Coach Dave

One of 2 great points on this thread.

No matter the focus and fancy description of arm/hand/wrist and even finger (really?) as stated, none of that matters when your arm is operating outside of ones functional plane dictated by the scapulas.

(the other great point is a releasing/stretching of pec minor... a major contributor to both awful posture and limited mobility as it relates to scapular angles)

Id be interested in the response to your post. Will keep an eye on it.

Basically when you watch (lionel) or others swim, picture their skeleton ... imagine the movement through the bones. Swimming is about the bones. If those bones are not aligned and functional, then having your thumb next to your pointer finger then moving it after a slight twist to your wrist in the middle of a breath movement doesn't mean shit.

daved

---

http://www.theundergroundcoach.com

Thanks for the post.

Expert contribution is always appreciated.

 
Can anyone explain to me in laymans English (I am but a simple man...)

What flexibility is required and what is rotating to get the early vertical forearm whilst having your arm in line with your shoulder (lengthways), assuming I am correctly understanding the Ledecky picture. I assume the shoulder isn't 'hunched and rolled forward' does she have a very high elbow?

here is the one part of your post i don't understand:

"8. The arm is a class III lever with a mechanical advantage of about 1/30...in other words, it offers no mechanical advantage to a swimmer"

it seems to me that one of - if not the - prime benefits of early vertical forearm is that you increase your pulling surface. your forearm joins the hand as a pulling surface because it is - well - "vertical." as you note:

"Hand must be moving backward relative to the water to generate propulsion"

if you can present to the water more surface area pulling "backward relative to the water" why is this not also a means to "generate propulsion."

i don't think i'm misunderstanding you, because you make this point separately in your post, and you are explicit. the point of EVF is to: "reduce frontal drag, not to increase propulsion, nor for more power."

i stipulate entirely to all the elements of your post, as regards to the "how to." but i'm not prepared to stipulate to the "why." as you rightly point out, i just love the "grip it and rip it" notion. a lot of emphasis in decades past was placed on arcane technical elements, such as seeing out undisturbed water to pull, when it seems axiomatic to me that the prime job is to place as much surface area as possible perpendicular to the water and then hoist yourself forward and past it.

but it seems to me that what you're saying here is that EVF does not work the way i envision, rather it's only an exercise in hydrodynamics.

---

Dan Empfield
aka Slowman

Is Gary Sr. suggesting that the body follows in the shadow of the EVF vs the EVF is outside of the body. In both cases you get the full propulsion from the EVF, however, when the body follows in the shadow of the EVF the hydrodynamic drag cumulative exposed to the water is lower. I THINK this is what is supposed to happen. Its not that propulsion goes down much (or if it goes down, its a good tradeoff) its that overall drag from arm+body goes down ?

Dan,

There is a mistaken notion globally among coaches and swimmers that much of the propulsion force is coming from the forearm moving backwards. While the forearm does contribute some propulsion resulting in the swimmer's velocity, the overall percentage is small, perhaps on the order of 10%.

The surface area of the forearm may be greater than the hand but the shape of the forearm is quite different. The hand is a flat surface compared to a rounded surface of the forearm. The flow around the forearm is much smoother than the flow around the hand.

Further, the hand is moving backward in the water at a faster velocity than the forearm. The drag caused by the hand or forearm moving backward is proportional to the square of the velocity.

A very simple experiment is to swim with your fists closed. While that does not eliminate the hand, it makes it's shape smaller and rounder. The result is a huge loss of propulsion.

The EVF does likely increase the propulsion coming from the forearm, but that is not why swimmer's do it. Were it not for the lowering of the frontal drag, the loss of biomechanical strength caused from using this awkward, high-elbow motion of pull would not be worth the trade, even with a little boost from the forearm.

Gary Sr.

The challenge of getting into the EVF position like Katie's is based on the anatomical restrictions imposed by the scapula, shoulder and elbow joints.

Assuming a swimmer rotates the body (shoulders) in freestyle as he or she should, then the arm enters the water in a slightly flexed shoulder joint position. If the objective is to keep the upper arm in the line of motion in order to minimize frontal drag (the upper arm is moving forward in the water until the hand reaches near the shoulder under water), then that involves internally rotating the shoulder and elevating and rotating the scapula (hunching), before flexing the elbow. The challenge is in the elbow joint, which is just a hinge joint.

