. . Published Ahead of Print a Systematic Review of the Energy

. . . Published ahead of Print

A Systematic Review of the Energy Cost and Metabolic Intensity of Yoga

D. Enette Larson-Meyer

Department of Family and Consumer Sciences, University of Wyoming, Laramie, WY

Accepted for Publication: 28 February 2016

ACCEPTED

Medicine & Science in Sports & Exercise® Published ahead of Print contains articles in unedited manuscript form that have been peer reviewed and accepted for publication. This manuscript will undergo copyediting, page composition, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered that could affect the content.

A Systematic Review of the Energy Cost and Metabolic Intensity of Yoga

D. Enette Larson-Meyer

Department of Family and Consumer Sciences, University of Wyoming, Laramie, WY

Corresponding Author: Enette Larson-Meyer, PhD, RD, FACSM Department of Family & Consumer Sciences 1000 E University Ave Laramie, WY 82071 (307) 766-4378 [email protected]

No funding was received for completion of this project. Results of the present study do not constitute endorsement by the American College of Sports Medicine.

CONFLICT OF INTERESTS: None

ACCEPTED

Purpose: With the increasing popularity of Hatha yoga, it is important to understand the energy cost and metabolic equivalents (METs) of yoga practice within the context of the American

College of Sports Medicine (ACSM) and the American Heart Association (AHA) physical activity guidelines. Methods: This systematic review evaluated the energy cost and metabolic intensity of yoga practice including yoga asanas (poses/postures) and pranayamas (breath exercises) measured by indirect calorimetry. The English Speaking Literature was surveyed via

Pubmed using the general terms “yoga” and “energy expenditure” with no date limitations.

Results: Thirteen manuscripts were initially identified with an additional four located from review of manuscript references. Of the 17 studies, ten evaluated the energy cost and metabolic equivalents (METs) of full yoga sessions or flow through Surya Namaskar (sun salutations), eight of individual asanas and five of pranayamas. METs for yoga practice averaged 3.3±1.6

(range=1.83 to 7.4 METs) and 2.9±0.8 METS when one outlier (i.e., 7.4 METS for Surya

Namaskar) was omitted. METs for individual asanas averaged 2.2±0.7 (range=1.4 to 4.0 METs) whereas that of pranayamas was 1.3±0.3. Based on ACSM/AHA classification, the intensity of most asanas and of full yoga sessions ranged from light-, less than 3 METS, to moderate-aerobic intensity, 3 to 6 METS, with the majority classified as light-intensity. Conclusion: This review suggests that yoga is typically classified as a light-intensity physical activity. However, a few sequences/poses including Surya Namaskar meet the criteria for moderate-to vigorous-intensity activity. In accordance with the ACSM/AHA guidelines the practice of asana sequences with

MET intensities above 3 (i.e., >10 min), can be accumulated throughout the day and count towards daily recommendations for moderate- or vigorous-intensity physical activity. Key Words: energyACCEPTED expenditure, yoga asanas, pranayama, metabolic equivalents, oxygen uptake, exercise intensity

Hatha yoga is an increasingly popular form of physical activity in the United States (4,

18, 21, 40) and may be one of the world’s fastest growing health and fitness activities (4). Yoga originated in ancient India where its practice was intended to help “redirect a person’s search for happiness from external sources to internal ones” and eventually result in life fulfilment, wholeness and enlightenment (8, 29). Hatha yoga is one path that traditionally integrates the physical practice of asanas (holding poses or postures), pranayama (breathing control/exercise), bandhas (muscular contractions), mudras (seals and gestures), kriyas (internal cleansing techniques) and meditation (contemplative thought) along with a spiritually-based philosophical framework (e.g., which includes the nonviolence, truthfulness, non-stealing, etc. Since the

1960’s and 70’s, Hatha yoga has undergone various adaptations in the US and has become a practice believed to promote physical fitness, stress reduction and relaxation (4, 8, 29). Yoga is offered in a majority of US health clubs (8) as well as a growing number of yoga studios and private homes. Classes are typically 60 to 90 minutes in duration and involve flowing through a series of asanas and pranayama. Depending on the style, studio and/or teacher, asanas are held standing, seated or supine for various amounts of time and may involve balance and inversion poses with focus on proper form, alignment and breathing. The rhythmic flow through a specific sequence of 12 asanas with controlled breath, termed Surya Namaskar (sun salutations), are often incorporated into many styles/classes and are thought to promote cardiorespiratory fitness (23).

Classes typically end in a supine posture called Savasana (corpse pose) and many incorporate meditation. ACCEPTEDSpecific styles of yoga such as Bikram (4, 7) and hot power yoga (4) have also separated from traditional Hatha practice. Both styles—although distinctly different-- incorporate set sequences of basic Hatha poses but are conducted in a hot and humidified room. Practice in

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. this environment is believed to loosen joints, muscles and tendons and help students push themselves, providing a gratifying sense of progress (4). Yoga has even emerged as a component of the new-generation active computer games (13, 22) with WII Fit plus software containing at least 18 modes of yoga (22).

Recent data suggests that as many as 20.4 million Americans (8.4% of the US population) practiced yoga in 2012, up from 15.8 million in the previous 2008 survey, with an additional 44.4% expressing interest in trying yoga (40). With the increasing popularity of Hatha yoga, it is important to understand the energy cost and intensity of yoga and its various asanas and pranayamas within the context of the public health and exercise prescription guidelines recommended by the American College of Sports Medicine (ACSM) (2, 10, 12, 16) and the

American Heart Association (AHA) (16). To promote and maintain health and reduce disease risk, the ACSM/AHA guidelines encourage 30 minutes of moderate-intensity aerobic physical activity five days per week or vigorous-intensity aerobic activity for a minimum of 20 minutes three days per week. The public health guidelines define absolute intensity in terms of metabolic equivalents (METs) (16) rather than estimates of relative intensity that are more commonly used for individual exercise prescriptions. These typically include percentages of maximal heart rate

(%HRmax), heart rate reserve (%HRR), maximal oxygen uptake (%VO2max) or maximal oxygen uptake reserve (%VO2R) (see Table 1)(12). METs are useful for expressing the energy cost and intensity of physical activity as a ratio to metabolic rate at rest, standardized as 3.5 ml/kg/min. in a manor comparable among persons of different weights and physical fitness. Moderate- and vigorous-physicalACCEPTED activity are defined as an intensity between 3 to 6 METs and greater than 6 METs, respectively (16). Current physical activity guidelines also emphasize that combinations of moderate and vigorous-intensity activity are likely to have similar health benefits as

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. continuous activity and can be combined in shorter bouts of at least 10 minutes throughout the day to meet guidelines. The goal is to achieve 450 to 750 MET minutes per week (i.e., METs X daily min accumulated X number of times per week) (16).

The purpose of this paper is to twofold: 1) provide a systematic review and evaluation of the literature concerning energy cost and intensity of yoga asanas and yoga practice according to the current ACSM and AHA guidelines (12, 16); and 2) evaluate the quality of published studies measuring the energy cost of yoga asanas, pranayama and complete practice via indirect calorimetery. Although a small handful of studies have measured the metabolic cost of individual yoga asanas and full yoga sessions, a summary of the energy cost and intensity of yoga is not currently available for yoga as it is for other sports (1). This information may prove useful to the exercise, nutrition and medical professional prescribing yoga as a fitness activity or recommending yoga practice for weight loss and/or weight maintenance (10). It may also be useful for yoga teachers and practitioners.

