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  #1  
Old 11-26-2010
wentod wentod is offline
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Default Physics of TI freetyle swimming. Mythical hip propulsion?

Hi all,
This is my first post. I apologize if the subject has been dealt with before.
11 months ago I searched for freestyle instructions on the web and found the amazing Shinji's video, ranked n°2 worldwide for viewings. I bought Terry's book and started learning TI swimming by myself in France. You are both my masters. Thank you.
But till now I have not found clear scientific explanations for propulsion in TI freestyle swimming. After lots of readings, drills, experiments, observation, and recalling physics I've been taught in college, here is an attempt to answer myself to some questions concerning 3 specific aspects of TI
ROLE OF ARMS:
Imagine an astronaut-swimmer in skating position in space with left arm extended. If he moves his recovery right hand along his body and suddenly spear it forwards. What happens? Nothing. Because the energy of throwing his right arm (mass of arm x speed) causes the rest of his body moving backwards at lower speed but with the same energy ( higher mass of body x lower speed) accordingly to a Newton's law (conservation of movement quantity). But if the astronaut puts his feet on the fuselage of a huge spatial vessel and repeat the same move, his whole body cannot be pushed back and so the energy of his spearing arm will pull him away. He can even double this energy if he pulls back his leading left hand. And faster he moves more energy he gains. That's the law! Theoretically energy is great if he has Popeye's big heavy arm. He can cheat and enhance his energy by wearing his arm with a heavy metallic sleeve or holding lead spheres in his hands (sorry I didn't try yet. Is it prohibited by swimming federation?). Only one limit : if he spears to fast his energetic arm would tear his shoulder and get its own way to the outer space.
In the pool the spearing hand and arm obeys to the same law. The other hand plays a multiple role. TI principles emphasize most on “anchoring”, “holding on” the water (pulling a little, no pushing necessary)... the idea is that the swimmer vaults on his leading pulling hand to slip trough the water (like the astronaut putting his feet on a huge spatial vessel to neutralize reaction backwards). But accordingly to the above physics law, only moving left arm backwards also provides energy we can transform into propulsion in the opposite direction. (Moreover if you push harder you can have some extra thrust but it's not TI philosophy).
ROLE OF CORE MUSCLES.
Imagine the same astronaut in space with both of his arms along his sides. He tries to raise his right shoulder a little bit, say 5 cm (yes he can! you try it at home in front of a mirror!) and normally moves back his left shoulder, as if he is crawling (regardless to his arms he can keep still). Depending on his flexibility some other parts of his upper body follow a similar direction (up for the right side and down for the opposite), at variable degree . This happens too when we swim freestyle (also called crawl swimming, right?). Now we use the Newton's law as above and we realize that core muscles move big masses of the body (but on short distances) and then produce energy we can transform-transmit into propulsion if we prevent reaction backwards (vaulting on a huge vessel in space or on the “anchoring” hand in the pool)
ROLE OF HIP ROTATION
Actually in crawl-swimming the leading shoulder does not follow a trajectory parallel to the body line. I'd rather imagine an arrow put diagonally on the back of a TI swimmer, the feather on the left butt and the tip on the right shoulder blade. This is grossly the direction of the acceleration produced when, from the skating position with right shoulder up , at the same time, he “spears his right hand and arm and shoulder, trying to far reach out” + ”vaults on his left hand (preventing backwards reaction of the body) to slip through the water” + “flicks his left foot downwards to induce a reaction-rotation (left hip up, right hip down)” + “activates core muscles”, altogether to create and transmit momentum. The resulting acceleration-arrow follows a helical (“screwing”) trajectory . Another Newton's law says : force = acceleration x mass (in the same direction). And there are two components-vectors of this diagonal force produced: 1) the “mythical” core-hip-drive-rotation-propulsion force directed forwards (Great, I have been so long looking for it! Snappy screwing move (= high acceleration) is the best, that's the law!), 2) a perpendicular force tending to roll the swimmer like a log (badly if it upset him with stomach facing the ceiling; but hopefully raising the left arm out of water at the end of the stroke neutralizes Archimede's upwards force and allow gravity to stop the rotation). Masters, you told us wide tracks are better for stability (gravity of the recovering arm multiplied by distance to the body line is greater for stopping over-rotation). Now I understand. And core-rotating-producing-propulsion emphasized by TI is no more mythical to me (I would replace rotating by screwing).
From my point of view I'm glad to see that all TI masters' empirical tips for propulsion are can be related to Newton's universal physics laws. Thanks again to Terry, the founder of TI method.
But I still am a newbie in swimming and no expert in physics. So welcome to comments of TI masters, coaches, veterans and fans. Is there a math geek, physics professor or astronaut around here? Please correct me if I'm wrong.
Sorry for the length of my post and for my french english. Hope you don't misunderstand.
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  #2  
Old 11-26-2010
borate borate is offline
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Quote:
Originally Posted by wentod View Post
...till now I have not found clear scientific explanations for propulsion in TI freestyle swimming.
This may interest you. Some TI principles have been refined since the article was published in 2006 --- http://tinyurl.com/2ev4jpf

Last edited by borate : 11-26-2010 at 09:01 PM.
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  #3  
Old 11-26-2010
Richardsk Richardsk is offline
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Hello Wentod

You needn't worry about your French English; it's a lot better than most people's English French.

