Is there still a bilateral breathing debate for competitive swimming? A review of the literature and an experiment!

Since my career as a professional triathlete seems to generate a good deal more bills than it pays, I am committed to keeping my day job.  My day job is Information Literacy Librarian at Illinois Wesleyan University. At the most basic level I am tasked with teaching college students how to find, evaluate, interpret, and synthesize information. In this day and age, the finding bit is cake, while evaluating, interpreting and synthesizing are incredibly difficult.

What does all this library gibberish have to do with bilateral breathing for competitive swimming? Quite a lot, actually.  Anytime there is significant disagreement on any topic within a community everyone should fall back on reliable evidence over opinion and plain old b.s. Is global warming a thing we should be concerned about? The preponderance of good evidence says yes. Should I vaccinate my kid? Yes, for god's sake, yes. Should I bilateral breathe when racing a distance swimming event or triathlon? This question has been debated ad nauseam on blogs just like this one. Blogging and internet forums provide a huge worldwide platform for misinformation. The way to cut through all the garbage is to rely on a combination of good science and authoritative information (man, this is just like another day in the classroom!) You should keep reading this particular blog because I pull together both the good science and authorities on this topic before drawing any of my own conclusions!

Definitions

Let's get our definitions straight before moving on.

Unilateral breathing: breathing only to one side in a 1:2 ration (breathe left, right stroke, breathe left)
Bilateral breathing: breathing on alternate sides, most often in a 1:3 ratio (breathe left, right stroke, left stroke, breathe right stroke)
Hybrid breathing: There are multiple hybrid patterns. Shown below is a 2:3 ratio (breathe left, breathe right, left stroke, breathe right)

Bilateral proponents believe fervently that bilateral breathing evens out your stroke and body roll which is true. Unilateral breathing proponents believe fervently in the importance of breathing air and that unilateral breathing gets you more (also true).

http://triathlon.competitor.com/2012/07/training/a-better-way-to-breathe_57071

Bilateral Breathing: a review of the literature.

 Just so you know, this ranks pretty high up on the list of most geeky things I have done and that is saying something. A literature review attempts to bring together all the relevant literature on a given topic. In this case, I only looked at the last 10 years of peer-reviewed journal articles. I didn't just half-ass my research and only read abstracts, through my library-awesomeness I found and read the full-text of the articles.  Over the years this has been my procedure for making all sorts of decisions related to training, racing and nutrition. I don't cherry-pick, I look at everything and make a decision on the preponderance of evidence (when that exists!). Using this process I found the following 12 articles. Most are not primarily looking at bilateral breathing, but it comes into play for whatever variables they are testing.  Many of these articles are looking at asymmetries of one sort or another, but it is critical to remember that when it comes to swimming perfect symmetry almost never happens, nor is it true that a symmetrical stroke is necessarily faster. Below I just pick out a few salient points and conclusions from each of these.

Barden, J. M., R. T. Kell, and D. Kobsar. The Effect of Critical Speed and Exercise Intensity on Stroke Phase Duration and Bilateral Asymmetry in 200-m Front Crawl Swimming. Journal of Sports Sciences. 29 (2011).

"...despite significant differences in asymmetry between the power and recovery phases of the stroke cycle, the level of asymmetry decreased proportionately in both phases as swimmers increased speed."

dos Santos, K.B., et. al. Propulsive Force Asymmetry during Tethered-Swimming. 32 Vol., 2013. International Journal of Sports Medicine.

Force measurements were taken on 18 average swimmers. The researchers found that "the present study did not confirm a breathing effect on symmetry, as the breathing preference did not influence propulsive force parameters" but they also found that "swimmers with best performance are less asymmetric than their counterparts." These seemingly contradictory results may derive from the test subjects who were not elite swimmers?

Lee, J., et al. Body Roll in Simulated Freestyle Swimming. International Journal of Sports Medicine. 29 (2008).

"A significant difference in timing and sequence pattern was found for the breathing stroke with the head preceding the movement of the hips and chest..."

Potts, A. D., J. E. Charlton, and H. M. Smith. Bilateral Arm Power Imbalance in Swim Bench Exercise to Exhaustion. Journal of Sports Sciences. 20 (2002).

When testing 10 swimmers on a swim bench the researchers found "Swimmers who normally use a bilateral breathing pattern appear to have a more equally distributed external power output, compared with their unilateral counterparts." Significantly these results were not correlated with performance.

