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GaryHallSr
November 10th, 2009, 05:27 PM
A while back, I jumped on the triathlon website Slowtwitch and got attacked for saying that the power in the freestyle pull comes in the front of the stroke (hand entry to shoulder), not in the middle (shoulder to belly button) or back (belly button to release). Nonsense...they said. Didn't you read the article by Popov's coach showing the power is at the end of the stroke?
That never made sense to me. After all, at the end of the stroke there is only about one muscle still working, the tricep, and the hand is not in that position for very long.
At last, I got the proof I needed. A few weeks ago I was tested on the Velocity Meter, a very cool device that measures the speed of the body through the entire stroke cycle. It was VERY revealing and provided tons of information I could not get elsewhere.
Such as:1) the body speed slows by as much as 40% from the fastest to the slowest point during a single arm stroke. 40%!!! That is huge. The difference in speed is directly caused by the body going from a relative streamlined position to a very non-streamlined position and back again.
2) The fastest point in the stroke cycle is when the hand first enters the water and the slowest point is when the hand is about at the shoulder underwater. That is when the upper arm is pointing nearly perpendicular to the line of the body (ie most drag).

I realize that the speed of the body at any given instant is a result of the propulsive power minus the drag forces, that one cannot determine just from the velocity that the power is really greater in front. But when the speed drops from 2.5 meters per second when the hand is in front to 1.4 meters per second when it is in the middle, I have to believe that the power in front is greatest.
By the way, the propulsive power of the arm is created by both lift forces at the beginning and drag forces in the middle, as the hand shifts from forward motion to backward motion (then forward again as it releases).
Anyway, read my latest blog on our website www.theraceclub.com to find out more revealing secrets from the Velocity Meter.

Gary Sr.

__steve__
November 10th, 2009, 06:07 PM
A while back, I jumped on the triathlon website Slowtwitch and got attacked for saying that the power in the freestyle pull comes in the front of the stroke (hand entry to shoulder), not in the middle (shoulder to belly button) or back (belly button to release). Nonsense...they said. Didn't you read the article by Popov's coach showing the power is at the end of the stroke? In the "Whats the Limit" video produced by touretski Popov's stroke was broken down into 4 phases:
1) Catch/Exit - Support and maintain speed
2) Outsweep/recovery - Optimum propulsion
3) Pushback/entry - Reach and maintain maximum speed
4) Pushback/reach - Maximum velocity

BR KnuckleDragger
November 10th, 2009, 06:24 PM
No disrespect to triathlon participants but I think a "Gary Hall SR" would know a little more about speed then a participant in a triathlon...

my :2cents:...

JMiller
November 10th, 2009, 06:34 PM
Anyway, read my latest blog on our website www.theraceclub.com (http://www.theraceclub.com) to find out more revealing secrets from the Velocity Meter. Gary Sr.

Hey Gary!!! We met back in 2005, in Edmonton at World Master Games...
Glad to see you are posting here! Any thoughts on if your son will be racing in Masters?

Also, I'd like your professional opinion on this excerpt!
Fun, and Fast - Page 31 - U.S. Masters Swimming Discussion Forums

Jonathan Jr.

knelson
November 10th, 2009, 06:49 PM
It sure is counterintuitive that we're actually decelerating at precisely the time when we're applying the most force to the water. I guess the fact is we've got to live with this deceleration to get the acceleration at the point that propulsive force outweighs the drag.

This got me thinking about rowing. You know how in rowing races you can see the shells in neighboring lanes surge ahead slightly or fall back based on when they are stroking? I guess I always assumed the "surging ahead" was happening when those rowers were stroking, but go watch a video and you'll see it's just like in swimming: the boat actually decelerates the instant the oars go into the water. It's obvious when you think about it. It's like putting on the brakes until the rowers are able to overcome all that drag caused by the oars. The boats probably start to accelerate somewhere around the point where the oars are perpendicular to the shell.

For swimming it certainly makes you wonder if there is some way we can stroke that will reduce that drag up front without sacrificing the power.

GaryHallSr
November 10th, 2009, 10:01 PM
The major contributor to drag (pressure drag) during the underwater pull is the upper part of our arm. That part of the arm is moving forward at all times, while the hand has a net zero velocity (forward at the beginning, backward, then forward again) and contributes little to forward drag.
What is very interesting is that positioning the arm straight down creates a larger drag coefficient than the arm positioned out to the side. That is why all great swimmers use high elbows....not for more power or surface area, but for decreased drag.
You can test this yourself by kicking 25 meters all out with fins, first with the arm positioned straight down (other arm in front) and then by bending the arm at 90 degrees to your side. Both contribute to a large drag (you will feel it!) but much more with the arm straight down.
I was amazed at how quickly we go from the fastest positon to the slowest position (a few tenths of a second) strictly based on these long arms of ours. Poor engineering for moving fast in the water, but we have to deal with the cards we are dealt.

Gary Sr.

The Fortress
November 10th, 2009, 10:17 PM
A while back, I jumped on the triathlon website Slowtwitch and got attacked for saying that the power in the freestyle pull comes in the front of the stroke (hand entry to shoulder), not in the middle (shoulder to belly button) or back (belly button to release). Nonsense...they said. Didn't you read the article by Popov's coach showing the power is at the end of the stroke?
That never made sense to me. After all, at the end of the stroke there is only about one muscle still working, the tricep, and the hand is not in that position for very long.
At last, I got the proof I needed. A few weeks ago I was tested on the Velocity Meter, a very cool device that measures the speed of the body through the entire stroke cycle. It was VERY revealing and provided tons of information I could not get elsewhere.
Such as:1) the body speed slows by as much as 40% from the fastest to the slowest point during a single arm stroke. 40%!!! That is huge. The difference in speed is directly caused by the body going from a relative streamlined position to a very non-streamlined position and back again.
2) The fastest point in the stroke cycle is when the hand first enters the water and the slowest point is when the hand is about at the shoulder underwater. That is when the upper arm is pointing nearly perpendicular to the line of the body (ie most drag).

