Middle latency auditory-evoked potentials (AEP-MLRs) of 10 healthy male subjects in the age range of 21-33 years, were assessed to determine whether yogic pranayamic practice would cause changes in them. The pranayama type assessed here is an exercise of consciously-controlled rhythmic breathing involving timed breath-holding in each cycle of breathing, while the subject holds utmost attention and experiences the touch of inhaled air in the nasal passage. The results revealed that the Na-wave amplitude increased and latency decreased during the period of pranayamic practice, whereas the Pa-wave was not significantly altered. The change is interpreted as an indication of a generalized alteration cause in information processing at the primary thalamo-cortical level during the concentrated mental exercise of inducing modifications in neural mechanisms regulating a different functional system (respiratory). Further researches are required to understand the operational significances of such changes.
BACKGROUND Reports suggest that vigilance or sustained attention increases sympathetic activity. A persistent increase in sympathetic activity can lead to an increase in blood pressure. Alternate-nostril yoga breathing has been shown to be useful to (i) improve attention and (ii) decrease the systolic and diastolic blood pressure. Earlier studies did not report simultaneous recordings of the blood pressure and performance in vigilance tests after alternate-nostril yoga breathing. With this background, the present study was planned to determine if 15 minutes of alternate nostril yoga breathing could improve the performance in a vigilance test without an increase in blood pressure. MATERIAL AND METHODS Fifteen healthy male volunteers participated in the study (group mean age +/-SD, 22.4+/-2.4 years). Participants were assessed on 3 separate days in 3 different sessions. These were (i) alternate nostril yoga breathing, (ii) breath awareness, and (iii) sitting quietly as a control. Blood pressure and the digit vigilance test were simultaneously assessed before and after each session. RESULTS Systolic blood pressure (p<0.01), mean arterial blood pressure (p<0.05), and the time taken to complete the digit vigilance test (p<0.05) significantly decreased following alternate-nostril yoga breathing. The time taken to complete the digit vigilance test differed significantly between sessions (p<0.05). The time taken to complete the digit vigilance test was also significantly decreased after sitting quietly (p<0.01). CONCLUSIONS Alternate-nostril yoga breathing appears to improve performance in the digit vigilance test, along with a reduction in systolic blood pressure. This is suggestive of better vigilance without sympathetic activation.
Introduction. Yoga is a holistic system of varied mind-body practices that can be used to improve mental and physical health and it has been utilized in a variety of contexts and situations. Educators and schools are looking to include yoga as a cost-effective, evidence-based component of urgently needed wellness programs for their students. Objectives. The primary goal of this study was to systematically examine the available literature for yoga interventions exclusively in school settings, exploring the evidence of yoga-based interventions on academic, cognitive, and psychosocial benefits. Methods. An extensive search was conducted for studies published between 1980 and October 31, 2014 (PubMed, PsycInfo, Embase, ISI, and the Cochrane Library). Effect size analysis, through standardized mean difference and Hedges'g, allowed for the comparison between experimental conditions. Results and Conclusions. Nine randomized control trials met criteria for inclusion in this review. Effect size was found for mood indicators, tension and anxiety in the POMS scale, self-esteem, and memory when the yoga groups were compared to control. Future research requires greater standardization and suitability of yoga interventions for children.
BACKGROUND: Previous research has shown a reduction in blood pressure (BP) immediately after the practice of alternate nostril yoga breathing (ANYB) in normal healthy male volunteers and in hypertensive patients of both sexes. The BP during ANYB has not been recorded. MATERIAL/METHODS: Participants were 26 male volunteers (group mean age +/-SD, 23.8+/-3.5 years). We assessed (1) heart rate variability, (2) non-invasive arterial BP, and (3) respiration rate, during (a) ANYB and (b) breath awareness (BAW) sessions. Each session was 25 minutes. We performed assessments at 3 time points: Pre (5 minutes), during (15 minutes; for ANYB or BAW) and Post (5 minutes). A naive-to-yoga control group (n=15 males, mean age +/-SD 26.1+/-4.0 years) were assessed while seated quietly for 25 minutes. RESULTS: During ANYB there was a significant decrease (repeated measures ANOVA) in systolic BP and respiration rate; while RMSSD (the square root of the mean of the sum of squares of differences between adjacent NN intervals) and NN50 (the number of interval differences of successive normal to normal intervals greater than 50 ms) significantly increased. During BAW respiration rate decreased. In contrast, respiration rate increased during the control state. ANYB and BAW were significantly different (2-factor ANOVA) in RMSSD and respiration rate. BAW and control were different with respect to respiration rate. CONCLUSIONS: The results suggest that vagal activity increased during and after ANYB, which could have contributed to the decrease in BP and changes in the HRV.