Since we need to keep the hand surface perpendicular to its backward or downward motion, with the limits of the elbow, we simply can't keep the upper arm perfectly straight during the lift and front quadrant propulsion phases. The closer to the line of motion we can keep it, the better. It doesn't take long (hundredths of seconds) for the big upper arm to put on the brakes in freestyle, once it start sticking out.

Hope this helps. It it makes you feel better, very few people understand the freestyle pulling motion.

Gary Sr.

can we just begin by acknowledging the cavernous gap between your knowledge and mine here? i believe in acknowledging professionalism, and honoring it, so i'm not arguing. but i am trying to understand this, which includes working through any gaps in logic or reasoning i can't reconcile.

for one - and i don't mean to be pedantic, and i think it is relevant - i don't see the arm as "moving backward", rather i see everything from the elbow to the fingertip as immobile in the water once presented to the water vertically. you're pulling your body past a sort of "grappling hook" that has anchored itself on the water. at least ideally. it seems to me the more surface you can deploy at that job of anchoring the pulling surface in the water, the less that surface will slip in the water.

i understand the math of this and it's pretty much the same as the math we use in bicycle aerodynamics. and i understand the difference between the shape of the hand and the shape of the forearm. but danged if - when on land - we still face a lot of drag even as we try to make the bike's shapes as aero as possible. i just don't know.

i understand all you're saying and, yes, when i try to swim fists-only i don't do very well. (i don't do very well in any case.) i guess i'm just surprised to hear that EVF is technique that increases propulsion, but to benefit hydrodynamics. i'm not doubting this, just surprised by this.

---

Dan Empfield
aka Slowman

Dan, you are not alone in that thinking. Some of the best swimming coaches in the world believe that is what happens, that the hand gets anchored in the water and the body moves past the hand.

That would only happen if we could grab onto a ladder or some immovable object in the pool to pull us forward, which we don't have. In a liquid medium, like water, the propulsion force is only generated by the source moving backward. It MUST move backward relative to the water. The amount of drag that the surface causes moving in the opposite direction determines the amount of propulsion.

The hand moves about 2 feet total distance backward under water during the pulling motion. It enters and leaves the water in nearly the exact same spot, but that does not mean it doesn't move while underwater. It does- forward, downward, upward then forward again, in almost a circular motion. You should read the chapter on the freestyle pulling motion in my book.

On a side note, the propulsion generated by the feet and legs is different because the flow dynamics are different behind the swimmer. The water is essentially still for the hands, but the slipstream forms a current moving behind the swimmer. The feet move almost straight upward forward then straight downward. Since they are moving through the vortices caused by the moving body and the moving feet and legs, they use these vortices to generate propulsion (potentially in four places during a single kicking cycle).

Thank you - I appreciate your time. I'm going to have a play next time I am in the pool! (and work on my flexibility)

Interesting. I regularly do some fist-closed pull sets, as part of a recovery workout nearly every week, and I have noticed that I am not actually that much slower when using closed fists - maybe ~2-3 sec/100yd slower*. Makes me wonder if I'm doing something really wrong, if I'm not maximizing the propulsion that my open hand provides, or maybe ~2-3 sec is a "huge loss of propulsion" in swimming terms...

* note that it did take me many months of doing closed-fist swimming just to do it smoothly and have it not completely disrupt my body position and balance. The first many sessions, it definitely threw my balance off and I felt like a dying fish flopping around

Hate to agree with you here, but you are likely not "holding water" well with your open hands, ie causing enough drag. Commonly seen problem where hands slip at various times during propulsion phases. If you were, you would likely see a greater difference in times. Your SR is also likely higher with the closed fists...while DPS is lower. SR x DPS = speed.

Pretty cool thread! As an adult onset swimmer, I really appreciate Gary’s, and everyone’s input here.

Although I might not agree with some of the hydrodynamic statements as declared, I think I can reconcile the descriptions with arguments that are physically sound.

