Shirley Telles, PhD, MBBS, MPhil, Sachin Kumar Sharma, PhD, Kumar Gandharva, MSc, Ami Gupta, MA, Acharya Balkrishna, DLitt , Patanjali Research Foundation, Haridwar, Uttarakhand, India.

Introduction 

Volitional breath regulation is a part of several Eastern spiritual traditions.1 Pranayama, or volitional yoga breathing, is the fourth of eight steps of yoga, where the eighth step is samadhi, considered the pinnacle of all spiritual activity.2– 4 Volitional yoga breathing is called pranayama in Sanskrit, where prana means life energy, and ayama is expansion, while yama is control.5 Pranayama is intended to regulate the mental state in preparation for meditation.6 Several pranayama practices are described in the yoga texts, such as the Hatha Yoga Pradipika (1301–1600 CE)7 and Gheranda Samhita (1601–1700 CE).8 e breath characteristics volitionally modified during pranayama include breathing nasally or orally, the breath rate, depth of breathing, and the ratio of inspiration to expiration (i:e), among other factors.9 There are reports of complex bidirectional associations among cognition, affect, and parasympathetic cardiac activity with breath frequency and/or depth,10 as well as with i:e.11– 13 

Sustained changes in breath characteristics give rise to breath patterns. Understanding breath patterns is common in clinical medicine as a useful way to determine pulmonary and extra pulmonary pathology.14 Breath patterns refer to changes in four factors: respiratory rate (frequency), depth of breathing (drive), mode of breathing (symmetry between inspiration and expiration), and regularity of breathing pattern (rhythm). However, understanding breathing patterns is not limited to pathological conditions; it is now understood that in normal health breath patterns can bidirectionally influence mood states,15 cognition,16 and vagus nerve activity.17 Although several studies support pranayama practice’s influence on various functions,9,18 the exact way in which each pranayama changes breath patterns based on recording of the respiration during the practice has not been reported. 

The understanding about changes in breath patterns during pranayama has been most often inferred from the descriptions and practice guidelines in traditional texts such as those mentioned above or from practice guidelines followed in contemporary yoga centers, with some differences reported between these two types of sources.19 Hence there is a need to document the actual breathing during pranayama practices. Changes in breathing during a pranayama practice would be helpful to explain physiological effects in normal health. Also, the changes in breathing during a pranayama can suggest applications of the pranayama in health and therapy, as well as precautions to be observed. 

A previous preliminary study on a single experienced practitioner of pranayama suggests that specific changes in breath characteristics occur during each pranayama; however, the preliminary research was limited to a single participant.20 

The present study hence aimed to determine breath patterns (from changes in breath rate, depth, inspiration:expiration duration, and periods of breath hold/pauses) consistent across trained practitioners for five pranayama practices and breath awareness, based on the recorded respiration, as this has not been reported so far. 

The pranayama practices selected for study were those that are commonly practiced and that have been researched for their psychophysiological effects and applications in health. These five pranayama practices have certain effects in common, including changes in mood, attention, and heart rate variability (HRV).9,18 However, certain pranayama practices have specific effects not seen in the other practices: (1) high-frequency yoga breathing (HFYB) increased attention scores compared to other pranayama practices, which showed no change,21 while reducing HRV22; (2) bumblebee yoga breathing (BBYB) increased positive mood states23–25 with increased HRV; and (3) bellows yoga breathing (BLYB) especially influenced reaction time responses favorably, although the studies did not compare BLYB with other pranayamas.26 Each pranayama may have unique effects specific to unique changes in breath characteristics during the practice, leading to a specific breath pattern with unique physiological effects for each pranayama. Hence, breath characteristics (i.e., breath rate, depth [height], and i:e) were recorded during (1) five pranayama practices and (2) breath awareness in 23 practitioners of yoga breathing who were experienced with the five pranayama practices (i.e., alternate-nostril yoga breathing [ANYB)], BLYB, BBYB, HFYB, and hissing yoga breathing [HIYB]), as well as breath awareness, which is a part of all yoga breathing practices. 

