As care was taken to match the two groups for age and sex and type, severity, and duration of asthma, we can attribute the improvement seen in the variables measured in the 53 patients in the Yoga group to the regular practice of yoga. The considerable reduction in their drug treatment score in contrast with a non-significant increase in intake of drugs in the control group strengthens this view, as do the significant differences between the groups in the number of attacks per week and peak flow rate.
McFadden clearly showed that the responsiveness of airways is noticeably increased in patients with asthma, who develop bronchoconstriction in response to smaller quantities of physical, chemical, and pharmacological stimuli than healthy subjects. A complex interplay of several factors namely, an inherent responsiveness of the smooth muscle to stimuli, an abnormality in autonomic nervous control, and a breakdown in airway defences may promote bronchial hyper-reactivity. Thus reducing the responsiveness of the tracheobronchial tree could benefit these patients considerably.
Abundant objective data now exist indicating that psychological factors can interact with the asthmatic diathesis to worsen or improve the course of the disease. The mechanisms of these interactions are complex and not well understood, but psychological factors may affect about half of all patients. Modification of vagal efferent activity seems to affect the calibre of airways. It has been shown that suggestion can actually decrease or increase the effects of pharmacological stimuli on the airway. The role of the psychic factor in inducing or prolonging attacks in acute exacerbations may vary from patient to patient and in individual patients from episode to episode.
Goyeche et al claimed that the psychosomatic imbalance is present in many, if not all patients with asthma1. Suppressed emotion, anxiety, dependence, and extreme self consciousness may all be accompanied by generalised and localised muscle tension, including that of the voluntary respiratory musculature. This increased muscle tension may be a precipitating or concomitant factor that perpetuates and aggravates the asthmatic syndrome.
Yoga seems to stabilise and reduce the excitability of the nervous system. Transcendental meditation (a traditional yogic meditation technique) and Savasana have been clearly shown to be associated with reduced metabolic rate2. Crisan showed a significant reduction in the level of anxiety after the practice of Pranayama, as evidenced by increased skin resistance and a reduction in pulse rate, urinary catecholamine concentration, Urinary cholinesterase activity, and anxiety scores12. Several workers have found an increase in alpha synchrony in electroencephalograms taken during transcendental meditation, which points to its stabilising effect on the nervous system. Yoga clearly relaxes the muscles and this deep physical and mental relaxation associated with the physiological changes seen in our patients after daily yoga seems to have a stabilising effect on bronchial reactivity, thus making the vagal efferent less excitable.
In conclusion, the reduction in psychological hyper-reactivity and emotional instability achieved by yoga can reduce efferent vagal reactivity, which has been recognised as the mediator of the psychosomatic factor in asthma.