Bernoulli ‘s principle is a consequence of Newtonian dynamics in fluids, and not a separate phenomenon, but I imagine Gary means to convey that sculling is not as effective as “pushing” the water. My slight contention here is that a truly symmetric “push” would result in strong vortex-induced instabilities, e.g if you swing an open palm underwater as fast as you can, it will involuntarily wiggle perpendicular to the motion. A slight asymmetry is required, and this should result in some additional propulsion, but as Gary suggests, is likely a smaller percentage. I would also guess that the suction side pressures of the hands and forearms are more significant contributors to propulsion than the “high” pressure side. Perhaps some food for thought regarding a purely momentum exchange model for swim propulsion, is that neither humans nor animals produce water currents of equal and opposite momentum, but rather wakes.

Regarding early vertical forearms, a straight and sweeping arm which creates the largest possible moment will have a center of pressure farther than 2/3rds of the length of the arm out, acting on a total area of “one arm”, but a shortened EVF will have approximately 1/2 arm of area with a center of pressure only ~1/4 arm lengths away from the shoulder joint. For the same torque from the shoulder, the EVF can create something like a (2/3)/(1/8) ~ 5x larger force, largely via faster relative motion through the water. Not to mention that the outstretched arm’s pressure is acting on an arc and only the horizontal component is creating propulsion, while a greater proportion of the EVF movement is always better oriented to provide propulsion.

Much of what I said in the previous paragraph is just napkin math on conventional swim wisdom, but beyond the simple dynamics, adding momentum to the water farther away from the body means that less of that momentum will be available to reduce the wake behind you, being instead lost to diffusion with the still water. This means you’re adding the work required to pull more water with you as your body’s wake itself diffuses momentum to still surrounding water.

As a slow swimmer, I’ve long blamed the lack of flexibility in my shoulders for my lack of improvement in front crawl speed. However, I swim almost as fast (read: slow) with open or closed fists. Based on Gary’s posts, I’m definitely going to do a lot more drills and stretching to focus on EVF. I don’t think I realized how much I’ve been out-sweeping during the catch as well as pulling deeper into the water than I had imagined.

Am I to understand that the (often referred to as recovery arm) plays no roll in forward movement?
Maybe you believe there is some benefit there, maybe you dont. But you have not talked about it.

As far as fist swimming, in my experiences, similar to another poster here, I have seen times within 2 or 3% of non-fisted swims (this is for experienced college age swimmers and advanced age groupers).... in the tri community that % is even closer as the closed fist allows triathletes to move through that "pull phase" (horrible name) and get to the arm throw (recovery as its often referred to) much easier and thus takes a lot of strain off the shoulders and back. IE they go just about as fast without trying to apply all that force on the hand under the water.

my simple points are:

The throw over the water is all to often neglected in swimming and is an area that can create more propulsion than any effort UNDER the water. (I would argue its less taxing energy wise to move ones arm through air than water... no?)

That throw over the water changes your (yes dan) anchor arm into a first class lever.

And the challenging thing in what you do with your arms when you swim is that the movement is simple. However our feedback loops, based on survival, and how we are wired make it extra hard to keep this simple. Over analyzing and over detailing only the underwater aspect of swimming w the arms is not surprising based on this knowledge. And also highlights our desire for more information here. Heck we have a whole host of swim tools that highlight our desire to focus on where our brains are getting feedback, while in the water... hands / paddles of all shapes and sizes and claims of improvement and feet / fins of all shapes an sizes and claims of improvement. And coaches who promote focusing only here by using fancy terms.

daved

---

http://www.theundergroundcoach.com

I know you did an experiment where you used a constant speed measuring tool and showed this to be true. Do you still have that article somewhere?

Wow wow wow, this is great stuff … thanks gary sr. Read the initial posts this morning then tried the tips in my morning swim. Fins and snorkel helped as it was very awkward at first

I forgot about the pinkie down; will have to try that next time. And this seems like a simple yet critical concept: “try to keep the upper arm as close to your line of motion as possible”

Regarding early vertical forearms, a straight and sweeping arm which creates the largest possible moment will have a center of pressure farther than 2/3rds of the length of the arm out, acting on a total area of “one arm”, but a shortened EVF will have approximately 1/2 arm of area with a center of pressure only ~1/4 arm lengths away from the shoulder joint.
---

Honest question- how does the shape of the arm affect the maths? Certainly the calculations would be different if the arm were as flat a surface as the hand, especially in terms of total area. But I have to believe that the rounded shape of the forearm changes the equation.