Methods Participants 

Twenty-three healthy volunteers (aged between 20 and 35; 12 males, 11 females) participated in the study. With a sample size of 23, an average effect size of 1.82 (calculated by mean change in the respiratory characteristics during the five pranayama practices and breath awareness compared to the respective preceding states), and α = 0.05, the present study had power (β) = 1.000, which was determined using the G*Power program.27 Participants were recruited from a yoga university, where they were enrolled in different courses for their graduate degrees. Recruitment was carried out by oral announcements in the lecture halls. Participants were not given any incentive to take part in the study. Participants were included in the study if they had normal health based on a semistructured interview, could perform the pranayama practices and breath awareness included in the study consistently and effortlessly in a single session (this was based on an oral discussion with each participant), and had normal lung functions based on scores of the Lung Function Questionnaire (those who scored > 18 were included, as a score of ≤ 18 indicates problems with breathing, particularly airflow obstruction28) and on normal forced vital capacity (FVC; i.e., those who achieved ≥ 80% of their predicted FVC values based on age, gender, height, weight, and ethnicity [South Asians in the present case]). 

The FVC was assessed with a standard cardiopulmonary assessor (Quark CPET, COSMED) according to the guidelines of the American Thoracic Society and the European Respiratory Society.29 Participants were excluded if they used tobacco in any form. The signed informed consent of each participant was obtained after explaining the study to them. The study had prior approval from the ethics committee of the institution (approval No. PRF/YRD/012/1-4). 

Study Design 

Each participant was assessed for breath characteristics during the pranayama practices and breath awareness in a single 48-minute session. The data of all subjects were collected on different days but at the same time of day. Each session consisted of six 3- minute practices (i.e., six 3-minute states for each of the five pranayama practices and for breath awareness), where each practice was preceded by a 5-minute nonvolitional breathing (NVB) state. Hence, each session had six 3-minute states of practices and six 5-minute states of NVB. 

The primary aim of the present study was to determine the breath characteristics of the pranayama practices and breath awareness in established practitioners. Therefore, we assessed the participants for respiratory characteristics of the practices in two distinct sequences: (1) a fixed order of pranayama practices and breath awareness within a session for 48% of participants, and (2) a randomized order of pranayama practices within a session for 52% of participants. These two sequences were chosen to rule out the carryover effect of a pranayama practice or breath awareness on the respiratory characteristics of the subsequent practices. The fixed sequence was considered to simulate practicing pranayama practice in fixed sequence during regular yoga practice. The random sequence of the pranayama practices for 12 participants was generated using an online randomizer (www.randomizer.org). 

Recordings were conducted in a well-ventilated, dimly lit, sound-attenuated room. The participants were monitored from an adjacent room throughout the session on a closed-circuit television, and instructions were given through a two-way intercom to allow the participants to be undisturbed during the sessions. 

Breath Characteristics 

Respiration was measured with a strain-gauge transducer (MP 45 Biopac Student Lab, BIOPAC Systems), which measures the changes in abdominal circumference that occur as the participant breathes. The transducer is designed to present minimal resistance 

to movement and measure arbitrarily slow to fast respiration patterns with no loss in signal amplitude, while maintaining excellent linearity during inspiration/expiration. As the respiration waveform may vary with the location of the transducer and the level of tension in the respiration transducer belt, the belt was not moved during the session after fixing it 8 cm below the lower costal margin when the subject was standing erect following a maximal exhalation at the start of the session.30 The respiratory metrics using this method are highly correlated to measurements from a medical-grade continuous spirometer taken on healthy participants at rest.31 

Respiration recording was in the form of a wave, with peaks (corresponding to expansion of the abdominal cavity due to inspiration) and troughs (corresponding to abdominal cavity contraction during expiration). The duration of inspiration in each respiratory cycle was determined by measuring the elapsed time in seconds from the trough of a preceding wave to the peak of the wave, whereas the duration of expiration was calculated by determining the time from the peak of a wave to the trough of the wave in the next respiratory cycle. The duration of inspiration relative to expiration was determined using i:e. The respiration rate was calculated by manually counting the numbers of peaks and presented as the mean number of breaths/minute in different states. Manual counting of the waves was preferred to detection using the Biopac software to enable the waveforms to be examined for any inconsistencies. The difference between the inspiration and expiration volume was measured (in mV) as the amplitude of the waveform generated by abdominal volume changes with respiration. 

