Swimming with your Body

RE: Swimming with your Body

Former Member — Mon, 23 Nov 2009 08:29:29 GMT

Would perhaps the best way to use your body be in loping or leaping?

RE: Swimming with your Body

Former Member — Fri, 20 Nov 2009 12:41:46 GMT

why not test the theory? swim a 25 without pulling underwater. just bring the arm back close to the body. now sling the arm forward during recovery and see how fast you can go. then consider how much energy it cost to do this.

RE: Swimming with your Body

Former Member — Fri, 20 Nov 2009 08:57:53 GMT

Yes, I agree that my arm is a lever, but I prefer to use the water as my fulcrum, and not my shoulders, which are actually the forward moving force that's moving me (the load) in the same direction.

RE: Swimming with your Body

Former Member — Thu, 19 Nov 2009 13:24:31 GMT

Dear Mattson, Forget the space analogy, my arm is a lever and my shoulder is a fulcrum. If i swing my arm and its deceleration is caused by the water, not muscle contraction, would that not transfer energy to my forward motion? What is the difference (other than weight distribution) between my arm and a 3 foot rope with a 5 lb weight attached to the end? The further the weight is away from the fulcrum, the better, but the principle still applies. Please advise. Gary Sr.

RE: Swimming with your Body

Former Member — Thu, 19 Nov 2009 11:10:59 GMT

With rotation, are we minimizing or maximizing the moment of inertia?

RE: Swimming with your Body

mattson — Thu, 19 Nov 2009 10:42:51 GMT

Dear Dsyphers, Thanks for straightening me out on the space analogy. However, there is still energy transferred to the body when one swings the arm around and stops it suddenly, just as if I were swinging a fishing poll and letting the line and sinker out the end, correct? And the rotational spinning of a bullet going down a gunbarrel does increase it's acceleration, does it not? As Dsyphers pointed out, if you were isolated in space, you would be able to twist but not gain any linear motion. The fishing poll/line/sinker analogy will not work, because you can't detach your hand or arm. :) (The position of your center-of-mass would remain the same, so if you lifted your arm above your head, the rest of your body would move backwards slightly to compensate.) The rotational spinning of a bullet is to stablize the flight-path, not for acceleration. Enough off topic... back to swimming!

RE: Swimming with your Body

Former Member — Wed, 18 Nov 2009 12:38:10 GMT

Dear Dsyphers, Thanks for straightening me out on the space analogy. However, there is still energy transferred to the body when one swings the arm around and stops it suddenly, just as if I were swinging a fishing poll and letting the line and sinker out the end, correct? And the rotational spinning of a bullet going down a gunbarrel does increase it's acceleration, does it not? Granted that there is more than just the stable pitching mound involved in the difference in velocity achieved from the water, but the point is the same. If we can create a counter force with our own rotational motion of the core (and likely the kick, as well) we will generate much more power with our arm pull than we can without it. By the way, there aren't too many two beat kickers left out there on the elite level. The two beat kick is basically used as a stabilizing force (with the hip rotation) and provides enough lift to keep the legs on the surface. It only works with a very fast arm stroke rate (Shirley Babashoff...one of most renowned 2 beaters used to take nearly 50 strokes per 50 meters) Propulsion from a two beat kick is minimal. Regards, Gary

RE: Swimming with your Body

moodyrichardson — Wed, 18 Nov 2009 10:31:34 GMT

These posts are EXACTLY what I need to be reading (and doing)! I have no coach on land but reading info like this puts thoughts in my head and something to think about when I swim. Please Gary keep your posts coming! I totally agree! GREAT post! It's something for me to keep working on, while I'm training.

RE: Swimming with your Body

Former Member — Tue, 17 Nov 2009 15:07:03 GMT

Rotating the body may decrease the drag (without doing a study on it, I'm not clear whether this is the case), but it clearly can change both the mechanical position (and stabilization that you mention), and create additional forces applied to the water (whether these will help or hinder you depend on how you do the rotation). For instance, compare to what happens in space. In space, the rotation of your shoulders requires a counter-rotation of your legs (conservation of angular momentum - since the forces are all internal), so that there is no net rotation. So in the water, rotating your torso, and applying force against the water to do so, requires your legs to rotate in the other direction, but they run into the water. If this is properly timed with your kick, you get an extra propulsive force from the kick relative to what you would get without rotating your torso. Impressive. I know it's just an hypothesis but I may be my missing bit. I am completely dum in physics. But I strongly disagreed with Maglischo's take on this topic (as stated in his latest edition: Swimming Fastest). On page 80, he basically discard the theory stating that body roll be a source of propulsion. He got distracted by this famous (and fallacious) analogy with the Pitcher. My take on this is based on what I feel more than on some theory. It's very simple. Picture yourself starting a good old gas fueled lawnmower. The ones with a strap. Imagine it's the first time you start it. First time of year. Try to do this without any torso twist. I know I know. This analogy shares some of the fallacious characteristics with the Pitcher one. But I am absolutely convince that if you put this lawnmower in the water, solidly anchored on the floor, some torso twist would help getting the strap going. I may be wrong, but when I swim the free style my pulling feels as if I was starting a lawnmower per stroke. Could be another fallacy, caused by the favorable impact of putting the body in a position to use powerful muscle masses but I'm sure there's something else. Also, I like to keep my arm entry / catch unloaded. That is I keep muscle contraction to minimum at that stage (for various reasons). But as you increase the stroke rate, it becomes more difficult to perform the catch whilst remaining relaxed muscle wise. I am positive on this: Downward body rotation helps me using the body weight on downsweep/catch to avoid putting stress on deltoids. This occurs pretty much in the same timeframe as I start the lawnmower (with the other arm).

