SUBJECTS AND METHODS

The study was conducted at VYASA, a residential yoga research foundation near Bangalore. Out of 140 subjects screened, 88 (39 women, 49 men) normal, healthy subjects (as assessed by clinical examination) were selected for the study. These subjects were not taking any medication and did not have any sleep disorder. They were in the age range of 20–55 years (mean age = 33 yrs ± 9.88) with a mean weight of 58.36 ± 8.94 kg, mean height of 1.48 meters ±
0.23 and a mean body mass index (BMI) of 21.59 ± 3.09). The yoga group consisted of 27 men and 24 women who were trained in yoga for a minimum period of six months and who had been practising yoga for at least two hours a day, five days a week for 25 days a month (Appendix A). The non-yoga control group consisted of 22 men and 15 women who did not practice yoga but were staying in the same yoga institute under similar environmental
conditions performing day-to-day activities of the center. Both the groups had similar activity profiles (other than yoga) and took the same simple vegetarian meal. The two groups were matched for weight, age and BMI [Table 1].
All subjects had an early, simple, non-spicy vegetarian dinner at 6 p.m. The assessments were made early in the morning at around 6 a.m. and between 8.30 and 9 p.m. to eliminate the thermic effect of food on metabolism. The subjects were randomized for assessment, 50% of them being assessed at 9 p.m. and the other 50% at 6 a.m. Assessments were made in the morning only after the subjects had reported that they had slept for about seven hours. The subjects were made to rest in a supine position for 20–30 minutes before the assessments were made twice for

15 min each with a gap of 15 minutes. The measurements were made in thermoneutral conditions at approximately 25ºC in quiet surroundings and the average of two readings was taken. The assessments were done by indirect calorimetry using OXYCON PRO from JAEGER, Germany. The instrument was calibrated daily for flow volume and gas analysis by using certified gases (mixture of 5.2% CO2 in nitrogen and atmospheric air, BOC, UK). VO2 (volume of oxygen), VCO2 (volume of carbon dioxide), VE (Ventilation), BF (Breath Flow), EE (Energy Expenditure) and RQ (Respiratory Quotient) were measured by triple V sensors-fast response gas analyzer based on the differential paramagnetic principle using a face mask. The gas analyzer is designed to analyze gases with a speed of 10 msec (100 Hz) with a breathing level of up to 80 breaths per minute. The 1985 FAO/WHO/UNU equations (26) were used to predict values of BMR based on age, sex and body weight.

The data was analyzed using independent t test for comparing the yoga and non-yoga groups, paired t test for analyzing the intragroup effects. Analysis of co-variance was used to adjust the BMR for differences in body weights between the groups. SPSS 10 package was used for all the analyses. Differences were considered significant at P < 0.05 for all statistical procedures. The data is presented as mean ± standard deviation (SD).