There is increasing interest in the fact that breathing exclusively through one nostril may alter the autonomic functions. The present study aimed at checking whether such changes actually do occur, and whether breathing is consciously regulated. 48 male subjects, with ages ranging from 25 to 48 years were randomly assigned to different groups. Each group was asked to practice one out of three pranayamas (viz. right nostril breathing, left nostril breathing or alternate nostril breathing). These practices were carried out as 27 respiratory cycles, repeated 4 times a day for one month. Parameters were assessed at the beginning and end of the month, but not during the practice. The 'right nostril pranayama' group showed a significant increase, of 37% in baseline oxygen consumption. The 'alternate nostril' pranayama group showed an 18% increase, and the left nostril pranayama group also showed an increase, of 24%. This increase in metabolism could be due to increased sympathetic discharge to the adrenal medulla. The 'left nostril Pranayama' group showed an increase in volar galvanic skin resistance, interpreted as a reduction in sympathetic nervous system activity supplying the sweat glands. These results suggest that breathing selectively through either nostril could have a marked activating effect or a relaxing effect on the sympathetic nervous system. The therapeutic implications of being able to alter metabolism by changing the breathing pattern have been mentioned.
In the present study of middle latency auditory evoked potentials during Brahmakumaris Raja Yoga meditation there was a decrease in the peak latency of the Na wave (a negative wave between 14 and 19 msec.) during meditation. Since the neural generator of this wave lies at the midbrain-thalamic level, from the results one can infer that the meditation reduces conduction time at this level.
This study assessed the effect of alternate nostril yoga breathing (nadisuddhi pranayama) on P300 auditory evoked potentials compared to a session of breath awareness of equal duration, in 20 male adult volunteers who had an experience of yoga breathing practices for more than three months. Peak amplitudes and peak latencies of the P300 were assessed before and after the respective sessions. There was a significant increase in the P300 peak amplitudes at Fz, Cz, and Pz and a significant decrease in the peak latency at Fz alone following alternate nostril yoga breathing. Following breath awareness there was a significant increase in the peak amplitude of P300 at Cz. This suggests that alternate nostril yoga breathing positively influences cognitive processes which are required for sustained attention at different scalp sites (frontal, vertex and parietal), whereas breath awareness brings about changes at the vertex alone.
BACKGROUND: The characteristics of yoga practitioners and factors motivating people to practice yoga have been studied in the US and in Australia. This study aimed to determine the characteristics of yoga users in India, the factors that motivate them to practice yoga, and the yoga techniques of choice. MATERIALS AND METHODS: The study was a one-time, cross-sectional survey based on convenience sampling. Inclusion criteria were (a) a minimum of 1 week experience of yoga and (b) at least 10 years of age. 14,250 people received the survey. After excluding those who did not meet the inclusion criteria or filled in the survey incompletely or incorrectly, 5,157 respondents were included in the study. RESULTS: Out of 5,157 respondents, there were more males (67.3%), aged between 21 and 44 years (33.7% of the sample surveyed), educated up to high school (62.5%), students (39.3%), and those who had between 1 and 12 months of experience in yoga (54.4%). The first most common reason to practice yoga for all respondents was physical fitness. Three of the remaining reasons to practice yoga differed significantly with age: (i) yoga for disease management (chi(2) = 17.62, p < 0.005), (ii) yoga as a hobby (chi(2) = 10.87, p < 0.05), and (iii) yoga based on the guru's (teacher's) instructions (chi(2) = 20.05, p < 0.001). The yoga technique of choice [i.e., (i) asanas (chi(2) = 23.17, p < 0.001), (ii) pranayama (chi(2) = 19.87, p < 0.001), or (iii) meditation (chi(2) = 9.64, p < 0.05)] differed significantly across age groups. CONCLUSION: In India, a yoga practitioner was more likely to be male, between 21 and 44 years of age, high school educated, and a student. The reasons to practice yoga and the yoga technique of choice differed significantly with age.
