The subjects had come to the Vivekananda Kendra Yoga Research Foundation, Bangalore, India, to receive one month’s training in Yoga. The study was explained to the subjects, and their signed informed consent was taken according to the ethical principles of the Indian Council of Medical Research, New Delhi, India. There were two groups with 24 subjects in each (i.e., a total of 48 subjects). All of them were males, with ages ranging from 25 to 48 years (Mean 34.07, SD 5.9 years).
The first group was randomly sub-divided into two groups. Both groups were given the customary training in Yoga (detailed below). In addition to this training, based on a random allocation, one group was asked to practice 27 respiratory cycles through the right nostril, repeated 4 times during the day (the Surya Anuloma Viloma Pranayama group or ‘S’ group). The other group practised 27 respiratory cycles through alternate nostrils (the Nadisuddhi Pranayama group or ‘N’ group), repeated 4 times during the day. These practices were continued throughout the one month of training. The other group was similarly randomly divided as two groups. For these groups also, in addition to the customary training in Yoga, one group was asked to practice 27 respiratory cycles through the left nostril, 4 timers a day, (the Chandra Anuloma Viloma or ‘C’ group) whereas the other group completed 27 respiratory cycles through alternate nostrils
(the Nadisuddhi Pranayama or ‘N’ group), which had the same pranayama practice as the ‘N’ group of the first batch). This design was chosen as the ‘N’ group was considered as a control for both the ‘S’ and the ‘C groups.
Parameters: In both groups the following parameters were assessed, at the beginning and at the end of the one month period viz. Galvanic skin resistance (GSR) and stethographic record of respiration using a 4 - channel portable polygraph (Lafayette, USA). The GSR was measured using specially designed metal plates placed in contact with volar surfaces of the ring and the index fingers. Oxygen consumption using the closed - circuit Benedict - Roth apparatus (INCO, India) was measured at 4.00 a.m. before the daily schedule began. Since the training camps were residential it was possible to keep several factors constant, such as the diet and meal times.
Design of the study and statistical assessment: Following their arrival at the Yoga training centre, subjects were given a day to get used to the routine, and then the initial assessments were made. After a month of yogic training, the assessments were repeated. The initial and final values were compared for significant differences using the non-parametric paired signed rank test (of Wilcoxan). No assessments were made during the pranayama practice.
Training in YOGA : All four groups of subjects received the same regular Yoga training. This consisted of different asanas (physical postures), Pranayama (voluntary regulation of breathing), meditation, devotional sessions, and lectures on the theory and philosophy of Yoga. The pranayama practice of the regular schedule consisted of nine rounds of Nadisuddhi Pranayama, as well as other varieties involving slow, deep respiration, but without manipulating the nostrils, as is required for Surya Anuloma Viloma and Chandra Anuloma viloma.
In addition, according to their random allocation to different groups, subjects were asked to practice one of the following pranayama (voluntary regulation of breathing) : (1) Surya Anuloma Viloma Pranayama (both inhalation and exhalation through the right nostril), (2) Chandra Anuloma Viloma Pranayama (both inhalation and exhalation through the left nostril), and (3) Nadisuddhi Pranayama (inhalation and exhalation through alternate nostrils). Subjects were asked to practice whichever Pranayama was specifically assigned to them, as 27 respiratory cycles, repeated 4 times everyday, throughout the one month of training.