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Stroke Length ... what's all the fuss?



 
 
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  #1  
Old January 7th 04, 11:14 PM
4precious
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Default Stroke Length ... what's all the fuss?

Most videos of elite swimmers are posted on the web at half speed. So
every once in a while, I double the playback speed to get back to real
time. And the frequency at which those folks are kicking their legs
and pin-wheeling their arms is always a revelation. I'm not sure I
would believe how fast their limbs are flying except that there's
often a timer displayed which does indeed show the seconds ticking off
at the correct interval.

Okay, so what's the big deal you say?

Well, I went to the usa-swimming website and got a little data and
compared it to how I swim. The data is listed below. The data from
the elite swimmers was taken from Spring Nationals, 2000. All data
has been averaged.

MEN CYCLE TIME (SEC/CYCLE) CYCLE RATE (CYCLES/MIN DISTANCE PER
CYCLE
400 FREE 1.44 42.86 2.35

WOMEN CYCLE TIME (SEC/CYCLE) CYCLE RATE (CYCLES/MIN DISTANCE PER
CYCLE
400 FREE 1.3 45.45 2.08

RECREATION
SWIMMER CYCLE TIME (SEC/CYCLE) CYCLE RATE (CYCLES/MIN DISTANCE PER
CYCLE
400 FREE 1.88 31.88 2.15


The recreational swimmer in the table is obviously me. It was 400
yards with a swim time of 5:20, or 1:20 per 100 yards. I took an
average of 8.5 cycles per 25 yards (17 arm pulls). (I computed the
Distance Per Cycle in meters). I expect these numbers to be about
mid-pack for recreation/masters swimmers.

The current paradigm in swimming is to work exclusively on stroke
length. Play "swim golf", count strokes, work on streamlining, etc.
But what does the data show? My stroke length is actually quite
comparable to elites. Not because I'm a great swimmer, but because
I'm gliding so much more than them. If the goal is to go faster
(which mine is), then the data really screams:

INCREASE YOUR STROKE RATE!!!!!!

I plan to buy one of those stroke cadence meters that fits under your
swim cap or straps to your goggles. They emit a beep everytime your
hand is supposed to hit the water for a given cadence. You can
program them for various beep intervals.

My swim cadence is terrible. The elites are well into the 40's for
strokes per minute, and I'm barely breaking 30. And of course, at
shorter distance, their rates go up even more. Both men and women are
in the 60's for 50 meter sprints. Does this mean I should increase
stroke rate, even if it means I become a "thraser" or "near-drowner".
No, of course not. But the biggest payback I can achieve will be in
stroke rate, not stroke length.

It makes sense to attack the problem from both sides. That is,
Distance Per Stroke AND Stroke Rate. After all, that's what cyclists
do, isn't it? They spend time pushing big gears to get strenght, but
also "spin" at ultra high cadences to improve their smoothness and
also their sprint times. Why would swimming be any different.

The reason my stroke rate is low is because I don't race. If you
race, and want to be competitive, you naturally have to go for high
cadences to keep up with your competitors. The whole "increase stroke
rate" thing can be over done, like everything else. But in today's
swim culture, not only is it not practiced, it's treated as the wrong
way to swim.

Eric
  #2  
Old January 7th 04, 11:58 PM
MJuric
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Default Stroke Length ... what's all the fuss?

On 7 Jan 2004 14:14:39 -0800, (4precious) wrote:

Most videos of elite swimmers are posted on the web at half speed. So
every once in a while, I double the playback speed to get back to real
time. And the frequency at which those folks are kicking their legs
and pin-wheeling their arms is always a revelation. I'm not sure I
would believe how fast their limbs are flying except that there's
often a timer displayed which does indeed show the seconds ticking off
at the correct interval.

Okay, so what's the big deal you say?

Well, I went to the usa-swimming website and got a little data and
compared it to how I swim. The data is listed below. The data from
the elite swimmers was taken from Spring Nationals, 2000. All data
has been averaged.

MEN CYCLE TIME (SEC/CYCLE) CYCLE RATE (CYCLES/MIN DISTANCE PER
CYCLE
400 FREE 1.44 42.86 2.35

WOMEN CYCLE TIME (SEC/CYCLE) CYCLE RATE (CYCLES/MIN DISTANCE PER
CYCLE
400 FREE 1.3 45.45 2.08

RECREATION
SWIMMER CYCLE TIME (SEC/CYCLE) CYCLE RATE (CYCLES/MIN DISTANCE PER
CYCLE
400 FREE 1.88 31.88 2.15


What is the (Distance per cycle) Measured in. Is that Meters per
stroke. If so that means that the pro's are taking 9.7 Strokes per
25yd length and you're around 10.63 per 25, Is that right?



