If you’ve seen your doctor or therapist for stress or anxiety recently, or you’ve been learning how of use your breath to help you calm and relax yourself, it’s likely you’ve heard of one or both of these breathing exercises:
Extended Exhale Breathing
Coherent Breathing
But, do they actually help reduce stress and improve wellbeing?
The findings of two recent studies (Birdee 2023, Fincham 2023) on these techniques weren’t as expected, so I wanted to unpack the results further.
Background
When we breathe in, our diaphragm and rib muscles move to expand the chest cavity, increasing the room around your heart, causing it to expand a tiny bit, slowing blood flow within the heart slightly. Neurons in your heart detect that the blood is moving more slowly and the brain sends a signal for the heart to speed up. Additionally, as the lungs expand they temporarily limit the blood flow in your chest, leading to less blood output from the heart and therefore, a slight drop in blood pressure.
The opposite happens when we breathe out. Everything contracts, including the size of the heart, causing blood flow to speed up and the brain to respond by slowing the heart rate. Additionally, more blood moves out of the lungs on the exhale, which leads to a temporary increase in blood pressure.
These mechanisms highlight the relationship between our breathing rate, heart rate and blood pressure, as well as our understanding of the inhale being more sympathetic dominant and the exhale being more parasympathetic dominant (meaning that if you want to calm down quickly, you need to make your exhales longer than your inhales).
Although the exact mechanism of how slow breathing reduces stress is not completely understood, the above provides some context for why Coherent Breathing and Extended Exhale Breathing are recommended to help people reduce stress and improve wellbeing.
Study 1
‘Slow breathing for reducing stress: The effect of extending exhale’ (Birdee 2023)
What they did?
Compared the effects of E > I vs E = I on both physiological and psychological stress
12 week randomised, single-blinded trial among 100 participants
12 weekly guided classes, plus daily at-home practice
Starting at ~6 bpm and reducing to ~3 bpm by week 12
What they found?
Regardless of exhale ratio, both groups saw significantly reduced psychological stress, but no in physiological stress (HRV)
What does it mean?
At first glance it doesn’t seem that extending the exhale is as beneficial as claimed. But, I don’t think that’s true.
Firstly, this was conducted on a healthy, not a stressed/anxious population and “future studies need to be examined to see if slow breathing with different breath ratios have a significant effect among populations with higher psychological and/or physiological stress” (1).
Secondly, this study examined the long-term impact of extended exhale breathing. An earlier study (Van Diest 2014) explored the immediate impact of extended exhales and found 'participants reported increased relaxation, stress reduction, mindfulness and positive energy’ and ‘more power in the high frequency component of heart rate variability’ (i.e. greater physiological relaxation) (2).
Thirdly, this study demonstrated that psychological stress reduced as breathing frequency gradually reduced, highlighting the benefits of adjusting your breathing practice over time and the impact that has on gradually building resilience to stress.
Lastly, slow paced breathing has been shown to be an effective treatment for reducing stress and anxiety (3). Extending your exhale during your breathing practice is simply another way to help you to slow down your overall breathing rate.
Study 2
‘Effect of coherent breathing on mental health and wellbeing: a randomised placebo-controlled trial’ (Fincham 2023)
What they did?
Evaluate the effects of coherent breathing on stress, mental health, sleep and wellbeing outcomes
Randomised sample of 400 participants
Placebo at 12 bpm and Intervention of coherent breathing at ~5.5 bpm
Asked to practise 10 min/day over 4 weeks
What they found?
While there were overall improvements from baseline to post-intervention in both groups, there was “no measurable effect of coherent breathing... at improving mental health and wellbeing” (4).
What does it mean?
These results are in stark contrast to the claimed benefits of coherent breathing, but with this study it’s important to dig a little deeper.
Firstly, the control group were instructed to breathe nasally and diaphragmatically as part of a ‘rhythmic breathing’ study. Having participants instructed to be aware of their breathing can make it difficult to distinguish between the impact of any intervention versus any beliefs they may hold about the benefits of breathwork.
Secondly, while 12 bpm was selected as the chosen control breathing rate, as it is ‘the lower bound of average resting respiration rate in adults’, it’s at the lowest end of what’s accepted as a standard respiration rate (12 - 20 bpm is considered the standard range). This therefore doesn’t consider that what is a relaxing or stress reducing breathing rate for one might not be the same for another.
A few final points to consider. The length of the study was only 4 weeks, which contrasts other similar studies on stress and wellbeing that ran for 12 weeks. Participants were given instruction via audio only, offering no opportunity for real-time feedback and technique adjustment. Lastly, the results were collated from self-reported and subjective measures, making conclusions slightly more challenging to reach.
Summary
Does the outcome of this study mean there’s zero benefit to practising either extended exhale or coherent breathing? Absolutely not. Both practices have been shown to help in the moment to help bring you back to a place of calm & relaxation.
For a long term practice, as another researcher in this field commented “the actual practice/pace itself doesn’t matter for stress reduction benefits, as long as it incorporates at least some form of slow breathing, where even 12 bpm is considered slow enough to be beneficial.” (Tanya Bentley, CEO and Co-founder Health and Human Performance Foundation).
Breathing Exercises For You
Start with 5-10 mins daily, and gradually work your way up to 15 mins twice a day (if you like). Keep the breathing nasal only and diaphragmatic (low down, activating the rib cage).
Coherent Breathing
~5.5 breaths per min
Sit or lie in a comfortable position
Inhale for 5 sec, exhale for 5 sec (or 6 sec)
Make your breathing nice and smooth
Don’t pause at the top or bottom
If this is too challenging, dial it back to 4 seconds
Extended Exhale Breathing
3-7 breaths per min
Sit or lie in a comfortable position
Inhale for 3 sec, exhale for 6 sec (7 bpm)
Make your breathing nice and smooth
Don’t pause at the top or bottom
If this is too challenging, dial it back by 1 second
When that tempo becomes comfortable, progress to:
4 in, 8 out (5 bpm)
5 in, 10 out (4 bpm)
6 in, 12 out (3 bpm)
If you found this article helpful, you might also like to read - The Best Breathing Exercise for Reducing Stress and Anxiety
References:
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