I realize that the speed of the body at any given instant is a result of the propulsive power minus the drag forces, that one cannot determine just from the velocity that the power is really greater in front. But when the speed drops from 2.5 meters per second when the hand is in front to 1.4 meters per second when it is in the middle, I have to believe that the power in front is greatest.
By the way, the propulsive power of the arm is created by both lift forces at the beginning and drag forces in the middle, as the hand shifts from forward motion to backward motion (then forward again as it releases).
Anyway, read my latest blog on our website www.theraceclub.com to find out more revealing secrets from the Velocity Meter.

Gary Sr.

Is this why you switched to straight arm freestyle?

knelson
November 11th, 2009, 10:27 AM
What is very interesting is that positioning the arm straight down creates a larger drag coefficient than the arm positioned out to the side. That is why all great swimmers use high elbows....not for more power or surface area, but for decreased drag.

I have to say I never even thought of this. I always assumed it was for mechanical reasons. I wonder how a stroke would work where your upper arm stays above the water for the entire cycle? I'm assuming not well, otherwise people would use it, but why not? Is it a biomechanical problem or the fact that your hand needs to dig into the "good water" down deeper to produce enough force? I'll have to try this out sometime.

This is interesting stuff, Gary. It would be great to have full time access to a velocity meter to really test out some radical stroke changes.

mazzy
November 11th, 2009, 12:35 PM
The major contributor to drag (pressure drag) during the underwater pull is the upper part of our arm. That part of the arm is moving forward at all times, while the hand has a net zero velocity (forward at the beginning, backward, then forward again) and contributes little to forward drag.
What is very interesting is that positioning the arm straight down creates a larger drag coefficient than the arm positioned out to the side. That is why all great swimmers use high elbows....not for more power or surface area, but for decreased drag.
You can test this yourself by kicking 25 meters all out with fins, first with the arm positioned straight down (other arm in front) and then by bending the arm at 90 degrees to your side. Both contribute to a large drag (you will feel it!) but much more with the arm straight down.


IMHO it's no due directly to the straight down arm ... the straight down arm move the center of mass of the swimmer down, altering the balance, and reducing a little bit the natural level of buoyancy, in a word increasing the boby drag. i think that this one is the reason because you go faster with higher elbow and higher center of mass.
In real swimming the "mechanical" advantage of higher elbow is another (main) reason to use it Vs dropped elbow/straight down arm.

ehoch
November 11th, 2009, 12:43 PM
) The fastest point in the stroke cycle is when the hand first enters the water and the slowest point is when the hand is about at the shoulder underwater. That is when the upper arm is pointing nearly perpendicular to the line of the body (ie most drag).


Going to disagree with this -

That's not what my speed graph looked like when I did the test with Dr. G.

My speed during my right arm pull was pretty even - there was a small dip when my arm was in the middle of the stroke (shoulder) - but that was also precisely the moment my other arm entered the water and when I was not pulling straight back with the hand (small s). I don't think it's drag related - my arms are moving faster than my body - I don't think it can be drag.

My left arm is another story - but that's more of being ineffecient than anything else.

qbrain
November 11th, 2009, 01:08 PM
While Erik and Gary figure out where the propulsion comes from, anyone have any tips for measuring drag?

I am all about getting faster by doing less work.

stillwater
November 11th, 2009, 01:13 PM
Wow, Gary Hall was a hero of mine when I was younger.

Isn't this kind of front quadrant swimming?

orca1946
November 11th, 2009, 01:20 PM
Does high elbow cause more drag in this case? More power ,but more drag?

quicksilver
November 11th, 2009, 01:32 PM
Every week or so a thread will pop up talking about the benefits of a high elbow and vertical forearm. In theory (and practice, for those with great flexibilty), the longer you can maintain a high elbow, you can decrease oncoming drag forces and achieve better leverage during the stroke cycle.

I think front quadrant swimming is counter-intuitive to many of us old school swimmers who were taught to finish our strokes. The strongest propulsion always seemed to be generated as the hand is pushing water past your hip pocket.


That said, I enjoyed the article swimming on the freeway (http://www.theraceclub.net/columns/2008/04/swimming-on-freeway.html), and have tried to apply this to both back and free over the past year. It seems to be much more efficient than a rotary style stroke (for me anyway). I still find myself using a strong finish even though the arms are in more of a front quadrant cycle.

Chris Stevenson
November 11th, 2009, 01:54 PM
That said, I enjoyed the article swimming on the freeway (http://www.theraceclub.net/columns/2008/04/swimming-on-freeway.html),

I enjoyed it too, and it also has what Gary Hall SR must believe contains the answer to poll's question:

"...when you dive into the water from a starting block for a split second you are going around 5 miles per hour. Yet, in just 5 seconds (without the help of a kick or pull out), you come to a virtual stop. That means every second in the water from the time you entered you slowed (decelerated) around 1 mile per hour each second. Or in a half a second you slowed 1/2 mile per hour and so on."

Accepting that you go from 5mph to a full stop in 5 seconds, I question his assertion that you lose 1mph per second. I think it much more likely that you lose speed exponentially.

The rapidity of exponential decays (sorry for the science-geek language) is characterized by the time/rate constant or, equivalently, by the "half-life" which is easier to understand for most. In chemistry it standard to consider a chemical is "gone" after 5 half-lives (theoretically it never completely disappears, right?).

So in this case if we take the half-life to be 1 second, that means you lose 50% of your speed in the first second after diving in, and 50% of the remaining one second later. Thus, it takes 2 seconds to lose 75% of your initial speed.