The recreational swimmer in the table is obviously me. It was 400
yards with a swim time of 5:20, or 1:20 per 100 yards. I took an
average of 8.5 cycles per 25 yards (17 arm pulls). (I computed the
Distance Per Cycle in meters). I expect these numbers to be about
mid-pack for recreation/masters swimmers.


If the above numbers are correct I'd put your SC way below mid pack.
I'd guestimate that the average 1:20-1:30 swimmer is probably closer
to 13-16 Strokes per 25. Probably higher if they're really trying to
grind out a fast lap.


The current paradigm in swimming is to work exclusively on stroke
length. Play "swim golf", count strokes, work on streamlining, etc.
But what does the data show? My stroke length is actually quite
comparable to elites. Not because I'm a great swimmer, but because
I'm gliding so much more than them. If the goal is to go faster
(which mine is), then the data really screams:

INCREASE YOUR STROKE RATE!!!!!!


Although it would appear that your stroke rate needs to
increase, what will the end result be if you increase your SR and
allow your SL to go down. You travel the same distance taking more
strokes, ultimately working harder probably in the same time. The goal
is to hold your current SL and increase your SC. This is exactly the
purpose of swim golf. The purpose of swim golf is to trade off a bit
of SL to see what gains can be made in time. The best score is a
combination of low time and low SC.


I plan to buy one of those stroke cadence meters that fits under your
swim cap or straps to your goggles. They emit a beep everytime your
hand is supposed to hit the water for a given cadence. You can
program them for various beep intervals.


Don't have one but I've heard that this also helps for "evening" out
one side to another. Basically forces you to have an even stroke on
both sides.


The reason my stroke rate is low is because I don't race. If you
race, and want to be competitive, you naturally have to go for high
cadences to keep up with your competitors. The whole "increase stroke
rate" thing can be over done, like everything else. But in today's
swim culture, not only is it not practiced, it's treated as the wrong
way to swim.

Eric


Actually I find quite the opposite. Most of the swimmers,
coaches etc around here will just short of force you to "Swim Faster"
by turning over faster. Few if any teach a technique oriented "Swim
Longer" method. Even those that understand that as a "good method"
really don't teach it or enforce it during classes, they simply say
"reach further faster" Pretty much 90% of my masters class is spent
"trying" to grind out faster 100's than the last. Yet an overwhelming
portion of our class just end up losing technique and going slower.
Matter of fact the only people I know that emphasis, possibly
overemphasis SL are associated with TI in some way, around here few
and far between.

~Matt

  #3  
Old January 8th 04, 12:05 AM
Larry Weisenthal
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Default Stroke Length ... what's all the fuss?

Eric,

That deceptively simple (actually brilliantly simple -- congratulations!)
little table of yours speaks VOLUMES to all of us!

Your analysis suggests the following to me:

Firstly, stroke rate is just as important as stroke length. That is obvious.
Velocity = stroke rate X stroke length. Equal importance.

Stay with me on this...I'm sort of thinking out loud.

How about this....

(1) Pick the event closest to your event (in your example, you chose the 400 --
for other swimmers (including triathletes) the more relevant distance might be
the 1500.

(2) Pick an elite swimmer closest to you in form (I'm thinking here that the
most important factor is kicking vs. non-kicking. If you are a non-kicker, you
shouldn't compare yourself to a kicker, but to a non-kicker, who are most
commonly female distance swimmers).

(3) Make up a "Kurth Table" similar to Eric's.

(4) Do the following additional math...

Look at your stroke rate as a function of your comparison elite's stroke rate,
e.g., in Eric's case it's 31.88/42.86 (using the male comparison...I don't know
if Eric's currently a kicker or a non-kicker, but I'm comparing him with the
kicker). This comes out to be 74% ... meaning Eric's stroke rate is only 74%
of his elite "buddy" swimmer.

Look at your stroke length as a function of your comparison elite's stroke
length, e.g. in Eric's case it's 2.15/2.35 or 91%.

Now, if Eric wants to improve his swimming, he should work not on further
increasing his stroke length, but rather on increasing his stroke rate.

Let's say that Eric starts to do this. I'm guessing that, as he increases his
stroke rate, his stroke length will start to fall. When he gets to the point
that his stroke rate ratio (relative to his elite "buddy" swimmer) is equal to
his stroke length ratio (relative to his elite "buddy" swimmer), then that's
the point where he has optimized his stroke rate and stroke length (relative to
his ability, training level, etc.).

This, I believe, would be applicable to virtually everyone. Some people may
have a stroke rate ratio (relative to elite buddy swimmer) of 0.9 or greater,
but a stroke length ratio (relative to elite buddy) of only 0.7. These are the
swimmers who would most profit from working on stroke length.

Eric, thank you for your brilliantly clear analysis which, for the first time,
offers a way for swimmers to objectively determine their own proper balance of
stroke length vs. stroke rate. Your contribution ranks right up there with
"Miller Torque" in the R.S.S. Swimming Science Hall of Fame.