The questions you raise are questions that have been raised many times before, I think, but because not that many swimmers are expert physicists and because expert physicists have often got more important topics to investigate, I don't think a really definitive answer has been found at the scientific level. Mind you I have read learned papers by physicists on whether buttered bread always falls face down or not and on whether a cat can really flip on to its feet if dropped with its back facing down. The answers are a) that buttered bread or toast doesn't always fall face down - it just seems that way because it's so annoying when it does and b) that a cat can indeed flip over on to its paws before landing.

As in your case, Terry's book, was my way into TI swimming and through it I was finally able to swim a somewhat presentable front crawl and became a masters swimmer at a fairly advanced age. Note that I wrote masters swimmer and not master swimmer, because mastery is still out there waiting to be approached but never to be mastered.

TI thinking has advanced somewhat since the famous blue and yellow book was published and Terry has announced that a successor tome is on its way, which is eagerly awaited. It is possible, I suppose, that the successor will be available as an e-book, which would be very welcome, although the paper book has something about it that no e-book can really match.

The fact that swimming takes place in water makes the scientific discussion of it difficult for non-scientists, even if they remember some bits of what they learned at school or have picked up over the years. To analyze swimming successfully one needs to have a good grasp of hydrodynamics, anatomy, biology and quite a few other scientific disciplines as well, I imagine.

Therefore, the accumulated wisdom of many years earnest searching for what works is something that is not to be dismissed lightly. What works for Olympic athletes might well work for us ordinary mortals if we had started to swim competitively at age five, and gone through an intensive training with skilled coaches - provided we had not lost our love for the sport through a combination of boredom, pain, bullying, disappointment, physical or psychological damage and so on.

For some of us, the thrill, first of being able to swim a couple of lengths of crawl, or back crawl - even butterfly and then to enter competitions and swim against ( or rather behind) swimmers who swam competitively in their youth is almost enough of a thrill. But there is also the thrill of trying to understand why Shinji can slide down the pool in nine strokes while barely disturbing the surface of the water and why one's own efforts are still so relatively puny, in spite of the visible progress that has been made.

It seems to me that many of the tenets of TI swimming are idealizations. We know that it is not really possible to hold on to the water like the rung of a ladder, but trying to do just that produces a somewhat similar effect that is superior to what we would have achieved if we had tried to grab the water in front of us and hurl it backwards. By trying to swim with our hips and torso we have engaged larger and more powerful muscles than those in the arm and shoulder. We also know that we haven't got the firm surface of the earth to press against, as we have when we throw a ball, or a punch, or swing a golf club or baseball bat, but we also know that our flick of the foot in the opposite direction has a similar purpose and effect.

Just thinking of your body being long and sleek seems to have a physical effect, which may call for some scientific explanation. Any volunteers?
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  #4  
Old 11-27-2010
Alex-SG Alex-SG is offline
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Quote:
Originally Posted by wentod View Post

But till now I have not found clear scientific explanations for propulsion in TI freestyle swimming... ROLE OF ARMS, ROLE OF CORE MUSCLES, ROLE OF HIP ROTATION.
Bonjour Wentod !

I am not a physics expert however this is my understanding of TI.
As you know there are 3 key pillars of Total Immersion in the following order:
1. Balanced position 2. Streamlining 3. Coordinated propelling movements

1. & 2. are about minimizing resistance/drag in the water (the shape of the boat)
3. is about moving forward (the engine of the boat)

Let's focus on 3.
At the end of the day I believe that what moves us forward is a combination of 3 actions happening almost simultaneously
-- The Spearing Arm moving forward while the whole body rotates
-- The Catch hand/arm grabbing/holding the water
-- The magical 2BK timing which helps initiate the body rotation and adds some forward movement

ROLE OF ARMS
--- Recovery arm (Spearing Arm): shift center of gravity forward to rebalance the body + spearing (like launching the swimmer inside a narrow pipe)
--- Catch Arm: Hold the water so that the whole body can rotate/ move forward around the anchor point

ROLE OF CORE MUSCLES
-- Help stabilize the body + keep legs to the surface
-- Help rotate from one side to the other

ROLE OF HIP ROTATION
-- Rotate... Drive the Spearing arm forward through the water
-- NOTE: Hip rotation itself is initiated by the well timed 2BK (Kick)

Back to your astraute example... if he kicks he does not move forward. If the anchors the arm he also cannot move forward.
But the swimmer in a medium like water can.