But that assumes no kicking, so I'm thinking it takes a little longer for someone in real life, especially for a good kicker. (Actually in real life you never lose 75% of your speed...1.25 mph is a slow swimming speed...)

GaryHallSr
November 11th, 2009, 02:25 PM
Dear Quicksilver,

When I posted the 5 MPH at entry it was based on what I had been told. Turns out that is wrong. From the velocity meter, the speed of the body, when the hand first touches the water after the dive, is around 15 mph. Now you'll still have to guess how long it takes to lose 75% of that speed, even in the most streamlined position we can manage.

Gary Sr.

knelson
November 11th, 2009, 02:50 PM
Yeah, the world record time of 20.94 for the 50 meter free actually translates to more than 5 mph (5.3 mph) for an average speed.

__steve__
November 11th, 2009, 03:07 PM
15MPH to 5MPH in less than 1 second

ande
November 11th, 2009, 03:23 PM
by the time your toes get wet?

water is thick & heavy, some say it's viscous

our torsos aren't streamlined to slice the water like dolphins, our hands, forearms, feet & calves are limited blades that lack the surface area & shape to apply sufficent power to propel ourselves through it. Our muscles quickly tire.



Dear Quicksilver,
When I posted the 5 MPH at entry it was based on what I had been told. Turns out that is wrong. From the velocity meter, the speed of the body, when the hand first touches the water after the dive, is around 15 mph. Now you'll still have to guess how long it takes to lose 75% of that speed, even in the most streamlined position we can manage.

Gary Sr.

Chris Stevenson
November 11th, 2009, 03:25 PM
When I posted the 5 MPH at entry it was based on what I had been told. Turns out that is wrong. From the velocity meter, the speed of the body, when the hand first touches the water after the dive, is around 15 mph. Now you'll still have to guess how long it takes to lose 75% of that speed, even in the most streamlined position we can manage.

5 or 15 mph, it shouldn't matter: if your claim of 5 seconds to a dead stop is correct, then it should be about 2 seconds (from the time you hit the water).

knelson
November 11th, 2009, 03:31 PM
If you've ever seen "the plunge" contested as an event you'll know that it takes much, much more time than five seconds to come to a dead stop. In fact, you'll also agree with Chris that velocity decreases aymptotically with time.

mattson
November 11th, 2009, 05:40 PM
... for saying that the power in the freestyle pull comes in the front of the stroke (hand entry to shoulder), not in the middle (shoulder to belly button) or back (belly button to release).
...
2) The fastest point in the stroke cycle is when the hand first enters the water and the slowest point is when the hand is about at the shoulder underwater. That is when the upper arm is pointing nearly perpendicular to the line of the body (ie most drag).

I have not seen the data you are looking at, so keep in mind that I'm floating a theory. You'll have to decide if it matches up with what you are seeing.

What you point out is still consistent with the power coming from middle or back part of the stroke.
A) The fastest point is when the hand first enters the water... That might be due to what the other hand is doing, which will be in the middle or back part of the stroke (depending if the person is more catch-up or more windmill).
B) The slowest point is when the hand is about at the shoulder... That implies that the swimmer is slowing down from hand entry to middle part of the stroke. This might suggest that the front part of the stroke is not where the power is. (At the very least, that position is not favorable for muscle leverage.)

What might be interesting is if you did the same swims with only one-arm and a pull-buoy (no kicking), to try to isolate what is happening during the stroke. It would be tough to make it close enough to a normal stroke (for comparison), but it would take some of the other variables (like the other arm pulling) out of the equation.

GaryHallSr
November 11th, 2009, 05:43 PM
From a pushoff my velocity went from a maximum of 2.9 m/sec to .6 m/sec in exactly five seconds, holding the tightest streamline my 58 year old body could manage. Not a dead stop....but pretty close. The 2.9 m/sec occurred just before the feet left the wall.
The deceleration is much greater on a dive because the initial speed is faster and there is more drag involved (which is very dependent on the entry).

Gary Sr.

quicksilver
November 11th, 2009, 06:11 PM
...agree with Chris that velocity decreases aymptotically with time.

Spoken like true scientists and engineers. :)


Not to get off topic, but Myth Busters had an episode were they wanted to see if bullets would stop (or significantly decelerate) when fired into the water. They did. And in a matter of feet.

YouTube- Underwater Shooting - 01

Chris Stevenson
November 11th, 2009, 06:35 PM
From a pushoff my velocity went from a maximum of 2.9 m/sec to .6 m/sec in exactly five seconds, holding the tightest streamline my 58 year old body could manage. Not a dead stop....but pretty close. The 2.9 m/sec occurred just before the feet left the wall.
The deceleration is much greater on a dive because the initial speed is faster and there is more drag involved (which is very dependent on the entry).

I am not an engineer, but it seems to me that a swimmer's drag will approximately follow Stokes' Law (http://en.wikipedia.org/wiki/Stokes'_law); in particular, the drag force will depend linearly on velocity. In other words, doubling the speed will double the drag.

If that's the case, then an exponential loss of speed is the result and the time to lose 75% of the initial speed will be the same -- all other factors being equal -- regardless of what that initial speed is and regardless of whether you push or dive. (The absolute rate of speed loss will be greater for the dive, but the relative loss will be the same if the person is just as streamlined, etc.)

If, however, we are experiencing "quadratic drag," then the relative fall-off will indeed be faster with the dive than with the push.

qbrain
November 11th, 2009, 07:00 PM
A doctor, an architect and a professor walk into a bar...

knelson
November 11th, 2009, 07:05 PM
I am not an engineer, but it seems to me that a swimmer's drag will approximately follow Stokes' Law (http://en.wikipedia.org/wiki/Stokes'_law); in particular, the drag force will depend linearly on velocity. In other words, doubling the speed will double the drag.

