Mastering your Sympathetic Nervous System
Before my life took on an entirely different trajectory post-accident I used to run/cycle in the mountains behind our home to control my excessive sympathetic nervous system (SNS) drive that ‘accumulated’ from managing the ‘weight of responsibility’ of obtaining my PhD. Indeed, hard exercise refreshed my body and cleared my head like nothing else, but, after I suffered brain and spinal cord injuries and lost my leg, I found that hard exercise robbed me of way too much energy.
I was thus desperate to find a more efficient way to regulate my sympathetic nerves and my heart rhythm. Though I understood very well from our StressEraser research just how powerful deep, slow breathing can be in calming the heart, I also realised that there is a deeper level that needs to be appreciated:
The breath is only effective when it aligns with the blood pressure (BP) rhythm
What this translates into is that the effective ‘ingredient’ underpinning Keeping Calm is the alignment of the heart rhythm with the BP rhythm. Given that the BP rhythm is under dominant SNS control, it necessitates that we must actively modulate the SNS drive, in addition to actively modulating the parasympathetic drive, in our bodies.
Cardiac Vagal Motoneurons
Restorative activities, such as deep breathing exercises, Mindfulness Meditation, Yoga, Qigong, etc. done in a quiet and secluded space, regenerates our bodies via our parasympathetic vagus nerve that originates in the cardiac vagal motoneurons in the Dorsal Motor Nucleus of the Vagus and in the Nucleus Ambiguus in the brainstem. It is possible to indirectly modulate these brainstem vagal nuclei via the Primate brain, more specifically via the ventromedial Prefrontal Cortex, but this more indirect modulation demands an appropriate brain state such as engendered by Mindfulness Meditation, Contemplative Meditation, Qigong, Yoga, etc. A more direct way to modulate cardiac vagal motoneurons is via the breath, i.e. via Primate brain ‘override of the spontaneous respiratory rhythm generated by our brainstem respiratory nuclei.
The 3 Groups of Nuclei controlling Respiration and the breathing circuitry
There are 3 groups of respiratory nuclei in the brainstem that control spontaneous breathing via neuronal circuitry that generates 1) inspiratory activity, 2) post-inspiratory activity and 3) expiratory activity. Note that the neuronal circuitry that generates expiration is passive during normal breathing, because our lungs are elastic and will deflate like a balloon once the inspiratory activity is ‘switched off’ by the post-inspiratory circuitry. Slowly adapting pulmonary stretch receptors in the lungs terminate inspiratory activity reflexively. This is known as the Hering-Breuer reflex that prevents over-inflation of the lungs. Our air-filled elastic lungs then deflate as we passively exhale. However, during speaking, exercise, stress, etc. expiratory activity is supported by expiratory muscles due to the increased respiratory drive accruing from the build-up of carbon dioxide.
The inspiratory circuitry decreases the vagal nerve activity to our hearts via inhibition of the cardiac vagal motoneurons in the brainstem, to thereby increase the heart rate. Once the inspiratory circuitry is disengaged this so-called vagal break is removed. This then switches the vagal drive to the heart back on to actively slow the heart rate down. Some of the fit young athletes (18-20-year olds) I have tested dropped their heart rates by more than 40 beats a minute with one deep slow out-breath!
I typically do my 10 sec deep breathing exercises just after midday to resynchronise my heart-brain-body loop. Note that this is a form of physical activity that necessitates your complete focus and engagement. Start by taking a sharpish 3 second in-breath followed by a 1 second post inspiratory lag, before taking an active and prolonged out-breath over 6 seconds. It is best to time your 10 sec breaths to be most effective. The gold standard is to take 60 breaths over 10 mins; but taking a minimum of 30 breaths over 5 minutes will also be heart healthy and improve your performance!
Follow your heart, but only if you know who is leading who.
If your Fight and Flight response is activated for whatever reason, you can kiss modulating your cardiac vagal motoneurons via your Primate brain – whether indirectly by engaging the appropriate brain state or more directly via breathing – goodbye. Powerful as the out-breath is in calming our hearts, the breath becomes part of the problem when our innate Fight and Flight responses highjacks our breathing rhythms & breathing aligned heart rhythms. As we saw above, the BP rhythm is a 10 second rhythm, which is noticeably slower than our ~4 second spontaneous breathing rhythms and much slower than our panicked 2-3 sec breathing rhythms. By training our Mammalian brain and bodies to align our heart rhythms directly with our innate 10 second BP rhythm, it is possible to remain composed even during high pressure situations.
Whenever the weight of responsibility bearing down on you becomes too great a burden, then take active steps to ensure that your heart stays closely aligned with your 10 second BP rhythm. But whatever you do – if your heart does become aligned with your flighty breathing rhythm when you are under pressure – DO NOT follow it there.
Spring Special for the months of August/September: Book now for a 2-session Zoom workshop with Dr Laurie on aligning your heart with your 10 sec BP rhythm for R950. Normally valued at R1250.