While assessing the breath characteristics, the following waveforms were predetermined for exclusion from analysis: (1) atypical waves correlated with participant postural changes based on observations on a closed-circuit television outside the recording room; and (2) oscillations of a waveform that exceeded one-third of the total height (amplitude in mV), occurring either during the upswing of the wave (during inspiration) or downswing of the wave (during expiration). The arbitrary cutoff of one-third of the total amplitude of the waveform was predetermined as the height of oscillation on either the upswing (inspiration) or downswing (expiration) for the wave to be excluded and considered a separate wave. No exclusions were required for these reasons. 

Pranayama Practices 

Details of the pranayama practices which are assessed in the present study are given below (in alphabetical order). The participants were seated with eyes closed in a cross-legged position with their back and neck aligned and straight. Participants assumed this position for all practices. 

Alternate-Nostril Yoga Breathing (Anuloma Viloma Pranayama) 

During ANYB, the nostrils are closed with the fingers of the dominant hand to facilitate breathing alternately through the left and right nostrils without breath holding. To begin, the right nostril is occluded with the right thumb while exhaling through the left nostril; then, inhalation through the left nostril is followed by left nostril occlusion with the right middle and ring fingers and exhalation through the right nostril, then inhalation through the right nostril and exhalation through the left nostril. This sequence is repeated as mentioned above. 

Bellows Yoga Breathing (Bhastrika Pranayama) 

During BLYB, participants are asked to inhale through both nostrils and then exhale with ease, repeating the process in the same way during the practice. 

Bumblebee Yoga Breathing (Bhramari Pranayama) 

In BBYB practice, the thumbs on both sides exert gentle pressure on both tragi in front of the ear canals, occluding them. The remaining fingers rest on the closed eyes. In this position, participants inhale, followed by a prolonged exhalation while producing a humming sound like a bumblebee. This is one cycle of BBYB, which is repeated during the practice. 

High-Frequency Yoga Breathing (Kapalabhati Pranayama) 

HFYB consists of breathing at an increased rate, with contraction of the anterior abdominal muscles during exhalation. 

Hissing Yoga Breathing (Sitkari Pranayama) 

The upper and lower teeth were clenched together and the lips were drawn aside as much as was comfortable. Participants were asked to breathe in slowly and steadily through the mouth with clenched teeth. At the end of inspiration, participants were asked to breath out through the nose with the mouth closed. 

Breath Awareness 

During breath awareness, attention was consciously directed to the flow of air as it passed through the nasal passages. Participants were instructed not to alter breathing in any way, only to pay attention to the breath. Breath awareness was selected as an intervention because being aware of the breath is part of all yoga breathing techniques. 

Data Analysis 

The data obtained were analyzed using SPSS (v. 24.0). A Shapiro- Wilk test was used to test normality of the data. The results of the Shapiro-Wilk test indicated that the data were not normally distributed. Therefore, the data were analyzed with nonparametric tests. 

Selection of the Nonvolitional Breathing State for Comparison with Pranayama Practices 

In each session there were six NVB states between the five interventions of pranayama practices and breath awareness. Hence, except for the first baseline NVB, each NVB was both a pre-state of a pranayama practice and a post-state of the previous practice, NVB 2 is the pre-state of HIYB and the post-state of ANYB). To determine whether the preceding pranayama practice influenced the following NVB, separate Friedman tests were used to detect differences in respiratory characteristics between the NVB states for participants assessed in fixed sequence (n = 11), random sequence (n = 12), and pooled data of participants in random and fixed sequences
(n = 23). 

Comparison of the Breath Characterstics of the Pranayama Practices in Fixed vs. Random Order 

To identify whether there were any differences between the breath characteristics of the pranayama practices when performed in a fixed versus random sequence, the breath characteristics of the pranayama practices carried out in a fixed sequence were compared with the respective practices carried out in a random sequence using Mann-WhitneyU tests. 

Comparison of Each Pranayama Practice with the Respective Preceding State 

The breath characteristics of each of the pranayama practices were compared with their respective preceding states using Bonferroni Holm–corrected Wilcoxon signed-rank tests using SPSS. The level of significance (α) was set at 0.05. Bonferroni Holm– corrected alpha level was determined by dividing the alpha value by the number of comparisons (i.e., 0.05/6 = 0.0083). 

Results 

Twenty-three participants of both genders (11 females, 12 males) aged between 20 and 35 and having a minimum of 36 months of experience of pranayama practices completed the study. 