No, Stokes flow is for very low Reynolds numbers (ratio of inertial to viscous forces). A human swimming in water has a high Reynolds number (possible in the 10^6 range) therefore Stokes' Law does not apply. Drag definitely increases quadratically.

GaryHallSr
November 11th, 2009, 09:34 PM
The velocity curves I am referring to were with a pull buoy strapped on my ankles to take the leg propulsion out of the picture and isolate the pulling force.
The peak velocity and trough velocity are repeatable occurring each time in the same place with each arm. The power is definitely not coming from the back end as the hand is actually moving forward again (trying to get back to the front asap).
Few realize the imposing drag forces that apply as we change our arm position from overhead in front to angled down, peaking when the arm is perpendicular to the body line. The bullet analogy should tell you how significant drag forces are...and a bullet is relatively streamlined.
What complicates the analysis of power vs velocity is that most objects don't change shape while moving through a medium. The human body swimming does. It goes from relatively streamlined to very unstreamlined (a brick) and back to relatively streamlined in a matter of a half second or so. The drag is so imposing in this process that even our powerful arm pulling up front do not keep us from decelerating.
The most compelling argument for accepting that the power is in the front is that we spend half of our stroke cycle time in that position. The other half is spent recycling our arm to get back to that position again. Unfortunately the route back creates huge drag issues.
Finally, the race dive involves going from air to water, just like the bullet. At the interface, a third drag is introduced that doesn't exist on the underwater pushoff, called surface or wave drag. It ,too, is significant...especially if you pancake into the water.

Gary Sr.

jim clemmons
November 11th, 2009, 09:57 PM
It ,too, is significant...especially if you pancake into the water.

Gary Sr.

Or worse, as some pancake "onto" the water.

I voted for the 1 second option, fwiw, just considering going from a dive and impacting the water, there's an immediate slowing.

funkyfish
November 11th, 2009, 10:02 PM
A doctor, an architect and a professor walk into a bar...
and after they hit their heads, all 3 fall down. At what rate do they decelerate as their bodies in motion approach the ground?:D

clyde hedlund
November 12th, 2009, 03:35 AM
The power occurs exactly when the water molecules start pushing us forward (paired forces) at the "power position." So the purpose of our shoulders is to move our high elbows forward.

mj_mcgrath
November 12th, 2009, 12:09 PM
Is this argument all about proving that increasing turnover is necessary to increase speed?

With all due respect to Mr. Hall Sr. who has forgotten more about swimming that I will ever know, isn't speed also about distance per stroke? I have no problem matching Jason Lezak's turnover rate (about 34 strokes for 50 meters) in the last 50 meters of his record Olympic freestyle relay. However, not in my wildest swimming fantasy, do I approach either his distance per stroke or his time. (Well, maybe in this one fantasy involving....no,no)

What interests me is how this power issue relates to distance per stroke.
--mjm.

Chris Stevenson
November 12th, 2009, 01:08 PM
I have no problem matching Jason Lezak's turnover rate (about 34 strokes for 50 meters) in the last 50 meters of his record Olympic freestyle relay. However, not in my wildest swimming fantasy, do I approach either his distance per stroke or his time. (Well, maybe in this one fantasy involving....no,no)

If I am reading this correctly, you have it backwards: if you can match his per-50 stroke count, you have the same DPS as Lezak. But if -- as likely :) -- you don't match his time, then he has the same DPS as you but at a higher stroke rate.

And of course you are correct that speed will be a function of both DPS and stroke rate. I remember that Maglischo made a comment in his book (I don't have it here to check) that most of the swimmers at the elite level have very similar DPS but the difference between the first and last place was turnover.

clyde hedlund
November 12th, 2009, 04:03 PM
Exactly, for only in the "power position" can you extract the power of the water. The trick is to efficiently extract it with perfect technique and streamlining or it is wasted. Let the water be your friend and power source.:bump:

mj_mcgrath
November 12th, 2009, 06:12 PM
Chris: if you agree that distance per stroke = speed divided by stroke rate, then at 34 strokes for 50 meters, we don't have the same DPS or the same SR. The DPS and the SR are below:

Lezak: 50 meters in 23 seconds = 2.17 meters per second
34 strokes in 23 seconds = 1 stroke every .67 seconds

MJM: 50 meters in 35 seconds = 1.42 meters per second
34 strokes in 35 seconds = 1 stroke every 1.02 seconds

Lezak: 2.17 meters per sec./.67 strokes per second. DPS = 3.23 meters

MJM: 1.42 meters per sec./1.02 strokes per second. DPS = 1.39 meters

So I should have said Lezak and I can take the same number of strokes for 50 meters. However, his stroke rate combined with his distance per stroke is not something I will achieve in my lifetime. --mjm:bow:

Mswimming
November 12th, 2009, 06:46 PM
Chris: if you agree that distance per stroke = speed divided by stroke rate, then at 34 strokes for 50 meters, we don't have the same DPS or the same SR. The DPS and the SR are below:



I think most people consider distance per stroke, (distance divided by # of strokes) . So for Lezak and you its 50M / 34 strokes = just under 1.5 meters per stroke.

Stroke rate is (# of strokes divided by some period of time). Lezak is 34 strokes / 23 seconds, Almost 1.5 strokes per second. You are 34 strokes / 35 seconds is less than 1 stroke per second.

The difference is that he can maintain that DPS at his higher stroke.

