Why we should rotate our bodies in freestyle and backstroke

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.

Core Strength

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.

Gary Hall, Sr., Technical Director and Head Coach of The Race Club (courtesy of TRC)

Gary Hall, Sr., Technical Director and Head Coach of The Race Club (courtesy of TRC)

Yours in swimming,

Gary Hall Sr.

https://www.linkedin.com/pub/gary-hall/9/908/671 [email protected]  
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23 Comments on "Why we should rotate our bodies in freestyle and backstroke"

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Don’t confuse body, linear drag with frontal drag. Frontal drag is only a function of the cross-sectional area of the body in motion. The frontal drag would be basically the projected area of your head, shoulders, and torso.

Frontal drag refers to the total of all drag forces of a body moving forward in a medium. The equation typically refers to a singularly shaped object moving through a single medium with an appropriate Reynold’s number and involves frontal surface area, surface friction and the form (pressure) drag, as well as the velocity of the moving object. However, since swimming occurs at the interface of two media, air and water, a third drag force is introduced which is surface or wave drag. All three types of drag play a significant part in slowing a swimmer down.

>”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.”

Maybe *on the surface of the water* our form drag is the same either way, but our wave drag is greater when we’re flat than when we’re on our side (with one shoulder submerged). Underwater kicking on one’s side wouldn’t yield this advantage, since the whole frontal profile is underwater in that case. That could explain why it’s faster to be on your side on the surface but not underwater.

Dr. Hall’s explanation here is outstanding. I think back on Janet Evan’s stroke and remember how many people, including Bud and Mark, two of her coaches, tried to force her into a traditional high elbow recovery. For her, and for a number of my own swimmers, the forces, in biomechanical terms (though I love the concept Gary poses here of “coupling) is summation of forces. Janet was able to use her recovery motions to enhance her power on the water. This isn’t as easy as it looks from the top. The timing and the catch on the water has to be perfect. People at the ICAR were surprised how efficient her stoke measured in the flume. Most people who try… Read more »

Great additional material to this, Steve. Thank you!

Mark Cianciolo

Thank you for the great explanation of the kick and the pull. I have thought that this was key, as I have always known the kick itself was key to this rotation. Until you see it on the bench, you do not get the perfect visual of your words.

I cannot stress enough the importance of kicking the coaches sets in practice. I have personal experience with a pull loaded swimmer……..and every day, I just wonder…….what if the kick was engaged.

I thought the reason we rotated our bodies was so we didn’t have to bend our arms backwards (a very unnatural position) on each recovery which we would have to do if we swam completely flat

About Gold Medal Mel Stewart

Gold Medal Mel Stewart

MEL STEWART Jr., aka Gold Medal Mel, won three Olympic medals at the 1992 Olympic Games. Mel's best event was the 200 butterfly. He is a former World, American, and NCAA Record holder in the 200 butterfly. As a writer/producer and sports columnist, Mel has contributed to Yahoo Sports, Universal Sports, …

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