The degree of optical illusion was assessed using standard Muller-Lyer lines in two groups (yoga and control) of thirty subjects each. All subjects were between eighteen and forty two years of age. The difference between the reading at which the lines were actually equal and the reading at which the subject felt them to be equal, was noted as the degree of illusion ("di"). Each subject was assessed at the beginning and end of a month. During the month the yoga group received training in yoga, while the control group carried on with their usual routine. At the end of the month the yoga group showed a significant (two factor ANOVA, Tukey test, P < .001) decrease in the "di" (86%), whereas the control group showed no change. The improvement following yoga could be attributed to the combination of focusing and defocusing involved in yoga practice, as these factors are known to influence the "di". Previous results which mentioned a 79% decrease in "di" with focusing alone, provided a comparison.
BACKGROUND: Walking and yoga have been independently evaluated for weight control; however, there are very few studies comparing the 2 with randomization. MATERIAL AND METHODS: The present study compared the effects of 90 minutes/day for 15 days of supervised yoga or supervised walking on: (i) related biochemistry, (ii) anthropometric variables, (iii) body composition, (iv) postural stability, and (v) bilateral hand grip strength in overweight and obese persons. Sixty-eight participants, of whom 5 were overweight (BMI >/=25 kg/m2) and 63 were obese (BMI >/=30 kg/m2; group mean age +/-S.D., 36.4+/-11.2 years; 35 females), were randomized as 2 groups - (i) a yoga group and (ii) a walking group - given the same diet. RESULTS: All differences were pre-post changes within each group. Both groups showed a significant (p<0.05; repeated measures ANOVA, post-hoc analyses) decrease in: BMI, waist circumference, hip circumference, lean mass, body water, and total cholesterol. The yoga group increased serum leptin (p<0.01) and decreased LDL cholesterol (p<0.05). The walking group decreased serum adiponectin (p<0.05) and triglycerides (p<0.05). CONCLUSIONS: Both yoga and walking improved anthropometric variables and serum lipid profile in overweight and obese persons. The possible implications are discussed.
BACKGROUND: Previous trials of yoga therapy for nonspecific low back pain (nsLBP) (without sciatica) showed beneficial effects. OBJECTIVE: To test effects of yoga therapy on pain and disability associated with lumbar disc extrusions and bulges. METHODS: Parallel-group, randomised, controlled trial. Sixty-one adults from rural population, aged 20-45, with nsLBP or sciatica, and disc extrusions or bulges. Randomised to yoga (n=30) and control (n=31). Yoga: 3-month yoga course of group classes and home practice, designed to ensure safety for disc extrusions. CONTROL: normal medical care. OUTCOME MEASURES (3-4 months) Primary: Roland Morris Disability Questionnaire (RMDQ); worst pain in past two weeks. Secondary: Aberdeen Low Back Pain Scale; straight leg raise test; structural changes. RESULTS: Disc projections per case ranged from one bulge or one extrusion to three bulges plus two extrusions. Sixty-two percent had sciatica. Intention-to-treat analysis of the RMDQ data, adjusted for age, sex and baseline RMDQ scores, gave a Yoga Group score 3.29 points lower than Control Group (0.98, 5.61; p=0.006) at 3 months. No other significant differences in the endpoints occurred. No adverse effects of yoga were reported. CONCLUSIONS: Yoga therapy can be safe and beneficial for patients with nsLBP or sciatica, accompanied by disc extrusions and bulges.