Psycharakis, S. G., and R. H. Sanders. Body Roll in Swimming: A Review. Journal of Sports Science. 28 (2010).

Review articles are research goldmines! If you are going to read one thing, read this review article. An important conclusion: "temporal differences in shoulder and hip roll, and shoulder roll side dominance exist in front crawl swimming, but there is no evidence to suggest they affect swimming performance."

Psycharakis, Stelios G., and Carla McCabe. Shoulder and Hip Roll Differences between Breathing and Non-Breathing Conditions in Front Crawl Swimming. Journal of Biomechanics 44 (2011).

12 elite male swimmers did various 25m trials with and without breathing. The researchers concluded: "Swimming speed was higher in the non-breathing than in the breathing trial. Swimmers rolled more to the breathing side when breathing...There was no evidence to suggest that temporal characteristics of shoulder roll or hip roll were associated with swimming performance."

Sanders, Ross H., Jacqueline Thow, and Malcolm M. Fairweather. "Asymmetries in Swimming: Where do they Come from?" Journal of Swimming Research 18 (2011): 1. Web.

"One of the major asymmetries in front crawl technique arises from the natural tendency, related to side dominance, to favor one side when breathing."

Sanders, Ross H. "How do Asymmetries Affect Swimming Performance?" Journal of Swimming Research 21.1 (2013): 1. Web. 

"There is a paucity of literature relating directly to the issue of how asymmetries might affect performance of swimmers. In particular, studies involving controlled interventions with pre and post quantifications of asymmetries and performance are extremely scarce."

Seifert, L., et al. Effect of Breathing Pattern on Arm Coordination Symmetry in Front Crawl. Journal of Strength and Conditioning Research 22 (2008).

"However, although bilateral breathing may have enabled balanced propulsion by ensuring symmetric arm coordination it did not lead to better propulsion. In fact, the observation of arm dominance led us to think that one arm is responsible for installing the swimming rhythm and probably produces higher forces; this would explain why elite swimmers use unilateral breathing in competition." Well that is not the only explanation, but good point!

Seifert, L., D. Chollet, and P. Allard. Arm Coordination Symmetry and Breathing Effect in Front Crawl. Human Movement Science. 24 (2005).

"Alternating the nonpreferential side with the preferential side might be advised during training sessions to minimize arm coordination asymmetry..."

Tate, Angela, et al. Risk Factors Associated with Shoulder Pain and Disability Across the Lifespan of Competitive Swimmers. Journal of Athletic Training 47 (2012).

Not much here regarding bilateral breathing. Cites an older study that found unilateral breathing increased the risk of shoulder injuries.

Tourny-Chollet, C., L. Seifert, and D. Chollet. Effect of Force Symmetry on Coordination in Crawl. International Journal of Sports Medicine 30 (2009).

This study ONLY looked at unilateral breathers and the researchers concluded: "Although it is often assumed that the forces developed in the right and left arms during  front crawl swimming are the same, it appears unilateral breathing and the development of greater strength of the dominant arm lead to a differentiation in the swimmer's arms."

What do the "Authorities" in the field say?

Vetted scientific literature has a great deal of reliability, but it is often so specific that it's practical applications are difficult to see.  Good evidence can also come from experts in the field, in this case, accomplished athletes and coaches.

Josh Davis, a five-time olympic medalist surveyed other American Olympians about their breathing practices and wrote about it on the site SwimSwam. His conclusion:

"What’s the most important ingredient to an athlete’s success? Endurance, Strength, Mental Toughness, Nutrition, Experience? Surely it’s technique, right?

NO!

IT’S NONE OF THOSE THINGS. THE MOST IMPORTANT INGREDIENT IS AIR!

In every event, other than the 50 free, the most critical ingredient to finishing well is breathing air! Even the demi-gods descended from Poseidon like Phelps, Ledecky, Adrian, Franklin, Yang and Lezak, have to breath air. I find it interesting that a lot of swimmers do breathing patterns different from what the World and American record holders do. I have been studying and competing in elite swimming for almost 30 years now, and my experience is that for the 100 and up, just about everybody that’s really fast breathes every two strokes. Breathing every “2” is the pattern of winners. Now, there is some variations when it comes to the 100, but for the 200 and up I would propose that every 2 is the way of winners."