- Larry



  #4  
Old January 8th 04, 12:12 AM
Bill Geiser
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Default Stroke Length ... what's all the fuss?

On 7 Jan 2004 14:14:39 -0800, 4precious wrote:

....snip....

Well, I went to the usa-swimming website and got a little data and
compared it to how I swim.


....snip again....

If the goal is to go faster
(which mine is), then the data really screams:

INCREASE YOUR STROKE RATE!!!!!!


Eric - you've overlooked one important point. The data you picked up from
USA Swimming was taken during competition in LC meter venues. Your data was
taken from swims performed in (what I assume to be) SC yards. There is a
big difference....and it doesn't simply relate to the difference in
distance.

While you attempted to normalize your data for the difference between yards
and meters (distance), you didn't normalize for the impact of turns. There
are twice as many turns in short course vs long course and their impact is
significant. The net result is you *swim* far less on a percentage basis
swimming SC than you do LC because of the glide you get when pushing off
the wall.

(Note: somewhere along the line I recall reading somewhere that in a 100
yard short course race, a typical collegiate swimmer *swims" about 60% of
it; with the other 40% being covered by the streamlining off the start and
turns. Assuming you get 10 yards for the start and each turn; the math
seems to work).

I'd recommend you find a long course pool (50 meters) and then see how you
match up....you might come to a different conclusion.

Swim Smart!
Bill

  #5  
Old January 8th 04, 01:01 AM
Larry Weisenthal
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Default Stroke Length ... what's all the fuss?

I'd recommend you find a long course pool (50 meters) and then see how you
match up....you might come to a different conclusion.

Eric was just illustrating a principle; but your point is certainly
valid...just as his principle is (brilliantly) valid.

I first thought that all I need do is to get out one of my old tapes of NCAA
Div I finals (swum scy) and measure/calculate corresponding stats. Then all of
us short course yards swimmers could see whether or not our SL/SR is or is not
way out of balance.

I think that your suggestion regarding taking measurements in a long course
pool is the better way to do it, though. Among other things, the break out
distance of elites is, if anything, even more impressively superior to that of
typical adult swimmers than are the SL/SR numbers. This would skew the data
more dramatically in a short course pool than in a long course pool, where the
SL/SR numbers would be more reflective of actual swimming performance.

- Larry

  #6  
Old January 8th 04, 01:22 AM
Larry Weisenthal
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Default Stroke Length ... what's all the fuss?

(Note: somewhere along the line I recall reading somewhere that in a 100
yard short course race, a typical collegiate swimmer *swims" about 60% of
it; with the other 40% being covered by the streamlining off the start and
turns. Assuming you get 10 yards for the start and each turn; the math
seems to work).

Thinking some more about this...

In a 500 yd free, a good male college swimmer (who typically have pretty good
kicks) would go about 4:20. Assuming that Eric could keep up his 1:20 per 100
pace for another 100, that would give him a 6:40. I'm guessing that the
average male college swimmer who goes 4:20 takes 15-16 strokes per 25 (compared
to Eric's 17). So Eric's "elite buddy" ratio for SL would be 15-16/17 or
0.88-0.94, while his SR ratio would be 340 strokes (per 500) divided by 400
seconds (for a 6:40 500), or 0.85 strokes per second. For the elite buddy, the
corresponding numbers would be 300-320 strokes (per 500) divided by 260 seconds
(for a 4:20 500) or 1.15-1.23 strokes per second. Therefore Eric's "elite
buddy" ratio for SR would be 0.85/1.15 to 0.85/1.23 or 74% to 69%.

So I'm guessing that Eric's initial conclusions will be confirmed if/when he
takes the measurements in a long course pool.

- Larry
  #7  
Old January 8th 04, 01:40 AM
Bill Geiser
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Default Stroke Length ... what's all the fuss?

On 08 Jan 2004 00:01:29 GMT, Larry Weisenthal wrote:

I'd recommend you find a long course pool (50 meters) and then see how you

match up....you might come to a different conclusion.

Eric was just illustrating a principle; but your point is certainly
valid...just as his principle is (brilliantly) valid.


Oh come on, Larry.....you doc's are always the first to point out flaws in
testing protocols.....what gives this time?

I understand the point Eric was making. And I agree SR is important. I was
simply pointing out his analysis methodology was flawed, because he ignored
a critically important factor that unquestionably impacts SR/SL
computations.

A good friend and one of the best US swimmers during the 70's, Jerry
Heidenreich (now deceased) wrote 'the 21 Laws of Swimming'. His law #12
stated:

"The fastest you ever travel is when you dive off the block and push off
the wall"

In terms of this discussion, what it means is you simply cannot compare
SR/SL ratio's between LC & SC swims.

