Effects of yogic breath regulation: A narrative review of scientific evidence

Pranayama or breath regulation is considered as an essential component of Yoga, which is said to influence the physiological systems. We present a comprehensive overview of scientific literature in thefield of yogic breathing. We searched PubMed, PubMed Central and IndMed for citations for keywords“Pranayama” and “Yogic Breathing”. The search yielded a total of 1400 references. Experimental papers,case studies and case series in English, revealing the effects of yogic breathing were included in thereview. The preponderance of literature points to beneficial effects of yogic breathing techniques in bothphysiological and clinical setups. Advantageous effects of yogic breathing on the neurocognitive, psychophysiological, respiratory, biochemical and metabolic functions in healthy individuals were elicited.They were also found useful in management of various clinical conditions. Overall, yogic breathing couldbe considered safe, when practiced under guidance of a trained teacher. Considering the positive effectsof yogic breathing, further large scale studies with rigorous designs to understand the mechanismsinvolved with yogic breathing are warranted.© 2017 Transdisciplinary University, Bangalore and World Ayurveda Foundation. Publishing Services byElsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Influence of Yoga and Ayurveda on self-rated sleep in a geriatric population.

BACKGROUND AND OBJECTIVE: Sleep in older persons is characterized by decreased ability to stay asleep, resulting in fragmented sleep and reduced daytime alertness. Pharmacological treatment of insomnia in older persons is associated with hazardous side effects. Hence, the present study was designed to compare the effects of Yoga and Ayurveda on the self rated sleep in a geriatric population. METHODS: Of the 120 residents from a home for the aged, 69 were stratified based on age (five year intervals) and randomly allocated to three groups i.e., Yoga (physical postures, relaxation techniques, voluntarily regulated breathing and lectures on yoga philosophy), Ayurveda (a herbal preparation), and Wait-list control (no intervention). The groups were evaluated for self-assessment of sleep over a one week period at baseline, and after three and six months of the respective interventions. RESULTS: The Yoga group showed a significant decrease in the time taken to fall asleep (approximate group average decrease: 10 min, P<0.05), an increase in the total number of hours slept (approximate group average increase: 60 min, P< 0.05) and in the feeling of being rested in the morning based on a rating scale (P<0.05) after six months. The other groups showed no significant change. INTERPRETATION AND CONCLUSION: Yoga practice improved different aspects of sleep in a geriatric population.

Spatial and verbal memory test scores following yoga and fine arts camps for school children.

The performance scores of children (aged 11 to 16 years) in verbal and spatial memory tests were compared for two groups (n = 30, each), one attending a yoga camp and the other a fine arts camp. Both groups were assessed on the memory tasks initially and after ten days of their respective interventions. A control group (n = 30) was similarly studied to assess the test-retest effect. At the final assessment the yoga group showed a significant increase of 43% in spatial memory scores (Multivariate analysis, Tukey test), while the fine arts and control groups showed no change. The results suggest that yoga practice, including physical postures, yoga breathing, meditation and guided relaxation improved delayed recall of spatial information.

Effects of sirsasana (headstand) practice on autonomic and respiratory variables.

The present study had two aims: (1) To assess heart rate variability (HRV) along with non-specific autonomic measures (used in earlier studies), before and after two minutes of the head stand. (2) To compare changes in two categories of subjects, i.e., those who practiced the headstand in a traditional way (without any support) and those who used the support of the wall (a present day adaptation). The subjects were forty male volunteers (age range 19 to 36 years), with twenty subjects under each category. The following changes were significant after the practice, compared to values at baseline. (i) Both categories had an increase in the power of the low frequency component (LF) and a decrease in the high frequency component (HF) of the HRV spectrum, increased LF/HF ratio, and decreased heart rate. (ii) Subjects who practiced the head stand with the support of a wall showed reduced finger plethysmogram amplitude suggesting increased sympathetic vasomotor tone. (iii) Practicing the headstand without support was associated with an increase in the skin conductance level, suggestive of increased sympathetic sudomotor tone. Hence, both categories showed similar changes in the HRV components though changes in sympathetic vasomotor and sudomotor activity were different. These changes suggest sympathetic activation, irrespective of the method of practice.

Improved performance in the Tower of London test following yoga.

Twenty girls between 10 and 13 years of age, studying at a residential school were randomly assigned to two groups. One group practiced yoga for one hour fifteen minutes per day, 7 days a week, while the other group was given physical training for the same time. Time for planning and for execution and the number of moves required to complete the Tower of London task were assessed for both groups at the beginning and end of a month. These three assessments were separately tested in increasingly complex tasks requiring 2-moves, 4-moves and 5-moves. The pre-post data were compared using the Wilcoxon paired signed ranks test. The yoga group showed a significant reduction in planning time for both 2-moves and 4-moves tasks (53.9 and 59.1 percent respectively), execution time in both 4-moves and 5-moves tasks (63.7 and 60.3 percent respectively), and in the number of moves in the 4-moves tasks (20.9 percent). The physical training group showed no change. Hence yoga training for a month reduced the planning and execution time in simple (2-moves) as well as complex tasks (4, 5-moves) and facilitated reaching the target with a smaller number of moves in a complex task (4-moves).

Factors influencing changes in tweezer dexterity scores following yoga training.

Yoga has already been shown to improve perceptual-motor skills, but the factors which influence its effects are not well defined. This study correlates age, gender, and motivation to learn yoga with the performance in a dexterity task following yoga. Tweezer dexterity was recorded in eighty subjects belonging to four groups. Two groups were given a month of yoga training. One group consisted of subjects who had volunteered to join for the training and the other group were deputed for the training as part of their job. The two remaining groups did not receive yoga training and were selected to match the respective groups receiving yoga, for age and sex, but not for their motivation to learn yoga. The test involved using a tweezer to place metal pins in evenly spaced holes in a metal plate within four minutes. Following yoga the scores of the volunteers who learnt yoga increased significantly, whereas there was no change in scores of deputed subjects and non-yoga groups. For reasons described in detail, factors such as age and gender did not appear to contribute to the difference in performance. Hence motivation to learn yoga appeared to influence the magnitude of increase.