Pre-teen children are at a stage of both promise and challenges, as they transition from childhood to being teenagers. Some of the challenges include an increase in academic pressure, a greater involvement in family and social dynamics, adjusting to changing social and behavioral demands of their peer group, and sometimes a growing difference in values and opinion with their parents and guardians [1
]. Along with these stressors, in India pre-teens face a definite increase in academic load as they begin to prepare to answer an important, competitive, and career-determining school leaving examination in the next two to three years [2
]. Academic pressure is a particularly important factor in those pre-teens the world over, who see education as a way to improve their own and their family’s social and economic prospects [3
Researchers from medicine and public health disciplines have assessed the usefulness and benefits of yoga for children in school settings [4
]. The benefits included improved psychological well-being, reduced rates of being overweight or obese, children being calmer and more attentive, more at ease, and completing assigned tasks successfully. In a separate study, yoga breathing techniques were introduced in a suburban, private, English medium school in north India [5
]. Two sections of the third grade (children aged 7–8 years), with approximately 50 students in each section were selected. One section received yoga breathing (i.e., deep breathing and alternate nostril yoga breathing) as a 5min intervention every school day for the academic year. Scores obtained in Math and languages (English and Hindi) were noted at the beginning and end of the year. In the group who practiced yoga breathing there was a statistically significant increase in cumulative scores. Though the effect size was small (eta squared = 0.108) the teachers reported other benefits such as better attention, improved classroom behavior, and active participation.
The neurocognitive effects of yoga breathing were further discussed in a narrative review, which searched PubMed, PubMed Central, and IndMed for citations with ‘Pranayama’ and ‘Yogic breathing’ as the search words [6
]. In the review, 68 studies reported the effects of yoga breathing alone and met other inclusion criteria, and hence were included. The studies were categorized and one sub-category was neurocognitive assessments. The yoga breathing techniques discussed included those which varied the rate of breathing, the depth of breathing, the nostril(s) breathed through, and where exhalation was associated with specific sounds. The details of these yoga breathing practices as well as others mentioned in this study are provided in Table 1
The neurocognitive assessments included electrophysiological variables (i.e., EEG, evoked potentials, and event related potentials), spatial and verbal memory tasks, auditory and visual reaction time, the Purdue pegboard task, and substitution and cancellation tasks. The authors concluded that pranayama or yoga breathing influenced neurocognitive abilities positively and that some practices were also useful in a clinical setting.
Among yoga breathing techniques the effects of those which influenced the rate of breathing were compared in young adults aged 18–25 years [7
]. Into three groups, 84 participants were randomized as (i) fast yoga breathing (rate not specified), (ii) slow yoga breathing (rate not specified) and (iii) a control group. Participants practiced the respective yoga breathing techniques for 35 min, thrice a week for 12 weeks. Assessments included cancellation tasks, trail making tests, digit span forward and backward, and reaction time (auditory and visual). With both fast and slow yoga breathing, performance in cancellation tasks, trail making tests, digit span forward, and auditory and visual reaction time improved, with a greater magnitude of improvement in the group who practiced fast yoga breathing.
Most of the studies described above assessed the effects of yoga breathing practiced for a number of days or weeks. However there are also acute or immediate effects of yoga breathing, which occur directly after the practice. Examples of the immediate effects of yoga breathing studied in children are discussed here. In 60 adolescents (mean age 14.6 years, 38 males), 45 min of yoga bumble bee breathing reduced the heart rate and blood pressure [9
]. Yoga breathing with an increased depth of breathing (called bellows breath), when practiced as nine rounds, where one round was one breath cycle, reduced the auditory and visual reaction time significantly in 22 healthy school boys (mean age 14.5 years) [10
]. A shorter reaction time suggested that participants responded sooner.
Similarly, the immediate effects of short durations of yoga breathing have been assessed in adults. Into two groups, 94 persons were assigned to(i) high frequency yoga breathing (mean age 39.3 years; 28 females; breath frequency 1.0 Hz) and (ii) breath awareness (mean age 39.8 years; 26 females) [8
]. The O’Connor finger dexterity task and a shape and size discrimination task were administered to all participants just before and after 10 min of high frequency yoga breathing or breath awareness. There were improvements in the way participants performed both tasks, though the magnitude of change was greater after high frequency yoga breathing. These tasks require tactile discrimination, fine motor skills, and eye hand co-ordination; hence the results suggest these abilities improved to a greater extent with 10 min of high frequency yoga breathing. A similar trend was seen with an assessment of the degree of optical illusion perceived, which is a measure of visual discrimination, in 30 adult males (mean age 26.9 years), where a greater degree of improvement followed 15 min of high frequency yoga breathing at 1.0 Hz compared to breath awareness [11
High frequency yoga breathing practiced at breath frequencies between 1.0 and 2.0 Hz improved the performance scores in an attention-based cancellation task as an immediate effect of practice across different age groups [12
]. The cancellation task requires the ability to focus attention, shift attention, as well as other abilities such as visual scanning and psychomotor speed [13
]. There was a 56.1 percent reduction in total errors in the cancellation task in medical students (n
= 46, age range 18–23 years); a 32.5 percent improvement in the net scores of middle aged adults (n
= 48, age range 30–59 years) and 16.4 percent in older adults (n
= 16, over the age of 60 years) [12
]. High frequency yoga breathing has not been specifically tested as a classroom based intervention in pre-teen children.
