A psycho-physiological model for breathing exercises

At the core of mindfulness practices is breathing which has been linked to stress reduction and relaxation. Many different techniques can be employed. Generally linked to yoga, Prana-yama breathing, from the root ‘’prana’’ which means both ‘’breath’’ and ‘’energy’’, aims to consciously regulate the breath either with it is frequency or deepness. Another technique is paced breathing, which generally aims at slowing the frequency of breath and is considered a component of biofeedback and progressive relaxation. 

The physiology underlying the benefits of breathing exercises are often confounded by other meditative techniques such as focused attention, which direct attention to the breath by counting them for example. So what role does breath control really have on our wellbeing and state? In a systematic review published in 2018, Zaccaro et al. analyzed 15 articles to assess the psycho-physiological outcomes of voluntary breathing techniques alone, putting an emphasis on its effects on cardio-respiratory and central nervous system.

Cardiovascular system

Biofeedback sessions, in which the breathing frequency is kept in the 5.4 – 6 breaths/min range for 30 minutes, and paced breathing sessions, with frequencies of 6-10breaths/min with different inspiration/expiration ratios, were linked with increased Heart Rate Variability (HRV) and Respiratory Sinus Arrhythmia (RSA). RSA is strongly correlated with increased parasympathetic tone (the “rest and digest” arm of our parasympathetic nervous system). HRV has been known to increase with decreasing breathing frequency. The elevated parasympathetic tone then bridges to the central nervous system and projects to the thalamus and limbic system, partly explaining its effect on emotional control and well-being.

Central nervous system

Different brain waves have been associated with various levels of consciousness. Slow breathing techniques have been shown to decrease “theta waves” and increase “alpha waves” activity on electroencephalogram (EEG), a device which can measure the brain’s electrical activity. These alpha waves are considered an index of inward shifts of attention towards breathing and are also linked to synchronization in the Default Mode Network (DMN), which is very active during states of mind wandering. It is hypothesized that this conscious shift of attention towards breath control is driven by the central executive network in the brain. In fact, a functional MRI study found that slow breathing was linked to increased activity in the prefrontal, motor, and parietal cortices, known to be related to voluntary breathing, and in subcortical areas such as the thalamus, linked to the regulation of  internal body state. 

A step closer towards a psycho-physiological model

The physiological effects described above were linked to better psychological and behavioural outcomes, from decreased anxiety and arousal to increased energy and emotional control strategies. Zaccaro et al. hypothesize that improved well-being are likely driven by the brain’s top-down processes. For example, the shift towards the voluntary control of internal bodily states through the thalamus could include the olfactory bulb as one of its mediators. 

What does this all mean?

Although this study had its limitations, it is a good step towards understanding the role that physiological underpinnings for how simply controlling your breath can affect well-being. While many questions remain to be answered, I invite to try to learn a few breathing techniques you can try on the go. Here is a little example to give you a head start:

© Illustration by Zoe O’Neill

You can do this 5-7 times until you feel your body physically relaxing. Stop the exercise if you feel faint or have difficulty breathing, however. It can also be useful to place one hand on your chest and a hand on your abdomen to help you focus on your breathing.

© Illustration by Yukyung Kang

This article was written by Salima Ramdani, a third year medical student at McGill University and a member of the McGill Med Mindfulness team.

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