MATERIALS AND METHODS

Subjects

Fifty male volunteers with ages ranging between 18 and 48 years (group mean±S.D., 27.0±6.3 years) took part in the study. Respiratory and metabolic variables have been shown to vary with the phases of the menstrual cycle (Das & Jana, 1991), hence the study was restricted to males. The subjects were undergoing yoga training at a yoga center. All of them were in normal health based on a routine clinical examination and none of them had a history of smoking or respiratory ailments. None of them was taking any medication and they did not use any other wellness strategy. They had experience of practicing both yoga techniques (i.e., CM and SH) ranging between 3 and 60 months (group mean±S.D., 15.3±13.3 months). The variables to be recorded and the study design was described to the participants and their consent to participate was obtained. None of them was aware of the hypothesis of the study.

Design of the Study

Participants were assessed in two types of sessions, namely cyclic meditation (CM) and shavasana (SH). For half the subjects the CM session took place on one day, with the SH session the next time, with a one day gap between sessions. The remaining subjects had the order of the sessions reversed. Subjects were alternately allocated to either schedule to prevent the order of the sessions influencing the outcome.
For all fifty participants assessments were made throughout a session which lasted for 33 min, of which 22 min 30 s was spent in the practice of either CM or SH, preceded (pre) and followed (post) by 5 min of supine rest. For a sub-sample of ten participants additional or repeat recordings were made with the post period longer (i.e., 30 min). Hence each session lasted for 63 min, of which 22 min 30 s was spent in the practice of either CM or SH, preceded (pre) by 5 min of supine rest and followed (post) by 30 min of supine rest. These ten participants were part of the fifty whose total session duration was 33 min, and for whom the post period was 5 min.

Assessments

The assessments of oxygen consumption, minute ventilation, tidal volume and breath rate were made with the subject breathing ambient air while wearing a mask, using an open circuit apparatus (OxyconPro system, Model 2001, Jaeger, Germany). The system was calibrated for ambient temperature, humidity and barometric pressure, flow rate; and gas analysis.

Interventions
Cyclic Meditation

Cyclic meditation lasted for 22 min 30 s. Throughout the practice subjects kept their eyes closed and followed instructions from an audiotape. The instructions emphasized carrying out the practice slowly, with awareness, and relaxation. The four phases of cyclic meditation consisted of the following practices. Phase 1 (5 min): The practice began by repeating a verse (1 min) from the yoga text, the Mandukya Upanishad (Chinmayananda, 1984); followed by isometric contraction of the muscles of the body ending with supine rest (1 min 30 s): slowly coming up from the left side and standing at ease (called tadasana) and ‘balancing’ the weight on both feet called ‘centering’ (2 min 30 s); Phase 2 (5 min): Then the first actual posture, bending to the right (ardhakatichakrasana, 1 min 20 s); a gap of 1 min 10 s in tadasna with instructions about relaxation and awareness; bending to the left (ardhakaticakrasana, 1 min 20 s); a gap of 1 min 10 s in tadasana; Phase 3 (5 min): Forward bending (padahastasana, 1 min 20 s); another gap (1 min 10 s); backward bending (ardhacakrasana, 1 min 20 s); a gap of 1 min 10 s in tadasana; Phase 4 (7 min 30 s): Slowly coming down to a supine posture for rest with instructions to relax different parts of the body in sequence (Telles, Reddy, & Nagendra, 2000).

Shavasana

During the 22 min 30 s of ‘supine rest’ subjects lay in the corpse posture (shavasana) with their legs apart and arms away from the sides of the body, with eyes closed. The state of shavasana was considered for analysis as four phases (the first three phases of 5 min each and the fourth phase of 7 min 30 s) to make it comparable to the state of CM practice, during the CM session. However, throughout the four phases, the subjects lay in the same posture.

Data Extraction and Analysis

The contiguous data obtained from breath-by-breath sampling were averaged for the ‘pre’, ‘during’ and ‘post’ states of each session. The ‘during’ state of the CM session had four ‘phases’ detailed above. These were analyzed separately and to make the analyses uniform, the 22 min 30 s of the ‘during’ phase of the SH session was also considered as four phases of comparable duration. Also, for the sub-sample of ten participants for whom the ‘post’ period was 30 min, this period was considered as six, 5 min phases. Statistical analysis was done using SPSS (Version 10.0). Repeated measures analyses of variance (ANOVA) were performed with two Within Subjects Independent Variables, i.e., (i) Sessions with two levels; CM and SH and (ii) States with six levels; pre, during 1 (D1), during 2 (D2), during 3 (D3), during 4 (D4), and post. In the ten participants who had a longer 30 min of post recording (i.e., six phases), each post phase was compared to the respective ‘pre’ (hence in this case for ‘States’ there were eleven levels). Post-hoc tests (with Bonferroni adjustment for multiple comparisons) were used to detect significant differences between mean values.