METHODS

The English Speaking literature was surveyed via Pubmed and cross checked with Web of Science using the general terms “yoga” and “energy expenditure” with no date limitations. To be included, articles had to use indirect calorimetry to calculate energy expenditure from measures of oxygen uptake and carbon dioxide production. Key variables of interest, including absolute and relative oxygen uptake, energy expenditure, MET values, heart rate, respiratory rate and rate of perceivedACCEPTED exertion (RPE) were evaluated and summarized from each identified article and the references scanned for additional manuscripts not identified in the initial literature search. Energy expenditure, METs and relative heart rate (i.e., as a percentage of actual or

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. estimated max) were calculated from available data if values were not reported by the authors using an assumed 5 kcal/liter of O2 consumed, a MET value of 3.5 ml/kg/min and an estimated maximal heart rate of 220 minus average age. Attention was also placed on indirect calorimetry protocol and methodology which could restrict or interfere with the practice of holding yoga asanas and on data reliability (i.e., calibration procedure, measurement performed after fasting or a standardized meal, 24 hours after the last bout of strenuous exercise). The names of poses are listed in Sanskrit with the common English translation listed in parentheses or defined in figure legends.

The quality of metabolic data collected by indirect calorimetry was evaluated by comparing methodology with commonly accepted standard procedures which included: a) the collection of expired air into a Douglas bag, meteorological balloon, gasometer or metabolic cart and analysis of gas content and volume using gas analyzers, calibrated against standard gases, and a gasometer or pneumotach, calibrated with a known volume of air; b) documentation of ambient environment including temperature, relative humidity and barometric pressure for adjustment of gas volume; c) control of time of day of measurement; d) control of subjects recent food and fluid intake, vigorous exercise and other factors such as sleep, medications, alcohol and tobacco that could alter energy expenditure. Because the various apparatuses may restrict or interfere with the practice of holding yoga asanas, attention was also placed on the apparatus used to collect expired air (e.g. mouthpiece and nose clips, face mask, and canopy hood), unless gases were collected within a room indirect calorimeter. Finally, documentation was made as to whether the ACCEPTEDyoga asanas were held to assure steady state of O2 uptake or whether the asanas were performed as a continuous flow. The commonly used standard during testing of moderate to

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. more vigorous exercise is to have a participant exercise at a given intensity for at least four minutes to ensure steady state and analyze only the last one to two minutes of data.

RESULTS

Seventeen articles were initially identified using “yoga” and “energy expenditure”; thirteen used indirect calorimetry to evaluate the energy cost of various yoga asanas or yoga practice and four were not relevant. An additional five were identified from the reference list of the 13 relevant articles, however, one was published only in abstract form with insufficient data for evaluation (5). The publication dates ranged from 1962 to 2015. Articles included yoga asanas practiced in traditional Indian centers (3, 23, 30, 31, 33, 34), U.S. and European health clubs (6, 7, 14), Bikram-style centers (26) and as part of active video games (Wii Fit Plus) (13,

22).

Indirect Calorimetry Methodology. Table 2 summarizes the indirect calorimetry equipment, procedures and subject control employed and/or reported compared to standard methodology. As noted in the table, less than half of the studies reported calibrating the metabolic cart (i.e. gas analyzers and pneumotach) prior to testing. Most did not report time of day of measurement or whether participants were asked to fast and/or follow a controlled run in diet before testing. Even fewer controlled for fluid intake, sleep or menstrual cycle phase in females, all of which could impact energy expenditure and/or heart rate response during yoga.

Most used commercially available metabolic carts with gases collected using either a mouthpiece and nose clipsACCEPTED (26, 32) or a face mask (13, 23, 30, 31, 33). Several studies, however, failed to report such detail. Two studies (14, 22) measured energy expenditure in a full-room metabolic

(respiratory) chamber, which allowed for free movement during yoga practice, and one used a

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. canopy system (ventilated hood) during pranayama (supine breathing) only (38). The test-retest reliability of the energy cost and METs of yoga practice was reported only using the full room calorimeter (14) and was found to be sufficiently consistent (ICC .0.97) (14).

Energy Cost and METs of Yoga Practice. As summarized in Table 3 and Figure 1, the

MET value of yoga practice, including exclusive movement through Surya Namaskar (Sun

Salutations Flow), ranged from 2.0 METs during a Wii Yoga session (13) to over 6 METs with the exclusive practice of Surya Namaskar in experienced practitioners (23). Of the studies included in Figure 1, five evaluated the energy cost of movement through various asanas (some including Surya Namaskar) that may be typical of a yoga practice or yoga class (7, 9, 14, 26, 33).

In three of these studies, yoga participants followed a sequence set by video- or audiotaped recordings which included a 56-minute commercially-available beginner Ashtanga yoga DVD

(14), a 30-minute videotaped, instructor choreographed Hatha yoga routine (7), or a 90-minute audio recorded Bikram session (26) which systematically transitioned through Bikrams 26 static asanas. In the other two studies, yoga participants flowed through a set sequence of static postures at a dictated pace. For example, Ray and colleagues (33) had participants hold seated

Hatha postures for one to three minutes for a total of 24-min with rest in the form of Savasana

(corpse pose) between postures. The other of Dicarlo and colleagues (9) had participants move through 12 Hatha standing poses performed twice per side for 40 seconds with 10-second jump transitions into and out of tadasana (mountain pose) between poses. As shown in Figure 1, a

MET value of greater than 3 was achieved by the standing Hatha flow with jump transitions (9) and flow throughACCEPTED Surya Namaskar (sun salutations) in three out of the four studies (7,23,34). Flow through Surya Namaskar in experienced practitioners achieved METs in the aerobically intense range (23). The Bikram yoga sequence (26) did not result in a greater energy cost or

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. MET intensity compared to traditional yoga in a thermal-neutral environment. MET values for yoga practice averaged 3.3±1.6 METS for all 10 studies and 2.9±0.8 METS when the study of

Mody (23), which appeared to be a high outlier, was omitted.

Energy Cost and METs of Individual Yoga Asanas. Eight studies (3, 6, 26, 30-33, 38) evaluated the metabolic cost of various yoga asanas held in traditional Hatha or Bikram yoga

(which is based off of Hatha asanas). The energy cost and METs of all asanas are summarized in

Table 2 and Figure 2. As previously noted, very few asanas were of the intensity to produce a

MET value greater than 3 with the exception of Dandayamana-Janushirasana (standing head to knee) (26), Dandayamana-Dhanurasana (standing bow), Trikanasana (triangle) (26) and

Tuladandasana (balancing stick) (26) during Bikram yoga. Standing asanas (9, 26), for the most part, produced slightly higher average MET values than seated poses (33), as did backward bending poses compared to forward bending postures (i.e., Dhanurasana vs. Paschimottanasana or seated wheel compared to forward bend) (3, 33), The average METs of supine poses (i.e.,

Savasana or corpse pose) was comparable to rest (MET value=1.0 (3, 30, 31).

