Yoga is an ancient Indian science and way of life which includes the practice of specific postures, regulated breathing, and meditation (Taimini, 1961). By practicing yoga a person is supposed to reach a state of mental equanimity, so that responses to favorable or unfavorable external events are well under the individual"s control and responses are moderate in intensity. Transcendental Meditation is adapted from ancient yoga texts and involves a daily 20-minute session during which an individual sits with eyes closed and repeats a mantram (a phrase or string of words) silently (Maharishi Mahesh Yogi, 1972). Repeated practice is supposed to ultimately help in reaching a state of perfect self-awareness or "transcendence". Twenty minutes of transcendental meditation reduced oxygen consumption by 17 percent (Wallace, Benson, & Wilson, 1971). This was believed to be due to reduced mental arousal and reduced muscular activity. Similarly, a 15 percent decrease in oxygen consumption followed meditation on a meaningful syllable (Telles, Nagarathna, & Nagendra, 1995). In contrast, two studies on a single subject practicing yoga breathing (ujjayi pranayama) reported increases in oxygen consumption by 19% and 9%, respectively during the practice (Miles, 1964; Rao, 1968). More recent studies on groups of yoga trainees showed that other yoga breathing practices also increased oxygen consumption by an average of 28 percent following a month of practice (Telles, Nagarathna & Nagendra, 1994) and by an average of 17 percent as an immediate effect of 45 minutes of practice (Telles, Nagarathna & Nagendra, 1996). The metabolic rate increased, both during a sitting (Rai & Ram, 1993) and a standing yoga posture (Rai, Ram, Kant, Madan, & Sharma, 1994), when these postures were compared with supine rest and with sitting in a chair. In particular, the standing yoga posture, virasan, induces a hypermetabolic state with increased sympathetic activity, with these disappearing with the subject adopting a supine posture (shavasan). These differences in reported levels of oxygen consumption were probably related to the use of differing types of yoga practices. In general, oxygen consumption decreased following meditation and increased during or after yoga breathing practices and postures. This observation may be explained by the fact that meditation reduces muscular effort, while yoga breathing and yoga postures, though practiced with relaxation, may increase muscular effort, relative to meditation. These findings are in line with known reports that lowered muscular effort is associated with reduced metabolic rate. The results also suggest that though all yoga practices are supposed to increase mental relaxation, the metabolism lowering effect is better following meditation, which may be associated with greater mental calmness compared with yoga postures or breathing. On the other hand, it is worth noting that traditional yoga texts say that it may also sometimes be desirable to activate the mind (Chinmayananda, 1984): "In a state of mental inactivity awaken the mind; when agitated, calm it; between these two states realize the possible abilities of the mind. If the mind has reached the state of perfect equilibrium then do not disturb it again". For most persons, the mental state while doing routine activities (not necessarily associated with yoga), is neither "inactive" nor is it "agitated", but is somewhere between these extremes, and hence a combination of "awakening" and "calming" measures may be better suited, to reach a balanced, relaxed state.
The foregoing idea, drawn from the traditional texts, was the basis for a yoga practice called "cyclic meditation". This technique includes the practice of four yoga postures interspersed with relaxation while supine, thus achieving a combination of both "stimulating" and "calming" practices (Nagendra & Nagarathna, 1997). In the activating phase, the yoga postures are practiced about four times slower than that required by classical descriptions. This slower practice requires more effort than the usual practice. We hypothesized that because cyclic meditation (CM) has repetitive cycles of "activating" and "calming" practices, based on the idea from the ancient texts, as discussed earlier, practicing CM would cause greater relaxation compared with supine rest in shavasan (SH). The present study was designed to compare the oxygen consumption and respiration after the practice of CM, with the same measurements made after a period of the equal duration of supine rest. In this way, we objectively sought to evaluate the CM technique based on ancient texts.