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Shapes and Skills Part I

In swimming, we have technical models that we tend to apply to our swimmers. In any swimming book, there are intricate descriptions about joint positions and angles, hand pitches and muscle activation patterns. While the concepts described are generally appropriate, I wonder if they’re being too rigidly applied to the swimmers we coach.

Some observations.

Ever notice how two siblings typically have very similar strokes? They recover their arms the same way, they ride through the water the same way, their stroke rhythm is the same, and more. While you could argue that they swim for the same club, the other swimmers on the club don’t necessarily look anything like the siblings. Why does this happen?

Ever notice how two siblings move similarly on land? They walk the same and they sit the same. I’ve worked with two brothers, about 4 years apart, one about 4 inches taller than the other. The first time I saw either of them do a pull-up, with no instruction from myself, they both assumed the same grip and pulled themselves to the bar in exactly the same way. Same rhythm, same posture, same everything. Why does this happen?

My idea (which is not particularly original)-

The way swimmers swim is dictated by their innate physical structure, the range of motion and strength of each of their joints, as well as the in-born preferences of their nervous system to organize movement.

I believe that these factors are AS influential if not MORE influential than learning experiences swimmers are exposed to over the course of their development.

For swimmers with very similar styles, their bones are about the same length and shape. You can usually see this. For the most part, their muscle bellies are usually about the same length and attach around the place in the joint. While you might not be able to really see this, you can tell that the muscles are ‘shaped’ differently. I’m sure you’ve heard coaches talk about looking for ‘long, lean muscles’ or ‘she’s built like a swimmer’. As opposed to what happens during training, these characteristics are as much a factor of muscular and skeletal structure than anything else. Some individuals are just built to swim.

Beyond the physical and the structural, there is a nervous system component. Individuals are born with innate preferences as to how they move. Don’t believe me? Which hand do you write with? At what age did you consciously choose to use that hand after much deliberation? You didn’t. One hand was just more natural. While this is the most obvious manifestation of this phenomenon, it likely exists at more subtle levels as well, and these differences show up in how we swim.

When considered from a constraints-led approach, we know that effective movement options can be limited by the environment, the task, and the individual. Our environment is set in the water and the tasks are defined by the rules of the competition style and the physical demands of the race distances. We’re comfortable exploring how skills can be improved within the confines of the rules.

However, we often fail to appreciate how our movement options are dictated by our structures and the physical capabilities. Some swimmers do not have access to certain ways of moving, either temporarily or permanently. This will absolutely affect how swimmers interpret any learning experience in the pool. Two individuals will receive the same experience and begin to move in very different ways.

Consider two young men. One has size 18 feet with loose ankles and the other has size 8 feet with rigid ankles. My guess is that these two individuals are going to swim very differently even if everything else is the same. And you can be sure that nothing else is the same either! Asking one swimmer to swim like the other is going to seriously limit one of these two swimmers.

How often are we asking swimmers to perform movements and learn skills they simply lack the physical ability to perform?

Some individuals cannot bench press 300 pounds because they lack the physical strength and structure to move the resistance. It is NOT a technical problem. Some individuals lack the muscle extensibility or the motor skill to touch their toes. It is NOT a ‘technique’ issue. However, physical and movement training can allow these tasks to be achieved in both cases. Without the training, it’s not going to happen.

The important point to grasp is that some swimmers simply cannot move in the desired manner because their physical structure does not permit it to happen. As coaches, we need to decide if these restrictions are permanent. If they are permanent, how can we work around them? If they are impermanent, how can we change them? As importantly, SHOULD we change them? Is it worth it?

An Issue of Permanence

Some aspects of structure can be modified, and some cannot.

With all of the physical characteristics described below, the point is NOT to necessarily assess any of these attributes. In many cases, you can’t assess them without X-rays and other medical images. Regardless, it’s not necessary. The point is not to evaluate, but to appreciate. By understanding that there are real and unchangeable limits to how individuals move, we can become wiser as to how we expect individual swimmers to move, knowing that these real limitations exist.

The Permanent

Some physical characteristics are innate and unmodifiable. They aren’t going to change without some pretty crazy surgeries. These permanent aspects are all structural in nature.

Bone length and shape. The length of swimmer’s bones and the manner in which they are shaped will both determine movement possibilities. Someone with a very large, round rib cage is going to move through the water differently than a swimmer with a flat and narrow rib cage. This can’t be changed. A swimmer with very long arm bones is going to need a different arm recovery strategy than a swimmer with very short arm bones. These same swimmers will require different combinations of stroke frequency and stroke length to be successful. Expecting swimmers to change to fit a model is not going to be effective.

