Acute effects of resonance frequency breathing on cardiovascular regulation

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Citation

Pagaduan J, Wu SS, Kameneva T, Lambert E. Acute effects of resonance frequency breathing on cardiovascular regulation. Physiol Rep. 2019 Nov;7(22):e14295. doi: 10.14814/phy2.14295. PMID: 31782265; PMCID: PMC6882954.

4 FUNDAMENTALS

 

1. Essential Background Material

 

This study examined differences in autonomic nervous system and cardiovascular outcomes from slow breathing at a person’s resonant frequency (RF) compared to one breath above their RF (RF + 1).

 

RF breathing is defined as the breathing rate that synchronizes heart rate oscillations with the breath and maximizes heart rate variability (HRV).

 

(Note: Most peoples’ RF is between 4.0-6.5 breaths/min, with 5.5 breaths/min being most common.  However, there’s a big range, so I’ll use 3-7 breaths/min throughout the 411 to account for this.)

It is theorized that breathing at our RF will amplify the benefits of our slow breathing practice.

However, in practice, it is unclear if this theory holds true.  Countless studies have shown positive results for both RF breathing and “plain old slow breathing” (usually a set pace of 3-7 breaths a minute).

 

So, it begs the question: How important is breathing at our precise RF?  And is breathing at a comfortable pace between 3-7 breaths/min good enough?

 

This study aimed to help address these questions by examining the differences between breathing at RF and RF + 1.

 

 

2. What Did this Research Do?

 

Ten healthy participants took part in the study (an incredibly small sample size…but we have to take what we can get with breathing studies).

 

On the first day, participants were taught to breathe slowly in a semi-supine position using a nasal inhale and pursed-lips exhale.  RF was defined as the breathing rate that maximized low-frequency HRV (LF-HRV).

 

(Nick’s personal note: This is one problem I have with “resonance.”  There’s no perfect characterization of it.  Typically, it’s the rate that maximizes LF-HRV or the mix-max heart rate difference, along with other factors.  Even though there is a published protocol for finding RF, it’s pretty complicated & subjective.)

 

On the second day, the volunteers came in and performed the following protocol:

  • 10-min of baseline measurements

  • 10-min of RF (or RF + 1) breathing

  • 10-min rest

  • 10-min of RF (or RF + 1) breathing

 

The RF or RF + 1 breathing was randomized.

 

Key measurements were:

  • HRV

  • Muscle sympathetic nerve activity (MSNA)

  • Blood pressure

  • Baroreflex function

 

 

3. What Were the Major Findings?

Overall, there were no significant differences between RF and RF + 1 breathing. Both slow breathing methods lowered blood pressure, reduced sympathetic nervous system activity, and increased HRV.

Here are some of the specifics:

·      RF breathing lowered blood pressure slightly more (-4.6 mmHg) than RF + 1 (-3.1 mmHg), but it did not reach significance.

·      Sympathetic nervous system activity was similarly reduced for both RF and RF + 1 as measured by MSNA burst frequency and phase.

·      Results suggested that a session of at least 10 min is needed to see changes in nervous system activity via MSNA measurements.

·      Both breathing approaches improved baroreflex efficiency, but neither affected the “baroreflex function” (there seemed to be some unresolved problems with measuring this).

 

And just to reiterate, a significant limitation of these results is that there were only 10 participants.

 

 

4. Why Do These Results Matter?

 

Determining (and breathing at) your precise RF can be complicated, and it costs money to buy the necessary equipment.  Moreover, a recent study published in Nature (411 coming soon) showed that our RF can frequently change.

 

Here, we learn that even if we breathe close to our RF, we get the same cardio-autonomic benefits.  Thus, this paper provides evidence that simply breathing at a comfortable rate between 3-7 breaths a minute is “good enough.”

 

Lastly, it’s important to acknowledge that this isn’t the only study to analyze RF versus non-RF slow breathing.  Some have found that you’ll get most of the benefits if you breathe “pretty close” to your RF.  Others have found that RF breathing does provide more benefits.  So, only time will tell, but slow breathing between 3-7 breaths/min still gives us many benefits without any extra equipment.

 

 

 

1 BIG TAKEAWAY

There are no significant cardio-autonomic differences between RF and RF + 1 breathing. This suggests that slow breathing at a comfortable pace, between 3-7 breaths per minute, is sufficient to get most of the benefits.

 

 

1 PRACTICAL APPLICATION

Practice slow breathing at any pace between 3 and 7 breaths a minute that is most comfortable for you. Use a nasal inhale and pursed-lips exhale and practice for at least 10 min per day to get the most benefits for your nervous system.