Respiratory Characteristics Recorded During NVB in Fixed and Random Sequences and Pooled Data 

NVB (i.e., the preceding states of the five pranayama practices significantly for respiration rate (χ (5) = 6.260, p = 0.282), and breath awareness) in fixed sequence (n = 11) did not differ duration of inspiration (χ (5) = 4.610, p = 0.465), duration of expiration, (χ (5) = 8.972, p = 0.110), ratio of duration of inspiration to expiration (χ (5) = 8.766, p = 0.119), or height of the wave (χ (5) = 12.247, p = 0.032) significantly for respiration rate (χ (5) = 3.663, p = 0.599), expiration, (χ (5) = 0.333, p = 0.997), ratio of duration of inspiration to. expiration (χ (5) = 3.667, p = 0.598), or height of  the wave (χ (5) = 6.238, p = 0.284).
NVB for pooled data of random and fixed sequences (n = 23) did not differ significantly for respiration rate (χ (5) = 5.157, p = 0.397), duration of inspiration (χ (5) = 3.646,
p = 0.601), duration of expiration, (χ (5) = 4.863), p = 0.433), ratio of duration of inspiration to expiration (χ (5) = 7.720, p = 0.172), or height of the wave (χ (5) = 5.186, p = 0.394). 

Breath Characterstics of the Pranayama Practices in Fixed vs. Random Order 

Time of inspiration was significantly higher during HFYB when performed in random sequence compared to fixed sequence (p < 0.05, Mann-Whitney U test). There were no other significant differences in the breath characteristics of pranayama practices carried out in fixed compared to random sequence. 

Respiratory Characteristics During Pranayama Practices with Respective Preceding States 

The breath frequency significantly increased during HFYB and decreased during BBYB, ANYB, and HIYB in comparison to the respective pre-state; the duration of inspiration decreased significantly during HFYB and increased during HIYB in comparison to the respective preceding state; the duration of expiration decreased significantly during HFYB and increased during BBYB, HIYB, and ANYB in comparison to the respective pre-state; the i:e increased during HFYB and decreased during BBYB and ANYB in comparison to the respective pre-state; and the depth of breathing (i.e., the height of the wave) increased significantly during ANYB, BLYB BBYB, HFYB, and HIYB (in all cases p < 0.0083, Wilcoxon paired signed-ranks test). 

Discussion 

Breath characteristics changed differently during the five pranayama practices studied but not during breath awareness. The changes during each pranayama are discussed below, emphasizing implications of the changes and agreement with previous research on the physiological effects of the five pranayama practices and with the practice guidelines for each pranayama practice mentioned in traditional yoga texts. 

HFYB is called kapalabhati pranayama in Sanskrit (where kapala = forehead/skull and bhati = shining).5 During HFYB compared to before, the breath rate increased by 373.3%, the depth of breathing increased by 275.0% (gauged from the height of the respiratory waveform31), and i:e increased by 177.0%. Fast and deep breathing can lead to symptoms of hyperventilation because of hypocapnia.32 Previously, a report on HFYB stated that despite 15 minutes of HFYB, participants did not report symptoms of hyperventilation.33 Hyperventilation symptoms were investigated with the Nijmegen scale, reported to be 91% sensitive to detect hyperventilation syndrome.34 

The absence of symptoms of hyperventilation related to HFYB33 may be related to the present finding of an increase in i:e during HFYB, with a relative increase in inspiration duration, which is known to influence carbon dioxide exchange. Hence, although HFYB does not appear to lead to hypocapnia, the effect of the increased rate and depth of respiration during HFYB would be expected to increase respiration-driven cortical activation.35 Cortical activation during respiration is impelled by afferent discharge from muscles of respiration (especially the diaphragm and intercostal muscles),36 which is expected to increase during HFYB. Increased cortical activation can explain some of the previously reported changes in HFYB, such as increased oxygen consumption,33 increased higher frequencies in electroencephalogram (EEG),37,38 and facilitated sensory information transmission based on sensory evoked potentials and increased performance in an attention task.21,39,40 Also, HFYB was previously reported to be associated with decreased HRV.22 The decrease in HRV during HFYB is explained by the effect of changes in the breath frequency on the respiratory sinus arrhythmia (RSA). During deep, slow breathing at 6 breaths/minute (i.e., a frequency of 0.1 Hz), the RSA is best elicited, and also synchronizes with baroreflex frequency.41 In contrast, as breath frequency increases, the RSA decreases.42,43 The RSA indicates cardiac parasympathetic activity,42 which is hence reduced in HFYB. 