Flotation potential. How swimmers float will influence how they move through the water, and the movement options they have as a result. The less work an individual has to perform to float effectively, the more work they can perform to create propulsion.

While the capacity of the lungs to hold air is somewhat modifiable, the shape of these organs is somewhat constrained. As importantly, the location of the lungs will dictate where the center of flotation will reside in the body. This is a factor that can’t be changed and will have a significant impact on how a swimmer floats.

The ability to float is also determined by the density of the bones. Bone density is influenced by gravitational experience and nutrition. A lot of strength training is going to increase bone mineral density. A total lack of any athletic experience outside of the pool through the lifespan is going to limit bone mineral density. For those who have only swam, this may be the case. Those with poor nutrition due to insufficient energy or calcium may also have reduced bone mineral density. Bone mineral density is also going to be influenced by genetics.

While it may seem like a good thing to have light bones, there are a lot of problems that can come with it. As we’ll see below, the strategies that can effectively reduce bone mineral density are not exactly health or performance enhancing.

Flotation is also dictated by the amount and distribution of bodyfat. More bodyfat will tend to increase flotation and a bodyfat distribution that is centered around the hips will tend to aid in flotation. For both of these reasons, women tend to float better than men. Bodyfat distribution is largely determined by genetics and almost impossible to manipulate.

Bodyfat amount is influenced by genetics, although highly modifiable by diet. While any individual can greatly reduce their bodyfat, it comes at a much greater cost to some than others. At some point, the body will ‘fight back’ when bodyfat gets too low, or the caloric deficit required to lose body fat becomes too extreme to sustain training. In this respect, genetics become a limiting factor. Some will be able to achieve and maintain a lower bodyfat percentage than others. Expecting all swimmers to achieve a similar body composition is unrealistic.

Joint structure. Joints occur when two bones meet. The ends of bones are ‘shaped’ to ‘fit’ with each other so that they can articulate, or move, effectively. The size and shape of these articulating surfaces is going to determine how freely the joints move. This will differ between individuals. Beyond bone shapes, the laxity of the ligaments involved, where ligaments attach, and the shape of cartilage tissues can also affect joint structure and thus movement potential.

Relative to other individuals, a given joint may allow for more stability in one person and more mobility in another. Both situations can be both advantageous and disadvantageous. A relatively more mobile joint can allow for more movement options while exposing a swimmer to greater injury risk due to a lack of control. A more stabile joint will limit movement options while allowing for greater control. To be successful in the pool, we need both. While mobility and control are both trainable to some extent, the relative starting points and ending points are limited by the joint structure.

Muscle attachments. Where muscles attach in a joint will influence the contractile properties of muscles. Muscles and bones work as lever systems that create torque. Torque is influence by the force the muscle creates and the length of the lever arm. Where muscles attach on the bone will affect both the length of the lever arm and the direction of the line of pull on the bone. TINY changes in the attachment points will influence the function of a joint.

A small change in the lever arm can create a major difference in how strong or how fast the joint action is for the same magnitude of muscular contraction. As importantly the direction of the torque, and thus the action of the limb, will also be altered with changes in attachment sites. These are innate characteristics of the musculoskeletal system that aren’t going to change. However, they influence how a swimmer will move.

While the attachments sites for a muscle such as the biceps are relatively straightforward as it is a simple muscle with singular origin and insertions, this is not the case for other muscles. There is not going to be that much variability. Take for instance, the pectoralis and latissimus muscles. They have very broad origin and insertion points. This means there is likely a lot more variability in how and where these muscles attach, implying more variability in movement options and how force is created. These two muscles just so happen to be the primary creators of propulsive force in swimming. This has obvious implications for how swimmers move through the water.


What we’ve cover so far, paints a pretty grim picture about movement options and skill acquisition. The main idea is not that skills can’t change, or that swimmers are destined to swim in a particular manner. It’s more about having respect for innate differences, and approaching skill interventions with a little modesty and caution.

Always ask, ‘do I REALLY want to change that?’.

However, there is hope. Range of motion, the ability to float can, force production, and resistance to fatigue can all be improved with consistent training. These improvements can enhance the ability for all of our swimmers to express their skills.

Part II will examine how these factors can be influenced, and what changes we can expect to occur. Rest assured, the ability to display skill can be improved significantly with targeted training.

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