Case in point, the sport science community goes to great lengths to totally
factor out the impact of starts and turns in order to calculate SR and SL.
I don't recall the exact protocol but it involves photographing /
digitizing a swimmer only in the center 20-25 meters of a 50 meter pool
(ignoring the first 15 meters off each wall). In other words, they only
take DPS and SR measurements in the center of the pool, long after the
swimmer's body has slowed up from the push off the wall.

This is the process by which the data Eric cited was computed. And its the
process by which this data has been collected and analyzed at most
International Swim events for the past 10 years or more.

So, if you really want to slice hairs, Eric should measure this in the same
fashion. I think he will find the experience most humbling (as would the
rest of of us) - his DPS is FAR LESS than he thinks it is....and in order
to make up the difference he'd have to generate a cycle rate approaching
90-100 CPM......

Incidentally, somewhere on the US Swimming sight they also state that the
primary difference beween average and elite swimmers is an elite swimmer
travels further with each stroke cycle. Therefore, I would emphatically
state that ignoring distance per stroke is a mistake for any swimmer
regardless of skill level

Swim Smart!

Bill




  #8  
Old January 8th 04, 02:12 AM
Larry Weisenthal
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Default Stroke Length ... what's all the fuss?

Incidentally, somewhere on the US Swimming sight they also state that the
primary difference beween average and elite swimmers is an elite swimmer
travels further with each stroke cycle.

This is a total apples versus oranges comparison.

The elite swimmers who make up that database are all GREAT KICKERS.

The average person on this newsgroup can't kick at all.

So you have to pick out a database of elite swimmers who DON'T KICK.

Such swimmers are almost exclusively female distance swimmers.

Most of the people on the newsgroup (save for the odd Donald Graft) are not 50
and 100 sprinters, but are distance swimmers (triathletes, open water swimmers,
fitness swimmers, etc.).

So if you look at female distance swimmers (the closest thing to the average
newsgroup reader), there is NO RELATIONSHIP WHATSOEVER between stroke length
and performance! What correlates is the ability to maintain STROKE RATE for
the entire race. The championship finalists maintain their stroke rates; with
the consolation finalists and non-qualifiers, the stroke rate falls off.

This should provide added incentive for Eric (and many of us) to stop
obsessing about our stroke length (if we want to swim like Alex Popov, we'd
surely better kick like Alex Popov, and if we can't kick like Alex Popov, we
are far better off swimming like Brooke Bennett, or Diana Munz, or even
Stanford's Morgan Henzten, who doesn't kick at all and who has a prodigiously
high stroke rate).

Swim Smart!

- Larry


  #9  
Old January 8th 04, 02:49 AM
Bill Geiser
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Default Stroke Length ... what's all the fuss?

On 08 Jan 2004 01:12:03 GMT, Larry Weisenthal wrote:

Incidentally, somewhere on the US Swimming sight they also state that the

primary difference beween average and elite swimmers is an elite swimmer
travels further with each stroke cycle.

This is a total apples versus oranges comparison.

The elite swimmers who make up that database are all GREAT KICKERS.

The average person on this newsgroup can't kick at all.

So you have to pick out a database of elite swimmers who DON'T KICK.



Let's revisit what started this thread - Eric's comparison of himself vs
elite swimmers....Eric stated his stroke *length* was comparable to the
elites.....I said it isn't because he didn't apply the same measurement
protocols. How can you argue with that?

But your point about elite swimmers all being GREAT KICKERS brings up a
different question.......how do you define a GREAT KICK? Is it:

a) A propulsive kick - ie enables swimmer to generate considerable forward
motion?
or
b) A strong kick - ie enables swimmer to generate considerable downward
power with each leg kick thereby allowing them to roll from one side to
another side faster (and would likely generate a faster SR)?

I would agree all elite swimmers fall into one or both of the two
categories. I would also agree if you don't fall in either category, you
ain't an elite swimmer.......

Swim Smart(er)!
Bill
  #10  
Old January 8th 04, 03:06 AM
Larry Weisenthal
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Default Stroke Length ... what's all the fuss?

I would agree all elite swimmers fall into one or both of the two
categories. I would also agree if you don't fall in either category, you
ain't an elite swimmer.......

Bill, once again you are forgetting to consider elite female distance swimmers
(who I maintain have vastly more in common with the average newsgroup reader
than the likes of Alex Popov and Ian Thorpe). Many of these ladies do not meet
either of your "great kick" definitions. Yet (particularly if they have won
two Olympic gold medals, e.g. Bennett) would have to be considered "elite" (as
would multiple US Nationals finalist Morgan Hentzen, who is a literal leg
dragger, with no kick at all). If you don't kick and if you are not a sprinter
and if you want to learn any lessons at all from elite swimmers to apply to
your own swimming, then you should look to the elite swimmers who don't kick
and don't sprint for your self-improvement insights.

Swim Smart(est)!

- Larry
 




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