In this article we will go through a brief history and background to breathing techniques and their application in biofeedback and stress management. We will then present some recent data on our approach to breathing biofeedback
Breathing practices have been an integral part of wellness practices for generations. While eastern traditions on meditation and specifically yoga have taken advantage of breathing to calm and regulate one’s mind for ages, with different breathing techniques such as nostril, abdominal, forceful or vocalised breathing, for western medicine, breathing is a relatively newly explored field.
Slow breathing techniques have particularly drawn attention in this domain, which are namely practices that aim to keep breath below 10 breaths per minute. The benefits of slow breathing have been progressively studied in the medical communities since the 1990s, fore-fronted by Konstantin Pavlovich Buteyko who has pioneered a breathing technique known as Buteyko method, which showed effects in treating patients with respiratory and circulatory diseases in the 1950s and 1960s (Bruton & Lewith, 2005).
Since then, slow breathing has been documented in the last decades for its versatile beneficial effects on cardiovascular, nervous, endocrine and respiratory systems (Chaddha, 2015, Nuckowska et al., 2019, Rosenthal et al., 2001, Russo et al., 2017, Wu et al., 2020, Yadav & Mutha, 2016, Zaccaro et al., 2018). These effects span lowering blood pressure to increased cortical and subcortical activity correlated with increased vigour and alertness.
So what is heart rate variability and why does it matter?
In the remainder of this article we describe a certain type of biofeedback training which utilises slow breathing to regulate the variability of oscillations in heart rate.
Our heart rate is under the control of our autonomic nervous system, which is controlled by sympathetic nervous system through release of epinephrine, and parasympathetic nervous system through release of acetylcholine from the vagus nerve. Sympathetic activity which increases in the presence of a perceived stressor/threat, results in acceleration in heart rate, and increased parasympathetic activity, which is responsible for vital body functions at rest such as digestion, results in deceleration. (Gordan et al., 2015)
A healthy heart is not a metronome. (Shaffer & Ginsberg, 2017)
Changes in the frequency of the heart rate is shown to correlate with parasympathetic nervous system activity and this variability reflects the ability of the autonomic nervous system to regulate its adaptive stress response to stimuli.
Termed as heart rate variability, an increase in this variability indicates self-regulation and resilience to stress. In a healthy physiology, your autonomic system should be able to control your heart rate efficiently by increasing it when there is stress, and decreasing when there is none, which would be reflected by a high variability in heart rate.
Studies in the field agree that exposure to stress, and chronic stress reduce the heart rate variability, while relaxation and generally a healthy psychology exhibits a more varied heart rate response. Not only used as a general marker for physical and psychological health to be employed in research and industry settings, heart rate variability is used in psychotherapy as a measure of success in outcome.(Steffen et al., 2017; Caldwell and Steffen, 2018; Lehrer, 2018; Fiskum, 2019). Moreover, some of the clinical fields that use heart rate variability as a diagnostic criteria include depression, panic disorder and anxiety which are all related to decreased HRV (Chalmers et al., 2014; Garakani et al., 2009).
HRV is systematically related to breathing frequency, with higher amplitudes achievable with slower respiration Badra et al., 2001, Brown & Ryan, 2003, Eckberg et al., 1985, Song & Lehrer, 2003). Researchers have been able to successfully show that breathing exercises can increase HRV (Caldwell and Steffen, 2018; Lehrer, 2018;Lehrer & Gevirtz, 2014).
Most studies find that maximum effects usually are achieved when breathing at a rate of approximately 0.1 Hz (six breaths per minute), with the rate changing slightly on an individual basis. This concept of optimal breathing frequency is coined in the field as resonance breathing frequency.
The concept of resonance comes from the synchrony observed between heart rate and breathing rate when breathing at this rate; when these two types of oscillations affect the blood volume in synchrony, this yields to the highest parasympathetic power influencing the heart rate, thereby leading to a decreased stress response.
Practicing to breathe at this frequency to reinforce this synchronisation is shown to strengthen the homeostasis of the overall cardiac and respiratory systems by reinforcing the effect of baroreceptor reflex on blood level pulsation. (Lehrer et al., 2003, Vaschillo et al., 2002, E. G. Vaschillo et al., 2006).
Comprehensive meta-analyses in the field show the effect of biofeedback that incorporates breathing at this frequency in benefitting treatment in asthma, COPD, IBS, cyclic vomiting, recurrent abdominal pain, fibromyalgia, cardiac rehabilitation, hypertension, chronic muscle pain, pregnancy induced hypertension, depression, anxiety, PTSD, insomnia, and performance (Gevirtz, 2013, Khazan, 2015). There is more and more recent research that is coming which outlines the beneficial effects of biofeedback that involves resonance breathing. (Jester et al., 2019, Pagaduan et al., 2019,Russo et al., 2017, Steffen et al., 2021)
At Sensae, we are interested in integrating this technique to our platform so we can improve physiological health through biofeedback powered with haptics.
Our recent data investigating the effect of biofeedback training utilising resonant breathing frequency shows promising and consistent results in increasing the heart rate variability along with other metrics associated with physiological health.
Example data visualisation that we use to assess a resonant breathing frequency for a person. We utilise our physiological signal detection platform and sophisticated algorithms.
After identifying the resonant breathing frequency, guiding users in our beta programme through a 10 minute breathing exercise shows effects in increasing heart rate variability. Our platform tracks other metrics associated with physiological health such as the power of parasympathetic and sympathetic nervous systems regulating the heart rate.
After the biofeedback session we see increases in the influence of parasympathetic nervous system in heart rate, which indicates increased self-regulation and resilience to stress.
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In line with the easing of restrictions, we have resumed in-person testing in our offices in Copenhagen
So if you are interested in learning your resonant breathing frequency, and experiencing a biofeedback session to increase your physiological health, you can book a free session by following this link: https://sensae.co/participate.