# The Science of Coupling

Recently, a physicist here in Florida informed me that I didn’t quite have the physics right in some of my explanations. In one of my recent blogs on the various energy systems of the body swimming down the pool, for example, he stated that the only forces that can really move the swimmer are external forces. In the case of the swimmer that means the foot or hand pushing back on the water, the starting block or the wall. Other energy systems, like the arms swinging through the recovery phase, might transform some energy into the water at the collision, but cannot, by themselves, move the body down the pool. He is right.

The paradox is that we don’t get to isolate any of these energy systems, the arm recovery, the body rotation or the head snapping down. They are all connected to the body and therefore, the action of one ‘system’ influences the others. We call this coupling. Some coaches refer to it as the connection.

A great example of coupling occurs while doing relay take-offs. Any swimmer who has practiced this enough knows that when it comes time to step forward for the take-off, by swinging the arms in a circle backward at the appropriate time, such that the bottom arc of the arm swing occurs simultaneously to the push of the feet off the block, a much better dive results, with more power and more distance. Yet if the athlete were to only swing the arms without any force coming from the feet against the block, there would be no forward motion gained. The swimmer would go nowhere.

The same would be true of the arm swing on the freestyle recovery. The swing of the arm by itself contributes nothing to the forward motion of the swimmer. Yet when coupled with the external forces created by the hands and feet, it becomes important and results in a stronger pull, in more distance per stroke. The same is true when the freestyle pull is coupled with the body’s counter-rotation or in the butterfly, when the entry of the hands from the straight-armed swinging recovery coincides precisely with the second hard down kick of the feet.

Exactly where the power comes from in these complex, coupled motions is not simple. A golfer that couples the arm swing with the correct body rotation ends up with a much longer drive than one that doesn’t. The same is true for a baseball player. Whether this additional power from coupling motions for the swimmer comes from an increased acceleration from the hand moving backward, a change in flow dynamics at the end of the pull that augments the force of the hand, or from the creation of angular body energy that somehow serves as a counter-force to pull against, or all of the above, doesn’t really matter. So long that we recognize that it works.

The challenge is that all of these energy systems when put into coupling mode require a lot of work. It is much easier and simpler to not use them and swim slowly. But then again, if you want to win, that may not be such a good idea. After all, no one said swimming fast was easy.

Yours in swimming,

Gary Sr.

### 7 Responses to The Science of Coupling

1. Timothy Allen

Gary, there was a great swimming coach back in “our” day named Charles Silvia from Springfield College. He operated a camp called PKSS (Pine Knoll Swim School.He and Indiana U’s “Doc” Counsilman had the podium in stroke mechanics…Im sure you know this but….Silvia had a term for this “coupling” in that he called it “Unit Movement” which included proper long axis rotation, breathing w head drive and hand drive together as well as a “kick explosion” at the same point forward “unit movement”. Its v interesting but if you watch video of M Phelps you can see this whole scenario in action. Coaches started the Phelps drills and Its questionable if Mr Phelps even understands what he is naturally doing or even the coaches adding the drill but it has been
successful.Enjoy reading your posts Gary….I swam at the Y nationals a few years ago and was able to swim with John Kinsella, as we are old now lol, but he was my idol back in the day….cheers! TA

2. Tom Fritschen

Dear Mr. Hall,