The heart rate variability (HRV) is an indicator of the cardiac autonomic control. Two spectral components are usually recorded, viz. high frequency (0.15-0.50 Hz), which is due to vagal efferent activity and a low frequency component (0.05-0.15 Hz), due to sympathetic activity. The present study was conducted to study the HRV in two yoga practices which have been previously reported to have opposite effects, viz, sympathetic stimulation (kapalabhati, breathing at high frequency, i.e., 2.0 Hz) and reduced sympathetic activity (nadisuddhi, alternate nostril breathing). Twelve male volunteers (age range, 21 to 33 years) were assessed before and after each practice on separate days. The electrocardiogram (lead I) was digitized on-line and off-line analysis was done. The results showed a significant increase in low frequency (LF) power and LF/HF ratio while high frequency (HF) power was significantly lower following kapalabhati. There were no significant changes following nadisuddhi. The results suggest that kapalabhati modifies the autonomic status by increasing sympathetic activity with reduced vagal activity. The study also suggests that HRV is a more useful psychophysiological measure than heart rate alone.
State anxiety, somatization of stress, quality of life, self-rated quality of sleep, and discomfort due to over-breathing which occurs when stressed were studied. Out of a total of 140 participants, seventy participants self-selected to be in a yoga group for stress relief (group mean age +/- SD, 33.0 +/- 6.5 years; 37 males). Seventy age and gender matched participants were in a control group. State anxiety, somatization of stress, quality of life, discomfort and self-rated quality of sleep were assessed using the State-Trait Anxiety Inventory, Symptom Checklist-90-R, SF-12, Nijmegen Discomfort Evaluation Scale and a Sleep Rating Questionnaire respectively. Assessments were made at the beginning and end of the week. Repeated measures ANOVAs with Bonferroni adjusted post-hoc analyses showed a significant decrease in state anxiety (P < 0.001), somatization of stress (P < 0.01), improved health-related quality of life (P < 0.01), self-rated quality of sleep (P < 0.01), and decrease in discomfort due to over-breathing (P < 0.001). No changes (except decreased discomfort due to over-breathing; P < 0.01) occurred in the control group. This study suggests that a brief yoga program may be beneficial in decreasing anxiety, somatization of stress and discomfort, improving health-related quality of life and self-rated sleep quality.
State anxiety, somatization of stress, quality of life, self-rated quality of sleep, and discomfort due to over-breathing which occurs when stressed were studied. Out of a total of 140 participants, seventy participants self-selected to be in a yoga group for stress relief (group mean age +/- SD, 33.0 +/- 6.5 years; 37 males). Seventy age and gender matched participants were in a control group. State anxiety, somatization of stress, quality of life, discomfort and self-rated quality of sleep were assessed using the State-Trait Anxiety Inventory, Symptom Checklist-90-R, SF-12, Nijmegen Discomfort Evaluation Scale and a Sleep Rating Questionnaire respectively. Assessments were made at the beginning and end of the week. Repeated measures ANOVAs with Bonferroni adjusted post-hoc analyses showed a significant decrease in state anxiety (P < 0.001), somatization of stress (P < 0.01), improved health-related quality of life (P < 0.01), self-rated quality of sleep (P < 0.01), and decrease in discomfort due to over-breathing (P < 0.001). No changes (except decreased discomfort due to over-breathing; P < 0.01) occurred in the control group. This study suggests that a brief yoga program may be beneficial in decreasing anxiety, somatization of stress and discomfort, improving health-related quality of life and self-rated sleep quality.
The performance in a maze learning task was assessed in adults of either sex (n = 31) before and after 30 days of yoga training and in an age and gender matched control group of subjects who did not receive training in yoga. Subjects were blind folded and used the dominant hand to trace the path in a wooden pencil maze. At each assessment, subjects were given 5 trials, without a gap between them. Performance was based on the time taken to complete the maze and the number of blind alleys taken. The time and error scores of Trial 1 were significantly less after yoga (two-factor ANOVA, Tukey test). Repeating trials significantly decreased time scores at Trial 5 versus Trial 1, for both groups on Day 1 and for the control group on Day 30. Hence the yoga group showed improved performance in maze tracing at retest 30 days later, which may be related to this group being faster learners and also the effect of yoga itself. Yoga training did not influence maze learning, based on the performance in 5 repeat trials.
