How yoga therapy works: Part 1

Yoga therapy is an emerging profession in the West, so perhaps the most common question yoga therapists receive is, “What IS yoga therapy, anyway?” ( has a section devoted to the answers.) Put simply, yoga therapy is the specific application of yoga tools—postures, breathwork, meditation, and more—to support an individual’s physical, mental, emotional, and spiritual needs. The positive effects of yoga have led doctors and scientists to research the practices in an effort to explain how they work. Below is one of the mechanisms behind yoga’s effects—future posts in this series will explore others.

Many studies* have shown that yoga can stimulate the parasympathetic nervous system, a primary agent in reducing stress.

Stress and the urge to breathe

Our systems register stress when the sympathetic branch of the autonomic nervous system (ANS) is activated. In contrast, relaxation is correlated with activation of the parasympathetic branch of the ANS. Physiological responses that occur in both ANS branches can be measured, providing a starting point for medical and scientific approaches to understanding yoga.

One such measurement is chemoreflex sensitivity. Chemoreflex is the dominant control mechanism for how we breathe: It tells our systems to breathe in, as well as how fast and how deep. Chemoreflexes respond to the amount of oxygen or carbon dioxide in our blood. When either level is lower than what our systems are accustomed to or need, the chemoreflex initiates an inhalation. The chemoreflex response is a sympathetic nervous system response: In essence, it is sensing a problem with our oxygen level, which is a survival issue. The system is now stressed. If this happens repeatedly due to disease or poor breathing patterns or mechanics, the body is chronically stressed.

Chronic stress is related to a range of conditions, including metabolic syndromes, cardiovascular pathology, inflammatory disorders, anxiety, depression, and decreased neuroplasticity and neurogenesis. Sympathetic nervous system activation and chronic stress set off cascades of physiological events in the body that contribute to the disease state. Interrupting these sequences is therapeutic and this is where yoga can help.  Many studies* have shown that yoga can stimulate the parasympathetic nervous system, a primary agent in reducing stress.

Yoga and parasympathetic nervous system response

Breathing is about gas exchange. We take in oxygen, it bonds to hemoglobin in our blood, and travels to our tissues. If the right amount of carbon dioxide is present, the oxygen lets go of the hemoglobin and goes into the tissues; the hemoglobin takes the carbon dioxide back to the lungs and we exhale it out. If not enough carbon dioxide is present, the oxygen won’t let go and you will gasp for air, which will continue the cycle. 

Deep, slow breathing—as you might do as part of a yoga therapy session—is associated with parasympathetic activation, decreased chemoreflex sensitivity, and stress reduction. By practicing this type of diaphragmatic breathing you can optimize the oxygen-carbon dioxide gas exchange, maintain parasympathetic activation, and reduce stress. The slow rhythm of this type of breathing produces several other physical and physiological changes, too, which we will discuss in subsequent posts.

*For example: 

Effects of a yoga-based stress reduction intervention on stress, psychological outcomes and cardiometabolic biomarkers in cancer caregivers: A randomized controlled trial

Effects of yoga and mindfulness practices on the autonomous nervous system in primary school children: A non-randomised controlled study

Effects of mind-body exercises (tai chi/yoga) on heart rate variability parameters and perceived stress: A systematic review with meta-analysis of randomized controlled trials