Stroke Length: Most strongly related to kicking

Stroke Length: Most strongly related to kicking

Post by RunnSw » Wed, 19 Jul 2000 04:00:00

Technique gurus have noted that stroke length correlates with performance and
have then gone about devising ways to enhance stroke length. So the idea they
come up with is to reach way forward, hold your arm out there in a bit of a
glide phase and add in trunk rotation and front back balance. The kick is not
considered important for anything other than maintaining rhythm.

But the question that no one ever seriously tries to address with data is the
following:  What makes a long stroke long in a successful competitive swimmer?

I don't think that people have made a serious effort to understand this.  It
reminds me of a type of question they used to ask on examinations in medical
school:

Two statements are made ("A" and "B").  Choices of answers are as follows:

1. A is true and B is false.
2. A is false and B is true.
3. Both A and B are false.
4. Both A and B are true and they are related.
5. Both A and B are true, but they are unrelated.

So here are the statements.

A. A long stroke correlates with performance of skilled competitive swimmers in
many (but not all) swimming events.

B. It is possible to achieve a long stroke through an extended forward reach
and retarding the pull until the opposite hand has completed its stroke and
most of its recovery.

My answer to the above question would be # 5, in the above list of choices.

Here's what I've observed...what makes for a long stroke (in order of
importance - most to least).

1. Effectiveness of the kick.
2. Side to side shoulder/trunk/hip rotation
3. Catch effectiveness/efficiency (lack of slippage)
4. Height/Wingspan
5. Hand/forearm extension

I'm sure that front/back balance is important at the level of the novice
swimmer, but all elite swimmers have excellent front/back balance (often
getting that way by kicking); so this is hard to show objectively.

What are the data to support these observations?  Well, they haven't been
published, but anyone who attends a major swim championship meet and is willing
to spend the time watching all of the freestyle races can easily confirm most,
if not all, of these assertions.

Here is what you do.

The single most valuable race to watch is the 400 meter freestyle, long course.
 In shorter races, the majority of swimmers have quite good kicks, making it
hard to compare.  In a short course pool, there is too much artifact associated
with turns and streamlines.  But the 400 is just right.  After you've reached
conclusions from a long course 400, you can proceed to other distances and
confirm that the overall truthfulness of the conclusions holds for all
distances.

So you want paper on a clipboard and a pencil.  At the beginning of each heat,
you score each swimmer's height and wing-span.  Scale of 3.  Short, medium,
tall.  Race starts.  You let them warm up for the first 100, while grading
their shoulder rotation.  Scale of 3.  Slight (water polo stroke-like), medium,
marked. Then, for the second and third hundreds, you get to the real meat of
the matter.  You count their strokes and you grade their kicks.  Stroke count
is just stroke count.  How many to go from one wall to the next wall.  Kick
effectiveness is again scale of three. Slight (leg dragger), medium (this is a
catch all category, which can range from an "effective" looking two beat kick
to an "ineffective" looking 6 beat kick).  This is a bit subjective, but clues
as to an effective kick are the amplitude of the stern wave and the turbulence
of the water.  With some practice, one can learn to distinguish between an
effective kick and a kick which appears to be active, but which is mostly
cosmetic.  A "marked" kick is a brisk 4 to 6 beat kick, which clearly disturbs
the trailing water, raising deep turbulence. The final things to grade/score
are (1) degree to which leading arm is outstretched, scale of three, ranging
from bent elbow entry (e.g. Brooke Bennett crab stroke) to pronounced and
prolonged extension, with "medium" being in between.  And (2) effectiveness of
catch and anchor, with respect to avoiding slippage of the hand/forearm in the
water.  This is very hard to score from the bleachers during a  race, and
really has to be done at the pool deck, walking alongside the swimmer in lane
1.

Now, when you have all of the above data, put them into a series of 3 x 3
tables (three rows; three columns).  But first you need to turn the stroke
counts into "low," "medium," and 'High" categories.  You do this by just
arranging all of your measured stroke counts and cutting (grouping) them into
tertiles or thirds.  Top third (most number of strokes) is "high." Middle third
is "medium."  Bottom third is "low."

So, for each of the factors that you want to compare with stroke length, you
list them in the 3 x 3 table.  The table has three rows (for "high," "medium,"
and "low" stroke counts).  It also has three columns (for "short," "medium,"
and "tall;" for "slight," "medium," and "marked," and so forth.

What you will find is that - by far, the strongest associations are between
stroke length and kicking effectiveness.  I have done this enough times and the
relationship is so obvious that I guarantee you that you will readily concede
that this is a correct observation.  The statistical significance can be tested
by means of a 3 x 3 Chi Square contingency table analysis (just punch "Chi" AND
"Square" AND "table" into a web search engine, and you will readily find what
this means and how to do it).  But you don't need statistics.  The relationship
is that strong and that obvious.

Once you have confirmed this relationship with a number of swimmers, it is fun
to make some individual correlations.  A few examples from the Janet Evans
Invitational this weekend:

1.  In the 400 and 1500, there were great races between Erik Vendt, Ryk
Neethling, and Chris Thompson.  Vendt is a shrimp (i.e. a short guy) with a
superb kick.  Neethling and Thompson are two tall guys with relatively weak
kicks (particularly in the 1500).  Vendt had the lowest stroke count, longest
stroke of any swimmer in the 400, despite being only 5'10" (and I think this
height is an exaggeration).  33 - 34 strokes, compared to > 40 for skyscrapers
Neethling and Thompson.  The latter two, by the way, both have great front back
balance, good shoulder rolls, and a long straight forward extension.  What they
lack (most of the time) are great kicks.  But watch what happens in those parts
of the race where the kick intensity is ratcheted up for both Neethling and
Thompson (when mounting a charge or sometimes when powering off of walls).
Their stroke counts go down, noticeably, as their kicks go up.  And then they
settle into the middle part of the pool in the middle part of the race and
their kicks go down, while their strokes go up.

Same thing with the women.  Claudia Poll and Lindsey Benko are skyscraping
women with usually weak kicks and very short strokes.  Lots of short kids swam
with great kicks and much lower stroke counts.  Obvious, obvious, obvious
relationship.  Nothing else (height, wing span, side to side rotation, even
long forward arm extension) is nearly as obvious.

My all time favorite example, however, is an up and coming young high school
distance swimmer named Aram Kevorkian, whom I have been watching since he was
12 (now, I think, 18) and who swims for North Coast Aquatics, in San Diego
County.  Aram has a very unusual stroke, to say the least.  Much of the time
(although he does change around at different stages in his races), Aram swim
with a long, slow stroke with his left arm and a much shorter and more rapid
stroke with his right arm.  Sure enough, when the right arm is reaching
forward, Aram starts to kick like blazes, but, during the right arm pull, his
kick goes entirely to sleep.  The result is like his stroke is being driven by
an electric motor, which is regularly shorting out during each cycles, only to
have power immediately restored.

So you want to know why elite swimmers have long strokes?  It's because they
have great kicks.  If you believe that long strokes are the key to successful
competitive swimming (and I don't believe that they invariably are the key to
success, with prime examples being short stroking Claudia Poll - 1:58.02 on
Saturday at the Janet Evans) or Brooke Bennett, or even Janet Evans herself
)...as I was saying, if you really believe that long strokes are the key to
success, then you should be teaching kicking at the very top of the stroke
length pyramid, because it is the kick, far more than anything else, which
produces stroke length in elite competitive swimmers.

- Larry Weisenthal
Huntington Beach, CA