why swim symmetrical

Some weeks ago I had an email discussion with my TI Coach colleague Bernardo Blanco in Spain. We were discussing the asymmetry observed in certain elite swimmers, and whether we should imitate this asymmetry or practice a symmetrical stroke. Coach Bernardo was going so far as to take video clips of various swimmers and measure, in hundredths of seconds, the time difference between the left side stroke to the right side stroke. Some were fairly even and some were significantly longer on one side. Bernardo is an engineer after all, and I loved his style of examining the topic.

Here is an example of the Assymetrical Stroke Timing for Michael Phelps that Coach Bernardo made.


The natural question:

Is an asymmetric stroke a good thing to imitate or not?

First, let’s ask some critical-thinking questions about asymmetrical strokes:

  1. Does the swimmer have that asymmetry in all swimming distances or does it become more prevalent at certain distances or intensities (sprints versus long)?
  2. Are just some of the elites showing these prominent asymmetries or most of them?
  3. Among those who have asymmetry what are the common characteristics or patterns we see in them?
  4. Why are these asymmetries present in these particular elite swimmers and not in others? And why only in certain events? Or only at certain intensity levels?
  5. Are these asymmetries a sign of good technique or a compensation for some technique deficiency elsewhere in the stroke?

Is Asymmetry Beneficial?

Short answer: It might be for Phelps, but I highly doubt it is necessary or beneficial for you.

Before jumping on the bandwagon of imitating the new stroke fad from an elite, I suggest that we master solid fundamental skills first. Physics will permit no shortcuts to speed.

Bernardo wrote: Despite the fact that I heard Bob Bowman (Phelps’ trainer) saying that breathing more often allowed Michael stay in more streamlined position longer, in this video he seems to lengthen his non-breathing stroke and I think his non-breathing stroke, like the rest of humans, is gliding and more streamlined.

mp br example

We can analyze features of Michael Phelps’ particular asymmetry but that does not tell us whether it is was actually productive for him or not. It is possible that an improvement in some other part of his stroke might eliminate the need for that asymmetry. We can only speculate about what Phelps is doing and why, in the races where that stroke is present.

It is possible that at the pace and tempo Phelps required in his winning sprints he must get in an extreme amount of air exchange within the constraints of his stroke tempo. The only way to get enough inhale time is to extend the stroke on that one side with a 2 stroke breathing pattern. But arguably he is working at a far higher intensity level and consuming far more oxygen than than everyday athletes. Imitating Phelps ‘technique’ under conditions unlike those he using it for could be a foolish thing to do.

Side note: Some time ago I made the argument that a swimmer should first learn to swim ‘slow’ like Phelps (how he swims when he swims at your speed) before trying to swim ‘fast’ like Phelps. I think there is a reason his stroke looks different at your speed than it does at his WR speed. I recommend that a swimmer discover that reason first and work his way up Phelps’ speed curve rather than try to jump to the top of it.

Should we work on a symmetrical stroke?

Bernardo: As TI swimmers do we have to work to equalize both side of the stroke and both kinds of strokes (breathing and non-breathing) despite the difficulty to achieve it? ( I think we do).

Short answer: Yes. I too think it is so clear that we should work on building a consistent symmetrical stroke. Our bodies will hold up the best, over intense efforts, and over many years when we load our bodies symmetrically. Breathing too can be mastered to where it is hardly any different from the non-breathing stroke.

Consider Sun Yang- the fastest human in the world at 1500 meters. He is stunningly fast, but there is obvious room to improve even more. (Is there any flawless champion?) He must breathe, and he does that to only one side, and his body contorts a great deal on that breathing stroke breaking the streamline he enjoys on the others.  As with Phelps, the demand for oxygen within the stroke tempo constraints may force this 2 stroke breathing pattern – his breathing pattern is not being challenged in this article, the fact of so much difference between non-breathing and breathing stroke control is being challenged.


