Yoga's power to boost energy whilst simultaneously evoking the parasympathetic healing mechanisms lie in the combination of Asana or specific postures with breath technique.
Consistent practice of yoga postures and pranayama increases overall lung function and boosts our overall stamina and efficiency.
Ashok at al observe
Back bending postures open the chest, improving both lung and heart functions.
Upper back bends and chest opening postures relieve hardness if it is harder to exhale during asthma attacks.
Forward bends and lower back bending poses relieve difficulty if it is more difficult to inhale. Inverted postures drain excess mucus from the lungs and balance the immune system.
A general yoga practice reduces stress, physical tension, and muscle tightness and increases overall feelings of well being by activating the parasympathetic nervous system.
Blood carries oxygen in two forms, the majority is bound to haemoglobin and the rest is dissolved in the aqueous phase of blood (the plasma). The dissolved fraction is dependent upon the partial pressure of oxygen. As the partial pressure increases, the dissolved fraction of oxygen increases. (1)
Human metabolism is the result of continuous anabolic and catabolic processes that maintain homeostasis and sustain life. Metabolic pathways include a complex network of inputs that are integrated by the nervous systems through pathways that monitor and maintain physiological functioning. All metabolic processes generate heat and are ultimately dependent on the expenditure of energy via consumption of oxygen, which drives oxidative phosphorylation.
The measurement of oxygen consumption can provide insights into overall homeostatic balance and response to stress, which are mediated through multiple pathways under the control of the autonomic nervous system and the hypothalamus. The sympathetic nervous system is involved in rapidly mobilising vital functions via sympathetic–adrenal–medullary pathways in response to acute stress which serves to increase oxygen consumption. Repeated or chronic stressful stimuli may lead to changes in the hypothalamic–adrenal–pituitary axis reducing the stress response involving cognitive, emotional, endocrine, and immune system changes. The parasympathetic nervous system provides a counter to the stress response reducing oxygen consumption by via enhanced vagal activity. Such hypo-metabolic states are suggested to enhance survival in plants and animals by facilitating restorative and repair functions.
Yoga has profound metabolic effects producing both increase and decrease in oxygen consumption, ranging from 383% increase with cobra pose to 40% decrease with meditation. Compared to non-yogis, basal oxygen consumption is reported to be up to 15% less in regular yoga practitioners, and regular yoga practice is reported to have a training effect with oxygen consumption during submaximal exercise decreasing by 36% after 3 months. (2)
Yoga breathing practices emphasise breathing patterns and retention ratios which appear critical in influencing oxygen consumption. A number of studies report extraordinary volitional control over metabolism in advanced yoga practitioners who appear to be able to survive extended periods in airtight pits and to exceed the limits of normal human endurance.
References and further reading:
(1) Ashok C Impact of asanas and pranayama on blood oxygen saturation level British Journal of Sports Medicine 2010;44:i69. First published December 17, 2010.
Available at: https://bjsm.bmj.com/content/44/Suppl_1/i69.1.info
(2)Journal of Evidence-Based Complementary & Alternative Medicine, Vol 18, Issue 4 page(s): 290-308I, October 1, 2013
Available at: https://journals.sagepub.com/doi/10.1177/2156587213492770