Inversion poses including Sirsasana (head stand) did not drastically increase metabolic rate above the range of 1.7 to 2.5 METs (6, 32). No published studies, however, measured the metabolic cost of some of the more difficult inversions/arm balancing poses including Bakasana

(crow/crane), Eka Pāda Gālavāsana (flying pigeon) and Adho Mukha Vṛkṣāsana (hand stand) which in the author’s lab produced MET values >3 (Larson-Meyer, unpublished data).

Cardiorespiratory Intensity of Yoga. The percentage of actual or estimated HRmax and

VO2max elicitedACCEPTED by yoga practice and/or individual asanas is shown in Table 3 for all studies that provided heart rate data (6, 7, 9, 13, 14, 23, 26, 33, 34) and/or measured VO2max (7, 9, 33). The intensity of typical yoga practice was highly variable among studies ranging from 49% (14) to

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 71% (9) of actual or estimated heart rate max and from 12 to 40% VO2max. More extreme ranges in heart rate were found between Wii yoga (40% HRmax) (13) and both Surya Namaskar (80%

HRmax) (23) and Bikram yoga (51-90% HRmax) (26). Interpretation of HRmax appears to vary according to asanas and room temperature. VO2max estimates are complicated by the aerobic fitness and sex of yoga participants, which ranged from an average of 33 to 35 ml/kg/min (7, 9) to 42 ml/kg/min (6) in female practitioners and 47 m/kg/min in male participants (9).

Metabolic Cost of Yoga Relative to Walking. In addition to evaluating the energy cost and intensity of yoga, four studies simultaneously compared metabolic cost of yoga practice to that of walking at 2.0 (14), 2.9 (26), 3.0 (14), 3.5 (7) and 4.0 mph (9). As stated in the ACSM guidelines, an adult walking at 3 mph on a flat, hard surface is expected to expend about 3.3

METs (16). The METs and intensity as percentage of HRmax or VO2max if available are summarized in Table 3. In general, walking at 3 mph produced a similar MET response compared to yoga (14), whereas walking at a faster velocity had a higher metabolic cost (7, 9).

Rate of Perceived Exertion. Only one study (9) reported the rate of perceived exertion

(RPE) or effort during yoga practice. The RPE according to the Borg scale, which ranges from a value of 6 at rest to 20 at maximal effort, was 14.8±1.8 METS for the aforementioned practice of standing Hatha asanas. This was significantly higher than the average RPE of 12.5±1.5 for treadmill walking at 4 MPH for the same subjects, despite the higher MET values elicited for walking (5.4 METs) vs. yoga practice (4.1 METs).

Energy Cost of Pranayama. Five studies (22, 26, 33, 36, 38) evaluated the metabolic cost of pranayamasACCEPTED or the controlled and specific breathing patterns/movements commonly practiced in yoga using a ventilated hood (38) , cart with face mask or mouthpiece (26, 33, 36) or full-room calorimeter (22). The metabolic cost of pranayamas is summarized in Figure 3. The

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. MET values of the majority of pranayamas was slightly above rest (MET =1.0) averaging

1.3±0.3 with the exception of Yoga Mudra, Kaki Mudra, high frequency breathing and standing deep breathing which had METs just above 1.5. The metabolic cost of Kapalbhati breathing was also slightly higher but the MET value varied between studies (33, 38). Pranayama did not elicit a significant change in heart rate response in the one study that simultaneously evaluated heart rate (26) but some such as kapalbhati did elevate ventilation above restful breath (33). High frequency yogic breathing was found to increase energy expenditure from carbohydrate whereas breath awareness decreased energy expenditure from fat compared to rest, but the respiratory exchange ratio unfortunately was not reported.

DISCUSSION

This work is the first to comprehensively review the published literature evaluating the energy cost and intensity of yoga practice, including individual asanas (poses/postures) and pranayamas (breathing exercises). Based on the ACSM and AHA classification system (2, 10,

12, 16), the intensity of yoga asanas and of full yoga practice ranged from light-aerobic (less than

3 METS) to moderate- (3 to 6 METS) to vigorous-aerobic (>6 METS) with the majority classified as light-intensity. The asanas and sequences of asanas that elicited MET intensities in the moderate-intensity aerobic range included Surya Namaskar (sun salutations) and specific standing and balancing postures including Tuladandasana (balancing stick) and Dandayamana

Dhanurasana (standing bow). This highlights that yoga is not typically practiced at an intensity that meets theACCEPTED ACSM/AHA recommendations for moderate-intensity aerobic exercise (12, 16), and is on average less aerobically intense than brisk walking. In accordance with the guidelines, however, it further highlights that the practice of sequences of asanas with MET intensities

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. above 3 METs (i.e., for ~10 min or longer) can be accumulated throughout the day and count towards daily (or weekly) recommendations for moderate- to vigorous-intensity aerobic activity

(16).

Energy Cost and Intensity of Yoga Practice. Despite a general classification as a light- intensity exercise modality, the findings from this systematic review suggest that the energy cost and MET intensity of a yoga session can be altered according to the asanas practiced, and the velocity of flow between asanas (i.e., jump vs. slow controlled transitions). Devotion of significant time to Surya Namaskar (7, 23, 34) and the inclusion of standing and balancing poses that involve isometric contractions with jump transitions between asanas (9) would be expected to increase overall energy cost and intensity of a yoga session (23). Alternatively, the inclusion of more seated versus standing poses with a slower flow through asanas would be expected to decrease energy cost and intensity. Quite surprisingly, this review did not find that environmental (or room) temperature had much effect on energy cost. Despite purported claims that a Bikram yoga session expends up to 1000 kcal in 90-minutes, the MET values of Bikram yoga (26), performed in hot room with 40% relative humidity, were within the same range as yoga practiced at room temperature. It could be argued, however, that differences might be found if the same practitioners had performed the same set of asanas in both a hot and more ambient environment. Bikram for example does not incorporate Surya Namaskar or flow transitions but instead transitions from static asana to static asana, which may require less energy than other styles with continuous flow through Surya Namaskar and other asanas. The ACCEPTEDvariability of MET intensities for Surya Namaskar (sun salutations), which ranged from 2.9 METs (light-intensity) (14) to 7.4 METs (vigorous-intensity), is intriguing. Flow through this specific sequence of 12 asanas which is performed rhythmically with controlled

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. breath involves the majority of joints and muscles and both static stretching and dynamic muscular exercise components (34). The sequence is said to be taught to Indian children at young age and is believed to promote cardiorespiratory fitness (23). Interestingly, higher MET intensities (7.4 METs) were observed by Mody (23) who studied five Indian men and women who had trained in Surya Namaskar for at least two years (23). Four rounds of Surya Namaskar were performed at a pace of three minutes per round. Although sufficient detail on sequence execution was not described, to achieve such high MET intensities the experienced practitioners most likely incorporated rapid stepping (or jumping) between asanas and an upward and/or downward push-up in Uttihita Chaturanga Dandasana, i.e., flow from plank pose to Bujangasana

(cobra pose) and back to plank before moving into Adho Mukha Svasana (down-dog). In agreement, a MET intensity of 6.4 was achieved in the author’s laboratory using Mody’s description of Surya Namaskar, transition jumps and full pushups (Larson-Meyer, unpublished data). In contrast, MET intensities in the moderate-intensity range were observed by both Sinha et al (34) and Clay et al (7) in 21 newly-trained male practitioners (recently completing three- months of intense training) and 26 semi-experienced female practitioners (minimum of one month of yoga attendance), respectively. The lower MET intensities of Higgins and colleagues

(14) were observed in 18 woman and 2 men who performed 28 minutes of Surya Namaskar as part of a 56-min beginning-level Ashtanga session. Unfortunately, sufficient information on the

Surya Namaskar flow was also not provided (7, 14, 34) but illustrations in the manuscripts of

Sinha (34) matched that of Mody (23) suggesting that the most common variation (Sun salutations A)ACCEPTED was employed in both studies. Taken together these findings highlight that Surya Namaskar can be practiced in such a way to achieve an aerobically intense effort but also slowed to result in a light- to moderate-intensity effort.

