There is no fixed physical reality, no single perception of the world, just numerous ways of interpreting world views as dictated by one’s nervous system and the specific environment of our planetary existence.
— Deepak Chopra
Our nervous system is constantly changing in response to our interaction with our environment. When that environment is our yoga mats, the changes can be quite profound. Understanding the different branches of the nervous system and how it relates to yoga is extremely useful information. When we feel tensile resistance in a stretch it is our nervous system firing for protection. When we feel that sublime calm after meditation or savasana it is our nervous system that has triggered drastic changes within our body.
Our nervous system is the key to applying different techniques that allow us to physically move deeper into a stretch, as we saw in previous posts. We cannot will ourselves to change the structure of our bodies in a given moment, but we can change how our nervous system is operating to create relaxation and diminish the factors that are limiting us.
Different styles of yoga alter which branch of our nervous systems is dominant. We can tailor our personal practices accordingly. If we are looking to lose weight, a dynamic practice will cause our nervous system to increase our metabolism. If we are looking to relax and allow our bodies to regenerate, a passive practice will shift our nervous system into healing mode. Let’s explore the different branches of our nervous system and the aspects associated with each.
The Main Branches
The nervous system is broken down into two main divisions: the central nervous system (CNS) and the peripheral nervous system (PNS). The central nervous system includes the brain and the spinal chord. The peripheral nervous system includes all of the nerves outside of the spine and brain.
The central nervous system is in charge of analyzing and interpreting data received from the peripheral nervous system. First let’s look at the two main types of neurons in the body.
- Afferent Neurons: These neurons carry information towards a central point, usually the brain.
- Efferent Neurons: These neurons carry information away from a central point.
The PNS is subdivided into the somatic and autonomic systems. The somatic system deals with voluntary functions and movements (like typing on a keyboard) while the autonomic system deals with our involuntary functions (like our heart rate). The autonomic nervous system subdivides once more into two branches:
- Sympathetic: this system is constantly engaged as it deals with our natural “fight or flight” response. It is always active to some degree so that our bodies are prepared to respond to any threats that arise suddenly.
- Parasympathetic: this system is not constantly engaged and deals with relaxation and functions like digestion.
Our bodies shift between sympathetic and parasympathetic dominance depending on what we are doing. Any activity that increases our heart rate and rate of respiration is going to encourage sympathetic dominance.
While the sympathetic system is dominant:
- Our catabolism increases so our bodies are prepared to break down stored fats into useful energy.
- Blood flow is directed towards the heart and brain so we are more prepared for action in response to stress. To compensate, blood flow is directed away from the digestive, reproductive, and eliminatory organs.
- The nerves activate the thyroid and adrenal glands to provide extra energy for when we decide to ‘fight’ or ‘flight’.
- Levels of cortisol, the stress hormone, are typically higher.
Any activity that decreases our heart rate and breathing rate is going to encourage parasympathetic dominance.
While the parasympathetic system is dominant:
- Our anabolism increases so our bodies use energy to combine smaller molecules to make larger, more complex molecules (like creating stored fats). This allows the body to grow new cells and maintain its existing tissues.
- Blood flow is directed from the muscles to the digestive, reproductive, immune, and eliminatory organs. This is why most digestion occurs while we are sleeping. It is also a reason why orgasms are common for women during sleep and erections are common for men.
- Relaxation occurs leading to lower levels of stress hormones.
We can generalize to say that the sympathetic system is designed to defend our bodies against harm while the parasympathetic system is designed for healing, elimination, and regeneration of the body. In today’s society, we tend to spend too much time in sympathetic dominance. This leads to a build up of stress hormones which can manifest in disease or degeneration of the body. If we are leading an overactive life and not obtaining enough sleep, we are spending too much time in sympathetic dominance.
(There is a third branch of the nervous system that is rarely mentioned: the enteric nervous system. We know much less about this system, yet new findings are revealing that it may play a much larger role than we realize. A later post will be devoted entirely to this topic.)
Yoga’s Role In Maintaining Balance
Yoga is a highly effective way of balancing out which system is dominant. Active styles of yoga, what I like to refer to as dynamic yoga, engage the sympathetic nervous system. These include ashtanga, active vinyasa, kundalini, power yoga, and any other style of yoga in which the heart rate is increased. More restorative styles of yoga and meditation engage the parasympathetic nervous system. These styles include yin, restorative, yoga nidra, or any activity that lower our heart rate and induces relaxation.
Does that mean that if we have an overactive lifestyle dynamic yoga is creating more stress for ourselves? Not so, due to the intelligent design of yoga classes. At the end of every yoga class is a period of rest during savasana. During this time we become human ‘beings’ instead of human ‘doings’. Resting for 5-10 minutes or more in savasana greatly decreases our heart rates and shifts us into parasympathetic dominance. The feeling of relaxation and release is sometimes even greater after an active practice because we have been tiring our muscles and using up energy. In fact, studies have shown that relaxation after a vigorous practice leads to deeper relaxation than relaxation by itself.
Just like a healthy yoga practice balances out strengthening and lengthening, it also should balance between activity and relaxation. Imagine the symbol of a yin-yang. Our active yang yoga stretches muscles and increases strength. Our more passive yin yoga stretches connective tissues and provides healthy stress to our bones, while promoting relaxation.
If we were to stay in sympathetic dominance all the time it would be like a country spending an exorbitant amount on the military for self-defense at the expense of education and the arts. Conversely, if we were to stay in parasympathetic dominance all the time it would be like a country spending all its money on education and the arts but having no security from outside threats. Just like governments attempt to balance spending between defense and culture (some more effectively than others), our bodies are striving for homeostasis between being prepared for any dangers and relaxing and healing.
The nervous system is the main communicator in the human body. So let’s listen to what it has to say. When a stretch feels particularly juicy, feel free to stay there and enjoy the sensations. When a stretch involves a level of discomfort, see if you can explore that discomfort with a curious mind and get to know it better. When a stretch transforms from discomfort to pain, listen to your body and modify! This is your chance to actually listen to the intuitive aspects of your body instead of your ego! There are always modifications and alternatives and yoga is a practice that develops over time, so stay patient.
Our bodies are constantly communicating to us, whether we listen or not. When we feel tired, it is our bodies way of asking us to slow down. Instead of reaching for a coffee or energy drink, maybe try a relaxing form of yoga or meditate for a bit. Sometimes when we are sluggish and feel in a rut, an energizing practice is just what we need to kick start our system. Yoga promotes being in touch with your inner self and how you truly feel. Not only physically, but mentally and emotionally.
The throat chakra is associated with communicating with others, and ourselves. Strive to listen to the truth of your body, tell the truth to others, and express your true self in a healthy way, no matter what form it is. We are all different and our yoga takes different forms, often different from doing asana on a yoga mat. Find what form your body is asking for this unique day and remember to share your uniqueness with others. After all, sharing your passions with others is one of the highest forms of communication!