The experimental design was sequential self-control study which was conducted between January 2009 and September 2009. Eighty eight medical undergraduate students voluntarily enrolled in the present study. Those having a history of active sports training, yoga practice, and medical illness such as, hypertension, diabetes mellitus, bronchial asthma, tuberculosis or major surgery in the recent past were excluded from the study. Informed written consent was obtained from the participants after explaining them the purpose of the study, testing procedures and sun salutation training schedule. The study protocol was approved by the institutional research council and ethics committee.

Procedure

Sun salutation training: Sun salutation training was imparted to the subjects by a trained yoga instructor as per the guidelines of Yoga Vidya Dham, Nashik Maharashtra, India. Practice sessions were held between 5.00 p.m. and 6.00 p.m., Monday through Saturday, for a duration of 24 weeks. Each session began with a prayer followed by Omkar chanting with appropriate ‘Bija mantra’ for each sun salutation and the session ended with prayer and shavasana. Subjects performed 6 cycles of sun salutation on the 1st day and the number was gradually increased to 24 over the next 15 days. This daily practice of 24 cycles of sun salutation was then performed for 6 days a week and continued for 24 weeks. Subjects in the study group were required to attend at least 80% of sessions to be considered in the study analysis.

Experimental protocol: All the tests were done under standard laboratory conditions after familiarising the subjects with testing procedure. Vital data including name, age (17.5-20 years), sex, height and weight of the subjects were recorded. Height was measured to the nearest 0.1 cm by using a standard stadiometer. In all subjects, the parameters described below were assessed before the beginning of sun salutation practice and after the 24 weeks of regular practice of sun salutation.

Upper body muscle strength: It was assessed by the one repetition maximum (1RM) technique for bench press and shoulder press exercises[5,6]. The 1-RM is defined as the maximum resistance a subject can overcome, using correct form, through a full range of motion, for no more than one repetition. All the subjects were asked to lift the light weights to learn proper technique and minimize muscle soreness for 1 week. After the 1 week of familiarization, the tester selected a light weight and asked the subject to perform the lift. A rest period of 4 minutes was given and the process was repeated with a heavier weight. With adequate rest periods, the process was continued till 1RM was obtained. The maximum weight in kg that could be lifted perfectly through only one repetition was noted as the strength. Bench press technique was used to assess pectoralis strength whereas shoulder press technique was used to assess strength of triceps and deltoids.

Lower body muscle strength: This was assessed by using a back and leg dynamometer (Anand Agencies Pvt. Ltd. Pune) [5].

Subject was asked to stand on the platform of the instrument with knees flexed at 45 degrees and was instructed to keep the back straight. The position of the rod to be pulled was adjusted so that it could be held with extended arms at the level of thigh. Then the subject was asked to pull the rod upwards just by knee extension with his full force. The reading on the dial to the nearest 1 kg was recorded as the lower body muscle strength. ( )

With the back and leg dynamometer strength of the back muscles was found out as follows: Subject was asked to stand with his knees extended and hip flexed at 45 degrees. Position of the rod was adjusted at knee level and he was asked to pull the rod by extending his back. The amount of force generated in kg was noted. ( )

General body endurance: It was evaluated by push-up and sit-up tests [5]. Maximum number of push-ups and sit-ups which could be performed with the rate of 20/min was recorded.

Body mass index (BMI): It was calculated from the height and weight measurements by using the formula: BMI=Body weight (kg)/Height2 (m2)

Body composition: Body fat percent was estimated with the help of bioelectrical impedance analysis (Citizen body fat analyzer BM100, Citizen systems Japan, Co. Ltd., Tokyo). In this method a small alternating current is passed through the body and the resistance offered to the current is noted. This in turn is related to body fat percentage based on height, weight, age and sex of the subject. This method is considered valid and reliable to measure resistance in biological tissues [7]. From percentage of body fat, percentage of lean body mass was calculated.

Perceived level of exertion: Immediately after the session, the subjects rated the intensity of exercise by Borg scale for rating of perceived exertion (RPE) [8]. In this scale, the exerciser rates his perceived feelings about the exertion level on a numerical scale ranging from 6-19 i.e. from very, very light to very, very hard.