Courtesy of Gary Hall Sr., 10-time World Record Holder, 3-time Olympian, 1976 Olympic Games US Flagbearer and The Race Club co-founder.
All of the elite swimmers of the world rotate their bodies along the long axis, the axis that their body is moving down the pool, while swimming freestyle and backstroke. They don’t just rotate a little bit. They rotate a lot. The question is, why?
Frontal Drag – Does It Matter
It is commonly believed by both coaches and swimmers that the reason for rotating the body is to reduce frontal drag; that the body has a lower drag coefficient on its side than it does on its stomach. Although I am all for reducing frontal drag, I do not believe that this is the reason that we rotate. I do not believe that the drag coefficient of the human body is significantly different in the water on its side than it is on its stomach. If it were, we would be kicking faster times on our sides…but we don’t.
The truth is that it takes a lot of core strength and work to rotate our bodies from one side to the other while moving down the pool. So if it is not to reduce drag, why then? I believe that there are two compelling reasons why we rotate our bodies on these two strokes. The first reason is a biomechanical one and the second is related to laws of motion or propulsion.
Laws of Motion or Propulsion
If I were to pin your shoulders to the wall in the gym and bring the pulley machine over, you could pull a certain amount of weight downward, using essentially the same pulling motion as you would in the water. If I unpinned your shoulders and allowed you to rotate your body inward toward the pulley machine and you duplicated that same pulling motion with the same elbow bend, I can guarantee that you will be able to pull more weight downward. The reason is that when you rotate in, your big back muscles, particularly the latissimus dorsi muscle, gets into the act. When your shoulders were pinned, that big muscle was sitting on the sidelines, unable to offer much help. By rotating our bodies in the water, we gain a biomechanical advantage of power on the pull.
Coupling – What Is It
The second reason we rotate our bodies is a little harder to understand, but it is just as important as the first. I call this second phenomenon coupling. The act of rotating our bodies from one side to the other has zero direct propulsive effect on our motion down the pool. Yet when this motion, which creates energy of its own, is coupled with the propulsive force generated by our pulling arm/hand, the two forces occurring together result in a stronger pulling force than if we were simply pulling alone, without the rotation. One can consider the relationship of these two motions synergistic.
The Coupling Effect
A good example of this coupling effect, and one that is easier to visualize, occurs with relay take-offs. With the correct start, the arms are swinging fast in reverse direction at full length at the precise moment we push off the starting block with our feet. The swinging of the arms alone has no effect of getting us off the block or down the pool, but when coupled this motion with the push off the block, it helps make the push more forceful, resulting in a better start than if we did not swing the arms.
Body Rotation – One Of The Coupling Motions
Body rotation is one of the coupling motions we use in swimming (arm recovery is another) in order to go faster. The bigger we are (more mass) and the faster we can rotate, the more energy we create to couple with the pull, and the faster we swim. When you add the biomechanical advantage that we gain from the rotation, those are two pretty important reasons to make the extra effort to rotate the body. At The Race Club we spend a lot of time teaching swimmers how to rotate the body effectively in freestyle and backstroke.
Yours in swimming,
Gary Hall Sr.
https://www.linkedin.com/pub/gary-hall/9/908/671 [email protected]
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