The changes in breath characteristics in HFYB reported here are consistent with the Sanskrit name given to the practice (kapalabhati), as “shining skull” implies increased brain activity.5 Also, as previously reported in a detailed analysis of the practice guidelines in the traditional yoga texts, the Sanskrit verses in the Hatha Yoga Pradipika (2.35) support rapid inspiration as well as expiration during HFYB.7 However, the breath characteristics reported here show that inspiration was longer than expiration during HFYB, which may also contribute to the decrease in RSA42 and hence the decrease in HRV during HFYB, although longer inspiration in HFYB may be preventing symptoms of hyperventilation during HFYB, as described above. 

The changes in breath characteristics during HFYB are in contrast to the changes during BBYB, where the breath rate reduced (75.4%), depth increased (307.0%), and expiration was prolonged (476.3%) compared to the preceding baseline. Slow and deep breathing is reported to increase calmness,44 and prolonged expiration relative to inspiration has been associated with an increase in pleasant and positive feelings.13 Hence, BBYB practice can be expected to be associated with calmness and pleasant feelings. Previously, BBYB practiced for 5 days a week over 6 months was reported to increase HRV,45 directly attributable to the low breath rate (≤ 0.1 Hz), which is reported to increase the RSA.42 In addition, breathing with low i:e and prolonged expiration has been shown to increase RSA and hence parasympathetic cardiac activity.11,42 

Bumblebee breathing is called bhramari pranayama in Sanskrit. The name of this practice is based on the humming sound a practitioner emits on expiration (bhramari is a female bumblebee). The Hatha Yoga Pradipika gives the practice guidelines for BBYB: accompanying a slow expiration with the humming sound of a female bumblebee and a rapid inspiration with the sound made by the male bumblebee. The sounds appear to provide auditory cues for the two phases of respiration.19 The duration of inspiration in our study was not shorter during the practice compared to the preceding phase, suggesting that the breath rate was slowed by prolonged expiration alone. 

During ANYB the changes in breath characteristics were comparable to those during BBYB. There was a decrease in
breath rate (55.3%), increase in depth of breathing (141.0%), and prolonged expiration (245.0%) compared to the preceding baseline; ANYB involved breathing slower, deeper, and with longer exhalation. While the practitioner’s attention is directed to regulating airflow through the nostrils, the changes in rate, depth, and expiration occur spontaneously. These changes are likely to be associated with increased calmness, as well as with pleasant and positive feelings.13 Previously, ANYB was found to increase HRV,46–48 specifically increasing root mean square of successive differences in RR interval, which is known to indicate cardiac parasympathetic activity.49 These changes can be attributed to the increase in RSA reported with slow, deep breathing and prolonged exhalation.42 Previous research reported an increase in higher EEG frequencies with reduced lower EEG frequencies during ANYB.50 The EEG findings may reflect increased focusing on the practice as the practitioner regulates airflow through the nostrils alternately in a fixed pattern. 

ANYB has been called anuloma viloma pranayama in Sanskrit, where anuloma is inhale and viloma is exhale. This contemporary yoga breathing practice differs from the traditionally described alternate-nostril breathing, which is called nadi shodhana pranayama (nadi being subtle energy channels and shodhana conveying purification or cleansing). The following practice guidelines for nadi shodhana are given in the Hatha Yoga Pradipika (2.7–9)7: 

The practitioner [yogi] should inhale prana (the vital principle/ life force) through the left nostril, hold [the breath], then exhale through the other nostril. Then inhale through the right nostril, hold the breath [inside] and then exhale through the left [nostril]. By practicing [breathing] this way through Surya [solar energy channels] and Chandra [lunar energy channels] alternately and following directions [the yogi] purifies all nadi [subtle energy channels]. 

