What is the Scientific Impact of Low-Frequency Breathing?
Years of doing psychology research, which means sitting at a computer, caused chronic lower back pain.
In my search for a treatment I turned to research databases. There I discovered that persistent pain is closely connected to stress. Psychological and nervous system level changes in response to chronic stress make us much more vulnerable to persistent pain, as well as many other forms of distress and disease.
I found that modes of change, normally considered automatic, were at the root of our stress-pain-distress relationship, and I began to wonder if I could directly affect my nervous system through attention and action. Perhaps I could change my experience of pain.
I combined my love of scientific study with my curiosity about the hidden potential for expanding awareness, and after almost a year I found what I was looking for.
This is why I found myself in a cramped and cluttered doctors office, strapped into heart-rate and breathing monitors.
On the screen in front of me I could see two graphed lines moving slowly from left to right, representing the changes in heart rate and respiration rate. There was no clear relationship between the two lines. Feeling frustrated, and a little disappointed, I let out a heavy sigh. To my surprise and delight both lines instantaneously syncopated and sloped downward. I just had my first view of coherence.
As I watched, the two lines quickly fell back into disarray and discord. What I was learning through biofeedback was that my breath and my heart were not as harmoniously connected as they could be. However, I was persistent, and after a few minutes I began to find that if I made subtle changes to my breathing pattern, my heart would begin to respond. Soon the two lines began to move in sync. I was breathing gently, deeply, and slowly. I found a particular rhythm, intensity, and pace worked best for encouraging coherence. The lines began to appear less separate, and for moments it looked like there was only one line. My heart was so closely following my breathing that the two waves were becoming one.
After about twenty minutes of practice, there was one smooth sine wave.
It’s hard to describe what this feels like, and some of it is probably just ineffable. In some basic sense it is like learning to dance with yourself. It is very literally a way of communicating to yourself, and with yourself. What I can say with certainty is that I felt deeply relaxed, calm, and content. The pain in my back, which at this point had been bothering me for years, was nowhere to be found. Instead, I felt what can only be described as the opposite of pain and stress: a deep pleasure in embodied experience.
While the small closet-like office, and strange entanglement cords, sensors, and monitors, gave the persistent impression of an archaic and forgotten science, it was actually one of the few places where you could experience a method on the forefront of what is possible. This method is known as heart rate variability biofeedback.
Biofeedback works because humans are cybernetic organisms. While this may conjure up images of science fiction fusions between machine and human, an image which is only aided by the fact that I was, in fact, strapped into a digital interface, the word cybernetic has another meaning. It has its roots in the ancient Greek word for navigation. Basically, it means that we are self-steering systems, and we engage in feedback-mediated change. When we act, or output behaviour, our actions create changes which quickly become inputs in the form of perceptions, which then affect later actions (outputs).
Input transforming into output, and output transforming into input, this is one of the signs of a feedback loop.
Internally, we have innumerable feedback systems, most of which work to keep our internal states within a particular range (known as homeostasis). This balance is not static, but dynamic, changing and adjusting to changes.
A simple way to think about this is a thermostat, which measures changes in the room temperature and controls a heater. The thermostat turns the heater on when a minimum threshold is reached, and turns it off when the maximum is reached. In some very generalized way, biofeedback was training me to become a better thermostat of my internal world.
The sensors measured signals from inside my body, like breathing frequency and heart rate, and represented them back to me visually. This gave me access to parts of my interior world that are normally hidden. By seeing how my actions changed the graphs on the screen, I could have an indirect view into what was happening inside my body. When I saw that my heart rate was getting too high, I could take a long slow exhalation, much like the thermostat detecting overheating and sending a signal to the heater to shut down.
Of course, the nervous system is much more complicated than the system of a thermostat and a heater. There are so many complex and interconnected nodes in our internal systems, it seems difficult to imagine finding a single point that could be used to change the entire system. But, in fact, there is such a place.
Where to intervene in a system as complex as our own being is a daunting question. Here, western scientific methods have taken their lead from older traditions of practiced study.
Breathing has been central to most spiritual and religious practices for millennia. Yogic pranayama, Buddhist mindfulness, Christian hymns, Jewish Kabbalah, and Sufi prayer are all tied by the common thread of breathing, particularly breathing at unusual rhythms and intensities. These traditions all sought to alter consciousness in various ways, normally to induce positive transformations, increase well-being, increase insightfulness, and expand awareness.
