There are three physical properties that govern all swimming technique. They are all important, complex and different. They are the properties of drag, motion and inertia. Of the three, the properties of drag are the most significant in terms of helping or hindering our speed. What about the properties of motion. In other words, what can we do with our bodies while swimming to aid our forward progress? Or can we do anything?
Imagine you are in space floating around and you spot a touch pad floating out there with you. How fast can you get to the touch pad? Or better question, how do you get there? You have nothing to push off of or pull against...just you in space.
You would figure out what worked in a hurry. One way would be to use your long arms as a lever and your shoulder as a fulcrum. Accelerating them into a wide circle swing then stopping (decelerating) them as quickly as possible in the direction of the touch pad. The further you could get the weight away from your body, the faster you could swing them and the faster you could stop the swing, the more energy would be transfered into forward motion.
Another way you might help yourself get there is that once you had established some motion toward the touch pad (say with your head pointing first and feet last), you would find that a sudden quick rotation and then a counter rotation, along the axis of your body, could also accelerate your motion forward, just as a bullet spins down the gun barrel.
Both of these motions help very good swimmers swim faster. The quick acceleration of the arm recovery (some today with a straight arm) and sudden deceleration of the arm as it hits the water, transfers energy to the forward motion. So does a quick rotation of the body.
There are two other compelling reasons why one should rotate the body to swim faster. The second is to put all of the muscles used in the arm pull into a more favorable mechanical position (stronger) and the third (and I believe strongest) reason has to do with stabilizing forces.
If a baseball pitcher can throw a ball at 90 mph from the pitching mound, the same pitcher would throw the ball at about 45 mph from the deep end of a swimming pool. The difference is that he doesn't have a stable pitching mound to push off of, so he loses half of his velocity. It is easy to visualize where our power comes from the start (pushing against the starting block) or the turn (pushing against the wall), but what creates the stabilizing force when we are out swimming in the middle of the pool? What are we pulling against? The answer is the counter-rotation of our bodies and principally our core (hips and abdomen). We initiate our catch with the right hand at the very same moment that we begin to rotate our hips to the right (counter clockwise). That rotation continues until our left hand enters the water and we begin the counter-rotation to the left (clockwise). We repeat this motion over and over again. The quicker and longer we can make each hip rotation, the stronger the force we will generate in order to pull against. In other words, we create our own stabilizing force with motion from our own body to gain more power from the pull. It works.
Swimming flat, like a surfboard that grew arms and legs, is a much easier way to swim. It takes less energy....and if you were swimming across the Atlantic ocean, it would likely be the best technique to use. I call it the survival stroke...because it is the stroke we all tend to use when surviving 10 x 400 freestyles on 6 mins. Its just that with the survival stroke you can throw the ball at only 45 mph instead of 90 mph. If you want to swim fast, you'd better learn to swim with your body.
So our goals as swimmers in order to get fast are: 1) minimize the drag forces 2) learn how to swim with our bodies effectively and 3) take advantage of inertia.
Just remember, in swimming, little changes make big differences. At The Race Club, we focus on the little changes. And sometimes, the not-so-little changes.
Next, I will talk about inertia; what it is and how we try to use it. I call it 'swimming on the freeway'
Yours in swimming,
Gary Sr.
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.
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.
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.
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 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!
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.
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).
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.
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
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!