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Influence of Practitioner Experience. It is not yet established whether practitioner experience impacts the metabolic cost of yoga practice, as it does with other types of exercise

(1). One could argue on one hand that with consistent practice yoga participants would learn to more fully express a pose which would in turn result in engagement of more muscle fibers/ muscle groups, more forceful contractions of engaged muscles and deeper movement into each pose. Full expression of many asanas, for example, requires near-maximal contraction of several muscle groups, including the abdominals and back, and an increased range of motion to lift higher or sink deeper into each asana. One could also argue on the other hand that experienced practitioners may have increased flexibility which could result in reduced passive torque in muscle tissue, reduced resistance to joint movement, and in turn both increased energy efficiency and lowered energy cost (7). Unfortunately, this review found only two studies that directly compared the energy cost of yoga practiced by experienced versus novice practitioners (26, 38), one evaluating Bikram practice (26) and the other focused on pranayamas. In the former, the energy cost of a 90-minute Bikram yoga session was 27% higher in experienced compared to novice practitioners (4.7±0.8 vs. 3.7±0.5 kcal/kg). Experienced practitioners also had a 67% greater elevation in core temperature than novice practitioners despite an 83% higher sweat losses alluding to increased work output in experienced practitioners. The pranayama study was in agreement (38). Experienced practitioners were able to substantially increased oxygen cost during breathing exercises compared to novice practitioners despite a lower oxygen cost at rest.

Additional research in this area is certainly needed to help establish how experience influences the energy costACCEPTED of yoga practice. Cardiorespiratory Indicators of Yoga Intensity. This review further supports that evaluation of exercise intensity using %HRmax, %VO2max and %HRR—more commonly used for

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. individual exercise prescription (12) —yields results similar to MET intensity. Using these criteria, the majority of studies also found that yoga does not meet the ACSM criteria for moderate-intensity aerobic activity defined as eliciting a heart rate in the range 64 to 76 %HRmax or an oxygen cost between 46 and 63 %VO2max. The exceptions include Surya Namaskar (7, 23,

34), standing Iyengar asana practice with jumps between poses (9) and Bikram practice (26).

These practices, except the Bikram session, increased MET values to within the moderate- intensity range. Use of absolute or relative (%HRmax) heart rate, however, may not be an overall valid indicator of exercise intensity during yoga. Several studies found that heart rate was disproportionally higher than the corresponding oxygen (energy) cost or MET intensity during both Hatha (7, 9) and Bikram (26) yoga. For instance, Clay et al (7) found that a 30-min session at 2.17 METs (15% of VO2R) elicited an average heart rate response of 67% %HRmax which is considerably higher than expected (see Table 1)(12). Heart rate was also 28 bpm higher during yoga compared to treadmill walking (133 vs. 105 bpm) at a higher MET value (3.5 mph, 4.6

METs). Di Carlo et al (9) observed that standing Hatha yoga induced higher heart rate and blood pressure responses (71% HRmax), than brisk walking at 4.0 MPH at a higher MET intensity of 5.4

METs (62% HRmax). Disproportionally higher heart rates during yoga which integrates arm movements and forceful isometric contractions, however, are expected. These exercise activities alter the hemodynamic and neural responses and elicit a greater heart rate response than exercises involving leg muscles and dynamic contractions at similar oxygen cost (20). Higher heart rates are also expected during yoga practiced in a hot and/or humid environment due to the reactionary ACCEPTED shift in blood flow towards the skin, in attempt to maintain thermal homeostasis, which reduces stroke volume and increases heart rate to maintain cardiac output (20). Similarly,

RPE using the Borg scale may also not be a valid indicator of intensity during yoga. The one

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. study that evaluated RPE found that standing Hatha yoga at 4.1 METs elicited an 18% higher

RPE than treadmill walking at 5.4 METs (RPE=14.8 ±1.8 verses 12.5 ±1.5) (9).

Quality of Measurement of Energy Expenditure. All studies included in this review used indirect calorimetry to measure oxygen consumption and carbon dioxide production to thereby calculate the energy cost of yoga. Gases were collected using a variety of apparatuses that included a ventilated hood (during pranayamas) (38), mouthpiece and nose clips (26, 32), or face mask (13, 23, 30, 31, 33), or employed a full-room respiratory chamber (14, 22). In the one study that evaluated testing reproducibility, the test-retest reliability of the energy cost of yoga measured in the respiratory chamber was sufficiently consistent with an interclass coefficient of

0.97 (14). Although it is tempting to speculate that use of the mouthpiece or mask might induce restraints on a yoga practice this review found no indication that the gas collection apparatus impacted energy cost. Respiratory chambers have the advantage of allowing freedom of movement without restraints of headgear, however they are expensive and metabolic carts have been used most commonly to measure the energy cost and MET intensity of most physical activities (1). For example, the energy costs of videotaped yoga sessions averaged 0.63 kcal/kg/min using a metabolic cart (7) and 0.58 kcal/kg/min when measured inside a respiratory chamber (14). The quality of data collected, however, was difficult to systematically critique due to lack of reported methodological detail. Therefore this review had to assume that included studies followed standardized procedures including calibration of gas and volume analyzers, enforced sufficient control of participant’s intake and exercise before testing, and ensured a steady state ACCEPTEDin oxygen consumption even during the continuous flow through various asanas (7, 14, 23, 27). If oxygen steady state was not achieved, which typically takes at least a minute with continuous exercise, energy cost would be underestimated. To ensure collection of reliable and

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. accurate metabolic data, future studies should control diet, caffeine, fluid consumption, exercise, sleep and medications of study participants at least 24-hours before measurement.

