How Asanas Improve Lung Function - Scientific Relevance to Pulmonary Disease

       

Depicting an asana

        In our pursuit of enhancing lung function and mitigating pulmonary diseases, integrating asanas (yoga postures) offers a scientifically validated, anatomical approach. 

Let me elaborate on it anatomically -

Fundamental Anatomy of the Respiratory System-

    Before detailing the benefits of yoga practices, it is crucial to grasp the anatomical structure and physiological function of the lungs -

3-D image of human lungs

Bronchial Tree & Airways - The trachea bifurcates into primary bronchi, secondary and tertiary bronchi, culminating in bronchioles. These airways facilitate air passage and distribute it uniformly to the alveoli.

Alveoli and Gas Exchange - Millions of alveolar sacs, lined with a thin epithelial membrane and surrounded by capillaries, enable the diffusion of oxygen (O₂) into blood and the removal of carbon dioxide (CO₂).

Diaphragm & Intercostal Muscles - Primary drivers of ventilation, contracting during inspiration to enlarge thoracic volume and relaxing during expiration.

Pleura and Lung Lobes - Each lung is encased in pleural membranes, providing frictionless movement within the thoracic cavity. The right lung has three lobes; the left lung has two lobes, accommodating cardiac space.

Respiratory Centres - These centres, which are found in the medulla oblongata and pons, control breathing rhythm, depth, and rate in response to input from mechanoreceptors and chemoreceptors.

Imagine a transparent 3D rendering of the thoracic cavity -

1. Diaphragm Movement - At rest, the dome-shaped diaphragm sits high in the thoracic cavity. During deep inhalation, it contracts, flattening downward, increasing vertical thoracic volume.

2. Rib Cage Expansion - Intercostal muscles contract, elevating ribs laterally and anteriorly, expanding the chest in a three-dimensional manner (anteroposterior, lateral, and vertical).

3. Bronchial Branching - Within the lungs, the trachea splits into two main bronchi. These branch into progressively smaller airways, culminating in a network of bronchioles that terminate in alveolar clusters.

4. Alveolar Exchange - Oxygen-rich air fills alveoli, diffusing into capillaries. Simultaneously, CO₂ from deoxygenated blood diffuses into alveoli for expiration. Visualise alveoli as balloon-like clusters inflating and deflating, tethered to capillary networks.

5. Pulmonary Circulation - The pulmonary arteries carry the right ventricle's deoxygenated blood, which then branches off into capillaries that encircle the alveoli.  Following gas exchange, oxygenated blood returns to the left atrium after collecting in the pulmonary veins.

6. Neural Feedback Loop - Stretch receptors in the lungs and chest wall send afferent signals to the respiratory centers, modulating breathing rhythm. Simultaneously, chemoreceptors in the carotid bodies and medulla detect blood gas changes, adjusting ventilation accordingly.

Impact of Specific Asanas on Lung Function and Pulmonary Health -

1. Bhujangasana (Cobra Pose) - Strengthening the Back Muscles and Extending the Thoracic Cage.

Cobra Pose

• Anatomical Focus - Spinal extension enhances intercostal muscle flexibility and sternal elevation, increasing anterior-posterior chest diameter.
• Physiological Effect - Cobra Pose actively engages paraspinal muscles, stretching the thoracic vertebrae and allowing greater lung expansion, thereby increasing tidal volume. Studies indicate that spinal extension postures reduce airway resistance by improving bronchial alignment.
• Pulmonary Disease Relevance - In conditions like chronic obstructive pulmonary disease (COPD), Cobra Pose helps combat thoracic rigidity, enhancing residual volume reduction and expiratory flow rates.
• Mind-Body Impact - This asana stimulates the parasympathetic nervous system, reducing sympathetic overdrive, lowering respiratory rate, and promoting calm mental states.

2. Matsyasana (Fish Pose) - Enhancing Upper Chest Expansion -

Fish Pose

• Anatomical Focus - Hyperextension of the cervical and thoracic regions lifts the sternum and clavicles, creating space beneath the rib cage apex.
• Physiological Effect -  By stretching the scalenes, sternocleidomastoids, and pectoralis minor, Fish Pose facilitates maximal inspiratory capacity. Enhanced upper chest flexibility improves upper lobe ventilation, crucial for efficient gas exchange.
• Pulmonary Disease Relevance - In asthma and restrictive lung disease, Matsyasana mitigates apical alveolar underinflation, reducing ventilation-perfusion (V/Q) mismatch.
• Mind-Body Impact - This posture reduces cortisol levels, promoting relaxation and alleviating anxiety-induced bronchoconstriction.

3. Ustrasana (Camel Pose) - Stimulating Diaphragm and Opening Anterior Thorax.

• Anatomical Focus - Diaphragm descent is made possible by a deep backbend that firmly extends the rectus abdominis, diaphragm, and obliques.
• Physiological Effect - Ustrasana improves diaphragmatic excursion by gently pressing abdominal organs downward, freeing the diaphragm to contract forcefully. An increased inspiratory reserve volume (IRV) is the result of a greater intra-thoracic volume.
• Pulmonary Disease Relevance - In pulmonary fibrosis, increasing IRV and lung compliance through lung tissue stretching can slow disease progression and enhance functional residual capacity (FRC).
• Mind-Body Impact - This posture triggers endogenous endorphin release, reducing perceived breathlessness and enhancing mindful awareness of breath.

4. Ardha Matsyendrasana (Half Lord of the Fishes Pose) - Promoting Thoracic Rotation and Lung Elasticity

Half Lord of the Fishes Pose

• Anatomical Focus - Intense spinal twist mobilizes thoracic vertebrae, stretching intercostal muscles on one side while compressing the opposite.
• Physiological Effect - Twisting encourages alveolar recruitment in underutilised lung regions, optimizing gas exchange. The alternation between stretch and compression serves as a passive bronchial drainage mechanism, facilitating mucus clearance.
• Pulmonary Disease Relevance - In diseases with bronchial congestion, such as bronchiectasis, this asana enhances mucociliary clearance and prevents atelectasis.
• Mind-Body Impact - Rotational poses balance hemispheric brain activity, promoting focused breathing and reducing anxiety-related respiratory irregularities.

5. Setu Bandhasana (Bridge Pose) - Enhancing Lung Capabilities and Respiratory Muscle Strength.

• Anatomical Focus - Elevation of the pelvis engages gluteal, hamstring, and paraspinal muscles, indirectly stretching the anterior chest wall.
• Physiological Effect - By creating an arch under the thoracic spine, Bridge Pose reduces thoracic kyphosis, improving vital capacity (VC). Long-term holds improve forced vital capacity (FVC) by strengthening the sternocleidomastoid and scalene muscles, which are accessory respiratory muscles.
• Pulmonary Disease Relevance - In restrictive lung disorders, increasing VC and improving chest wall compliance can mitigate rapid fatigue and exertional dyspnea.
• Mind-Body Impact - This asana stabilises the vagus nerve, improving heart rate variability (HRV) and promoting respiratory coherence.

        This article explores the direct impact of specific asanas and pranayama on pulmonary health, presenting detailed physiological mechanisms, research findings, and a descriptive 3D sketch of internal lung function. These practices strengthen respiratory muscles, optimise gas exchange, and modulate neurophysiological responses.

(Note - In my next article, on the same topic, I will elaborate and shed light on Pranayama.)

- Tanmay Bhati