Pull Swimming

Is Pull the right term for our arms in Swimming?

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Is Pull the right term for our arms in Swimming?

I was recently asked if using the term pull for the arm motion in Swimming is the right term. Another term that was suggested for the arm motion was the word leverage. Here is why I disagree with using the term leverage for a swimmer’s arm motion.

The word leverage implies the use of a lever. In most cases, we think of levers as something that increases the mechanical advantage- enabling us to use a small force to lift or move big objects, but they don’t always do that. 

The arm is definitely used as a lever in Swimming. In fact, it is a Class III lever. That means that the effort load (muscles moving the arm and hand through the water) and the resistance load (mainly applied to the swimmer’s hand) are located on the same side of the lever’s fulcrum (shoulder joint). 

With the arm, the distance between the fulcrum (shoulder joint) and the effort load (insertion of the muscles) is called the effort arm. The distance is very short, perhaps an inch or two, as the muscles moving the upper arm insert into the head of the humerus bone. The distance from the fulcrum (shoulder) to the resistance load, or hand, is called the load arm. That distance is much longer- more than 30 inches in adults. 

The mechanical advantage of a lever is defined by the ratio of the effort arm/load arm. In a swimmer’s arm, the mechanical advantage is around 1/30, significantly less than one. Unless the ratio is more than one, there is no mechanical advantage. We cannot move the insertion of the muscle on the arm, but we can move the hand closer to the fulcrum by bending the elbow (also a class III lever). While this would increase the arm’s mechanical advantage as a lever and reduce the torque on the shoulder, the ratio would still be considerably less than one. Even if one were to consider the entire wingspan of a swimmer, from one tip of the fingers to the other, as a single continuous lever (which is not true), with the fulcrum in the middle of the back (class I lever), the arms would still not provide a mechanical advantage greater than one.

A mechanical advantage of less than one means that the muscles moving the arm must contract with a greater force than the resistance caused by the hand and arm moving through the water (load). The advantage of a class III lever, and particularly one with a low mechanical advantage, is that it enables the arm to have a greater range of motion, allowing the swimmer to extend the hand from way above the head to the swimmer’s side, applying force all along the way.

One may wonder why, then, do we see Anthony Ervin winning the Olympic gold medal in the 50-meter freestyle using such a deep pull if using that technique reduces the mechanical advantage of the pull and adds torque to his shoulder joint? The biomechanics of a deeper pull engage the larger and stronger latissimus dorsi muscles and the pectoralis muscles more than the bent, high-elbow pull. While the mechanical advantage of a bent elbow pull may be greater, the biomechanical advantages of a deeper pull are favorable for greater propulsion. That deeper pulling motion also causes more frontal drag (mostly from the upper arm during the lift and front quadrant propulsion phases). For that reason, we don’t see the deep pull technique being used effectively in any event other than a short sprint.

Since the arm is a class III lever and offers the swimmer no mechanical advantage in the pulling motion, I don’t think we should use the term leverage to define this motion. We do not use our recovering arms’ kinetic energy to gain leverage or mechanical advantage for the pulling arm, but we do use it to gain propulsion. The kinetic energy of the recovering arm (and of the rotating body) of a swimmer does increase the effect of the effort load on the pulling arm, increasing propulsion. There is no propulsion generated from either the recovering arm nor from the rotating body. Still, because the body parts are all connected to each other, the energy from these two motions increases the pulling hand’s propulsion (and kicking feet) through a process called coupling. 

The problem is that very few coaches or swimmers really understand the concept of coupling. To get the message across and achieve the teaching goals, coaches are sometimes left with the option of using terms or analogies that, while may not be accurate, still get the job done. For example, at The Race Club, we use the analogy of Octane levels to describe the amount of elbow bend on the arm recovery. A fuel additive used for cars has nothing to do with the human body, but if it makes sense to our swimmers and parents and improves technique, it is a good thing. If using the word leverage, or anchoring, or holding water, or vaulting helps improve the swimmer’s technique and leads to a faster swim, then I am all for it, accurate or not. In order to be good coaches, we need to communicate in a way that swimmers will understand.

Finally, I can understand why the term pull may be misleading. Pull implies that a force is being applied toward the swimmer’s body. Push implies that the force is being applied away from the swimmer’s body. As the hand begins the pulling motion, it moves toward the swimmer’s body (as the body moves forward). Once it reaches the shoulder, the hand is moving backward or away from the swimmer’s body. Technically, the first part of the arm motion might be considered a pull, and the end of the motion considered a push

While I do hear many coaches describe the end of the pull as a push out the back, if we have to pick one word to describe a swimmer’s arm’s motion, I am not ready to throw out the term pull yet.

Yours in Swimming,

Gary Sr.

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Responses

  1. Great article Gary! In response to the third to last paragraph, I was wondering if you could publish an aqua note where you discuss the origin of coupling motions based on Newton’s laws. When I first heard about coupling from The Race Club I was in high school going through physics and I recall working through the free-body diagrams and how they show that coupling works. I think it would be really valuable for a lot of people, and I personally would be interested to see how you all describe the phenomenon.

    1. Great question, Tolik. When discussing the coupling phenomenon with physics experts, they agreed that these motions were profound and influential in swimming, as well as in most other sports. In reviewing the literature, I could not find any reference to them specifically by name ….so we named them coupling motions. If you are aware of some other name for them, please let me know, but I could not find one. Diagrams would probably help, but I find that many people still have a hard time understanding how the kinetic energy from moving one part of the body can positively impact another part of the body, even though the parts are all connected.