The Benefits of Yoga. Placing the findings of the current review into a larger discussion of yoga’s potential benefits requires consideration of both the benefits gained from physical activity of lower cardiovascular intensity and yoga’s potential to improve strength and balance, impact the nervous system and help control stress (4). The ACSM acknowledges that exercise at a lower intensity reduces sedentary behavior and may provide health benefits for older and unconditioned individuals (2, 12, 16). Exercise below the moderate-intensity threshold (12), including the practice of yoga and pranayama (19, 25, 39), have also been shown to improve metabolic markers of chronic disease (i.e., insulin resistance, blood pressure and lipid profiles) without the corresponding improvements in VO2max. Additionally, yoga offers an alternative for individuals who cannot engage in traditional forms of physical activity or who prefer light- over more intense aerobic exercise. Yoga is perceived to be a gentler form of exercise and may be a more sustainable means of daily practice for individuals with joint problems, rheumatoid arthritis

(17) or back pain (24). A recent review found that yoga was superior to other forms of exercise for improving self-reported health status, aerobic fitness and muscular strength in older adults

(28). For instance, eight weeks of yoga participation improved treadmill walking time to fatigue, by three minutes (37). Yoga has also been found to benefit those who are more aerobically fit. A study of distance runners found a small but significant improvement in running performance after a single yoga session (11). Similarly, 24 sessions of yoga performed over 8 weeks led to improved balance,ACCEPTED leg strength and leg muscle control in young athletes (15). Many of these benefits may be linked to yoga’s ability to increase strength, balance and flexibility, calm the mind and reduce stress (4). The ACSM position statement for exercise prescription emphasizes

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. that multifaceted physical activities that involve combinations of neuromotor exercise, resistance exercise, and flexibility exercise, which includes yoga, have numerous benefits beyond cardiovascular fitness (12). Results of this study suggest that certain aspects of yoga practice, particularly the more intense asanas, can count towards the weekly amount of physical activity suggested by the ACSM guidelines (16).

Study Limitations. Currently published studies are somewhat limited in that they were conducted mostly in fairly experienced Indian men (23, 30-33, 35, 36) or women practicing in

U.S. metropolitan cities (7, 14, 27) who were relatively young, apparently healthy and of normal weight. The exception was for the Wii yoga studies that included Japanese and English adolescents and older individuals (13, 22). Results are therefore not generalizable to individuals with obesity or adverse health conditions, the elderly or young children. The MET intensities included in this review are also only average summaries from included studies which rarely reported the full range of oxygen and MET intensities. Consequently, the range of energy cost and MET intensities for yoga asanas, pranayama or full yoga sessions are not available.

Regardless, the review provides information for exercise professionals, yoga instructors, health care providers and yoga practitioners considering practicing yoga as part of physical activity- related goals. It also provides a summary of MET values that may be useful for future MET tables (1) and exercise guidelines. Future studies are needed to better understand how experience and individual variability influence the energy cost and intensity of yoga. ACCEPTED

ACKNOWLEDGEMENTS No funding was received for completion of this project. Results of the present study do not constitute endorsement by the American College of Sports Medicine.

CONFLICT OF INTERESTS None

ACCEPTED

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. REFERENCES 1. Ainsworth BE, Haskell WL, Whitt MC et al. Compendium of physical activities: an

update of activity codes and MET intensities. Med Sci Sports Exerc. 2000;32(9

Suppl):S498-504.

2. American College of Sports M, Chodzko-Zajko WJ, Proctor DN et al. American College

of Sports Medicine position stand. Exercise and physical activity for older adults. Med

Sci Sports Exerc. 2009;41(7):1510-30.

3. Brahmachari D, Vachani S, Sahani S, Ram K, Rai L. A comparative study of some

individual yogic postures on ventilatory responses in yoga proficient subjects. J Res Edu

Ind Med. 1989;3:7-17.

4. Broad W. The Science of Yoga. The Risks and the Rewards. New York: Simon &

Schuster Paperbacks; 2012, 310 p.

5. Carroll J, Blansit A, Otto RM. The metabolic requirements of Vinyassa yoga (abstract).

Med Sci Sports Exerc. 2003;35(5):S155.

6. Ce E, Maggioni MA, Boniello S, Veicsteinas A, Merati G. Anthropometric and

physiologic profiles of female professional yoga practitioners and energy expenditure

during asanas execution. J Sports Med Phys Fitness. 2015;55(1-2):51-7.

7. Clay CC, Lloyd LK, Walker JL, Sharp KR, Pankey RB. The metabolic cost of hatha

yoga. J Strength Cond Res. 2005;19(3):604-10.

8. Corliss R. The power of yoga. Time. 2001;157(16):54-63. 9. DiCarloACCEPTED LJ, Sparling PB, Hinson BT, Snow TK, Rosskopg LB. Cardiovascular, Metabolic, and Perceptual Responses to Hatha Yoga Standing Poses. Med Exerc Nutr

Health. 1995;4:107-12.

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 10. Donnelly JE, Blair SN, Jakicic JM et al. American College of Sports Medicine Position

Stand. Appropriate physical activity intervention strategies for weight loss and prevention

of weight regain for adults. Med Sci Sports Exerc. 2009;41(2):459-71.

11. Donohue B, Miller A, Beisecker M et al. Effects of brief yoga exercises and motivational

preparatory interventions in distance runners: results of a controlled trial. Br J Sports

Med. 2006;40(1):60-3; discussion -3.

12. Garber CE, Blissmer B, Deschenes MR et al. American College of Sports Medicine

position stand. Quantity and quality of exercise for developing and maintaining

cardiorespiratory, musculoskeletal, and neuromotor fitness in apparently healthy adults:

guidance for prescribing exercise. Med Sci Sports Exerc. 2011;43(7):1334-59.

13. Graves LE, Ridgers ND, Williams K, Stratton G, Atkinson G, Cable NT. The

physiological cost and enjoyment of Wii Fit in adolescents, young adults, and older

adults. J Phys Act Health. 2010;7(3):393-401.

14. Hagins M, Moore W, Rundle A. Does practicing hatha yoga satisfy recommendations for

intensity of physical activity which improves and maintains health and cardiovascular

fitness? BMC Complement Altern Med. 2007;7:40.

15. Hart CE, Tracy BL. Yoga as steadiness training: effects on motor variability in young

adults. J Strength Cond Res. 2008;22(5):1659-69.

16. Haskell WL, Lee IM, Pate RR et al. Physical activity and public health: updated

recommendation for adults from the American College of Sports Medicine and the AmericanACCEPTED Heart Association. Med Sci Sports Exerc. 2007;39(8):1423-34. 17. Haslock I, Monro R, Nagarathna R, Nagendra HR, Raghuram NV. Measuring the effects

of yoga in rheumatoid arthritis. Br J Rheumatol. 1994;33(8):787-8.

2000;28(3):67-81.

19. Malhotra V, Singh S, Tandon OP, Sharma SB. The beneficial effect of yoga in diabetes.

Nepal Med Coll J. 2005;7(2):145-7.

20. McArdle W, Katch F, Katch V. Exercise Physiology. Baltimore: Wolters Kluwer

Health/Lippincott Williams & Wilkins; 2014. p. 303-354.

21. Mees PD. Yoga participation surges - Exploring the clinical implications. Physician and

Sportsmedicine. 2005;33(5):12-5.

22. Miyachi M, Yamamoto K, Ohkawara K, Tanaka S. METs in adults while playing active

video games: a metabolic chamber study. Med Sci Sports Exerc. 2010;42(6):1149-53.

23. Mody BS. Acute effects of Surya Namaskar on the cardiovascular & metabolic system. J

Bodyw Mov Ther. 2011;15(3):343-7.

