How much extra propulsion does optimal roll deliver?

[Zenturtle]

Assume we have 2 identical swimmers. Both have shoulders of steel, and very flexible.
One is swimming with a shoulder/hiproll of only 10 degress, the other with a roll of 45 degrees.
The rest of the stroke is as identical as can be.
Swimmer 1 is holding 1.40/100m pace for a 1500.
How fast is swimmer 2?

[Danny]

I can't be as quantitative as you would like, but here is the trade-off as I see it.

If you have better shoulder flexibility you can get your forearm vertical with less roll. The danger in this is, of course, messing up your shoulder. On the other hand, as your stroke rate increases, you have less and less time to rotate, and most of us tend to sacrifice rotation to varying extents in the interest of speed. So less rotation can be done faster, but it has the danger of messing up your shoulder if you try to maintain a good catch.

It's not surprising that there's a lot of individual variation in this, because people have variable shoulder flexibility and also variable ability to rotate fast on the long axis. Seems from your post that you are aware of this trade-off, so I'm not sure I understand your question. If we were to redesign our anatomy to be better suited to freestyle, our arms would be like the paddle wheels on old steamers and we wouldn't need to rotate at all. We would still, however, want to use shoulder extension to do as much work as possible with our core. Would we try to take advantage of gravity in some way? Using gravity is just a way to store energy and give your body an intermittant rest in between strokes. Or it may be a form of load leveling to reduce the intensity of the pull phase up front. So, here again, how much rest do you need between strokes and how much load leveling do you need.?

[s.sciame]

That's interesting, hard to say and hard to compare. Ten degrees is almost flat, I think of it as a waterpolo style which allowes for an easy high SR and short DPS. Viceversa 45 degs allow for longer DPS but slower SR. Since we're talking about cruising speed over a 1500, first of all I find it hard to imagine any swimmer, even one with super strong and flexible shoulders, cover such a distance with only 10 degs of body rotation (even those who seem flat above the water, actually rotate much more in my opinion).
Anyway, in this example I would imagine swimmer 1 taking advantage of an higher SR than swimmer 2 and holding pretty much the same speed (at least if I swim waterpolo style with little body rotation it's not slower than my cruising pace over a 1500 with full body rotation).
If instead you meant that the 2 swimmers are supposed to hold the same SR, e.g. 60SPM, swimmer 1 would be disadvantaged only for having to limit his SR when he could easily swim at 75SPM, given his almost flat body position. Swimmer 2 with his 45 degs would instead be comfortable at 60SPM and probably rushed at 75. So it's hard to compare for me.

When I feel like I'm rotating best, I usually shave 1SLP and gain about 4s/100m over my 1500m pace (at the same SR), but I cannot hold this for more than 600 or 800m, so it's not for free. Perhaps neuromuscular training would help here.

Cheers,
Salvo

[Zenturtle]

If you have better shoulder flexibility you can get your forearm vertical with less roll. The danger in this is, of course, messing up your shoulder. On the other hand, as your stroke rate increases, you have less and less time to rotate, and most of us tend to sacrifice rotation to varying extents in the interest of speed. So less rotation can be done faster, but it has the danger of messing up your shoulder if you try to maintain a good catch.

It can be surprising to check your range of motion on dryland. Try this for yourself:
Standing straight and looking in the mirror I can get the hand and forearm in a horizontal plane (vertical in swimming position) almost at top of head level.
Now its posible to move this hand and forearm in that horizontal plane like an helicopterblade to see where are the limits of the range of motion.
Looking from above, pointing the hand and forearm in that helicopterbladeplane straight ahead toward the mirror is 0 degrees.
(In swimming this is lying zero degrees rotated, hand and forearm pointiong straight to the bottom at a vertical plane touching the top of your head.)
Looking from above and talking about the right hand/forearm , rotating it clockwise to the right inthe horizontal plane I soon run into trouble. Rotated 30 degrees to the right my shouder already starts to hurt. I can almost feel the bones rub against ech other. Not a smart idea the repeat thousends of movenets at his position.
In fact, this is the posution where I am rotated 30 degrees right shouder down and getting the hand/forearm vertical vertical at top of head level.
Concllusiion: At 45 degrees rool angle I anly can get the hand/veratm vertical at a lower level, say about eye level.
So swimming at this effective aquatic traction position is working right at the end of the range of motion of the shoulder.
In other words, I can get a higher vertical elbow position at a lower roll angle.(when the hand/forearm is pointed straight down in the pool)


The surprinsing thing for me was how much the hand/forearm could be rotated in the hleicopterbladeplane in the other direction.
So moving the right hand/forearm to the left shoulder, thats minus 90 degrees, and evn fiurther, pointing backwards, another 45 degrees.
So the range of movement looked up from above is from plus 30 degrees (closckwise) to minis 135 degrees(anti clockwise).The middle between these extremes is about 80 degrees, the hand somewhere above and in front of the forehead.
Actually, a lot of beginners pull a bit like this. Entering close to the head, and close to the centerline.
So the EVF at a high roll angle certainly is an annutural movement, balancing on the end of the range of shoudermobility.
Nathan Adrion does rotate his EVF hand/forearm more anticlockwise than most of the elites His right forearm is pointing more towards the left side instead of downwhen he starts his pull.

swimmer 1 and 2 both have enought shoulder flexibility to get the same EVF, the only difference is the different roll angle.

