Subjects were assessed in two types of sessions, namely CM and SH. For half the subjects the CM session took place on the first day, with SH the next day. The other subjects had the order of the sessions reversed. Subjects were alternately allocated to either schedule, to remove any contribution of a retest effect to results following the two sessions. Assesment were made before and after the practice. but not during them. In general. Subjects were told that the experiment aimed at comparing the effects of the two yoga practices. The aim of the experiment (i.e.,whether a combination of activation and relaxation, in CM, as compared with relaxation alone, in SH would alter the metabolic and breath rates in the same or different directions)was not explained to them. During recordings, subjects were asked to sit erect in the chair, with no specific in structions about breathing except that they were to breath as normally as possible.
Oxygen consumption was recorded with a closed-circuit Benedict-Roth apparatus (INCO, Ambala, India) using the standard method (Mountcastle, 1980). The subject breathed into an oxygen tank from which exhaled carbon dioxide was excluded by absorption in sodium hydroxide. The subjects were asked to breathe into a mask, which covered their nose and mouth but were not given specific instructions about breathing except that they were to breathe as normally as possible.
Data extraction and analysis
The end expiratory points of the respirogram were joined as a slanting line, the slope of which gave the difference between initial and final volumes of oxygen in the tank in a given period, which was approximately 5 minutes in most cases. The breathing rate and respiratory (tidal breathing) volume were also obtained from the record. The height of the respiratory wave (in mm) was converted to volume (in ml), based on the calibration of the apparatus, i.e., 10 mm = 100 ml. The minute ventilation was calculated as the product of respiratory rate and breath voulme. The values of oxygen consumed (in ml/min) were converted to ml/min Standard Temperature and Pressure Dry (STPD), according to the accepted method (International Union of Physiological Sciences Commission, 1991).
The data were analyzed using 2-factor analysis of variance (ANOVA), the Tukey test for multiple comparisons of mean values, and the paired t test (to compare before and after values). The ANOVA was used to determine if there was a significant difference between sessions (factor A) and between assessments made before and after the sessions (Factor B). Pearson correlation coefficient was used to correlate percentage change after both CM and SH session in (1) oxygen consumption, (2) respiratory rate, and (3) breath volume, with (1) experience in yoga (2) experience in CM and (3) experience in SH.
Cyclic meditation lasted for 22 minutes 30 seconds. Throughout the practice the eyes were closed and subjects followed instructions on an audio tape, to carry on the practice slowly, with awareness and relaxation. The practice began by repeating a verse from teh yoga text (40s); followed by isometric contraction of the muscles of the body ending with supine rest (1 min) standing at ease (called tadasana) and "balancing" the weight on both feet (2 min); then the first actual posture. bending to rhe right (ardhachakrasana, 1 min 20 s); a gap of 1 min 10 s with instructions about relaxation and awareness; bending to the left (1 min 20 s) ; a gap as before (1 min 10 s); forward bending (padahastasana, 1 min 20 s) ; another gap (1 min 10 s); a gap as before (1 min 10 s); forward bending (Padhastasana, 1 min 20 s); another gap (1 min 10 s); backward bending (ardhacakrasana, 1 min 20s); supine rest with instructions to relax the body in sequence (10 min). The postures were practiced slowly, with awareness of all the sensations that are felt. This slower practice required greater effort than usual. This grater effort was both physical (to do an action slowly) and mental (to resist completing the physical activity with the usual speed, a process with prevented the thought from "wandering" and incresed teh awareness of the self).
During SH, or the corpse posture, the subject lay supine with legs apart and arms away from the sides of the body and eyes closed. This practice lasted 22 min. 30 sec., so that the duration was the same as for CM.