Chris Stevenson
November 12th, 2009, 07:11 PM
Chris: if you agree that distance per stroke = speed divided by stroke rate, then at 34 strokes for 50 meters, we don't have the same DPS or the same SR. The DPS and the SR are below:

Lezak: 50 meters in 23 seconds = 2.17 meters per second
34 strokes in 23 seconds = 1 stroke every .67 seconds

MJM: 50 meters in 35 seconds = 1.42 meters per second
34 strokes in 35 seconds = 1 stroke every 1.02 seconds

Lezak: 2.17 meters per sec./.67 strokes per second. DPS = 3.23 meters

MJM: 1.42 meters per sec./1.02 strokes per second. DPS = 1.39 meters

So I should have said Lezak and I can take the same number of strokes for 50 meters. However, his stroke rate combined with his distance per stroke is not something I will achieve in my lifetime. --mjm:bow:

Mswimming pretty much said what I would say. The problem with your math is that "1 stroke every .67 seconds" is not the same as ".67 strokes per second."

E=H2O
November 12th, 2009, 07:18 PM
A while back, I jumped on the triathlon website Slowtwitch and got attacked for saying ......
Gary Sr.

Someone getting attacked for voicing their opinion on Slowtwitch? So what else is new. It can be a very helpful forum, but it can get brutal if the crowd turns against you. By the way I thought you handled yourself just fine. I just did not feel as comfortable about the product pushing that seemed to accompany your otherwise very insightful analysis.

Allen Stark
November 12th, 2009, 09:14 PM
Re: where does the power occur,in my viewing of the velocity charts that Dr. G has shown in various publications the peak velocity usually occurs when the propulsive arm is about mid-chest,when it has both the maximum hand/arm area perpendicular to the direction of propulsion and the most large propulsive muscles employed.Provided the arms are moving backwards faster than the body is moving forward they cannot be causing form drag to slow you down,rather their form drag is the primary thing you are pushing against to move forward.Therefore you want to maximize the arm's form drag to maximize propulsion,hence EVF.
Re: the poll question,there are too many variables to answer it.Velocity off the block,height achieved in flight,angle of entry,and ,probably most important, ability to enter"through the key hole" will all affect the entry speed and deceleration.A more important question is what are the optimal angles in leaving the block and at entry and why.Many coaches seem to be teaching leaving the block nearly parallel to the water which gives limited flight time,therefor minimizing the time when you are at your fastest.Is that really wise?Should the angle be different with the new starting blocks?These are answers I'd like.

clyde hedlund
November 13th, 2009, 06:02 AM
If your arm is moving backwards, then you're not moving forward. Instead, you're moving water backwards instead of propelling the body forward. The goal should always be to develop that magic touch of the hand exiting ahead of where it entered the water.

mj_mcgrath
November 13th, 2009, 09:07 AM
Mswimming and Chris: thanks for correcting my math:agree:. It never was my strong point. The comparison to Lezak means that I can match his strokes per length and distance per stroke but that is not nearly as important speedwise compared to turnover rate and maintaining dps over distance. :doh: --mjm

knelson
November 13th, 2009, 10:50 AM
The goal should always be to develop that magic touch of the hand exiting ahead of where it entered the water.

In my opinion the "magic" here is kicking hard. I don't care how efficient your pull is, there's no way your hands exits ahead of where it entered unless your kick is propelling you forward.

__steve__
November 13th, 2009, 12:58 PM
An educated working-class, novice perspective here:

The greatest power occurs at the point in stroke where swimmer achieves peak speed given drag forces are constant (whatever stroke position that may be). This might vary from swimmer to swimmer.

One thing I haven't noticed being mentioned by you elite swimmers is the the factor of swimmer density. The mass/volume ratio will play a significant part in overcomming drag force deceleration after the start.

Even though I haven't even tried a start on the block yet, the way I look at it, the taller, skinnier, relatively muscular (for density) swimmer will have a given advantage. I'm wondering if it's not really the velocity of start opon entering the water, but how far out you are when you enter.

quicksilver
November 13th, 2009, 12:58 PM
If your arm is moving backwards, then you're not moving forward. Instead, you're moving water backwards instead of propelling the body forward.

Here's another perspective...

I don't view hand and arm in the stroke cycle as "paddling" in that you move water backwards. Rather it's kind of like doing a one armed pull-up on an underwater ladder. As each hand grabs onto a rung, you pull yourself past the point where you latched on. It's just a slightly different take on what's going on under the surface.

And as Kirk said, you would need some additional momentum for the hand to exit past the point of entry, but it does happen with very good swimmers.



Getting back to what Gary Hall Sr. described about the power position, I guess it's more about swimming long and stealthy by keeping the arms out front and extended...in the front quadrant.

GaryHallSr
November 13th, 2009, 02:03 PM
Steve,

The key phrase in your analysis is 'if the drag forces remain constant'. In swimming, they don't. Far from it. The difference between the drag coefficients in water with the hand-in-front, outstretched position (other hand releasing) (relatively streamlined) and the arm-sticking-straight out position when hand is at chin or shoulder (very unstreamlined) is off the charts.
Taking an armstroke in freestyle is like streamlining, then throwing a parachute out the back, then cutting the cord to it and back to streamlining again...that occurs with each arm pull. That is why we decelerate into that horrible arm-out position in spite of a significant force being applied up front.
To appreciate the drag forces we are dealing with when our hand is at our shoulder underwater, try kicking fast with fins on with one arm over your head and the other sticking straight down. You will see what I mean about the parachute.
What makes swimming complicated to analyze is that we have significant changes in power from front end to back end of the pull with even more significant changes in drag occurring simultaneously. Now, throw in the propulsive and drag forces of a six beat kick and you have one complicated mess.

Yours in swimmming,

Gary Sr.

