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Why is the duration of exhalation longer than inhalation in pranayama practices?
The process of inhalation activates the sympathetic nervous system and exhalation activates the parasympathetic nervous system.
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Sanjeev K Yadav
Photo by Ivan Samkov/Pexels
The mechanism of breathing
During breathing, the air in and out of the lungs is accomplished through the coordinated action of several muscles, including the diaphragm, intercostal, and abdominal muscles. The breathing process involves inhalation and exhalation, and the nervous system regulates each phase.
Inhalation occurs when the diaphragm contracts and moves downward while the intercostal muscles between the ribs contract and lift the rib cage upward and outward. This increases the volume of the chest cavity and creates a negative pressure gradient, causing air to rush into the lungs. Inhalation is controlled by the respiratory center in the brainstem’s medulla oblongata, which sends nerve impulses to the thorax and abdomen muscles to coordinate their actions.
Exhalation, on the other hand, is a passive process that occurs when the diaphragm and intercostal muscles relax, causing the chest cavity to decrease in volume. This increases the pressure within the lungs, forcing air out of the respiratory tract. Exhalation is also influenced by the respiratory center in the medulla oblongata, which signals the muscles to relax.
The respiratory center in the medulla oblongata receives input from chemoreceptors that monitor the levels of oxygen and carbon dioxide in the blood. When oxygen levels are low or carbon dioxide levels are high, the respiratory center sends signals to increase the rate and depth of breathing, which can result in more forceful inhalation and exhalation. Additionally, other brain regions, such as the cerebral cortex and hypothalamus, can influence breathing by altering the activity of the respiratory center.
The process of inhalation and exhalation during breathing is controlled by the nervous system, specifically the respiratory center in the medulla oblongata of the brainstem. Inhalation is an active process that involves the contraction of the diaphragm and intercostal muscles, while exhalation is a passive process that occurs when these muscles relax. Chemical and neural signals and higher brain regions can influence the rate and depth of breathing.
The sympathetic and parasympathetic nervous system
The sympathetic nervous system is responsible for many automatic functions, such as controlling heart rate, blood pressure, and breathing rate. According to the National Heart, Lung, and Blood Institute, the sympathetic nervous system increases breathing rate. Therefore, it can be inferred that the sympathetic nervous system is activated during inhalation, increasing the breathing rate to ensure the body receives enough oxygen. However, it’s worth noting that slow, deep breathing, which activates the parasympathetic nervous system, can relax and reduce overall blood pressure.
Exhalation can activate the parasympathetic nervous system. The parasympathetic nervous system is responsible for the “rest and digest” response in the body and is activated during relaxation. Deep, controlled exhalation is one technique that can activate the parasympathetic nervous system and induce a relaxation response in the body. Spending time in nature, getting enough sleep, and practicing deep breathing are other techniques that can strengthen and activate the parasympathetic nervous system. In addition, breathing exercises that emphasize extended, controlled exhalation effectively activate the parasympathetic nervous system and reduce anxiety.
Pranayama, SNS and PNS
Pranayama, a yogic practice involving breath control, has been found to impact the autonomic nervous system (ANS). The ANS has two branches, the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). The SNS controls the body’s stress response, while the PNS promotes relaxation and restoration. Pranayama is believed to help balance the activity of the ANS by increasing PNS activity and decreasing SNS activity.
Specifically, slow and controlled breathing techniques, often part of pranayama practice, can help activate the PNS by stimulating the vagus nerve. This can decrease heart rate and blood pressure, inducing relaxation and reducing anxiety. Pranayama has also been found to decrease allostatic load, which is the cumulative impact of chronic stress on the body, and to increase GABA activity, the primary inhibitory neurotransmitter system in the brain.
In summary, longer exhalation during pranayama practices can regulate the functions of the sympathetic and parasympathetic nervous systems by increasing PNS activity and decreasing SNS activity, leading to relaxation and reducing anxiety.
About the Author
Sanjeev Yadav, M.A. Yoga, P.G. Psych., DNHE
Mr. Sanjeev is a yoga professional specializing in applied yoga, psychology, and human excellence with over more than 8 years of experience as a health and life coach, well-being trainer, and psycho-yogic counselor. He is completing his Ph.D. dissertation in Yoga.