The study aimed at determining whether novices to yoga would be able to reduce their heart rate voluntarily and whether the magnitude of reduction would be more after 30 days of yoga training. Two groups (yoga and control, n = 12 each) were assessed on Day 1 and on Day 30. During the intervening 30 days, the yoga group received training in yoga techniques while the control group carried on with their routine. At each assessment the baseline heart rate was recorded for one minute, this was followed by a six-minute period during which participants were asked to attempt to voluntarily reduce their heart rate, using any strategy. Both the baseline heart rate and the lowest heart rate achieved voluntarily during the six-minute period were significantly lower in the yoga group on Day 30 compared to Day 1 by a group average of 10.7 beats per minute (i.e., bpm) and 6.8 bpm, respectively (p < .05, Wilcoxon paired signed ranks test). In contrast, there was no significant change in either the baseline heart rate or the lowest heart rate achieved voluntarily in the control group on Day 30 compared to Day 1. The results suggest that yoga training can enable practitioners to use their own strategies to reduce the heart rate, which has possible therapeutic applications.
The study aimed at determining whether novices to yoga would be able to reduce their heart rate voluntarily and whether the magnitude of reduction would be more after 30 days of yoga training. Two groups (yoga and control, n = 12 each) were assessed on Day 1 and on Day 30. During the intervening 30 days, the yoga group received training in yoga techniques while the control group carried on with their routine. At each assessment the baseline heart rate was recorded for one minute, this was followed by a six-minute period during which participants were asked to attempt to voluntarily reduce their heart rate, using any strategy. Both the baseline heart rate and the lowest heart rate achieved voluntarily during the six-minute period were significantly lower in the yoga group on Day 30 compared to Day 1 by a group average of 10.7 beats per minute (i.e., bpm) and 6.8 bpm, respectively (p < .05, Wilcoxon paired signed ranks test). In contrast, there was no significant change in either the baseline heart rate or the lowest heart rate achieved voluntarily in the control group on Day 30 compared to Day 1. The results suggest that yoga training can enable practitioners to use their own strategies to reduce the heart rate, which has possible therapeutic applications.
The study aimed at determining whether novices to yoga would be able to reduce their heart rate voluntarily and whether the magnitude of reduction would be more after 30 days of yoga training. Two groups (yoga and control, n = 12 each) were assessed on Day 1 and on Day 30. During the intervening 30 days, the yoga group received training in yoga techniques while the control group carried on with their routine. At each assessment the baseline heart rate was recorded for one minute, this was followed by a six-minute period during which participants were asked to attempt to voluntarily reduce their heart rate, using any strategy. Both the baseline heart rate and the lowest heart rate achieved voluntarily during the six-minute period were significantly lower in the yoga group on Day 30 compared to Day 1 by a group average of 10.7 beats per minute (i.e., bpm) and 6.8 bpm, respectively (p < .05, Wilcoxon paired signed ranks test). In contrast, there was no significant change in either the baseline heart rate or the lowest heart rate achieved voluntarily in the control group on Day 30 compared to Day 1. The results suggest that yoga training can enable practitioners to use their own strategies to reduce the heart rate, which has possible therapeutic applications.