GaryHallSr
November 13th, 2009, 02:13 PM
knelson,

You are right. The long dps guys use a hip-driven, leg-driven stroke (Phelps, Thorpe, Hackett, Lezak) and they are all dependent on having Mercury motors for legs behind them.
Strong legs not only add significant propulsion, they create lift and most importantly they help sustain speed (helping to overcome the inertia problem). If you don't have stong legs and you try to hold out in front like they do, you are sinking.
In other words, no legs and you'd better learn to increase your stroke rate.

Gary sr.

clyde hedlund
November 14th, 2009, 03:11 PM
The reason for that "horrible arm-out position" is because you're flying. At that position, you've already propelled part of the body beyond where the hand entered the water. Yes indeed, I vote for the power up-front position, for that is where all the action is taking place. It is where the hand applies force to the water and the water responds back with equal force and propels us ahead.

GaryHallSr
November 16th, 2009, 05:50 PM
OK....I have kept everyone in suspense long enough. The answer to the poll question is that an excellent swimmer (my son Richard 1:37 200 free in college) who does a very clean sling shot racing dive, hit the water at 14.8 MPH and at one second from that time (he is now completely submerged, streamlined and even starting a kick) he has slowed to 3.5 MPH, quite a bit slower than his race speed. That is a 76% reduction in speed that occurs in exactly one second with an excellent dive.
Congratulations to those of you who got it right.
The moral to the story is unless you have legs like Phelps, Lochte, Leveaux, Coughlin or Hyman, you'd better get your rear end up to the surface and start swimming. Otherwise you are just losing ground.

Gary Sr.

tomtopo
November 17th, 2009, 03:45 PM
The beginning of every competitive stroke only starts the production of power or inertia. Drag forces in conjunction with lift forces (the hand moving into stable water) are the most potent producers of power and occur later in the stroke. The first quadrant of any stroke merely sets the wheels in motion (setting-up the stroke), so peak drag and lift forces can take place during the transition from the first quadrant and into the second quadrant of each competitive stroke. The hand entry and beginning of the stroke does not produce any significant power but is critical in establishing peak efficiency as the hand and forearm become vertical. The power that is produced during the end of the first quadrant and through the start of the second quadrant is where peak power (torque) is produced. The end of the second quadrant of the stroke where the arm extends (and away from the body) can help maintain the power gained through the power phase. There is a lot of research done at the Olympic Training Camp Biomechanics’ Facility showing that peak power is produced during the transition from the 1st and into the second quadrant (another spike comes at the end of the stroke when the hand tends to accelerate (this maybe one reason it seems power is generated at the beginning of the stroke).

clyde hedlund
November 17th, 2009, 07:29 PM
It's nice to partition the stroke, but only if the body remains still. However, the body moves forward and the hand remains fixed in location and ideally exits ahead of where it entered.:angel:

SolarEnergy
November 18th, 2009, 08:55 AM
2) The fastest point in the stroke cycle is when the hand first enters the water and the slowest point is when the hand is about at the shoulder underwater. That is when the upper arm is pointing nearly perpendicular to the line of the body (ie most drag). I'd be tempted to say that the reason why your fastest point in th estroke cycle be when hand first enters the water, is that whilst this is occuring, the other hand has just finished its job, that is ensuring the the peak power occurs near the end of the stroke.

Peak power during the pulling path in Free Style occurs by the second half of the pulling.

Gary, there's one very simple way to experiment and measure this: Swim with one arm only!!

shane
November 18th, 2009, 08:14 PM
In my opinion the "magic" here is kicking hard. I don't care how efficient your pull is, there's no way your hands exits ahead of where it entered unless your kick is propelling you forward.

don't forget that after the hand enters there is arm extension, maybe some glide, then a drop to the catch position. during all this time you(and your hand) are still moving forward even if you are using a pull bouy. by the time you start to pull it is not hard to imagine that the hand is well ahead of where it entered the water. if the distance from hand entry to hip is roughly 4ft and you can pull 25yds in 15 strokes then each arm stroke is moving you about 4ft assuming a 5yd pushoff. of course sadly for me, a good kick also helps.

clyde hedlund
November 19th, 2009, 06:35 AM
Also consider that, if we're doing it right, our stroke is getting a little bit of help from lift, which is actually moving our hand forward. If not, then the hand stays put (fooling around with drag) while our arm changes position indicating continuously how far our body has moved forward.

knelson
November 19th, 2009, 12:42 PM
Also consider that, if we're doing it right, our stroke is getting a little bit of help from lift, which is actually moving our hand forward.

I disagree. Lift is a component of force perpendicular to the mean flow. Since we're moving forward in the water, lift can only affect our body position, not move us forward. The only thing moving us forward is a propulsive force with a forward compnent caused by the arms and legs reacting against the water.

david.margrave
November 19th, 2009, 12:54 PM
Where's that physics prof?

GaryHallSr
November 19th, 2009, 08:43 PM
The power forces of the hand change from almost pure lift in the outstretched position, to nearly pure propulsive drag when the hand is about at the shoulder level. The motion of the hand is in nearly a perfect circle of about 2 feet. It moves forward, down, then back, up and forward again, leaving almost exactly where it started. In between these points at the top of the circle (pure lift, moving forward) and the bottom (pure drag, moving backward), there are vectors of force for both lift and propulsion occurring simultaneously. Lift likely has the effect of increasing our velocity by reducing drag, if we have any significant propulsion with our legs. It turns out, understandably, that the best hold-out-in-front, lift swimmers have the best kicks (Thorpe, Phelps, Hackett, Lezak etc). Out front, they are generating lift not just from the hand, but from the entire arm. Also, the more speed they can generate while holding out in front, the more lift...just like a plane taking off down the runway.

Gary Sr.

