Swimming performance: is bilateral breathing a must?

Many swimmers may have read or been told that bilateral breathing is superior to breathing on one side only. But is it really essential? John Wood provides the answers…

In swimming, bilateral breathing means breathing to both sides during the front crawl stroke. This usually equates to breathing on an odd number of strokes – eg 3, 5, 7 etc. For many swimmers, bilateral breathing can be really useful for keeping the stroke even, and helping to maintain a straight line during a swim. Additionally, the swimmers who tend to get shoulder and neck injuries tend to be those who only breathe to one side – a feature of poorer posture and reliance on one side of the body doing the majority of the work.

In this article however, we’ll argue that breathing bilaterally is not a strict necessity and could potentially hold athletes back in the water. This is especially true for (but not confined to) new swimmers such as those taking up triathlon. There are so many things to try and focus on that breath control becomes really difficult, and trying to hold on to breathing every third stroke results in very quick fatigue.

In most sports, we don’t have to work very hard to get oxygen. But in swimming, specifically in freestyle, we have to turn our head to get air. Simple logic suggests that it’s a great asset to be able to breathe to both sides, but this is especially true in open water where waves, wind or bright sunshine could make breathing on only one side much more difficult.

Breathing numbers

Cycling or running at maximal exertion requires a breathing rate of between 50 and 60 breaths per minute. If you are swimming anywhere from 400 metres to 2.4 miles, chances are your stroke rate is 50 to 60 strokes per minute. A swimmer taking 60 strokes per minute and breathing to one side on every stroke cycle (1:2 ratio) takes 30 breaths per minute. However, in bilateral breathing when you breathe every third stroke (1:3 ratio), your respiratory rate is only 20 breaths per minute, which is even lower (see figure 1). It’s not surprising therefore that maintaining bilateral breathing can potentially be a challenge!

Dr. Mitch Lomax, who is a leading researcher on inspiratory muscle fatigue (IMF), said the following: “As breathing has the potential to disrupt stroke mechanics and streamlining (at least during front crawl), reducing breathing frequency is advantageous. However, this has to be balanced with the need to supply the muscles with oxygen1.”

Studies on swimmers of varying abilities show that breathing causes a change in body mechanics in all three planes (front to back, horizontally and vertically). As a result, during that breathing phase, there is an asymmetry or difference in the arm movement, and a fluctuation in the power produced while breathing2 3 4. In other words, keeping the head still and swimming without breathing means we are more likely to swim straight because as the research shows, it also means we’re likely to swim more mechanically efficiently and theoretically faster.


What to work on

The findings from research are all well and good in theory, but in practice there are limits! When coaching, I prefer to focus on making sure that the swimmer in front of me has a balanced stroke – ie that both the left side and right side are doing the same thing, and that the core and spine are staying straight and not bending round to one side or another. Once this is the case, you can ensure that general breathing technique is good.

If a swimmer is swimming high in the water, and not dragging themselves along, this is a good start. A good body position makes it easier for you to breathe, making it possible to disrupt your stroke as little as possible. I normally start with getting swimmers to look down in the water rather than forward. This can be quite counter-intuitive as human nature suggests that you want to look forward.

You can try this before you get in the water. Looking straight ahead, turn your head so you are looking over your shoulder (assuming that you have no neck issues, I imagine this should be quite easy). Now raise your chin so that you are looking forward and up – and repeat the movement of trying to look to the side. The likelihood is that doing this is much more challenging, and there is a smaller range of motion too.

In the water of course, there will be some body roll to the side (which helps to rotate the head to the side and facilitates breathing). However, the less lift you have from the head and the more you can just pivot from the neck, the better. Hopefully you can see that a smoother breathing action will minimise asymmetry in your stroke, and make it easier for you to breathe full stop.

A great drill to work on this is side kicking (see figure 2), where you are lying fully on your side with the lower arm extended parallel to the surface of the water, and with the legs kicking along the surface of the water (ie side to side rather than up and down). As we saw in an earlier article, side kicking is also a good leg conditioning drill and for body positioning. However, for the purposes of this article, you can use it to focus on minimal head movement while breathing – looking down for the majority of the time, then turning the head to breathe. What you are aiming for here is to not lift the head up.


The next step is to make sure that when breathing, you don’t let your hand cross under your body in an attempt to balance yourself. For example, if you breathe to the left, you need to make sure that your right arm doesn’t ‘follow’ you across. My favourite drill is to practice swimming without breathing – not to try and push your limits, but to feel how smoothly you can swim when your stroke is balanced and your head is still. Try swimming 25-metre repetitions, alternating between swimming as far as you can without breathing, then switching back to your normal breathing pattern.