---

---

---

Take a short break from ST and read my blog:
http://tri-banter.blogspot.com/

Shape affects things of course, but that’s just “napkin math.” If we’re presuming the same arm then these details approximately cancel out in the grossly simplified ratio.

Other hidden assumptions are that for a straight arm pull, the velocity of the water varies linearly with distance from the shoulder, but the corresponding pressure forces grow faster than linear with velocity, hence the “farther than 2/3rds.” The centroid of a triangular (linear) distribution is at 2/3rds.

I think you’re overselling the value of the overarm movement, but he does talk about it here:
4. The speed of the hand entry of the recovering arm is directly tied to the speed of the shoulder rotation- both powerful coupling motions for your pull.
5. Therefore, focus on driving the recovering hand and arm hard to the water (fully extended). The fast shoulder rotation comes with it. It is the only BOGO I know of in the sport of swimming. Too many swimmers enter their arms like a modern toilet seat with a spring hinge on it.
Fact remains that it’s only productive based on how it’s translated to the pulling arm, unless I’m mistaken.

Expert? I need to know credentials before i throw that label around?

fair point... Im guilty of having my eyes glaze over some of these threads as I just simply disagree with this over complication of what the hand/arm does under the water.

Folks arm movement is very simple. It's our brains that complicate it bc of how we are built/wired.

Imagine yourself laying down in a shallow satelite dish (equal to your natural scapular arch) and making a "snow angel" movement. That is the movement. Of course the arms alternate.
Youll want to over think it.
Youll want to add to it
Youll tell me Im missing stuff and it cant be that easy

But it is.

daved

---

http://www.theundergroundcoach.com

Google who the writer is, and you will find he is more successful than most people in the swimming world.

:) Longtime readers will 'get ' the joke..lol

The kinetic energy of the recovering arm (particularly at the end of the recovery) as the hand nears the water, and the kinetic energy of the rotating body (shoulders and hips rotate at different times about .2 seconds apart) do, in fact, augment the effect of the two sources of propulsion, pull and kick. We call these motions Coupling Motions. Neither one generates any propulsion, but when they occur during the propulsion, or while the propulsion is still in effect, they will augment the effect.

It just so happens that the aggressive arm/hand entry will cause the shoulders to rotate faster, increasing the kinetic energy in both motions. That is the BOGO I refer to. Sprinters tend to use a straight, fast arm recovery with very high SR to maximize this coupling effect.

I think we agree that the Bernoulli effect at the speed of swimming and with the small size of the wings (hands/arms) it is not a significant force. Sculling, if purely a motion out and back will generate lift but no propulsion. The hand(s) must move backward to do that.
You are correct in that when we try to move the hand in a direct line backwards very quickly, the hand swerves a little. If you kick very fast with fins on and one arm is pointing straight down, we don't have the strength to keep it straight. It swerves from the tremendous amount of drag it is causing. That small amount of excursion of the hand caused by the frontal drag forces is not the same as the in sweep or out sweep so often seen in swimmer's pulling motions.
As the hand passes the shoulder on its way back, the elbow and upper arm elevate in order to try to keep the hand moving backward, not upward. The hand sort of cuts off the corner of the circle from 6 to 9 o'clock on its way back, so the motion is more linear than you might think.
Someone in the thread mentioned that the arm is a class 1 lever. It is not. Like the forearm, the entire arm is a class 3 lever with fulcrum being the shoulder joint, effect load being at the insertion of the major muscles moving the arm into the head of the Humurus, very near the fulcrum. Even if the force load is 2/3 the way down the arm (as you suggest) or at the hand (where I believe most of the force is being applied), the mechanical advantage is far less than one. While the EVF brings the hand closer to the fulcrum, increasing the mechanical advantage, meaning we can push the hand through faster with the same amount of force, I believe that we lose too much biomechanical advantage in this awkward motion to win in the overall propulsion battle. But we do win in the drag battle, and that takes precedence, unless we are swimming a 50 sprint.