Chapters : Heart rate and the Autonomic Nervous System ; Heart Rate Variability (HRV) ; Vagus Nerve ; Neural Exercises ; Nadis
HEART RATE AND THE AUTONOMIC NERVOUS SYSTEM
A normal healthy heart rate has 65 to 72 beats per minute.
The Autonomic Nervous System is composed of :
The Parasympathetic Nervous System (PNS), which slows the heart rate down
The Sympathetic Nervous System (SNS), which accelerates the heart rate.
Any activity, or just a thought of action (thinking about running, feeling anxious, making plans for something, etc...), causes the Sympathetic Nervous System to be activated in a more dominant manner (because it is always activated, but not always dominantly), which increases the heart rate.
When we move back to a calmer state, or a state of non-activity, then the Parasympathetic Nervous System becomes dominant, and the heart rate slows down.
This also happens with respiration :
When we inhale, the Sympathetic Nervous System is activated so the heart rate speeds up slightly.
When we exhale, the Parasympathetic Nervous System is activated, and our heart rate slows down a little.
HEART RATE VARIABILITY (HRV)
In a heart rate, the measure of two top waves (which are beats), from the R to R waves, is the measure which is taken in Heart Rate Variability. It is called the beat to beat difference.
The heart rate has to change constantly from more and less activity. It is normal. If our heart rate was the same all the time, with no waves at all, it would be represented by a flat line, and that would mean death of the physical body.
Poor or low Heart Rate Variability is associated with stress, inflammation, or more serious diseases.
Good or high levels of Heart Rate Variability is associated with Resiliency (our ability to bounce back from anything : illness, anxiety, etc...).
Resiliency is one of the characteristics to Homeostasis (homeostasis is our body's ability to always go back into balance).
When we measure all the beats of the heart, in comparison to how we breathe, we're getting a very good idea about how our Autonomic Nervous System is making us function physiologically.
Is the Sympathetic Nervous System optimally doing what it is supposed to do (getting us ready to fight or flight) ?
Is the Parasympathetic Nervous System optimally doing what it is supposed to do (slowing us down and bringing us towards a rest and repair state) ?
VAGUS NERVE
The Vagus Nerve, which contains motor and sensory fibers, is the longest nerve of the Autonomic Nervous System, from the brainstem to the intestines.
Within the Vagus Nerve, we have information going in both directions, although 80% of the nerves are sensory.
For example, if we put our finger on a candle flame, we're going to feel the heat (a sensation is a sensor information), so we will automatically jerk the finger away (a reaction is a motor activation) without even thinking about it.
The information comes down from the brainstem, goes into the soft palet, the larynx, the trachea, the heart, the lungs, the liver, the spleen, the pancreas, the kidneys, the large intestine, and the small intestine.
The sub-diaphragmatic level is :
Everything below the diaphragm
The digestive organs, containing the microbiome (which is the digestive tract, composed of more or less 90% bacteria, and only about 10 % human genetic material). From the microbiome, many signals are sent up from the visceral organs to the brain, to tell the brain what is the condition of our internal organs (digestive organs, liver, spleen, kidneys, etc…), what needs to be done, how does the brain need to adjust the rest of the body mechanisms, in relation to what's happening in the gut.
The super-diaphragmatic level is :
Everything above the diaphragm
Information from the heart and the lungs is also coming to the brain, passing through the vagus nerve first.
Charles Darwin referred to the Vagus Nerve as “the nerve plexus of the expression of emotion”, because it is the Vagus Nerve that makes us able to modulate our vocal tone, and this is how we express many emotions like crying, laughing, screaming, using a high pitch tone to talk to a baby, a deeper voice to reprimand someone, etc...
The Vagus Nerve also has connections going to the inner ear (more specifically the cochlea), where we're able to discern and understand modulations of vocal tone.
NEURAL EXERCISES
Stephen Porges, scientist who created the Polyvagal Theory, has identified neural exercises that strengthen our nervous system.
Balance of the Autonomic Nervous System (ANS) through Sadhanas (= exercises) :
1. Behavior :
Heart-brain axis (emotions are linked to the heart, and the heart is linked to the brain
Meditations (full of love and kindness)
Yamas : Ahimsa (always being kind towards other beings, never harming any human or animal) ; Satya (always being truthful and honest) ; Asteya (never stealing anything from anyone) ; Brahmacharya (being moderate and overcoming impulses, addictions, sexual desires, etc... ; Aparigraha (letting go of, and not wanting, what we don't need)
2. Vocalizations :
Effect on the laryngeal nerves (nerves in the larynx)
Breathing with sound, constricting the glottis, making a vibratory effect through the larynx, which is stimulating the vagal tone
Yogic chanting, or any kind of singing (mantra, classical, jazz, blues, soul, modern, etc...)
3. Pranayama (Breathing control) :
Practices consisting of controlling inhales and exhales, breathing through one nostril at a time, retaining the breath, etc..., which balance the two branches of the Autonomic Nervous System.
Learning to breathe freely within the Asanas (physical postures), so that our breathing becomes balanced, and then the Sympathetic and Parasympathetic Nervous Systems also become balanced.
Practicing Mula Bandha and Uddiyana Bandha, because it sends signals up through the nervous system, through the Vagus Nerve, to the brain, to give info on how we want to balance our nervous system.
4. Asana :
The sense organs are connected with the nervous system. So in order to control the senses, we have to make our nervous system strong. In order to make the nervous system strong, our breathing has to be correct. And for our breathing to be correct, the Asana needs to be correct.
Every time we stand up straight or hold ourselves in a posture, we send a message through the carotid baroreceptors (artery), through the Vagus Nerve, to the brain, to indicate something about balancing or regulating our blood pressure.
Mood change associated with the posture (being all curled up on our chair, as if we were sad, or sitting straight, as if we're present and ready)
Bhavana : Emotion ; Mood ; Attitude ; Feeling good while doing yoga, wether we feel tired, or sad, or stiff, we must put that aside during practice, and just feel good. When the mind is quiet, the Asana is correct. It doesn't matter how flexible or stiff we are, because when our mind is quiet, then the posture has achieved its desired result.
NADIS
Nadi (nadī नदी), which means river, artery, vein, pulse, nerve, blood vessel, tubular organ, is an important concept in Hindu Philosophy. The number of Nadis in the human body differs from one system to another. According to Tantric texts, the human body contains 72,000 Nadis that channel Prana (our vital energy, our life force) to every cell of our body. Others claim there are millions of Nadis within us. But overall, three are considered the most important, or known, Nadis. They are :
Pingala Nadi, which represents : Ha (Sun) ; Masculine energy ; Logic ; Language ; Math ; Walking in a straight line ; Talking in a monotone voice ; Active Sympathetic Nervous System ; Inhaling ; Right nostril (people who think all the time, are super mentally active and a little stressed out, find their right nostril clogged more often than the left, which is more often open)
Ida Nadi, which represents : Tha (Moon) ; Feminine qualities ; Emotions ; Intuition ; Poetry ; Dance ; Singing ; Cooling Parasympathetic Nervous System ; Exhaling ; Left nostril (people who are more intuitive, more responding to the arts and emotion, and seeing things in a holistic fashion, find their left nostril clogged more often than the right, which is more often open)
Sushumna Nadi, which represents : Central column, where Kundalini moves from under the navel up to the top of the head
