DISCUSSION The
present study was conducted on male subjects to avoid any possible effect
of menstrual phase on RT as reported by earlier workers (8). In our
subjects, pre- mukh bhastrika ART was significantly shorter than VRT and
this is in agreement with previous reports (1, 6, 8). After mukh bhastrika
also ART was significantly shorter than VRT. Although Madanmohan et al (1)
and Malathi et al (6) have reported that yoga training produces a
significant reduction in VRT and ART, to the best of our knowledge there
is no report on the immediate effect of pranayam on RT. Kapalabhati, a
yogic breathing practice utilizing abdominal maneuvers and bellows type
breathing that is similar to mukh bhastrika, has been reported to increase
mental activity (16) and induce a calm and alert state (17). This type of
‘ready’ state can explain the mukh bhastrika-induced shortening of RT
in our subjects. Hatha yogic practices like agnisar, nauli and bhastrika
have been shown to induce EEG changes around the somatosensory and
parietal areas of the cerebral cortex suggesting an affective arousal (13,
14). As these practices utilize forceful abdominal contractions similar to
mukh bhastrika and bring about EEG changes through strong stimulation of
somatic and splanchnic receptors (13, 14), we suggest that mukh bhastrika
results in shortening of RT through similar mechanisms. The faster
reactivity of our subjects after mukh bhastrika can also be explained on
the basis of generalized alteration in information processing at the
primary thalamo-cortical level that has been reported during concentrated
mental exercise of pranayam breathing (7). Mukh
bhastrika involves active and rapid expiratory efforts and it is
interesting to note that hyperventilation has been found to selectively
depress motor cortical inhibition in humans (18). This release of motor
cortical inhibition may be one of the mechanisms by which mukh bhastrika
results in shortening of RT. However an important difference between yogic
bellows-type breathing like mukh bhastrika or kapalabhati and
hyperventilation is that prolonged hyperventilation produces abnormal EEG
changes whereas there are no abnormal EEG changes even after 10 minutes of
kapalabhati (16). The present study shows that mukh bhastrika produces an
immediate reduction in RT. A decrease in RT indicates an improved
sensory-motor performance, which can be explained on the basis of enhanced
processing ability of central nervous system. Mukh bhastrika may be
improving this processing ability by i) greater arousal and faster rate of
information processing ii) improved concentration power and/or iii)
ability to ignore or inhibit extraneous stimuli. Greater arousal and
faster information processing can be explained on the basis of mukh
bhastrika-induced alterations in afferent inputs from abdominal and
thoracic regions, which in turn can modulate the activity at ascending
reticular activating system and thalamocortical levels. This
shortening of RT is of applied value in situations requiring faster
reactivity such as sports, machine operation, race driving and specialized
surgery. RT has been reported to be altered in trainable mentally retarded
children (19). On the basis of the present study, we suggest that yogic
techniques like mukh bhastrika may be used as an effective means of
training to improve the RT in such children. It has also been reported
that older soccer players perform poorly on measures of conceptual
thinking, RT, and concentration (20). We suggest that yogic techniques
like mukh bhastrika may be used as an effective means of training such
players. ACKNOWLEDGEMENTS We
gratefully acknowledge the financial support from the Central Council for
Research in Yoga & Naturopathy (CCRYN), New Delhi. |