RE: Swimming with your Body

dsyphers — Tue, 17 Nov 2009 11:16:04 GMT

Addendum: By the way, I believe this is why a 2-beat kick and a six-beat kick work, but a 4-beat kick doesn't work. When you rotate a shoulder down, you want the opposite leg to be kicking. On a 4-beat kick, if you left is kicking down when you drop your right shoulder, then it will also be your left that is kicking down when you drop your left shoulder. But the body's reaction to dropping your left shoulder is to pull your left leg up, thus reducing the power of your kick on half of your strokes. On both the 2-beat kick and the six-beat kick, your opposite leg will always be kicking when the opposite shoulder/arm is executing the roll/stroke. Even more, if you watch some powerful swimmers in slow motion you may notice a light asymmetry in the cadence of the kick, designed to give more emphasis to the kick that is in sync with the major part of the body roll. They are using the mechanical advantage caused by the torso roll for its maximum effect.

RE: Swimming with your Body

dsyphers — Tue, 17 Nov 2009 11:00:28 GMT

I hesitate to bring some physics into this discussion, but here goes (forgive me, please -- it's the occupational hazard of being a physics professor): I'm sorry to bring this up, as what you suggest for motion in the water might be appropriate, but the analogy with the person in space is not a good analogy. If a person is motionless in space, with nothing to push off of, not even air, then after any motion they make stops they are once again at rest. They can move the position of their torso by repositioning their arms, but it doesn't matter how they do it. No energy is transferred to forward motion because the interactions in the system (i.e. within you) are internal (with every internal muscular force action countered by an equal and opposite reaction force), and there are no external interactions (nothing to push off of). This means your momentum in this situation is conserved, so if you were at rest initially, you are at rest at the end. The same goes for putting rotations into your motion if you already happen to be moving (in space). You can't do it -- all you can do is twist your body. Every part of you that moves clockwise about your axis is countered by some part that moves counter-clockwise. Sorry to be such a wet blanket, but I think the point is that you need something to push off of. In swimming, you have to push/pull against the water, and the water is also responsible for the drag as you move through it. The key is to maximize the time averaged push/pull on the water, while minimizing the drag. Rotating the body may decrease the drag (without doing a study on it, I'm not clear whether this is the case), but it clearly can change both the mechanical position (and stabilization that you mention), and create additional forces applied to the water (whether these will help or hinder you depend on how you do the rotation). For instance, compare to what happens in space. In space, the rotation of your shoulders requires a counter-rotation of your legs (conservation of angular momentum - since the forces are all internal), so that there is no net rotation. So in the water, rotating your torso, and applying force against the water to do so, requires your legs to rotate in the other direction, but they run into the water. If this is properly timed with your kick, you get an extra propulsive force from the kick relative to what you would get without rotating your torso. When I have this working well I can feel it -- it feels like my kick is doing more. Further, how you rotate your torso, and what its position is relative to the turbulence created by your hand pulling through the water can also decrease (or increase) your drag, depending on how you do it. The problem with the pitcher analogy, which I've seen used many times by others, is that the pitcher is using gravity as well as the changing position of their body. In the pool, the buoyant forces basically remove almost all of gravity from the picture. To get a sense of what is needed, you have to think about what internal forces are generated in your body, and what that leads to in terms of how your body creates the external forces (forces on the water). The stabilizing force for the body's position comes from how a change in that position requires other parts of the body to change position (using the correct space analogy) and therefore "runs into" the water. If you use this correctly you can turn it to your advantage. Used incorrectly, it just slows you down. Gary does have it right though, that it is all about the trade-offs between drag and propulsion. Body rotation and the position of your arms definitely matters, as does how you time your kick to take advantage of it all. Making it work for you is what we each struggle with every practice. Happy swimming!

RE: Swimming with your Body

Bobinator — Tue, 17 Nov 2009 08:37:03 GMT

RE: Swimming with your Body

Former Member — Tue, 17 Nov 2009 08:15:21 GMT

The key is to maximize the time averaged push/pull on the water, while minimizing the drag. Thank goodness for water's inertia. We use it as a fulcrum to propel us ahead. So like a rocket in space, everything happens up front, and not in the back.

RE: Swimming with your Body

Former Member — Tue, 17 Nov 2009 06:36:02 GMT

Thank you for an excellent analysis. Just the kind of things I'd like to read and hear discussed now. I'm recently finding inertia is very important. I think that is also associated with momentum, especially at the beginning. I'm eagerly looking forward to your next topic, the inertia. By the way, all these, rotations, inertia, etc., will not work if there is not a good timing, right? Only a perfect timing of the movement of each part of the body can generate the wave that propel you forward without effort. I've been having more than enough frustrating experience with timing. Occasionally when I happened to have a great timing, the wave just carries me forward and it feels like flying. Unfortunately more often I struggle with the "wrong" waves, and it is very exhausting. :( Thanks again for the post.

RE: Swimming with your Body

__steve__ — Tue, 17 Nov 2009 01:04:53 GMT

Addendum: By the way, I believe this is why a 2-beat kick and a six-beat kick work, but a 4-beat kick doesn't work. The other night I was trying to visulize the 4-beat kick when I was trying to fall asleep. I was able to picture the 2 and 6-beat symetrically with perfect timing, but the 4-beat would only be symetric with each leg kicking twice at one point with a pause. Didn't rest too well that night.