in
>>the water and positioned out in front of the swimmers head, it is
>creating a
>>smoother transition of cross-sectional areas.  In other words, the
>flow
>>about a swimmers body is gradually and relatively smoothly being moved
>out
>>of the way when the arm is in this position.  As opposed to the head
>and
>>shoulders having to perform this operation alone.  This will seem
>obvious
>>if you compare the push off from the side of the pool with your body
>in a
>>streamlined position and with your arms at your sides.  The arms
>breakup
>>the flow gradually if they are out in front compared to your blunt
>head
>>and shoulders alone.  If you try this, you can actually feel a
>>etc

>This might explain the training techniques reported on Popov and other
>Russian swimmers out of their hard training phase.  I read somewhere
>that they were in the US and did nothing but long, easy catch up
>stroke.  It stands to reason (based on the explanation above), that
>keeping a hand out front at all times will aid in reducing resistance,
>if not keeping the maximum "length of boat" as well.

>Thanks Mr. Science!

>Ed

The hand out front at all times was actually tried many years ago, Maglicio
talks to it in his book.  I don't have it in front of me, but if I remember
correctly, the loss of propulsive power out weighed the decrease in drag.

LJ

 
 
 

Distance per stroke

Post by Tom Key » Sat, 25 May 1996 04:00:00



Quote:
> However, it is a fact that the longer the hull length at the waterline,
> the faster the maximum theoretical speed of the boat.  Any nautical
> engineer or sailor can verify this, and it is supposed to be related to
> the trough distance between bow and stern waves.

FWIW, the above is true. The reason is the following: a displacement-hull
boat is stuck in the trough of it's own wave, whose wavelength equals the
length of the boat. The speed of a water wave is proportional to the
square root of the wavelength, so the max boat speed is proportional to
sqrt(boat length) - as someone else said it works out to
speed(knots)=1.4*sqrt(length in feet).

For this to apply to swimming, the swimmer would have to be stuck in the
trough of the wave he makes. I have no real definitive knowledge about
this, but swimmers do not look at all to me like heavy displacement
cruisers that make deep waves. My guess is that it does not apply...TK

--
Tom Keyes, Theoretical/Computational Chemist
Chemistry Department, Boston University, Boston MA 02215
http://chem.bu.edu/~keyes