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CoachStuartMcDougal 11-04-2015 08:24 PM

The Propulsion Paradox
A fascinating piece from Science Editor, Sara Knapton, Telegraph UK: "For nearly 100 years, it has been assumed that mimicking natural swimming meant finding ways to generate high pressures. Now we realize we've had it backward": Could humans swim quicker by imitating eels and jellyfish?.

This falls on the heels of a recent blog from Terry: Swimming Principle #2: Most of what we know [or have accepted] about swimming is wrong!.

Also an interesting video from Coach Boomer, "throwing recovery arm (or high side) weight forward connected to pelvis generating (forward) momentum in its rhythm cycle and space": Freestyle Re-imagined



Zenturtle 11-04-2015 08:50 PM

To my knowledge you only can create a low pressure region in a swimming movement by creating a high pressure region somewhere else.
You could also say that the low pressure region in front of the underwaterarm is sucking the swimmer forward, instead of the pressure on the rear side is pushing the swimmer forward.

What about this swimmers throwing the arm weight forward and connecting everything? (when she gets in her optimal rhythm)

tony0000 11-04-2015 09:21 PM

I'm all for undulation, but let's remember that throwing the arm forward requires pushing the rest of the body backward. (For every action, there's an equal and opposite one.)


"Swim by the mile; improve by the inch."

Zenturtle 11-04-2015 09:29 PM

The arm can be thrown forward because the other arm is holding water and acts as a foundation.
The underwater arm makes the whole action like a ratchet mechanism.
Without it the body would decellerate when the arm over the top accelerates forward in the first half, and accellerates again when the over the top arm decellerates in the second 90 degrees.
The nett effect would be zero without the anchored underwater arm.
If the underwaterarm would be totally static relative to the body it would just act as a movement damper, damping the body movement from the waving arm on top of the body.
The ratchet works best when the resistance of the underwaterarm is highest when the above arm is accelerated, using the foundation of the underwaterarm, and the arm is in a more streamlined position when the upperarm decellerates, taking the body forward in the action+reaction cycle.
Thats basically a kayak arm timing, the opposite from catchup.
These arm throwing swimmers often move more toward kayak timing compared to the lineair high elbow swimmers like Mack Horton.
Thats also the case in the above posted video example.

If loping has some undulation in it, these swimmers already perhaps have found out some of this jellyfish stuff.
Often coaches learn form the very best swimmers and a little bit the other way around

tomoy 11-04-2015 11:15 PM

Kind of wondering if someone will invent a new form of swimming. I imagine it would be some rolling or twisting version of an underwater dolphin kick which would rotate the mouth to air. Or maybe very dolphin like with several kicks on the back, surfacing to air, then diving back deeper for propulsion. Humans are just built wrong... or need bigger lungs.

Disruption in the water - maybe it's time :


CoachStuartMcDougal 11-05-2015 04:59 AM

I love paradox - it removes long lasting filters and broadens your view. Research is beginning to show we've had it all wrong even with aquatic creatures too, largely due to looking through the human lens of vessels that operate on terra firma where we spend the majority of our life. Although I don't think a new stroke will appear anytime soon at meets or open water swims, i.e. the "Eel". What it does tell us is locomotion is not necessarily generated from pushing water back.

Paying attention to how Boomer describes the recovery arm momentum swinging forward connected to pelvis for propulsion is fascinating, and I dare say, very forward thinking. Paraphrasing Coach Boomer: "The bottom side (arm in the water) creates a platform beyond which the body can slide. Initially or instinctively we use the bottom arm as an impulse generator to move water backwards; when you move water backwards you do not move forward very well. The purpose of the bottom arm is to create thick water to hold as you throw recovery arm weight in front of it (the bottom arm)".

Coach Boomer is (and has been) removing filters of conventional wisdom, looking at swimming from a completely different lens, or better, a far bigger lens. Aquatic creatures creating vacuum or suction from lateral low pressure zones for locomotion - who would have ever thought? Science - great stuff.


Zenturtle 11-05-2015 06:09 AM

This transfering of force from the recovering arn to the water holding arm is another sign that great gains can be made by using as much of semy- static tension/connection to produce propulsion on the underwater arm.

For now we still move by increasing pressure on the underwater arm

- this accelerating above body parts that increases pressure on the locked arm in the water.
- Using rotation energy to transfer force to the underwater arm
- Using some core bending on top of translation to move the whole shoulder complex from core muscles instead of only local movement in the shoulder joint.
- Using up and down weight pulses to fall in the anchored arm, also using static shoulder girdle -body connection.

All these actions take as many bodyparts as possible to move forward in some way through the water.
Whole body swimming.
Splashing beginners also try to use whole body swimming, only problem is there is zero control.
Their wiring is still landbased and wrong.

CoachStuartMcDougal 11-05-2015 02:59 PM


That is a common, and accepted view - pressure on arm moving back, faster the pull and high pressure = more propulsion. The "For now..." is really the lens you are looking through at the moment. I suspect the college swimmers in attendance looking through a similar lens as you listening to Coach Boomer certainly turned their perceptions of catch and pull as primary propulsion on its head. The recovery arm connected to the pelvis driving momentum *forward* (not back) past low side arm is whole body movement. In TI this is characterized as weight shift with hip driving recovery arm past (low side) lead or anchoring arm.

I really like Coach Boomers visual or analogy of "creating thick water" with low side arm and creating rhythmic cycles and space dividing the body down the middle and not at the waist. I've been experimenting with his drill; although the momentum from body rotation is missing, the release of arm before the (recovery) arm swings forward and drops in rotating body to opposite edge. It's another version of single arm switch with focus on the rhythm of recovery - excellent stuff.


Zenturtle 11-05-2015 04:47 PM

I am certainly convinced that the mental picture of holding on to the water and anchoring your arm in it as if its concrete is usefull.
This mental image just works for a lot of people. For some the image of swimming through a sea of kittens also works.You dont want to rip through these kittens with your arm and hurt them, but spread the load over as much kittens as possible to move yourself forward over (sorry)/past them.
But in the end its that underwaterarm acting as an anchorpoint that moves you forward.
Now there are a whole range of possible mechanisns to transfer power to that arm (mentioned earlier), but the tyre has to transfer the power to the road eventually.
And to move a car forward, the wheels have to rotate also. Same with the arm.
Do the experiment with the underwater arm pressed against the body.
Or with a dropped elbow arm shape
Or without moving the arm relative to the body(not pushing back)
Or try it with catchup armtiming, underwater arm pointing forward.
Or compare its effectiveness with a good armshape that offers maximal resistance to backward movement when you throw the arm over.

Anyway, plenty of things to experiment with.

bx 11-05-2015 11:37 PM

It's been a while (years) since I parted with any cold, hard cash on my swimming, but I'm going to spring for this Freestyle Reimagined by Bill Boomer - thanks for the link, coach Stuart. If any UK readers are similarly inclined, but put-off by their prohibitive $39 shipping (ouch!), I emailed them to complain nicely, and they can send it by USPS , like TI uses, for under $20, albeit uninsured. Caveat emptor. (Apologies if this reads like an advert. It is not.)

I love this forum and the analysis, but sometimes I just have to see what the guy (no less than Boomer!) actually has to say... I will report back.


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