It's not surprising that there's a lot of individual variation in this, because people have variable shoulder flexibility and also variable ability to rotate fast on the long axis. Seems from your post that you are aware of this trade-off, so I'm not sure I understand your question. If we were to redesign our anatomy to be better suited to freestyle, our arms would be like the paddle wheels on old steamers and we wouldn't need to rotate at all. We would still, however, want to use shoulder extension to do as much work as possible with our core. Would we try to take advantage of gravity in some way? Using gravity is just a way to store energy and give your body an intermittant rest in between strokes. Or it may be a form of load leveling to reduce the intensity of the pull phase up front. So, here again, how much rest do you need between strokes and how much load leveling do you need.?

What do you mean by load leveleing?

[Danny]

Originally Posted by Zenturtle

What do you mean by load leveleing?

Load leveling is when you do some work at the back end of your stroke (where you're no longer working hard) in order to save work at the front end of your stroke (where the work is hardest). For example, it is an easy thing at the back end of your stroke to rotate your arm and shoulder out of the water against gravity, so that you can let it fall again at the front end of the stroke as a means to propel you forward.

As far as the dry land exercise you mentioned, I have done this many times. Many years ago I dislocated my right shoulder and the range of motion in each shoulder is different. I need more rotation on the right side in order to keep my elbow up in recovery, and, when I see film of myself swimming, it is usually the right side where my recovery is poor due to lack of rotation. What amazes me the most is that there are some elite swimmers who seem to have super-human shoulder mobility. Here is a picture of Kornelia Ender (East German record holder from the 1970s, lower right in the picture). She uses almost no body rotation at all and still manages to have a vertical fore-arm in the front quadrant.

[sclim]

@ZT: After an extensive session in front of the mirror with arm above head, mulling over your post and just about dislocating my shoulder, I think I get what you're saying (sure glad my wife didn't walk in during my experiments -- too hard to explain briefly!)

So the rotation may be partly to compensate for imperfect shoulder mobility to get EVF with lead arm starting as far ahead as possible for efficiency.

It wasn't clear to me where you were going with your 2 comparable swimmers example.

So, let's say that one has perfect shoulder hypermobility, so one could in theory get the perfect lead arm EVF far ahead, in right parallel track position etc., with zero body rotation. Would one ideally swim like this to save energy? Or does one actually exploit the swinging body pendulum to some degree to finesse the flywheel effect to transform and transmit core momentum into forward propulsion?

@Danny: my experience may be deficient here, of course, but it seems to me that you can't say Kornelia Ender swims with zero or little rotation from looking at the four still photos because the still photos may indeed show zero rotation (and good arm EVF position in the zero rotation photo), but we can't tell whether or not she is passing through the zero position in the midst of a 30 degree amplitude left-right swing or if she is truly has a "permanently zero degree rotation angle" pendulum motion that is, a zero degree amplitude. Actually, One of the photos (bottom left) seems (to me) to show her in some axis rotation.

[sclim]

BTW, for those struggling like me to reconcile what we are experiencing in the pool with high school physics (50 years ago, in my case arrrrrgh) my initial problem was that I remembered Galileo's genius was to recognise the swaying church chandelier as a pendulum that kept perfect periodic regularity irrespective of the amplitude of swing.

So how do we change speed then? And why would a lower amplitude help us at faster RPMs?

Well, the answer, partly, as I finally remembered, was that the pendulum only has a regular period (time per swing) at low amplitudes, (where the tangent of the arc approximates the sine of the arc, to get technical, about 4 degrees or less). The amplitudes we are talking about plus or minus 20 to 80 degrees are way out of that range, and large amplitudes do lead to longer periods. The other part of the answer is also that we aren't a simple passive pendulum. We can shorten and lengthen our axial pendulum at will, and add all kinds of extraneous acceleration and deceleration to the swing by complex 3 dimensional contortions.

[Danny]

Originally Posted by sclim

Actually, One of the photos (bottom left) seems (to me) to show her in some axis rotation.

The other pictures are not of Kornelia Ender. The only picture of her is bottom right. I can't say how much she uses rotation (although I suspect the answer is very little) but try standing in front of the mirror and doing what she is doing in the lower right.

[sclim]

Originally Posted by Danny

The other pictures are not of Kornelia Ender. The only picture of her is bottom right. I can't say how much she uses rotation (although I suspect the answer is very little) but try standing in front of the mirror and doing what she is doing in the lower right.

Oh yeah, of course, Doh!

No thanks, lol.

[s.sciame]

Originally Posted by Zenturtle

The rest of the stroke is as identical as can be.
Swimmer 1 is holding 1.40/100m pace for a 1500.
How fast is swimmer 2?

So Zenturtle, how fast could be swimmer 2 according to you? And do you assume that the 2 swimmers would hold the same stroke rate or not?