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Technical Foundations Part II

In part I, I laid out the case for an understanding of the foundations of effective swimming. The foundational tasks for swimming fast are reducing drag, creating propulsion, and moving with rhythm. In this section, we’ll explore how swimmers create propulsion, as well as the factors that influence the effectiveness and magnitude of propulsion.


Creating Propulsion


Relatively speaking, the forces created during swimming strokes are not that large, at least compared to what we see in ground-based sports. While some of this is due to the musculature involved (upper versus lower body dominant), a gap is still present. When looking to the upper extremity forces required to successfully compete in gymnastics, we realize that what is required of swimmers is not particularly impressive.


In contrast, HOW forces are applied is critically important. Better swimmers are better able to effectively apply force to the water in a manner that moves the body forward. Force must be applied in a manner that results in forward progression, otherwise it is simply wasted effort. Some less skilled swimmers may very well be able to create MORE force than much more skilled swimmers. However, those forces are not oriented effectively and do not contribute to forward motion, just fatigue.


Force Application


Force application is about managing how the forces are directed, the consistency of these forces, as well as the duration that these forces are applied. Forces should be directed in a manner that facilitates forward motion. While this seems to indicate backward limb motions, this doesn’t seem to be entirely true based upon watching elite swimmers, an understanding of joint mechanics, as well as research evidence. Swimmers should strive to move water backwards, although this will likely not entail a linear hand path.


Beyond the direction of force application, the duration of effective application is important. All swimmers orient forces correctly at some point in the stroke cycle. However, better swimmers are able to orient forces correctly for a greater period of time. They start effective force application earlier in the stroke cycle by getting into appropriate positions right away, and they are able to sustain these positions for a longer period of time.


The consistency of force application is also important. Swimmers often exhibit ‘force gaps’ during transitions in their strokes where force production drops. While this can occasionally be useful to set up better force production later in the stroke, it’s often a lost opportunity that will result in a temporary loss in velocity. Once force application begins, swimmers should strive to maintain stroke patterns that allow for force to be maintained throughout the pulling pattern.


While there is certainly a skill to force application, each swimmer is limited by the capabilities of their musculoskeletal system. Anatomical structure does contribute to the ability to swim fast. Taller individuals tend to have longer arms. Longer arms tend to be more effective levers. Wider shoulders also create better leverage. Bigger hands and longer forearms also create bigger propulsive surface areas for better force application. Anatomy matters. Unfortunately, there’s not much that can be done to alter limbs lengths, so there’s not much sense in worrying about it. It just is what it is.


Beyond the lengths of our bones, our ability to manipulate those bones without restriction also influences force application. The mobility of our joints affects the ability to get into the positions that best facilitate propulsion. All coaches are familiar with the value of having flexible ankles. Individuals with this trait just kick faster. They are better able to apply force, not so much due to skill, but do to the possibilities afforded to them by their mobility. The same concept applies to upper body force application.


While anatomy is fixed, we do have more control over the mobility of joints. When range of motion is restricted due to the muscular system, we can effect change over time. Effective range of motion can improve to a significant degree with the appropriate targeted training over time. However, range of motion is also limited by joint structure and the relative stiffness and attachment sites of ligaments in the joint. This is probably an area that coaches don’t want to mess with, as the potential for injury is real.

All of these physical attributes are critical, yet they are not related to training outputs. They are part of an advantaged mechanical system that contributes to more effective force application.


Force Magnitude


Assuming forces are being applied effectively, larger forces will create more propulsion. For those individuals who do not apply forces particularly well, they can make up for this discrepancy by creating larger forces. When looking at the best swimmers, relatively large forces are applied effectively. They have great application and they produce a lot of force relative to the demands of their event (the 50 requires a lot more than the 1500!).


Creating large forces is dictated by the surface area that is used to create propulsion and the strength of muscles involved. The more surface area that is used to create propulsion, the more potential there is for force creation.


Anyone that has used paddles or fins, especially paired with extra resistance, is aware that bigger forces can be created with more surface area. You can feel the extra work done by the muscles. Force production will be limited by surface area, and even if a swimmer is ‘strong’, they may not be able to apply large forces if they do not create a large enough surface area.


Creating a large surface area is a skill that is limited by anatomy. Skilled swimmers can manipulate the hand and forearm to create more surface area. However, bone size matters as well. To some extent, force magnitude will be dictated by anatomy, as larger hands, forearms, and feet all provide a better foundation with which force can be generated against the water.


Assuming a large surface area can be created, swimmers must also possess the muscular strength to take advantage of that potential leverage. While some individuals possess more strength innately, strength is also highly trainable, as is the development of muscular size.


While there are challenges in measuring forces in the pool, the level of force required for fast swimming do not seem to be that high, especially relative to other sports. Anecdotally, we are all aware of fast swimmers who are VERY weak. While this may not be the case at the highest level of sprinting, most swimmers should be capable of attaining the necessary strength. If the muscles don’t have the strength capacity, doesn’t matter. It can be trained.


There is also a skill component to creating high levels of force. Force tends to increase over the course of the stroke cycle, and patient application of force in the beginning of the stroke can often yield higher forces later in the stroke cycle. If swimmers are impatient and create too much force too soon, they may end up ‘losing their hold’ on the water that is required to create force in the force place.




Creating moving forward requires propulsion and propulsion requires force. Better swimmers apply force more effectively and they have the ability to apply more total effective force. They may apply higher forces, apply forces more consistently, apply forces for longer, or all of the above. Most importantly, they apply forces in the right direction.


As with minimizing drag, the ability to accomplish these tasks is a combination of innate physical characteristics, trainable physical characteristics, and the skill use of these traits. While coaches can’t change a swimmer’s skeleton, they can influence mobility, strength, and power, as well as help swimmers harness these abilities. In an upcoming article, we’ll take a look at the strategies to effectively develop these skills.


While it’s easy to get caught up in technical nuances of pitch angles, joint positions, and other details, it’s valuable to take a step back and appreciate what matters at a fundamental level. Simply, swimmers need to move water large amounts of backwards as directly as possible as long as possible with as much force as possible. This is how they create propulsion. All of the details emerge from this requirement. This allows us a lot more freedom in our coaching and training prescription.


Next up, we’ll take a look at the underappreciated importance of rhythm and timing.




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