BACKGROUND: Stress places a metabolic burden on homeostasis and is linked to heightened sympathetic activity, increased energy expenditure and pathology. The yogic state is a hypometabolic state that corresponds with mind-body coherence and reduced stress. This study aimed to investigate metabolic responses to stress and different yoga practices in regular yoga practitioners (YP), non-yoga practitioners (NY) and metabolic syndrome patients (MS). METHODS: YP (n = 16), NY (n = 15) and MS (n = 15) subjects underwent an experimental protocol that comprised of different 5-minute interventions including mental arithmetic stress test (MAST), alternate nostril breathing (ANB), Kapabhati breathing (KB) and meditation (Med) interspersed with 5 minutes of quiet resting (neutral condition (NC)). During the intervention periods continuous body weight adjusted oxygen consumption (VO2ml/min/kg) was measured using open circuit indirect calorimetry with a canopy hood. RESULTS: This is the first study to report oxygen consumption (OC) in yoga practitioners during and after MAST and the first to report both within and between different populations. The results were analysed with SPSS 16 using 3X9 mixed factorial ANOVAs. The single between-subject factor was group (YP, NY and MS), the single within-subject factor was made up of the nine intervention phases (NC1, MAST, NC2, ANB, NC3, KB, NC4, Med, NC5). The results demonstrated that the regular YP group had significantly less OC and greater variability in their OC across all phases compared to the MS group (p = .003) and NY group (p = .01). All groups significantly raised their OC during the mental arithmetic stress, however the MS group had a significantly blunted post-stress recovery whereas the YP group rapidly recovered back to baseline levels with post stress recovery being greater than either the NY group or MS group. CONCLUSIONS: Yoga practitioners have greater metabolic variability compared to non-yoga practitioners and metabolic syndrome patients with reduced oxygen requirements during resting conditions and more rapid post-stress recovery. OC in metabolic syndrome patients displays significantly blunted post-stress recovery demonstrating reduced metabolic resilience. Our results support the findings of previous randomised trials that suggest regular yoga practice may mitigate against the effects of metabolic syndrome. CLINICAL TRIAL NUMBER: ACTRN12614001075673; Date of Registration: 07/10/2014.
BACKGROUND: Stress places a metabolic burden on homeostasis and is linked to heightened sympathetic activity, increased energy expenditure and pathology. The yogic state is a hypometabolic state that corresponds with mind-body coherence and reduced stress. This study aimed to investigate metabolic responses to stress and different yoga practices in regular yoga practitioners (YP), non-yoga practitioners (NY) and metabolic syndrome patients (MS). METHODS: YP (n = 16), NY (n = 15) and MS (n = 15) subjects underwent an experimental protocol that comprised of different 5-minute interventions including mental arithmetic stress test (MAST), alternate nostril breathing (ANB), Kapabhati breathing (KB) and meditation (Med) interspersed with 5 minutes of quiet resting (neutral condition (NC)). During the intervention periods continuous body weight adjusted oxygen consumption (VO2ml/min/kg) was measured using open circuit indirect calorimetry with a canopy hood. RESULTS: This is the first study to report oxygen consumption (OC) in yoga practitioners during and after MAST and the first to report both within and between different populations. The results were analysed with SPSS 16 using 3X9 mixed factorial ANOVAs. The single between-subject factor was group (YP, NY and MS), the single within-subject factor was made up of the nine intervention phases (NC1, MAST, NC2, ANB, NC3, KB, NC4, Med, NC5). The results demonstrated that the regular YP group had significantly less OC and greater variability in their OC across all phases compared to the MS group (p = .003) and NY group (p = .01). All groups significantly raised their OC during the mental arithmetic stress, however the MS group had a significantly blunted post-stress recovery whereas the YP group rapidly recovered back to baseline levels with post stress recovery being greater than either the NY group or MS group. CONCLUSIONS: Yoga practitioners have greater metabolic variability compared to non-yoga practitioners and metabolic syndrome patients with reduced oxygen requirements during resting conditions and more rapid post-stress recovery. OC in metabolic syndrome patients displays significantly blunted post-stress recovery demonstrating reduced metabolic resilience. Our results support the findings of previous randomised trials that suggest regular yoga practice may mitigate against the effects of metabolic syndrome. CLINICAL TRIAL NUMBER: ACTRN12614001075673; Date of Registration: 07/10/2014.