Hope my understanding is correct. Comments are welcome.

J'espere que ca aide. A+.

ALEX

Last edited by Alex-SG : 11-27-2010 at 10:16 AM.
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  #5  
Old 11-30-2010
wentod wentod is offline
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Thanks for your feed-back.
Borate : you showed me an interesting discussion about strategies for efficient swimming.
My concern was rather about how to create forces and transform them into momentum with minimun of losses. Thinking about action+reaction committed me to focus on preparing my anchoring hand as a "soft hook" BEFORE spearing hand+arm+shoulder. This helped me last week to reduce my usual SPL from 9 to 8 in a small pool (12.5m).
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  #6  
Old 12-02-2010
madvet madvet is offline
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Swimming's main propulsion is the pulling arm, assisted somewhat by kicking. As you said, spearing hands don't propel, hips don't propel, corkscrew torsos don't propel.

The thing is that the body ultimately moves forward by the laws of physics but the way to get your body to work the most effectively does not necessarily involve visualizing the physics correctlly.

When our brain thinks of using our arms obeying the laws of physics, we tend to use the small muscles of our arms. Arm muscles are small, weak, and tire quickly. We need to trick our minds into using the much stronger, high-endurance core muscles. So we come up with these frankly physics-violating visualizations of spearing, hip-drive, torso-twisting.

Those actions end up propelling the arm just the same, but different muscle groups are used. It is a trick of the mind, and many of us find it to be a rewarding challenge.

There can be some value to investigating the physics of the hands, body and feet and how they may move to generate better streamlining and more efficient leverage. But it is a completely different story than how to engage our brain to generate that movement.
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  #7  
Old 07-17-2011
solothesailor solothesailor is offline
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This should be a good read also (I think it's a general body of knowledge not necessarily specific to TI):
Hip Rotation in Freestyle Swimming"
http://www.coachesinfo.com/index.php...283&Itemid=138
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  #8  
Old 07-17-2011
Lawrence Lawrence is offline
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In my view one should be very careful in interpreting the terminology used by TI (and other swimming schools). There is a lot of superficially attractive and intelligible jargon which, upon closer examination, clouds issues rather than clarifying them.

'Hip drive' is an example but there are many others. I spent a good while trying to nudge my hip quickly downwards in the hope I would suddenly experence effortless propulsion. Needless to say, whatever hip drive is, it isn't nudging one's hip quickly downwards.

If there's one thought I have more than any other while watching those swimmers at my local pool who appear to be committed to improving their freestyle, it's that 99% of them are looking in the wrong place. I can't help thinking that jargon, which tends to be imprecise at best and meaningless at worst, is part of the problem.
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  #9  
Old 07-18-2011
KatieK KatieK is offline
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Quote:
Originally Posted by Lawrence View Post
In my view one should be very careful in interpreting the terminology used by TI (and other swimming schools). There is a lot of superficially attractive and intelligible jargon which, upon closer examination, clouds issues rather than clarifying them.

'Hip drive' is an example but there are many others.
Agreed

Quote:
Originally Posted by madvet View Post
The thing is that the body ultimately moves forward by the laws of physics but the way to get your body to work the most effectively does not necessarily involve visualizing the physics correctly.
True. But I personally have to understand the physics. Otherwise my mind can't stop trying to figure it out. Not everyone is wired that way. But for the ones who are, it's a huge distraction not to be able to make sense of it.

So here's my two cents on the subject:
The "hip drive" contributes leverage, not propulsion.

As Madvet and others have mentioned, you don't want to use your arm muscles to propel you. One reason is that they fatigue easily.

Instead, you're trying to use your arm like an oar. Your pecs hold the lead arm in position as long as possible, while the core rotation forces it down. The catch propels you forward, but the power comes from your core muscles rather than your arms.

Quote:
Originally Posted by Richardsk View Post
You needn't worry about your French English; it's a lot better than most people's English French.
My adult-onset English French is an abomination. I can't stay out of the water long enough to practice.
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  #10  
Old 07-19-2011
bx bx is offline
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I'm trying to get a handle on what a hip-drive-assisted stroke feels like.
I know I should be aiming for a "vaulting over the catch arm" feeling.

Quote:
Originally Posted by KatieK View Post
The "hip drive" contributes leverage, not propulsion.
Yes! This is a key point!

Quote:
Originally Posted by KatieK View Post
Your pecs hold the lead arm in position as long as possible, while the core rotation forces it down.
I'm not sure I know how to use my pecs to hold my arm out! I can't even "activate" my pecs! Should I do more bench press?

So, when the catch arm is approximately vertical (or, at least after it has gently travelled down from the spear position), do you sort of lock the arm in place using the lat muscles (or pecs still?), and use the core rotation to assist the arm during this power part of the stroke?

[Post edited to include KatieK's points]

Last edited by bx : 07-19-2011 at 02:13 PM. Reason: Further priceless insights
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