A common explanation for the ubiquity of breathwork in mystical traditions is that breathing can be used to train awareness; focusing on breathing demands sustained attention, which requires that the parts of the brain which repeatedly detect mind-wandering, including the Anterior Cingulate Cortex (ACC), notice if we’ve strayed, and guide our attention back to the task at hand.
Research has shown that over time this process becomes more effective and efficient. Essentially, training breathing awareness is a form of self-steering, which alters the connective efficiency of parts of our minds that direct, or steer, other parts. The accuracy of this form of self-directed attention gets better over time. Meaning that it takes less time and energy for the ACC to refocus. The parameters narrow, signals are intensified, communication becomes more efficient, and the power to detect changes is strengthened.
This kind of cybernetic change in the pathways of attention is absolutely a part of any meditative training. If you're interested in learning more about how meditation changes awareness and creativity, and what changes to expect from specific kinds of meditation, consider reading this article next.
This explanation of breath as an ‘anchor’ of awareness, which is often offered in introductory mindfulness courses, is only part of the puzzle, and does not fully satisfy the curiosity of the scientific skeptic. If we stop there, many questions are left unanswered.
If attentional focus is the main outcome of intentional breathing, then why not focus on literally anything else? Is there something special about breath awareness? If so, are there particular ways of breathing that are better than others?
The short answer is that breathing is unique, and particular frequencies are best.
To understand why breathing is an incomparable way of transforming experience and physiology, we have to know a little bit about how the nervous system interacts with itself and the world.
Our autonomic nervous system mediates most of what we do automatically, particularly the function of many of our organs; it has two branches that are normally in dynamic interplay. One of these branches, the sympathetic branch, if it becomes dominant, sends as much glucose and oxygen to the skeletal muscles as possible, preparing us for intense physical exertion. Our heart rate speeds up and becomes very rhythmic, our breath becomes rapid and choppy, our blood pressure increases, and chemical messengers are released throughout the body that prepare us for action. We share this threat-detection response with all mammals and reptiles.
As we evolved from reptiles into the highly social mammals that we now are, things changed quite a bit. In part, we had to learn how to overcome our most basic threat-detection responses in order to live in social groups. Our social engagement system depended on our capacity to relax, which was basically our capacity to inhibit our survival mode. More accurately, in order to survive, we had to disengage our older survival mode that was based on threat-response, and learn to engage a newly evolving system which allowed us to function in social systems. In short, to live harmoniously, we can’t be looking for a fight, or running away.
Our nervous system evolved a structural dichotomy between stressful threat-detection and relaxed engagement.
When we are relaxed, something happens that is quite opposed to the stress response. Our breathing slows and becomes more gentle, our heart begins to vary with our breathing, our average heart rate drops, and our blood pressure decreases.
In industrialized areas, our health crises are often connected to problems that have a sympathetic component, which is to say they are related to stress. When we are unwell, we become stressed, which actually inhibits our long term ability to recover. Worse yet, prolonged or chronic stress can cause serious negative health effects all by itself.
In my case, work stress led me to pay less attention to acute physical pain, and when I became injured, the prolonged nature of the stress made the pain much worse.
On the other hand, research has shown that having a healthy autonomic nervous system, which is characterized by the capacity to move out of the sympathetic stress response quickly, means that we are more resilient and adaptive. If we can recover from stress more quickly, we are more likely to be able to rest, heal, digest, and connect to others.
Let’s briefly return to the example of a thermometer, and imagine that the psychological state of stress would be a room overheating. External influences like the weather can influence the room temperature, but so can internal functions like the thermometer. By analogy, stressful events can make serious changes to internal states, but if we have a well attuned nervous system (thermometer) then we can keep calm, cool, and collected. This is not to say that stress is all in the mind, but rather to say that our capacity to respond effectively to stressful events is based in part on the resilience of the nervous system.
Just like stress and illness can influence each other, our physiology interacts in two-way causal relationships.
The autonomic nervous system has many rhythmic oscillation patterns (waves), which can be measured. Blood pressure, heart rate, and breathing all rise and fall, and when graphed they appear as a wave function. Electrical signals come in waves of intensity through massive nerves descending from the brain down through the entire torso, interconnecting the brain, lungs, heart, digestive system, and more. All of these rhythmic waves are interdependent.
In many ways, this interdependence is a good thing, because it indicates that the system is functioning well.
The body has systems that regulate the movement of resources and energy. These systems, which undergo rhythmic fluctuations, need to stay within particular limited ranges in order for the body to function at peak performance; a wider set of parameters determines the range at which we can stay alive.