Hence the present study was designed to assess performance in an attention based cancellation task immediately before and after 18 min of high frequency yoga breathing in 61 pre-teen children, compared to sessions of yoga based breath awareness or quiet rest of equal duration, in a random sequence, on separate days.
The group mean values (SD) for SLCT, STAI-S, and VAS are given in Table 2
. ANOVA values for SLCT and STAI-S are given in Table 3
3.1. Repeated Measures Analyses of Variance (RM-ANOVA)
In the whole group, the STAI-S scores differed between States (F = 39.606, df = 1,60, p
< 0.001). A significant interaction between Sessions × States was noted in net scores of SLCT (F= 3.766, df = 2,120, p
< 0.05) suggesting interdependence of the two factors [19
]. The STAI-S scores differed between States for boys (F = 25.420, df = 1,35, p
< 0.001) as well as for girls (F = 14.595, df = 1,24, p
< 0.01). There was a significant interaction between Sessions × States for the total attempted scores (F = 5.791, df = 2, 48, p
< 0.01) and net scores (F = 6.817, df = 2,48, p
< 0.01) in girls alone.
3.2. Post-Hoc Analyses
For the whole group, there was a significant increase in the total attempted scores (p < 0.05; 95% CI = −4.75, −0.34) and net scores (p < 0.05; 95% CI = −4.47, −0.15) of SLCT after HFYB, while there was a significant increase in wrong attempts after BAW (p < 0.05; 95% CI = −0.97, −0.02). The Anxiety decreased significantly after all three sessions i.e., HFYB (p < 0.001; 95% CI = 3.09, 7.17), BAW (p < 0.001; 95% CI = 2.59, 6.82), and QS (p < 0.001; 95% CI = 2.73, 6.58). The average (SD) visual analog scale scores for HFYB, BAW, and QS were 8.4 (1.8), 8.3 (1.3) and 8.4 (1.6), respectively.
For boys alone, no changes were seen in the scores of SLCT after any of the three sessions; however the anxiety was decreased after all three sessions i.e., HFYB (p < 0.001; 95% CI = 3.10, 884), BAW (p < 0.01; 95% CI = 1.37, 6.90) and QS (p < 0.01; 95% CI = 1.39, 5.78). The average (SD) visual analog scale scores were 8.8 (1.8), 8.6 (1.3), and 8.7 (1.3) for HFYB, BAW and QS respectively for boys.
For girls alone, the total attempted scores (p < 0.05; 95% CI = −8.22, −0.58) and the net score (p < 0.05; 95% CI = −8.22,−0.58) of SLCT were significantly increased after HFYB. After BAW there was an increase in wrong attempts (p < 0.05; 95% CI = −1.83, −0.13) and a decrease in net scores (p < 0.05; 95% CI = 0.53, 5.71). The anxiety was decreased after all three sessions in girls also [(HFYB = p < 0.05; 95% CI = 0.96, 6.88), (BAW = p < 0.01; 95% CI = 2.01, 9.03), (QS = p < 0.01; CI = 2.60, 9.80)]. The average (SD) visual analog scale scores for HFYB, BAW and QS were 7.8 (1.2), 7.8 (1.7), and 7.8 (1.6), respectively, for girls.
The study was intended to determine whether an 18 min school-based intervention would increase performance in an attention task and decrease anxiety. In 61 pre-teen children the level of anxiety decreased comparably immediately after 18 min of high frequency yoga breathing, breath awareness, and sitting quietly at rest. The performance in an attention-based, cancellation task improved after yoga breathing alone.
The decrease in anxiety after all three interventions may be due to some common as well as some distinct factors. Yoga breathing has been associated with reduced anxiety, which may be due to multiple factors [20
]. Similarly breath awareness and mindfulness are widely known to reduce anxiety though different mechanisms. During breath awareness and mindfulness the mental state is focused on the breath and is less likely to be diverted to stressful thoughts. This benefit of mindful-awareness has also been shown in school settings [23
]. Sitting quietly at rest may have induced a quiet meditative state in these pre-teen children who already had 1–2years’ experience of yoga, since an earlier study in adult yoga practitioners showed that persons with experience in yoga have lower levels of arousal demonstrated by lower basal metabolic rates at rest compared to non-yoga practitioners [24
]. Sitting in silence has been shown to be stress reducing as an in-school intervention, practiced as quiet time [23
Breath awareness in the present study cannot be considered the same or as effective as mindfulness meditation or mindful breath awareness. Breath awareness is a part of yoga breathing which may be as effective to reduce anxiety as sitting quietly with random thinking. However yoga-based breath awareness and mindful breath awareness can be expected to differ, as mindful breath awareness involvespaying attention to experiences as they occur along with maintaining a non-judgmental and accepting mental state, whilestable attention and associated cognitive processes arehighlighted [25
]. The children in the present trial were trained in yoga breathing and in breath awareness as a part of yoga practice.