BACKGROUND: Stress places a metabolic burden on homeostasis and is linked to heightened sympathetic activity, increased energy expenditure and pathology. The yogic state is a hypometabolic state that corresponds with mind-body coherence and reduced stress. This study aimed to investigate metabolic responses to stress and different yoga practices in regular yoga practitioners (YP), non-yoga practitioners (NY) and metabolic syndrome patients (MS). METHODS: YP (n = 16), NY (n = 15) and MS (n = 15) subjects underwent an experimental protocol that comprised of different 5-minute interventions including mental arithmetic stress test (MAST), alternate nostril breathing (ANB), Kapabhati breathing (KB) and meditation (Med) interspersed with 5 minutes of quiet resting (neutral condition (NC)). During the intervention periods continuous body weight adjusted oxygen consumption (VO2ml/min/kg) was measured using open circuit indirect calorimetry with a canopy hood. RESULTS: This is the first study to report oxygen consumption (OC) in yoga practitioners during and after MAST and the first to report both within and between different populations. The results were analysed with SPSS 16 using 3X9 mixed factorial ANOVAs. The single between-subject factor was group (YP, NY and MS), the single within-subject factor was made up of the nine intervention phases (NC1, MAST, NC2, ANB, NC3, KB, NC4, Med, NC5). The results demonstrated that the regular YP group had significantly less OC and greater variability in their OC across all phases compared to the MS group (p = .003) and NY group (p = .01). All groups significantly raised their OC during the mental arithmetic stress, however the MS group had a significantly blunted post-stress recovery whereas the YP group rapidly recovered back to baseline levels with post stress recovery being greater than either the NY group or MS group. CONCLUSIONS: Yoga practitioners have greater metabolic variability compared to non-yoga practitioners and metabolic syndrome patients with reduced oxygen requirements during resting conditions and more rapid post-stress recovery. OC in metabolic syndrome patients displays significantly blunted post-stress recovery demonstrating reduced metabolic resilience. Our results support the findings of previous randomised trials that suggest regular yoga practice may mitigate against the effects of metabolic syndrome. CLINICAL TRIAL NUMBER: ACTRN12614001075673; Date of Registration: 07/10/2014.
BACKGROUND High-frequency yoga breathing (breath rate of 2.0 Hz) has been associated with changes in oxy-hemoglobin in the prefrontal region of the brain. The present study assessed the effects of high-frequency yoga breathing (HFYB) at 1.0 Hz on frontal oxy-hemoglobin (oxy-Hb) and deoxy-hemoglobin (deoxy-Hb). MATERIAL AND METHODS Forty healthy male participants were recruited for the study. The experimental group consisted of 20 participants 23-40 years old (group mean +/-S.D., 26.4+/-4.7 years) with at least 3 months of experience performing HFYB (group mean +/-S.D., 16.3+/-9.8 months). The control group consisted of 20 participants ages 23-38 years (group mean age +/- S.D., 27.4+/-4.1 years), who were seated quietly for the same duration and their average experience of yoga practice was (+/-S.D.) 4.3+/-2.7 months. Each participant in the experimental group was assessed at 2 sessions (HFYB and breath awareness [BAW]) on alternate days. Hemodynamic changes were assessed using a functional near-infrared spectroscopy sensor placed over the forehead. Data were analyzed using repeated-measures analyses of variance followed by post hoc Bonferroni adjustment. RESULTS A significant reduction was observed in oxy-Hb during and after HFYB on the left and right sides compared to values before. We also found a significant reduction in deoxy-Hb during and after the quiet sitting control session compared to pre-session values on left and right sides. CONCLUSIONS The decrease in oxy-Hb during and after HFYB suggests that there was no frontal activation during HFYB when practiced at the rate of 1.0 Hz.
Heart Rate Variability (HRV) and respiratory sinus arrhythmia are directly associated with autonomic flexibility, self-regulation and well-being, and inversely associated with physiological stress, psychological stress and pathology. Yoga enhances autonomic activity, mitigates stress and benefits stress-related clinical conditions, yet the relationship between autonomic activity and psychophysiological responses during yoga practices and stressful stimuli has not been widely explored. This experimental study explored the relationship between HRV, mood states and flow experiences in regular yoga practitioners (YP), non-yoga practitioners (NY) and people with metabolic syndrome (MetS), during Mental Arithmetic Stress Test (MAST) and various yoga practices. The study found that the MAST placed a cardio-autonomic burden in all participants with the YP group showing the greatest reactivity and the most rapid recovery, while the MetS group had significantly blunted recovery. The YP group also reported a heightened experience of flow and positive mood states compared to NY and MetS groups as well as having a higher vagal tone during all resting conditions. These results suggest yoga practitioners have a greater homeostatic capacity and autonomic, metabolic and physiological resilience. Further studies are now needed to determine if regular yoga practice may improve autonomic flexibility in non-yoga practitioners and metabolic syndrome patients. Clinical Trial No 'ACTRN 2614001075673'.
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