Maria Schilt, Age 64
In my earlier post on vagal tone Vagal Tone and Yoga, I described the vagus nerve and the wide-ranging tasks it regulates, including heart rate, breathing, respiration and digestion, peristalsis of gut, small intestine and colon, sweating, muscle movements in the mouth, speech, and hearing. The vagus nerve, which is the 10th cranial nerve and the largest of the cranial nerves, starts at the base of the skull and extends all the way down to the heart, lungs, digestive tract, and other abdominal organs, and transmits information between the brain and these internal organs.People with optimal vagal tone are more resilient under stress and can easily shift from an excited state to a relaxed state and vice versa without getting unduly perturbed. These individuals tend to have good resistance power and are healthier. In contrast, a low vagal tone is linked to inflammation, emotional stress, negative moods, and heart attacks. People with low vagal tone are easily disturbed, have weak digestion, and frequently suffer from physical, mental and emotional instability. Thus, an optimal vagal tone is linked to physical and psychological well-being while an under-performing vagal tone is linked to sickness, negative moods, depression, and heart issues.
Since the vagal tone defines the functional status of the vagus nerve, it may seem obvious, then, that people with an optimally active vagal tone switch on the parasympathetic nervous system and exhibit “feel good and cool attitude” as opposed to individuals with a low vagal tone who exhibit an increased activity of the sympathetic nervous system and are basically in a stress or Fight or Flight mode (see Heart Health and Yoga: An Overview). Better prognosis of the health status can be predicted by the strength of the vagal tone especially in people who are recovering from chronic diseases. However, vagal tone is not static; it keeps fluctuating based on our activities, lifestyle, and moods. We all need to strive to increase the activity of the vagal nerve to optimal levels and sustain that optimal tone. Today’s write up is about yoga practices that keep the vagal tone optimally functioning.
Asanas and Vagal Tone
Since the vagus nerve innervates the chest, any kind of practices or activities that influence the energy flow through the vagus nerve will have a profound effect on the respiration and circulation. Yoga asanas coupled with the breath stimulate electrical and mechanical activities in the body. The electric activity is reflected in the vagus nerve stimulus that initiates in the brain and travels deep down to the organs for mechanical actions to be initiated. The mechanical action is in the form of:
- contraction and relaxation of most if not all of the skeletal muscles of the body
- rapid flow of blood and lymph through the arteries and lymph glands respectively
- pumping action of the heart
- smooth venous return
Gentle or full inversions, a flow sequence that involves moving into each asana from Sun Salutations (Surya Namaskara), and gentle backbends all optimize the vagal tone, gradually warm up the body and the cardiovascular system, and strengthen and stretch the connective tissue and muscles that line the abdomen thus facilitating more efficient flow of blood.
Inverted Poses. These poses use gravity (the heart is superior to the head) to control the blood pressure. In addition to full inversions, such as Headstand and Shoulderstand (Sarvangasana), there are several “partial” and” gentle” inversions that are as effective at stress reduction as full inversions (see All About Supported Inversions). Classic examples are Legs Up the Wall pose (Viparita karani) and Supported Bridge pose (Setu Bandha sarvangasana). The relaxation achieved with these partial/gentle inversions is similar to that achieved from restorative poses.
Flow Sequences. These sequences involve moving into an asana from Sun Salutations. Such a sequence cultivates agility, benefits the heart, stretches the muscles, and facilitates the blood flow (Cultivating Agility with Yoga). Thus, flow sequences are invigorating, and can be highly stimulating (a sign of optimal vagal tone) especially if the individual is feeling dull, depressed or lethargic.
Backbends. These poses also help relieve sluggishness, dullness, and lethargy (a sign of improved vagal tone). Standing poses could be modified to include a backbend as in Mountain pose (Tadasana) with the arms raised overhead into a slight backbend. From here, exhale, bring the arms down to the floor and initiate your Sun Salutations. Even a resting pose like Savasana could be modified such that the torso is supported by a bolster or stack of blankets, thus opening the chest and also allow the back to be in a slight backbend.
All of the above sequences have a quieting effect on the nervous system, encouraging a shift from Fight or Flight mode to Rest and Digest mode, a hallmark of an optimally functioning vagus nerve.
Pranayama and Vagal Tone
While we do not have a control over the autonomic nervous system, through pranayama (breath practices), we can make a shift from Fight or Flight mode to Rest and Digest. Remember, you can voluntarily alter your breathing, and this is the key to modify the energy flow through the vagus nerve and thereby alter the nervous system as well. This is a technique you can use in times of acute stress. In this case, pranayama practice should involve longer exhalations than inhalations, for example, a one-second inhalation and a two-second exhalation (see Pranayama: A Powerful Key to Your Nervous System) to calm down that stress response. Additionally, humming on the exhalation as in Bhramari Pranayama (see Pranayama for Everyone: Brahmari Breath), or a slow exhalation as in Sitali breath (see Yoga for Menopause: Managing Hot Flashes) will slow down the rapid heart rate as well. This decreased heart rate sends a message to the brain that circumstances are more peaceful, and this stimulates the parasympathetic portion of the autonomic nervous system to allow the individual to calm/ rest, recover, and heal in the Rest and Digest mode. So pranayama practices that lengthen the exhalation are excellent to optimize the vagal tone.
If your inhalations and exhalations are the same length, for example, by intentionally taking a three-second inhalation and a three-second exhalation or by practicing alternate nostril breathing, you are affecting the vagal tone very subtly depending on your current state (Balancing Your Nervous System with Alternate Nostril Breathing). So this practice is good to sustain the optimal vagal tone that will harness the mind in the present moment without having a strong effect on the nervous system.
Take Home Message: Start the day by taking a few deep breaths and do not forget your daily asana practice. Your vagal tone will be happy, and your body and brain will thank you for it!
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