The present-day practice of ANYB has been derived in yoga schools in India, excluding the periods of breath holding to make the practice easy for novices and those who practice yoga breathing for health and therapeutic benefits. Further research should examine alternate breathing with breath holding, as breath holding (called kumbhak, meaning pot) has unique effects and challenges.51 

The pranayama practices described above are nasal breathing practices. However, yoga breathing also traditionally includes practices with volitional oral breathing; an example is HIYB. The changes in breath characteristics support HIYB as slow breathing. Yoga practitioners customarily consider such oral inspiratory breathing as “cooling,” although research did not show a change in core or peripheral body temperature during the practice.52 The description as cooling may reflect the calm state observed traditionally related to the practice. Although in our study the breath rate reduced (along with a comparable increase in inspiration and expiration, keeping i:e the same during HIYB as at baseline), there were post inspiration pauses. The pauses may be related to the time taken to switch from nasal to oral breathing, which has been observed in pathological conditions that require such a switch.53 The Hatha Yoga Pradipika (2.54) gives instructions to perform HIYB: “Sitkari is performed by drawing in the air through the mouth, keeping the tongue between the lips. The air thus drawn in should not be expelled through the mouth.”7 However, there are no clear practice guidelines about the breath rate, depth, or i:e. 

The fifth intervention in the present study was BLYB. During this practice there was an increase in depth of breathing but no change in the breath frequency or i:e. This change may be expected based on the instructions given to the practitioner to breathe deeply.21 An increase in the depth of breathing is usually achieved with diaphragmatic breathing.10 Previously, diaphragmatic breathing practiced over 8 weeks was found to improve sustained attention, increase positive affect, and decrease cortisol levels.10 However, in the previous report diaphragmatic breathing was combined with a low breath frequency (4 breaths/minute), which could also account for the effects seen in the previous report but not in the present study. 

Compared to other pranayama practices, fewer reports exist on the physiological effects of BLYB. There are reports of improved reaction time with fewer anticipatory responses after BLYB.54,55 Based on the increased depth of breathing, it may be speculated that BLYB increases parasympathetic activity through the Hering-Breuer inflation reflex,56 which helps the practitioner to be less impulsive during a reaction-time task, as short-term decreases in impulsivity are reported with increased parasympathetic activity.57 

BLYB in Sanskrit is bhastrika pranayama, as bhastrika is the bellows used by a blacksmith.4 BLYB can be a considered a consistent and repetitive movement, with air flowing between the “heart lotus” and “chest-throat” up to the cranium (Hatha Yoga Pradipika 2.59–62). Breath rate during BLYB is mentioned differently in two traditional texts: Whereas the Hatha Yoga Pradipika mentions a fast movement of air like a bellows, the Gherandha Samhita mentions slow movement.7 In certain schools of yoga, both fast and slow bhastrika pranayama are practiced.5 In the present study, the breath rate was around 11 breaths/minute during bellows breathing, suggesting a slower practice. 

There were no significant changes in the rate, depth, or i:e during breath awareness. Hence, breath awareness is supported as an active control intervention for pranayama. A previous report of decreased blood pressure during breath awareness58 is probably related to directed awareness rather than to changes in breathing. 

Limitations and Future Directions 

The findings of the present study, which aimed to determine breath patterns during five commonly practiced pranayamas, are limited by the small sample size (n = 23) and the fact that the participants were recruited from a single yoga institution; hence, the study should be considered exploratory. Despite the difficulty in recruiting practitioners capable of practicing several pranayamas consistently in the laboratory, future research on breath patterns during pranayamas should endeavor to involve larger samples. 

Also, in the present study participants belonged to a single yoga school, and although many principles of pranayama practice are consistent across yoga schools (e.g., maintaining breath awareness during practice), practice guidelines differ between schools. Researching breath patterns across yoga schools is necessary to understand common features and differences in the ways pranayama is practiced. This understanding is important in the application of pranayama in health and disease management, as well as in understanding research on the physiological effects of pranayama practice. Comparisons of breath patterns across yoga schools could be a direction for future research. 

The findings are also limited by having no simultaneous recording of blood gases. Although the pranayamas are voluntarily regulated and under central cortical control, changes in blood gases can be expected to occur because the pranayamas involve various changes in the breath, including increasing or reducing the breath rate (with expected hypocapnia and hypercapnia, respectively). Without data on blood gases, the interplay between cortical control and chemoreceptor input to the respiratory center during pranayama practice remains to be understood. Future research on breath patterns in pranayama should include simultaneous recording of blood gases. 

Future research could also include assessments carried out on separate days (rather than in a single session, as in the present study), as well as recording during pranayama for a longer duration than the 3 minutes of the present study. 

In summary, the present study determined how each pranayama practice changes breathing volitionally, specific to the practice, and demonstrated no changes in breathing during simple breath awareness. 

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Keywords; breathing, Yoga