Where does the power occur?

[GaryHallSr]

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__]

Originally Posted by GaryHallSr

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

[brett olson nads]

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 ...

[JMiller]

Originally Posted by GaryHallSr

Anyway, read my latest blog on our website 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

Fun, and Fast - Page 31 - U.S. Masters Swimming Discussion Forums

Jonathan Jr.

[knelson]

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]

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]

Originally Posted by GaryHallSr

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]

Originally Posted by GaryHallSr

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]

Originally Posted by GaryHallSr

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]

) 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]

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]

Wow, Gary Hall was a hero of mine when I was younger.

Isn't this kind of front quadrant swimming?

[orca1946]

Does high elbow cause more drag in this case? More power ,but more drag?

[quicksilver]

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, 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]

Originally Posted by quicksilver

That said, I enjoyed the article swimming on the freeway,

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]

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]

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.

[quicksilver]

Originally Posted by GaryHallSr

Dear Quicksilver,

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.

I'm going guess as follows...based on kinesthetic awareness from my best 50 free time.

2 seconds of flight time from the starters horn...2 seconds of maximum forward motion after entry...and 1/2 a second for my brain to tell my arm to break out because I perceive a slight decline in speed.

So.... 2.5 seconds (from entry to the onset of slowdown)...plus a 1/2 second for the 75% reduction to occur.

3 seconds is my final answer.

[__steve__]

15MPH to 5MPH in less than 1 second

[ande]

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.

Originally Posted by GaryHallSr

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.