24. Monro R, Bhardwaj AK, Gupta RK, Telles S, Allen B, Little P. Disc extrusions and

bulges in nonspecific low back pain and sciatica: Exploratory randomised controlled trial

comparing yoga therapy and normal medical treatment. J Back Musculoskelet Rehabil.

2015;28(2):383-92.

25. Naruka JS, Mathur R, Mathur A. Effect of pranayama practices on fasting blood glucose

and serum cholesterol. Indian J Med Sci. 1986;40(6):149-52.

26. Pate JL, Buono MJ. The physiological responses to Bikram yoga in novice and

experienced practitioners. Altern Ther Health Med. 2014;20(4):12-8. 27. Pate ACCEPTEDRR, Pratt M, Blair SN et al. Physical activity and public health. A recommendation from the Centers for Disease Control and Prevention and the American College of Sports

Medicine. JAMA. 1995;273(5):402-7.

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. 28. Patel NK, Newstead AH, Ferrer RL. The effects of yoga on physical functioning and

health related quality of life in older adults: a systematic review and meta-analysis. J

Altern Complement Med. 2012;18(10):902-17.

29. Payne L, Feuerstein G. Yoga for Dummies, 3rd edition. 3rd ed. Hoboken, NJ: John Wiley

& Sons; 2014. p. 1-32.

30. Rai L, Ram K. Energy expenditure and ventilatory responses during Virasana--a yogic

standing posture. Indian J Physiol Pharmacol. 1993;37(1):45-50.

31. Rai L, Ram K, Kant U, Madan SK, Sharma SK. Energy expenditure and ventilatory

responses during Siddhasana--a yogic seated posture. Indian J Physiol Pharmacol.

1994;38(1):29-33.

32. Rao S. Metabolic cost of head-stand posture. J Appl Physiol. 1963;17(1):117-8.

33. Ray US, Pathak A, Tomer OS. Hatha yoga practices: energy expenditure, respiratory

changes and intensity of exercise. Evid Based Complement Alternat Med.

2011;2011:241294.

34. Sinha B, Ray US, Pathak A, Selvamurthy W. Energy cost and cardiorespiratory changes

during the practice of Surya Namaskar. Indian J Physiol Pharmacol. 2004;48(2):184-90.

35. Sinha B, Sinha TD, Pathak A, Tomer OS. Comparison of cardiorespiratory responses

between Surya Namaskar and bicycle exercise at similar energy expenditure level. Indian

J Physiol Pharmacol. 2013;57(2):169-76.

36. Telles S, Singh N. High frequency yoga breathing increases energy -expenditure from carbohydrates.ACCEPTED Comment to: Assessment of sleep patterns, energy expenditure and circadian rhythms of skin temperature in patients with acute coronary syndrome Hadil Al

Otair, Mustafa Al-shamiri, Mohammed Bahobail, Munir M. Sharif, Ahmed S.

clin res. j. 2011;17(9):LE7-8.

37. Tran MD, Holly RG, Lashbrook J, Amsterdam EA. Effects of Hatha Yoga Practice on the

Health-Related Aspects of Physical Fitness. Prev Cardiol. 2001;4(4):165-70.

38. Tyagi A, Cohen M, Reece J, Telles S. An explorative study of metabolic responses to

mental stress and yoga practices in yoga practitioners, non-yoga practitioners and

individuals with metabolic syndrome. BMC Complement Altern Med. 2014;14:445.

39. Vyas R, Dikshit N. Effect of meditation on respiratory system, cardiovascular system and

lipid profile. Indian J Physiol Pharmacol. 2002;46(4):487-91.

40. Yoga Journal Editor. New Study Finds More Than 20 Million Yogis in U.S. 2012.

ACCEPTED

Figure 1. Average METs from all participants for full yoga sessions including exclusive devotion to flow through Surya Namaskar (Sun Salutations) with error bars representing the standard deviation of the mean. Bars are without error if only means were reported in the original study or if METs were calculated by the current study author from published VO2 and body weight data. The average METs for yoga practice was 3.3±1.6 METS for all 10 studies and 2.9±

0.8 METS when the study of Mody (23) was omitted.

Figure 2. Average METs from all participants for asanas with error bars representing the standard deviation of the mean. Bars are without error if only means were reported in the original study or if METs were calculated by the current study author from published VO2 and body weight data. The study reference is shown in parentheses. Adho Mukha Svasana, down dog;

Anjaneyasana, Crescent lunge; Ardha Chandrasana, half moon; Ardha Matsyendrasana, half lord or half spinal twist; Bhujangasana, cobra; Dandayamana Janushirasana, standing head to knee;

Dandayamana Dhanurasana, standing bow; Dhanurasana, wheel/seated bow; Mandukasana,

Frog; Maha Matsyendrasana, Wiseman; Matsyasana, Fish Pose; Paschiimottanasana, seated- forward bend/fold; Poorna Salabhasana, full locust; Sarvangasana, Shoulder stand; Siddhasana

(also called Ardha Pashimottanasana), half clip/half forward fold; Sirsasana, head stand;

Trikanasana, triangle; Tuladandasana, balancing stick; Utkatasana, chair; Virabhadrasana I,

Warrior I; Virasana, hero pose; Virksasanan, tree pose.

Note the reference of Raj (31) illustrates the standing pose Anjaneyasana in the methods but refers to theACCEPTED pose as Siddhasana (seated hero pose). The pose shown in the figure Anjaneyasana was used in this figure summary because the MET value aligns better with Anjaneyasana rather than Siddhasana.

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Figure 3. Data represents average of METs from all participants for pranayama (breathing exercises) with error bars representing the standard deviation of the mean. The average METs for yoga practice was 1.3±0.3 METS. Bhastrika, Bellows Breath; Bhramari Pranayama, Humming

Bee Breath; Kaki Mudra, Crow’s Beak breath; Kapalbhati, Breath of Fire; Nadi Sodhana, alternate nose breathing; Sukhasana, Easy Breathing; Yoga Mudra, relaxed breathing while seated cross-legged with fingers holding a yoga seal.

ACCEPTED

Intensity METs %HRmax %V02max %HRR or

VO2R

Very Light <2 <57 <37 <30

Light 2.0 to 2.9 57 to 63 37 to 45 30 to 39

Moderate 3.0 to 5.9 64 to 76 46 to 63 40 to 59

Vigorous 6.0 to 8.7 77 to 95 64 to 90 60 to 89

Near ≥8.8 ≥96 ≥91 ≥90

Maximal

METs, metabolic intensity; %HRmax, percentage of maximal heart rate;

%V02max, percentage maximal oxygen uptake; %HRR, percentage heart rate reserve; %VO2R reserve, percentage VO2 reserve. Adapted from reference (14)

