METHOD

Subjects

The subjects were 80 girls from a state community-home. They were between 12 and 16 years of age and had been admitted because of difficulty in adjusting at home, at school, or in society. Fifteen were from broken homes, with one or both parents dead or separated. Their duration of stay in the home ranged from 6 to 36 months. The 80 girls were divided into pairs matched for age and duration of stay in the home. It was possible to form 30 such pairs. Subjects of a pair were randomly assigned to either one of two groups viz., yoga (CHY) and physical activity (CHP). A third group of girls who were staying at home and attending an ordinary school (SCH), were matched as far as possible for age (+ 6 months to 2 years) with the two groups from the community-home. All three groups (CHP, CHY, SCH) were assessed similarly. However, it was not possible to collect data on the degree of optical illusion in the control (SCH) subjects. Hence data obtained on adults living at home were used as control values. For each of the tests the number of subjects was different (Table 1).

Design of the Study

All three groups i.e., community-home group who had practised yoga for six months (CHY), community-home group who had training in physical activity for the same duration (CHP), and girls who were staying at home and attending a normal school (SCH), (or as described above, for the degree of illusion assessment, normal adults), were assessed for each of the four tests (detailed below) on four separate occasions. 

Parameters: All subjects were assessed in the four parameters described below. 

(i) Hand grip strength was measured using a hand grip dynamometer. Subjects were asked to extend their arms horizontally parallel to the ground, without support and grip the dynamometer using maximum strength. Three trials were given for each hand, alternately, with 10 Sec gap between trials, the highest among the three values was used for analysis

Table 1. Number of subjects (n) and mean age ± SD of each group for all the four assessments.

(ii) Tweezer dexterity was measured using the O'Connor tweezer dexterity apparatus, which consists of a metal plate which has 100 holes (2.0 mm in diameter and 20.0 mm deep) spaced 15.0 mm apart. The subject was instructed to pick up metal pins (1.5 mm in diameter and 25.0 mm in length) with a tweezer and place them in the holes as quickly as possible. The number of pins placed within 4 min was noted.

(iii) Critical flicker fusion frequency was measured using an electronic flicker fusion apparatus, with flicker rate ranging from 12 to 95 Hz. The flickering stimulus was a red light, 6 mm in diameter with intensity of 50 mcd, surrounded by a white surface with illumination of 150 lux. Subjects were seated 50 cm away from the apparatus, with their gaze on level with it. All subjects were assessed in ten ascending trials, which began with minimum frequency (12 Hz for the apparatus used). The frequency was increased at the rate of 0.5 Hz per step, till the subjects felt that the stimulus was no longer flickering, i.e. it was "fused" (fusion threshold).

(iv) Optical illusion was measured using Muller-Lyer lines. Subjects were assessed in two types of trials, i.e., " in" and "out" using "the method of limits" with the experimenter varying the lengths of the lines. The Muller-Lyer lines, though of equal length, appear unequal due to two different types of arrows drawn at the ends of the line. In the apparatus used, for the present study, the line on the left had close-ended arrows at either end, making it appear shorter. The length was fixed (in mm). In contrast the length of the line on the right could be varied. This line had open-ended arrows at either end which made it appear longer. The experimenter manipulated the length of the line according to the subjects specifications. The exact position at which the subject perceived the two lines to be of equal length was noted, i.e. subjective reading - "sr" . The difference between the reading at which the lines were actually equal and the " sr " gave the degree of illusion, "di" . Each subject of three groups was assessed in two types of trials (ten each, given alternately). For "in" trials the examiner adjusted the length of the adjustable line, 1 mm at a time, changing the length from maximum (200 mm) till the subjects perceived the length to be equal to that of the fixed line (actual length = 160 mm). For "out" trial the procedure was reverse, the adjustable line was kept to minimum length and the length was gradually increased till the subjects perceived the length to equal that of the fixed line. In both cases the difference (in mm) between the actual length of the fixed line and the perceived length was noted as the degree of illusion, "di" .

For all 4 tests the apparatuses were from Anand Agencies, Pune, India

Yoga training

Staff members of the community-home who were previously trained in yoga, were involved in teaching and supervision. A trained yoga teacher visited the class every fortnight to cheek the practice. Yoga techniques included: (i) simple yogasanas for 50 minutes (these are postures which are maintained for as long as possible, while relaxed), and (ii) a 10 minute period of relaxation in shavasan (corpse posture). Throughout both practices the emphasis was on relaxation and awareness of physical and other sensations.

Physical activity

Physical activity training included stationary jogging, rapid bending forwards and backwards, twisting and bending sidewards. These practices were for 40 minutes. The session also included 20 minutes of playing games such as relay races in which all the girle had to participate actively.