Elements within the system have adapted to interact, and they affect each other either positively (inducing an increase) or negatively (inducing a decrease). One system which interacts with itself in this way is the cardiovascular system, involving both the lungs and heart. The heart conducts the rate of blood throughout the body, and breathing acts as an interface between the inside and outside of the body, and maintains a dynamic balance (homeostasis) through gas exchange. Just like the feedback loop between a thermometer's input (temperature reading) and it’s output (sending a signal to the heater), our heart and lungs have feedback loops that affect each other and act as an interconnected and interdependent system.
This system has resonance. Resonance, when used in its technical ‘systems theory’ sense, has a very specific meaning. The rhythmic oscillations (waves) influence each other. Amplitude and frequency changes can transfer from one element in the system to another, so that changes in one are a function of changes in the other. There are points at which this transfer of wave features is most prominent. Crucial for our purposes: there is a point at which breathing frequency most affects heart rate, and the two fall into a coherent and attuned relationship. The frequency at which this happens is known as the resonant frequency.
When we breathe at our resonant frequency, our heart begins to vary with our breathing. As oxygen is being taken in, the heart pumps quickly, moving as much blood through our lungs as possible. There, the blood takes on oxygen and is sent back to the heart which distributes it throughout the body. The heart needs to beat quickly while it is acting as an intake pump, but does not need to beat nearly as quickly while oxygen is not being loaded into the bloodstream. If relaxed, our nervous system will act to help us conserve resources. In this way, the best organized and most harmonious relationship between breathing and heart rate would be two synchronized waves.
As we breathe in, our heart rate should increase, and as we breathe out, our heart rate should decrease. Breathing at the most resonant frequency improves the functioning of the cardiovascular system by entraining heart rate with breathing.
It is believed that part of what deep breathing does is increase the degree to which the brain and heart communicate via the vagus nerve pathway. This is known as neural regulation of the heart. By practicing deep breathing repeatedly over time, the parasympathetic connection between the brain and heart gets stronger. Training this response means that we are training the connection between our mind and body along the vagal pathway, which is the pathway that electrical signals travel most often when we are resting, digesting, healing, and connecting to other people.
Experiments show that there are particular frequencies at which the heart becomes most resonant with the breath. The most effective frequency is around 5.5 breaths per minute. This means one breath cycle takes a little longer than 10 seconds. This is significantly slower and deeper than most of us normally breathe, which means many people are not breathing in a way that encourages the most harmonious interplay of our internal systems. It should come as no surprise that innumerable scientific studies have found that breathing at the resonant frequency pace can help many people experiencing all kinds of distress. Just a taste of this research is given below.
Does Resonant Breathing Reduce Blood Pressure?
Another crucial system of feedback loops within the body is the Baroreflex, which links the heart and the brainstem. When the heart is beating quickly, its output intensity increases, and blood pressure increases. Crucial arteries, which carry blood away from the heart, are stretched by this increase in pressure. Special receptors (known as baroreceptors) detect this stretching and send a signal to the brainstem, which responds by sending parasympathetic signals along the vagus nerve. These signals tell the heart to slow.
Breathing at a resonant pace has been shown to decrease blood pressure, probably by increasing heart rate variability (HRV) through baroreflex stimulation of the parasympathetic vagal pathway. This is why paced breathing is offered as part of a treatment plan for hypertension. By regularly engaging in paced breathing at the right frequency, some people can lower their blood pressure.
Remember that in feedback loops an output can become an input, and thus an effect can become a cause. Resonant frequency breathing increases heart rate variability partly through increasing parasympathetic vagal activation. With time and training, this activation becomes normal, so that with a regular paced breathing practice our baseline becomes more parasympathetic, meaning more restful, healing, and connected. Having a more relaxed and connected baseline allows us to be more resilient and adaptive. In this way resonant frequency breathing’s effects ultimately become causes of other significant improvements.
This is why regular training in this type of breathing improves quality of life across both physical and emotional dimensions.
Just as with stress, many, if not all forms of psychological distress have an autonomic component, and involve some degree of dysfunction in crucial areas coordinated by the autonomic nervous system, such as arousal, feelings of safety, sleep, appetite, and sex. Because these functions are directly connected to the functioning of our internal organs, they are in part regulated (or dysregulated) along the vagal pathway. It should come as no surprise that stimulating this pathway through paced breathing can be life changing.
Depression is no exception, and the evidence that depression involves a disharmony of the autonomic nervous system abounds. A recent meta-analysis of 21 studies found that heart rate variability is significantly lower among adults diagnosed with major depression. Another meta-analysis found the same reduction in HRV among depressed teenagers. What’s more, another meta-analysis has shown that this lower HRV among depressed people is not due to cardiovascular disease. The same study showed that treatment with antidepressants does not improve HRV.