GaryHallSr
November 19th, 2009, 09:14 PM
Dear Tomtopo,

I have not seen the research from the Olympic Training Center, but I can tell you that one cannot determine power by knowing what the velocity, acceleration or deceleration is at any given moment in the stroke cycle. The reason is that one can accelerate (or decelerate) by either a change in propulsive power or a change in resistive drag or a combination of both. Most objects we study in motion do not change shape, but the motion of the human body swimming freestyle is complicated by both changes in propulsive power and drastic changes in shape, significantly increasing pressure drag, as the arm moves through the underwater cycle.
Although there is deceleration (40% loss of speed) of the body from its fastest point in the cycle (with arm outstretched and other arm preparing to release) to its slowest point (with upper arm nearly perpendicular to the body line, hand about at the chin), I submit that this deceleration or loss of speed is not due to reduction of power but rather to a huge increase in drag force.
Anatomically, it makes no sense to say we have no power in front when virtually all of the muscle groups are working. By the time we release the hand, very few muscles are left working (tricep?). The power generated is also influenced by the counter-rotation of the hips (core), creating a counter force against which we pull, which is initiated with the catch and continues during the entire underwater pull.
The strongest argument one can make for believing there is significant power in the front quadrant is that we spend half of our cycle time in that front area. The other half is spent in the back quadrant and the complete over water recovery....ie hurrying to get our arm/hand back out in front again. If we weren't getting power there, I don't think we'd be spending so much time up there.

Gary Sr.

SolarEnergy
November 19th, 2009, 09:20 PM
Where's that physics prof? His presence would be a bonus, but all that has been throughly studied, analyzed and described since 1980 by Ernest Maglischo.

And again, to better guess when the power occur just perform one-arm freestyle. It then becomes clear.

Georgio
November 19th, 2009, 11:18 PM
Does lift in the stroke keep you higher in the water creating less drag?

Or does the added "surface turbulence" just slow you down?

I have no hard numbers to compare, but my Early "Nearly" Vertical Forearm stroke has evolved to my elbows barely below the water surface .....with the forearm at about 5 - 10 deg. to perpendicular to the bottom.....creating some lift. I will concentrate on perpendicular (no lift)to see what outcome.

Georgio :bolt: :bliss::argue:

clyde hedlund
November 20th, 2009, 03:48 AM
I disagree. Lift is a component of force perpendicular to the mean flow. Since we're moving forward in the water, lift can only affect our body position, not move us forward. The only thing moving us forward is a propulsive force with a forward compnent caused by the arms and legs reacting against the water.

Whether lift or drag, propulsion occurs when the forces pair up, and lift indeed is a propusive force that pulls my hand forward. Now that kind of assistance I'll accept gladly.

Allen Stark
November 20th, 2009, 01:55 PM
I disagree. Lift is a component of force perpendicular to the mean flow. Since we're moving forward in the water, lift can only affect our body position, not move us forward. The only thing moving us forward is a propulsive force with a forward compnent caused by the arms and legs reacting against the water.

Kirk,you are right about the direction,but the key is the hands,not the body. When the hands generate lift it is because they are moving side to side relative to the body(the old S stroke idea) and that "anchors" the hand allowing it to be used for thrust.Sculling is lift generated propulsion.It works,just evidently not as well for freestyle as the more drag dominant EVF pulls currently in vogue.

SolarEnergy
November 20th, 2009, 04:55 PM
http://books.google.com/books?id=cSSW4RhZOiwC&dq=swimming+fastest&printsec=frontcover&source=bl&ots=qjoxbuUX44&sig=P_mqJjh8SvXzWclyzme127CKGJc&hl=en&ei=nv24SvvFC87rlAeemqzGDg&sa=X&oi=book_result&ct=result&resnum=3#v=onepage&q=&f=false

Page 9
- Paragraph on Lift
Page 11
- Paragraph on Bernouli's Principle
Page 18
- Paragraph on Newton's Third Law of Motion (don't miss the Q/A FAQ)

Finally, I think that both Maglischo and Councilman are on the same page. In fact, they have been in synch over years. They both went wrong in thinking that Lift was mainly responsible for forward thrust (more than a decade ago).

clyde hedlund
November 21st, 2009, 02:03 PM
Appreciate the reference SolarEnergy, for it is a matter of contribution, which Ross Sanders brought up years ago. Also noticed that there is no discussion on Newton's 2nd law of motion: acceleration. Yes, water will accelerate backwards, but before it does, it accelerates us forward, and that is the period we want to exploit.

tomtopo
November 21st, 2009, 02:40 PM
http://books.google.com/books?id=cSSW4RhZOiwC&dq=swimming+fastest&printsec=frontcover&source=bl&ots=qjoxbuUX44&sig=P_mqJjh8SvXzWclyzme127CKGJc&hl=en&ei=nv24SvvFC87rlAeemqzGDg&sa=X&oi=book_result&ct=result&resnum=3#v=onepage&q=&f=false

Page 9
- Paragraph on Lift
Page 11
- Paragraph on Bernouli's Principle
Page 18
- Paragraph on Newton's Third Law of Motion (don't miss the Q/A FAQ)

Finally, I think that both Maglischo and Councilman are on the same page. In fact, they have been in synch over years. They both went wrong in thinking that Lift was mainly responsible for forward thrust (more than a decade ago).

I agree in that lift forces are not the primary propulsive force in the freestyle. Drag and lift forces will never be in "vogue" they wil always be a matter of fact. Every single person on the face of the earth, who wants to propel themself more effectively, must put their hand and forearm in a vertical position and the quicker the better, thus the EVF. An early vertical forearm is no more in vogue than an effective kick (making it better makes you faster). The force of the hand as it enters, is in, and as it exits perpendicular, establishes the most propulsive force in swimming. Movement of the hand to and away from the midline of the body allows maximum pressure because moving the hand straight back causes the water to create a vortex (behind the hand) that decreases drag. A person's strength and flexibility are just two important variables that determine how effective a swimmer's pulling pattern can become. We can all rationalize (and very well) how force is created in a freestyle swimmer's pull but we should all agree that the vertical position of the forearm and hand is not in vogue but a constant reality to freestyle swimming.