ACCEPTED

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Table 2. Indirect Calorimetry and Calibration (Cal) Procedures, and Control of Environmental (Env) and Participant Factors, Timing and Subjects’ Diet, Physical Activity and other Factors Prior to Testing Ref Indirect Calorimetry Control Control of Timing and Participant Intake, Activity and Sleep Other Prior to Testing Indirect Calorimetry Cal Steady Env Morning Fasting or No PA Sleep State Control Diet Caffeine Restriction Rao, Benedict type spirometer; NR yes NR NR NR NR NR NR 1963 Breathing “apparatus”- mouth piece (per photo) Brahma Met Cart (Oxycon-4); NR yes (5 NR NR NR NR NR NR chari, Face Mask min) 1989 Rai, Met Cart (Oxycon-4); NR yes NR Yes On “Empty NR NR NR Non-smokers 1993 Face Mask stomach” Rai, Met Cart (Oxycon-4); yes NR Yes On “Empty NR NR NR Non-smokers 1994 Face Mask stomach” DiCarlo, Daniels Valve with NR no NR NR Fasting > 3 h NR NR NR 1995 Parkinson Covan CD-4 dry (40 sec) Normal diet gas meter; apparatus NR 24 h prior Sinha, Met Cart (Oxycon NR yes- reach 24 - Yes On “Empty NR “sedentary” NR 2004 Champion); apparatus NR baseline 28°C stomach” assumed btwn asanas Clay, Met Cart (PARVO Medics); yes continuou NR NR Avoid food None for No strenuous 6-8 h No tobacco 2005 apparatus NR s flow* and ETOH 4h >4 h PA day of sleep prior prior; drink prior testing plenty fluids 24 h prior Hagins, Room Calorimeter; no ass continuou Cont NR NR NR NR NR 2007 apparatus required um s flow* rolle ed d; detai ls NR Graves, Metamax 3B portable cart; yes yes (10 NR NR Fasting 2 h NR NR NR 2010 Face Mask min) prior Miyachi Room Calorimeter; no yes yes (8 25°C NR Fasting > 5 h > 5 h None 1 y NR Free of disease , 2010 apparatus required ACCEPTEDmin) 55% prior prior prior that could alter

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. RH metabolism Ray, Met Cart (Oxycon yes yes ? 26 - NR NR NR NR NR 2011 Champion); Face Mask (2 min) 29°C 60- 80% RH Mody, Portable Metabolic Cart; NR baseline NR NR NR NR NR NR 2011 Face Mask steady state between asanas Telles Quark CPET COSMED; yes Yes 22°C yes Control diet NR Avoid PA Cont- Spent night 2011 Metabolic Cart 55% night before rolled before in lab RH Tyagi, “canopy hood” *Quark yes yes (5 23°C 7-9 AM Fasting > 8 h > 8 h NR NR No tobacco; No 2014 CPET India” min) prior analgesic meds Ce, Portable Quark b2 yes yes (5 20±1 NR NR NR NR NR Follicular phase 2014 (Cosmed); min) °C of menstrual Face Mask 50% cycle RH Pate, Met Cart (PARVO Medics) yes continuou 105° NR NR NR NR NR NR 2014 headgear; nose clip s flow C 40% RH METs, Metabolic Equivalent; NR, not reported; NA, not applicable; ETOH, alcohol; PA, physical activity: RH, relative humidity

ACCEPTED

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. Table 3. Summary of Studies Evaluating Energy Cost and/or Intensity of Yoga including Yoga Asanas, Pranayamas and Full Practice Sessions

Ref Subject Number and Experience Yoga Practice Rest Gas METS* Energy - Percentage Other Measures Characteristics Summary Before Collect- Kcal/min Maximal ion (kcal/kg/min) † Heart Rate

Devise or VO2max Rao 6 male medical Experienced 15 min NR mouthpi HEAD HEAD 1963 students in Head Sirsasana (Head ece? 2.49 1.62 (0.032†) Indian Stands Stand;HEAD) HS HS 19-22 yr; 50 kg Hanging 1.7 1.44 (0.029†) BMI: 17.6 kg/m2 Suspended (HS) (in laboratory) Brahm 10 male yoga teachers Experienced Savasana (SAV) 20 min face SAV SAV SAV RER, Ventilation, & RR achari, Indian (> 2 yr) Paschimottanas Corpse mask 1.0±0.6 1.2±0.7 (0.02†) 40% HRmax RER=0.7 to 0.72 for all 1989 29.3±4.4 yr; 58.7±5.2 ana (PAS) pose PAS PAS PAS poses. RR higher kg Dhanurasana 1.3±0.6 1.45±0.2 39% HRmax during DHA (29.0±8.7) BMI: 20.4 kg/m2 (DHA) DHA (0.025†) DHA vs. PAS (19.7±4,5) and (location NR) 2.3±0.6 DHA 49% HRmax SHA (13.3±4.5) 2.6±0.6 (0.045†)

Rai, 10 male yoga teachers Experienced Savasana (SAV) 20 min face SAV SAV NR RR: several had RR 1993 Indian & resting in mask 0.81 slow 0.91 slow RR below and above 25-37 yr; 58.7±5.2 kg Anjaneyasana chair RR 1.04 fast RR normal range BMI: 20.4 kg/m2 (ANJ) * 0.97 fast RR ANJ (in laboratory) ANJ 2.12 slow RR 2. 1 slow (0.036†) RR 2.76 fast RR 2.53 fast RR (0.047†) Rai, 10 male yoga teachers Experienced Savasana (SAV) 20 min face SAV SAV NR RR: several had RR 1994 Indian & Siddhasana resting in mask 0.81 slow 0.91 slow RR below and above 25-37 yr; 58.7±5.2 kg (SID) a chair RR 1.04 fast RR normal range BMI: 20.4 kg/m2 (in laboratory) 0.96 fast RR SID Measured RER<0.7 in SID 1.12 slow RR fasting indicative of 1.0 slow RR (0.019†) fat or ketone burning. 1.2 fast RR 1.35 fast RR (0.023†) ACCEPTED

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. DiCarlo 6 male, 4 female Experienced 12 Standing 5 min NR 4.2 4.74 71% HRmax Treadmill walking , practitioners (> 1 yr) Iyenga-style stretching (MEN:0.064†) @4.0 mph: 1995 38 to 47 yr; Georgians poses (held for (WOMEN: 0.09†) 33% VO2max 5.4 METs, 61.7% Men:74.4±6.7 kg; 40 sec, 2X per HRmax, 44% VO2max 17.5±4.8% Body Fat side; jumps into BMI: 20.9 kg/m2 Tadasana & VO2max: 48±5 into next pose) ml/kg/min (in laboratory) Women: 52.8±10.6 kg; 25.14.4% Body fat BMI: 22.8 kg/m2 VO2max:36±2 ml/kg/min Sinha, 21 male practitioners Beginners 28 min Yoga Rest NR SUN SUN ~46.7% RER: 0.8 to 0.9 in 2004 Indian who Asanas between ~3.5 3.8±1.0 HRmaxEST various poses. 22±1 yr; 62.3±4.3 kg underwent (including Sun poses (0.061†) BMI: 20.9 kg/m2 3 months of Salutations, NonSun Salutations training (6 SUN), 10.5 min published by Rai d/wk) pranayama, 5 min medication (in laboratory) Clay, 26 female practitioners Some 30 minute Resting in NR SUN SUN SUN Treadmill walking@ 2005 Texans Experience videotaped a chair 3.74±0.7 3.76±1.0 67±10% 3.5 mph: 4.6 METs; 23±4 yr; 59.6±11.8 kg (> 1 month routine Other (0.063†) HRmax 71.9% HRmax, 44.8% 2 BMI: 22.7 kg/m formal yoga) including Asanas Other Asanas 40% VO2max VO2max Body fat: 22.8±7.7 % common poses 2.1±0.4 2.28±0.6 (0.038†) Other Asanas VO2max:33±5 and Sun 56±9% HRmax ml/kg/min salutations 22% VO2max (SUN) (in laboratory) Hagins, 18 female, 2 male yoga Experienced Beg-level 30 min All Practice All Practice All Practice Treadmill walking @2 2007 practitioners (> 1 yr) Ashtanga yoga seated 2.5±0.8 3.2±1.1 49±12%HRmax mph: 2.5±0.4 METS; New Yorkers DVD: 24 min rest SUN (0.05†) SUN 51±8%HRmax & 3 31±8 yr; 64.3±9.0 kg sun salutations 2.9±0.7 SUN 55±12 mph:3.3±0.4 METS; 2 BMI: 23.6±3.0 kg/m (SUN); 20 min 3.75±0.1.0 %HRmax 58±11%HRmax standing poses, (0.058†) 8 min ACCEPTEDsitting/lying