So there is good evidence that heart rate varies less among depressed people. If we imply feedback-loop logic, we could imagine that depression might be reduced by increasing heart rate variability. And it turns out this is true. HRV biofeedback training has shown promising signs of treating depression.
Because the biofeedback works by helping find the resonant frequency and prolong the coherence between respiration and heart rate variability, it would follow that the biofeedback is not necessary and that simply breathing at the resonant frequency should improve HRV and mood, and an experimental test has found that it does. This study also found significant improvements in blood pressure.
So we know that psychological distress can be linked to higher stress. Our vulnerability or resilience to stress is influenced by our autonomic nervous system. The amount that our heart varies is an indication of autonomic balance, which is significantly lower during distress. Depressed people have lower HRV, but teaching people to breathe at their resonant frequency improves HRV and helps alleviate depression and improve mood.
It appears that the biofeedback is not necessary to induce many of the physiological changes, and instead simply breathing at the correct frequency can be tremendously helpful.
Because the autonomic nervous system coordinates relative levels of stress and relaxation, it stands to reason that a breathing technique that increases the parasympathetic signals would reduce stress. It might even be more accurate to say that decreasing stress and increasing parasympathetic activation are the same thing. Remember that our relaxation system inhibits our stress response. Either way, breathing at the resonant frequency accomplishes these changes.
One study found that resonant breathing reduces anxiety, even for those with clinically high anxiety. Because anxiety is a complex phenomena, it’s important to note that resonant frequency breathing has effects on multiple dimensions, both subjective and objective. The resonant breathing pace improved subjective tension and anxiety, and importantly also reduced physical and objective signs of stress, specifically sweaty hands, which is calculated by the degree of electrical conductivity on the surface of a finger.
It’s worthwhile to briefly consider the larger implications of this. Emotions do not just generate changes in breathing, but changes in the body affect emotions. One study, published in the journal of Emotion and Cognition, titled ‘Respiratory Feedback in the Generation of Emotion’ found that emotional changes consistently produce unique breathing patterns, and that unique breathing patterns consistently produce emotional changes. This means emotion involves feedback loops.
After an intense experience of danger or a prolonged sense of being unsafe, we can get stuck in what is known as hyperarousal. This is especially likely if we do not have healthy strategies for self-soothing. This state of hyperarousal is marked by increased sympathetic activity, increased reactivity to perceived threat, rapid breathing, and importantly it involves lower heart rate variability.
Based on our understanding of respiratory feedback, heart-lung resonance, and the baroreflex, it stands to reason that learning methods of deeply relaxing, engaging parasympathetic response, and increasing heart rate variability would be very helpful for traumatized people.
Experimental research and case studies have indeed provided evidence that learning to breathe in resonant ways improves PTSD symptoms. Because PTSD is marked by a serious imbalance in autonomic activity, learning to rebalance can be life changing.
Returning to where we started. It is well documented that chronic pain is associated with chronic stress. This is of course in part due to the fact that being in constant pain causes stress. But it’s more complicated. Stress itself can increase the risk of developing chronic pain.
There are many causal pathways that determine this relationship. Stressed people have trouble taking care of themselves. Pain and stress are also connected because chronic stress interferes with rest and recovery. There is even evidence that chronic stress changes which signals get priority in the central nervous system.
All this is to say that reducing stress effectively could significantly improve the well-being of people with chronic pain. And scientific experimentation has borne this out. When people are trained to breathe in a resonant way, it induces a relaxation response which changes the function of the nervous system in ways that are deeply helpful for people with chronic pain. This has been shown in multiple controlled experiments.
Through my own experience with chronic pain, I discovered that stress influences the degree to which we have internal resonance. When stressed, our breathing and heart rate become less synchronized. Over time this can have a seriously negative impact on our physical and mental health.
Researchers have found that there are ways of getting our internal rhythms back in sync. This required learning about the feedback and resonance characteristics of the cardiovascular system. It turns out that there is a particular frequency of breathing which induces resonance in the heart. The two patterns can become harmonious, leading to innumerable benefits for physical, mental, and emotional well-being. Breathing at this frequency can help improve mood, blood pressure, reduce stress and fear, and reduce pain. This all happens because our bodies are dynamic and interconnected systems. Changing something as crucial as breathing has cascading effects.
While these discoveries were made using complex technologies, the method that developed out of them is very simple. Breathing at the resonant frequency can be life changing.
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