In eight yoga instructors, we examined changes in brain rhythms and natural
killer cell activity (NK activity) during yoga exercises. We found that th
e practice of all three exercises studied resulted in increased alpha activ
ity. There were no apparent changes in NK activity after a series of postur
al (asana) and meditative (mantra) exercises. During respiratory exercises
(pranayama), however, changes in Nk activity were observed in the eight sub
jects, positively correlating to increases in alpha frequencies (r = 0.83,
P < 0.02). Copyright (C) 2001 John Wiley & Sons, Ltd.