You should notice in the video clip that as he breathes only to one side, he tilts his head higher than necessary while breathing (only the lips need to touch the air, not the eyes!) and scoops the opposite hand upward while he does it, sometimes even scraping the surface with his fingers.

sy br moment

Those two small details cause excessive drag and could be corrected, freeing up a few more drops of energy per stroke, without touching his stroke length or tempo. Those improvements would require an increase in his awareness during training to improve precision without requiring an increase in his exertion. Those are obvious drag-inducers, but he gets away with it. Why? Probably because his opponents have even more costly flaws. No one is perfect – but that shouldn’t stop the best from striving for it. He can be sure one of his opponents will.

There are major advantages to maintaining symmetry of movement , to evenly loading and developing the body, and minimizing variations between the sides and the breathing/non-breathing strokes.

Let’s name a few:

  • Evenly divided power generation in the body
  • Even loading on the joints
  • Straighter swimming
  • Smoother acceleration/deceleration curve (less drag differentiation)
  • More consistent balance and stability
  • Smoother transfer of power through the body

There may be a case for asymmetry once a human tries to accomplish something that is above what the human body is normally designed to do.  But these are not sustainable patterns.  We may be forced into asymmetry under extreme, short term conditions, or because of structural deformation – but it is easy to understand that asymmetry movement patterns produce uneven loading, uneven wear and increased risk of injury over longer distance, or under more intense repetitive physical forces.

Symmetry of movement for humans  is well supported by our observations in nature.  We can easily make the case that humans are designed for long-distance endeavors (example: Born To Run) and symmetry is a friend of long-distance. Can you imagine running a marathon with a gallop, or asymmetric stride? We know that gravity will punish this runner. Water is punishing an asymmetrical stroke also, but we’re just not feeling the consequences in the same way.

Is there a time to use asymmetrical stroke then?

Short answer: ask that question once you’ve mastered the fundamentals and squeezed every benefit you can get out of them. That approach won’t let you down.

If the (young) swimmer is looking to win the Olympics (within his very short, and very intense training career) then he may feel compelled to push his body into an imbalanced movement pattern to get an edge in an extremely competitive arena. This is the zone of risk in elite competition where many athletes will impose all sorts of questionable patterns on their bodies to look for a competitive edge. And how many get injured doing it? Too many, but that is the risk these athletes choose to make.  (This would lead us to discuss the responsibility coaches have for perpetuating an injurious culture in swimming).

I would like to say that only the elite of the elite wander into this zone of risk because they have absolutely tapped out all the benefits they can get from the fundamentals, and yet still need more to win the biggest races. But it is not so. It is easy to find fundamental flaws in the swimmers of an elite event; they could all find room for improvement in technique. Example: consider how many look forward out of habit, tradition, or ignorance, when a swimmer can prove in a 20 second test  that looking forward adds considerable more drag to the body profile.

Those irregularities and asymmetries always catch our interest on the video clip but it is very very hard to prove (with rigorous testing instead of speculation) that they actually contribute to success rather than work against it. I argue that there is likely an overwhelming accumulation of advantages in that successful swimmer which compensate for the idiosyncratic liabilities we see in their stroke. We have to employ a bit more critical thinking to sort out which might be which when seen in a video clip. But swimming with a symmetrical stroke is a safe way to avoid the risks of those unaccountable techniques.

The swimmer seeking a ‘lifestyle of swimming’ will do well to avoid an asymmetrical stroke because of what it will do to his body over the course of a lifetime of repetition, or even over the course of a long, demanding swim. Too few people are lucky enough in their genetics to get away with asymmetry without injury. Not to mention a lop-sided swimmer is far more vulnerability in open water – he will suffer when wild water and weather does not respect the side he favors.

Symmetry is one of those universal characteristics – or principles, really – that we would be very wise to respect unless we have a very good, short-term reason to violate it. Phelps may have had a good reason to risk violating it at his level. I do not have a good reason to violate it, and none of my swimmers and athletes have a good reason to violate it either, until they have squeezed all the benefits possible out of the solid, universally-applicable fundamental swimming skills: balance, streamline, synchronized propulsion.

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