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. poses (in room calorimeter) [8] 14 adolescents None 5 min Wii Yoga NR face 1.7±0.3 3.0 (teens) 42.6% (teens) Wii balance, muscle Graves English Incorporating mask ? (teens) (0.045†) 40.1% (adult) conditioning and 2010 16±1 yr; 66.2±11.3 common poses 1.9±0.3 2.8 (adult) 51.9% (older) aerobics 15 young adults (adult) (0.042†) HRmax 28±5 yr; 65.9±8.7 1.9±0.4 2.9 (older) 13 older adults (older) (0.049†) 58±7 yr; 81.5±13.5 Miyach 7 men & 5 women None 8 min Wii Yoga Resting in None 2.1±0.6 ~2.3 (0.036†) NR Wii balance, i, 2010 Japanese non-yogis (in room chamber (room 1.4 (deep resistance exercise 34±6 yr; 64.3±15.0 kg calorimeter) calorime breathing) and aerobics BMI: 22.9 kg/m2 ter) to 2.9 (floor) Ray, 20 male yoga Indian Experienced 24 min seated 30 min face 1.3 to 2.2 1.8 to 3.05 (0.031 14 to 26% RER: 0.79 – 2011 teachers/practitioners (practicing 6 asanas; supine mask (mean NR) – 0.052†) VO2max 0.91;pulmonary 27±3 yr; 58.8±9.6 kg to 10 yr) 8 min breath rest ventilation, tital 11±3% body fat movements; 5 volume BMI: 21.2 kg/m2 min meditation meditation VO2max NR Mody, 3 male & 2 female Experienced Surya 5 min of face ALL 7.9 (0.128†) 80±9 % HRmax RER: 0.96±0.06 2011 Surya Namaskar (>2yr in Namaskar: 12 “typical” mask 7.4±1.7 (carb oxidation) practitioners Asian Surya repetitions of prep Indian Namaskar) 12 asanas X 4 at With PREP 19±1.5 y; 61.0± 5 kg “typical” pace 6.3±1.4 BMI: 20.4 kg/m2ex (~3 min/round) (in laboratory) Telles 47 male practitioners Experienced 35 min seated 5 min NR NR HFYB NR EE from CHO and Fat: 2011 Indian (31±49 cross-legged: breathing 1.6±0.3 EE increased during 23±4 yr; Body mass NR months 15 min high HFYB & decreased BMI: 22.5±2.9 kg/m2 experience frequency yoga BAW with normal breathing with yoga breathing 1.08± 0.3 which followed. EE breathing) (HFYB, 1 from fat decreased breath/sec) (1 during BAW vs. rest. min rest every 5 Respiratory Exchange min) OR Breath Ratio NR ACCEPTEDAwareness

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. (BAW), 15 min normal breathing (in laboratory) Tyagi, 18 Yoga teachers/ Experienced 9 X 5-min 10 min canopy ANB Average (ANB & NR Mental arithmetic 2014 Practitioners Indian (> 6 months phases in hood ~1.26 ( EY) KB) 32±10 yr; 62± 7 kg in recumbent ~1.26 (NY) ~1.4 ( EY) (0.02†) BMI: 21.1±1.6 kg/m2 pranayama) position ~1.17 (MS) ~1.5 (NY) (0.02†) 18 Non- practitioners including: KB ~1.8 (MS) (0.02†) 30±11 yr; 69± 12 kg alternate nostril ~1.29 ( EY) BMI: 24.9±4.0 kg/m2 breathing ~1.26 (NY) 18 Patients with (ANB), ~1.22 (MS) metabolic syndrome kapalbhati MED 41±5 yr; 86± 9 kg breathing (KB) ~1.0 ( EY) BMI: 31.5±1.7 kg/m2 and meditation ~1.08 (NY) (MED) 1.14 (MS) (at Yoga Research Center)

CE, 10 female yoga Experienced Series of 6 10 min face Range=1.4 Range=1.35 to Range=~40- VO2max of long- 2014 professionals (Yoga asanas held 5 rest lying mask to 1.7 1.65 (0.025 – 45% HRmaxEST distance runners, 32±7 yr; 54.5±1.4 professional min each with 5 supine on 0.03) & 12-15% sprinters, karate 2 BMI: 20.6±1.2 kg/m only) min rest mat VO2max athletes and controls 41.9±2.2 ml/kg/min between: (n=10 each) Siddhasana, Bhujangasana, Mandukasana; Maha Matsyendrasan a, Virksasanan & Sirsasana) (at Yoga facility)

Pate, 19 female, 5 male Novice & 90 min NR other headgea Range=1.67 ~2 to 5.3 75% HRmaxEST Treadmill walking @ 2014 Bikram (hot) yoga Experienced beginning than r & nose (standing, (041 novice) (all)Range=51 2.9 miles/hr (data practitioners, Bikram Yoga savasana clips deep (0.052 -90% HRmaxEST NR), sweat 33±13 yr; Weight NR Class; 26 breathing) experienced rate:0.6±0.2 & 1.1±0.5 Men: BMI: 21.6±2.0 ACCEPTEDpostures X 2 to – 3.98 l/min and core

Copyright © 2016 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited. kg/m2 audio recording (standing temperature change: Women: 52.8±10.6 kg; bow). 1.0+0.8 & 1.8+1.4 in BMI: 24.7±4.3 kg/m2 (in 2.7 (all) Novice & Experienced environmental respectively. chamber) METs, Metabolic Equivalent; NR, not reported; BMI, body mass index; RER, respiratory exchange ratio; RR, respiratory rate; EE energy expenditure; CHO, carbohydrate.

Savasana (also called Shavasana), corpse pose; Paschimottanasana (seated forward bend/fold); Dhanurasana; Anjaneyasana, cresent lunge; Siddhasana, half clip/half forward fold; Tadasaana, mountain pose; Sun Salutations, Surya Namiscar; Bhujangasana, cobra,

Mandukasana; frog, Maha Matsyendrasana, wiseman; Virksasanan, tree

*Note the reference of Raj (31) illustrates the standing pose Anjaneyasana in the methods but refers to the pose as Siddhasana (seated hero pose).

ACCEPTED