In that regard a totally straight arm pull (not including the release or finish) achieves a perpedicular position later and can maintain propulsive force, especially when you have a tall swimmer with strong shoulders (Alain Bernard).
Can a freestyler like Alain Bernard swim faster if he improved his EVF? The answer should be an immediate yes because a totally straight arm negates the propulsive opportunity during the "setting up of the stroke" or beginning of the first quadrant. Bernard's stroke doesn't have to change to one that looks like Rebecca Adlington's but a quicker EVF would certainly help in my opinion.

I must tell you that I have found this thread to be very interesting. I do think that the research done by Doc, is still the best for what swimmers want to know, and that's how to swim faster. Doc's book should be on everyone's shelf.

clyde hedlund
November 21st, 2009, 04:44 PM
And depending on how much fulcrum (water) you want to use, your hand and arm will adjust accordingly to achieve this in order to increase the duration of the propulsive phase of the stroke.

tomtopo
November 21st, 2009, 07:19 PM
And depending on how much fulcrum (water) you want to use, your hand and arm will adjust accordingly to achieve this in order to increase the duration of the propulsive phase of the stroke.

Clyde ~ You said this very well and I'd like to rephrase it. Swimmers who can adjust and increase the duration of the most propulsive phases of each competitive stroke are going to improve their swimming performance. I hope you don't mind me using this because it is really at the core of many threads on many swimming forums. Thanks, Coach T.

clyde hedlund
November 22nd, 2009, 01:47 AM
Clyde ~ You said this very well and I'd like to rephrase it. Swimmers who can adjust and increase the duration of the most propulsive phases of each competitive stroke are going to improve their swimming performance. I hope you don't mind me using this because it is really at the core of many threads on many swimming forums. Thanks, Coach T.

Coach T: Why of course not, please continue to spread the gospel and help us swimmers achieve better performance.

tomtopo
November 22nd, 2009, 05:05 PM
I really enjoy trying to help. This is becoming a super site for swimming information and t's fun to be involved. I hope my two-cents helps. Good luck, Coach T.

SolarEnergy
November 23rd, 2009, 04:37 PM
I do think that the research done by Doc, is still the best for what swimmers want to know, and that's how to swim faster. Doc's book should be on everyone's shelf. I think so too. And shame on me, I do not own any of these. So far I have been counting on Maglischo to provide me with a synthesis of all these works.

But yeah. It seems that Doc's works on this topic over years have shown several other researchers the right way.

Also. Note that Maglischo (and others) still don't know about these things. It's all hypothesis. Therefore I don't pay that much attention to this.

Put yourself in my position. I have been following Maglischo's work since his first edition. Every new edition he changes his mind drastically. So... What is it going to be next?

clyde hedlund
November 25th, 2009, 01:10 PM
Regarding the poll, supposed we convert it into a swim stroke: Then I'd be only 75% efficient and 25% lost to slippage?:2cents: Happy Thanksgiving

dsyphers
November 26th, 2009, 11:09 AM
Where's that physics prof?

Sorry to have been silent on the rest of this thread. I've been buried under a mountain of work, chairing our tenure committee with meetings deep into the evening, and pitching in while my wife dealt with her mother's decline/death this month.

The general principles, most of which are being discussed in this thread, are pretty clear -- thrust, drag, lift (in that it changes body position in the water), and turbulence. Beyond that, the specifics really require measurements of force as a function of time, speed as a function of time, etc. correlated with the motions of the swimmer. There is currently some research being done along these lines, and I expect we'll see some general principles come out of this work. They may not be that different from some of the general principles (like EVF) that have been around already.

However, the situation of each of our own bodies moving through the water is sufficiently complex, that what is really useful is to have your own personal self tested while you swim. Systems in development now will make that easier in the future, but now they are mostly in the research stage. I'll be tested myself in a couple of weeks using the research system at my college, but it is still a little early in the research cycle to be able to take the data and unambiguously relate motions, or changes in motions, to the data. Why is it so hard? Even subtle differences in body position create differences in drag; applying forces to the water creates turbulence, as does changes in body position, and turbulence decreases the effectiveness of the applied force, etc. Figuring out the relative importance of all of these individual components (with all the swimming motions together) when they are all combined to give only 2 pieces of information (the net linear force in the direction you are swimming, along with your speed, both as a function of time) is not as easy as you might think.

Happy Thanksgiving to all!

clyde hedlund
December 2nd, 2009, 06:02 AM
[QUOTE=quicksilver;198594] "I don't view hand and arm in the stroke cycle as "paddling" in that you move water backwards. Rather it's kind of like doing a one armed pull-up on an underwater ladder. As each hand grabs onto a rung, you pull yourself past the point where you latched on. It's just a slightly different take on what's going on under the surface."

Even in paddling, the objective is not to move water backwards, but to move the boat (like the body) forward (past the blade or hand). So like the hand, the paddle doesn't move backwards, but remains fixed in location. And like your "underwater ladder," I actually practice on land using a four (4) foot long skateboard and propel myself with the swim stroke. My neighbors think I'm nuts going up and down the sidewalk, but boy, my shoulders get a workout. I wear leather garden gloves and get my hips involved too. If you have access to an outdoor basketball court with a smooth surface, try flinging yourself with one-arm pulls. Doing this will give a good mental picture of how far the body travels during the swim stroke in relation to arm position. Of course, even on land, my hands always exit ahead of where they begin the stroke.

ps: please wear a helmet if you try the skateboard drill. thank you, clyde