The cells lining the bronchial tree are soothed by the improved blood flow and breathing mechanics of back bends. The sympathetic system being stimulated, the bronchi dilate. Constrictive activity is reduced with the lowered parasympathetic tone. During acute attacks such poses cannot be done by some patients. For such people forward bends are helpful.
Forward bends are useful during an attack, but the requirement varies from person to person.
The posterior lungs are made to open out or supported and rested, the secretions squeezed out and the nervous tone altered, relieving the stress on the lungs. Inverted poses condition the lungs for exertion of a particular kind. They flush the lungs free of accumulated toxins and enhance fresh blood flow, healing the irritated areas. The circulation of the bronchial tree has to be soothed and refreshed to prevent an allergic response. Props are usually needed.