Science of Breath: What is the ideal respiration rate?
Tim H. Tanaka, Ph.D.
Breathing is a basic living activity that everyone performs every single moment without paying any attention to the act. Besides the simple exchange of air, breathing plays another critical role. Breathing can become a powerful tool to balance and optimize our nervous system and hormonal activity, thus creating a positive impact on our entire physiological system.
Breathing techniques have been a key element of many natural therapeutic modalities or wellness exercises, although exact breathing methods (e.g., using mouth/nose, abdominal/chest breathing, inhale/exhale/hold time, posture, etc.) have been taught and practiced mainly based on tradition and empirical belief. Even widely promoted abdominal breathing, surprisingly does not carry sufficient research evidence of benefit over the more common thoracic (chest) breathing. Although there is not much doubt that many forms of breathing techniques have been benefiting peopleï¿½s health in a variety of ways, different teachings in breathing methods are confusing for many people. Exciting news is that recent studies have clarified at least one important issue regarding breathing: rate of breathing.
Powerful optimization of the autonomic nervous system occurs only when breathing at a specific rate
The heart does not beat constantly like a metronome. In fact, a healthy heart changes its beating speed in quite a dynamic fashion. This normal healthy fluctuation of heart rhythm is called heart rate variability (HRV). HRV is often decreased among individuals with poor health status and high stress. It also tends to decrease with age. A part of HRV specifically associated with respiration is called respiratory sinus arrhythmia (RSA). A figure displayed here demonstrates how significantly our moment to moment heart beat is affected by the way we breathe:
Top Graph: Controlled respiration at 12 breaths per minute
Middle Graph: Controlled respiration at 6 breaths per minute
Bottom Graph: Controlled respiration at 3 breaths per minute
When the respiration rate is 12 breaths per minute, the heart rate is rather consistent with small variability. RSA is greatest at the respiration rate of 6 breaths per minute (middle graph). Heart rate slows down during exhalation phase due to the activation of the parasympathetic nervous system (PNS). Heart rate increases during the inhalation phase due to PNS inhibition. The PNS controls virtually all of the internal organs and closely interacts with hormone and immune activities. Thus, our internal organic functions are generally more enhanced during exhalation and inhibited during inhalation phase. This demonstrates an important physiological rationale behind the traditional teaching of Eastern healing exercises such as yoga, Tai Chi or Qi Gong, all of which strongly emphasize the importance of long exhalation.
So, should people practice breathing as slow as possible?
Taking a deep breath and slowing down respiration augments HRV. However, the highest and most desirable HRV pattern cannot be observed among most individuals during extremely slow breathing rate, (i.e.: breathing at a rate of less than 4-5 breaths per minute).
For most individuals, by breathing at a rate
of approximately 6 breaths per minute, the
maximum HRV and most coherent HRV would be induced. As seen in the middle graph, besides a large HRV when breathing at 6 breaths per minute, there is an almost perfect synchronization between heart and respiration rhythm which is near 0 degrees in phase relationship between heart rate and respiration (180 degrees inverse relationship with beat-beat blood pressure rhythm). In this rhythm, our important physiological reflexes (i.e., baroreflex) are enhanced and powerful optimization of our entire physiological system occurs. Some scientists call the HRV in this state of rhythm, resonant frequency or coherent rhythm.
The resonance could not be observed when respiration was faster (12 BPM) or slower (3 BPM) as shown in the top and the bottom graphs. The exact resonant frequency rhythm varies between individuals and can be determined by performing a series of more precise tests using our HRV and respiration dual monitoring system. However, a very similar trend to the displayed example can be observed in most individuals.
It is important to note the difference between much of the relaxation type breathing (e.g., breathing exercises during mediation, yoga, or classic biofeedback training, etc.) and the breathing exercise using HRV index. While the former is generally aimed at decreasing the overall average heart rate, the latter is aimed at maximizing the HRV amplitude (increasing the range of heart rate changes). This, in turn, stimulates reflex mechanisms and proactively trains the modulation function of the autonomic nervous system.
Implementation of ancient wisdom in modern acupuncture practice
Many of our patients have pleasantly noticed that the Japanese acupuncture procedure at The Pacific Wellness Institute is distinctively gentle and mild, yet they often wonder, why is it so effective?
Applied cardio-respiratory physiology research and acupuncture has been successfully integrated into treatments at The Pacific Wellness Institute. The concept may sound like a non-traditional, modern, scientific-based acupuncture approach, however the importance of respiratory phases during acupuncture needling has been documented centuries ago in Yellow Emperorï¿½s Classic of Medicine (an ancient Chinese medical text, believed to be written over 2000 years ago).
Repetitive deep breathing may induce hyperventilation or other unfavorable conditions for some individuals. Please consult your health care provider before incorporating breathing exercise or any other lifestyle changes.