Gary Hall Sr., has held 10 world records, '69 and '70 he was named World Swimmer of the Year, elected by U.S. Olympic athletes to carry the American Flag for the '76 Games, founder of "The Race Club"

  

"When Sun Yang (hip-driven world record holder in 1500 meters) swims the 1500, except for the final 100, his stroke rate is about 60. Except for the turns, he breathes every cycle (respiratory rate of 30). Going in to and out of every turn, however, he changes his pattern to breathe on two or three successive strokes going in and about three successive strokes coming out of the turn. In my opinion, this extra oxygen gives him a clear advantage and helps him to finish faster than anyone else ever has (by far). In London, he finished in 25.6 on the final 50 meters!"
Source: Swimming Myths from The Race Club website

Breathing Technique and Breathing Patterns video with  Gary Hall Sr.

Very clear-cut breathing patterns article on Triathlete.com from Gary Hall Sr.

Bob Bowman, Former coach of University of Michigan, Coach of the North Baltimore Aquatic Club whose swimmers (including Michael Phelps and gobs of other olympic medalists)

Freestyle Breathing Video: "If you watch Michael swimming he may breathe to the left side for a 25m in practice and then he will flip and when he comes back he will breathe on his right side for 25m. So that he is getting symmetry in the breathing, but he is also breathing every stroke so he gets more air and he is also rotating more..."

 
Jordan Rapp, professional triathlete, multi-time Ironman winner.

Jordan Rapp did not come from a swimming background, but has become a student of swimming in his pursuit of triathlon excellence.  I came across this short post from the Slotwtwitch forum -which to be clear is not at all a reliable or authoritative source of information- but I think what he writes there is very much in line with everything above.

"Why on earth would you want LESS oxygen? Even swimming unilaterally, you are still probably breathing less often than you want.

The *ability* to breathe on both sides is important, because sometimes sun/waves/etc. make it hard to breathe on one side during a race. But nobody I know breathes bilaterally during any regular training, and certainly not during racing. If I'm going to breathe "bilaterally" in training, that means 50m to one side, then 50m to the other. But I'm always breathing unilaterally. I just will switch which side I breathe unilaterally to.

It's an aerobic sport. More oxygen is more better."

Bilateral Breathing: The Races

To add one more layer of empirical evidence to my analysis into bilateral breathing I went out and watched all sorts of recent distance world record swims, Olympic finals, and open water championships. The open water stuff is harder to pick out breathing patterns. I didn't quantify the numbers, but nearly every swimmer did some sort of unilateral or hybrid breathing pattern. What I found interesting is that both Sun Yang and sometimes Katie Ledecky (1500m World Record h olders) often double-breathe going into and coming out of turns.  It looks funky, but it gets you more air.

Sun Yang's double-breathing is quite clear in this video. Wild, but it works. 
Also pay attention to his body rotation, it is definitely not symmetrical.

A Bilateral Breathing Experiment with Crowd-Sourced Guinea Pigs!

Some people could care less about evidence from scientific articles and authorities in the field. This is more problematic when it comes to global warming and vaccination than for choosing whether or not to breath bilaterally. Still, I can appreciate the rugged individual approach and sense an opportunity to gather even more empirical evidence through experimenting on all y'all! Here's our crowd-sourced science project. Three, 500yd trials on different days with different breathing patterns. Don't take my word for it, figure out what works for you and by what magnitude! Report back and I will analyze and share all the data! Want in?  Here are the details on the breathing patterns and a form to fill out when done!

Conclusions and Recommendations

So after all that, here's where you finally get to hear from me!  A quick Google -or triathlon forum search- will turn up all sorts of "experts" telling you how to swim using bilateral breathing without backing it up with anything. You're just supposed to believe THEM because they have a BLOG and they swam in high school for a whole YEAR.

The basic conclusion here (which you should be able to draw yourself at this point) is that bilateral breathing is not the best choice for racing distance freestyle events. Traditional bilateral breathing restricts oxygen uptake too much for race situations.

Asymmetries in force generation, arm position, and body roll are the norm in freestyle. Counter-intuitively small -and even moderate asymmetries- do not necessarily yield slower performances.

For triathletes, you will commonly hear that we need to be able to breathe unilaterally to either side (note this is different than bilateral breathing) in order to avoid waves and site landmarks. There is some truth to this. It is not a necessity, but a nice skill to have.

There are certainly appropriate times for bilateral breathing and those times are: during warm-up, cool-down, as a drill, and during moderate intensity long sets or moderate intensity open water swims.

For both pool swimming and open water there may be some performance benefits to incorporating a hybrid breathing pattern that includes breathing on consecutive strokes (double-breathing).

So there you have it!  Don't take my word for it, look at the evidence!