The cancellation task used in the present study, chiefly assesses the ability to focus and shift attention but also assesses short term recall (of the test letters), as well as visual scanning and motor performance [13
]. In 107 adults (age range 18–30 years), active inhalation improved facial expression recognition and object recall [26
]. Since high frequency yoga breathing involves exhaling actively and passively inhaling through the nose at an increased rate, this breathing practice may directly influence recognition and recall. In earlier studies on adults the immediate effect of high yoga breathing was an improvement in visual perception [11
]. This ability may also have partially accounted for the improvement in the letter cancellation task performance in the present study. The present results suggest that yoga breath awareness, which does not involve breath manipulation is less efficient compared to yoga breathing with respect to the attention-based cancellation task, since an increase in wrong attempts in the group as a whole occurred after breath awareness.
The 25 girls in the study showed the same results as the whole group, i.e., better performance in the attention task following high frequency yoga breathing, increased wrong attempts after breath awareness and reduced anxiety after all three interventions. The boys showed a decrease in anxiety after all three interventions, with no increase in the attention task performance after any of them. This gender-difference may be explained on the basis of another study as follows. The differential effect of gender on the degree of engagement and the degree of effectiveness of a mindfulness program was compared in male and female adolescents [27
]. Females were more engaged than males in the class and also reported less stress post-intervention. Despite the small sample size (10 female and 5 male adolescents), the results of the study may also explain the present gender differences following yoga breathing in which girls alone showed an increase in total attempts and net scores after yoga breathing, with increased wrong attempts after breath awareness. Apart from this, normative data for performance in the six letter cancellation task were obtained in India, in 819 school students between 9 and 16 years of age (mean age 12.1 years) [28
]. The children had normal health and were proficient in English. The authors reported that girls had higher scores than boys but did not provide a possible explanation for the difference. However, given that girls score better than boys in the cancellation task this advantage may be further enhanced by an intervention, in this case, high frequency yoga breathing. Finally, the program for International Student Assessment, which is a triennial international survey has observed that even though several countries have been able to close gender gaps in learning outcomes—boys and girls differ in their attitudes towards learning—their behavior in school, how they choose to spend their leisure time, and the confidence they have (or do not have) in their own abilities as students [29
]. These factors may have also been responsible for the gender-difference in the present study.
Since the present study aimed at assessing a yoga breathing intervention for use in a school setting, another study which attempted a similar exercise is discussed here. In this earlier study two yoga breathing practices were introduced for 5 min each school day for a year [5
]. This was in an English medium school near New Delhi. Two sections of the third grade, where students are between 7 and 8 years of age were selected. One section (n
= 54) was assigned the yoga intervention while the other section (n
= 51) acted as the control. The scores in Math and languages (English and Hindi) were noted in both groups at the start and end of a year. The yoga group had a significantly higher cumulative gain in academic scores compared to the control group. The teachers also reported other benefits (e.g., an increase in attention span, more active participation in the class room) in the yoga group. The findings are limited by the fact that the children were not randomly assigned to the two interventions and the additional practice could have been a source of motivation to the yoga group, while the control group may have been less motivated in the absence of this additional attention [31
Unlike the present study the teachers in the study cited above were trained for a week before introducing the yoga program in the classroom (whereas in the present study yoga teachers had a two year post graduate degree in yoga). The students also took a shorter time, as they were trained in one month (which included many holidays, as mentioned by the authors) [5
]. The main reason for this could be the difference in yoga breathing practices. In the earlier study [5
], children were taught deep breathing (which involved deep nasal inhalation and exhalation) and alternate nostril breathing (which involves inhalation and exhalation through left and right nostrils alternately). High frequency yoga breathing is appropriate for pre-teens and has been described to take approximately two weeks for beginners to reach a breath frequency of 22 breaths per minute if they started with 11 breaths per minute, after which participants are asked to increase the rate by 11 breaths per minute every two weeks [32
]. Hence for novices to reach a breath rate of 55–60 breaths per minute (which was the breath rate practiced by the pre-teen participants in the present study), the time required would be 8–10 weeks.
In the present study the finding that 18 min of high frequency yoga breathing are beneficial, is limited by factors such as (i) the study was conducted in a residential school, which helped regulate experimental conditions but may not be entirely the same for pre-teens living at home, (ii) the children had already been practicing yoga for one to two years (iii) there were no assessments which would have allowed a better understanding of the mechanisms involved, and (iv) the 18 min yoga breathing intervention was not tested in novices to yoga.