Improve Autonomic Nervous System Function with Yoga
By John M. de Castro, Ph.D.
“Among its many beneficial effects, yoga has been shown to increase strength, flexibility, and balance; enhance immune function; lower blood sugar and cholesterol levels; and improve psychological well-being.” – Timothy McCall
There is an accumulating volume of research findings to demonstrate that Mind-body practices have highly beneficial effects on the health and well-being of humans. These include yoga, tai chi, and qigong, among many others. Because of their proven benefits the application of these practices to relieving human suffering has skyrocketed. Yoga practice has been shown to have a large number of beneficial effects on the psychological, emotional, and physical health of the individual and is helpful in the treatment of mental and physical illness.
One way that these Yoga may have their beneficial effects is by providing balance in the autonomic nervous system. The sympathetic division underlies activation while the parasympathetic division underlies relaxation. When these divisions are out of balance the individual may be overly stressed or overly sedentary. Appropriate balance is important for health and well-being. A measure of balance is provided by the parasympathetic produced baroreflex. It regulates blood pressure fluctuations.
In today’s Research News article “Autonomic Tone and Baroreflex Sensitivity during 70° Head-up Tilt in Yoga Practitioners.” (See summary below or view the full text of the study at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7735502/ ) Anasuya and colleagues recruited adults aged 20-50 who were aged matched and either yoga-naïve or trained experienced yoga practitioners. The participants underwent a 70 degree head up tilt. “Participants lay on the table and the table is tilted from a supine position to an angle of 70° at a speed of ~2.3°/s. Each subject was held at 70° HUT position for 5 min.” They were measured before during and after the tilt for blood pressure, respiration, respiratory carbon dioxide, and electrocardiogram (ECG).
They found that at rest the yoga group had significantly lower respiration rate at rest and significantly higher respiratory carbon dioxide at rest and also during the tilt. They also found that during the tilt the yoga practitioners had a significantly larger baroreceptor response, that is decrease in blood pressure, and a significantly larger increase in heart rate variability.
Both increases in the baroreceptor sensitivity and heart rate variability are indicative of increased activity on the Vagus nerve producing increased parasympathetic (relaxation) activity and decreased sympathetic (activation) activity in the autonomic nervous system. Hence, yoga practice produces a greater relaxation response in the practitioners at rest and when challenged with a tilt. This suggests that yoga practice alter the autonomic nervous system to produce a larger parasympathetic dominance and thereby greater ability to physiologically relax. In essence this reduces stress responses. Such improvements in the practitioner’s ability to deal with stress may underlie, at least in part, many of the health benefits of yoga practice.
So, Improve Autonomic Nervous System Function with Yoga.
“Yoga is a practice which helps regulate the nervous system. Yoga trains our mind and body to find a healthy balance within our nervous system, or in other words to help our bodies find homeostasis.’ – Anne Spear
CMCS – Center for Mindfulness and Contemplative Studies
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Anasuya, B., Deepak, K. K., & Jaryal, A. K. (2020). Autonomic Tone and Baroreflex Sensitivity during 70° Head-up Tilt in Yoga Practitioners. International journal of yoga, 13(3), 200–206. https://doi.org/10.4103/ijoy.IJOY_29_20
The intervention of yoga was shown to improve the autonomic conditioning in humans evident from the enhancement of parasympathetic activity and baroreflex sensitivity (BRS). From the documented health benefits of yoga, we hypothesized that the experience of yoga may result in adaptation to the orthostatic stress due to enhanced BRS.
To decipher the effects of yoga in the modulation of autonomic function during orthostatic challenge.
Materials and Methods:
This was a comparative study design conducted in autonomic function test lab, of the Department of Physiology, All India Institute of Medical Sciences, New Delhi, India. Heart rate variability (HRV), blood pressure variability, and BRS were analyzed on forty naïve to yoga (NY) subjects and forty yoga practitioners with an average age of 31.08 ± 7.31 years and 29.93 ± 7.57 years, respectively. All participants were healthy. Seventy degrees head up tilt (HUT) was used as an intervention to evaluate the cardiovascular variability during orthostatic challenge.
During HUT, the R-R interval (P = 0.042), root mean square of succesive R-R interval differences (RMSSD) (P = 0.039), standard deviation of instantaneous beat-to-beat R-R interval variability (SD1) (P = 0.039) of HRV, and sequence BRS (P = 0.017) and α low frequency of spectral BRS (P = 0.002) were higher in the yoga group. The delta decrease in RRI (P = 0.033) and BRS (P < 0.01) was higher in the yoga group than the NY group.
The efferent vagal activity and BRS were higher in yoga practitioners. The delta change (decrease) in parasympathetic activity and BRS was higher, with relatively stable systolic blood pressure indicating an adaptive response to orthostatic challenge by the yoga practitioners compared to the NY group.