The aim of this drill is to maintain as much of the ‘no breathing’ smoothness as possible when you reintroduce the breathing to your stroke. You could do sets of four lots of 1-length swims with plenty of rest, slowly bringing more breathing in. For example:

  • *No breathing (or as far as possible), then breathing every 7 strokes, then breathing every 5 strokes, then breathing every 3. Or:
  • *Swim 8 x 1-length laps as: two no breathing (or as much as you can manage) then two breathing every 6 strokes, then two breathing every 4 strokes, then two breathing every 2 strokes. Try swapping your breathing side each length and remember to keep your stroke the same as you take more breaths per length!

As an alternative to holding your breath, you can try using a front-mounted snorkel (see figure 3). The idea of this drill is that you can keep your head still without the stress of trying to hold your breath! It also gives you time to be aware of your stroke and hopefully improve your ‘feel and memory’ of what your body is doing and where.


Another drill that you might do is single arm freestyle – with the other arm down by your side. Keep your left arm by your side and use your right arm to pull yourself along (see figure 4). As your right hand enters the water, pop your left shoulder and hip out of the water, while making sure that you breathe as smoothly you can (which will make your life a lot easier!).

If that drill is simple enough, you can make it more challenging by breathing to the opposite side from the arm you are using. For example, if you are using your right arm, breathe to your left hand side. The aim of this drill is that with only half the propulsion (only the one arm pulling), you have to be as level with your breathing and stroke as you can, lift your head as little as possible, and cause as little disruption to your stroke as you can.


Close your eyes

To make sure that you are balanced and getting equal power from your left side and right side, you could try some closed-eye swimming (if it is safe to do so!). When you swim in open water you obviously don’t have a black line to follow, so if your breathing is causing your stroke to be asymmetric you may have a tendency to veer to one side.

Try this: swim a length and count your strokes. Next, swim the following length with your eyes closed, stopping two strokes short. You may find that with no visual stimulus to keep you straight, you end up bumping off a lane line. Repeat the exercise, eyes open and get a real feel for where your arms are in relation to your body and what is keeping you in a straight line. Then try to replicate that with your eyes closed. You may well find that if you only breathe to one side, that you veer to that side of the lane. If this is the case, make sure that you ‘reset’ your balance/centre line so that you are pulling equally with both arms/sides of your body.

The most important point throughout all of this is that a balanced stroke (when unilateral or bilateral) is always going to be the best for performance, reducing the risk of getting injured, and the quickest/smoothest. If you can swim evenly only breathing to one side, but you can get enough oxygen in to swim hard, then why not? Trying to hold a bilateral pattern might be even smoother for you but if it leaves you gasping for air, then it is slowing you down.

CASE STUDY: Gareth Gates

When I met Gareth, he was already swimming at a reasonable speed, with a pace of around 1min.41secs per 100 metres. However, he had been stuck at the same speed for quite some time. He was breathing every third stroke and swimming very smoothly. But every time he was approaching his limit, he was burning up, running out of breath – and that was his limiting factor. Gareth’s technique was pretty sound, and he was doing strength work outside of the water.

After a bit of convincing, I persuaded Gareth to try different combinations of breathing – both every second stroke, and a three-two-three pattern (ie breathing twice to each side in an alternating fashion). Gareth settled on breathing every two strokes as it was an easier rhythm for him, and it unlocked some extra speed, especially over more than 25 metres. Having only been able to hold 22 seconds per 25 metres for a length and a bit, he was able to maintain that speed for close on 100 metres at a time. His pace improved all because he was able to get more oxygen into his lungs, and then on to his muscles.

Gareth is hoping to qualify for British age group representation over the sprint distance, and already had a strong bike and run leg. Now he has an improving swim to make sure that he can get out of the water and into T1 near the leaders. Gareth’s case study illustrates perfectly that while it offers some theoretical advantages, a bilateral breathing pattern doesn’t automatically result in a faster pace!

See also:


  1. International Journal of Swimming Kinetics. 2(1) : 3-12, 2013
  2. Human Movement Science. 24(2), 234–256, 2005
  3. J. Swimming Research, Vol. 18 (2011)
  4. Journal of Strength & Conditioning Research. 22(5), 1670-1676, 2008
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