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he potentiality of yoga to improve O2max is often questioned because of its low exercise stimulus onsidering the positive effects of oga reathing aneuvers ( ) on cardio-respiratory systems its effect on O2max needs to be studied So possible role of in improvement in O2max in yoga training was observed.32 healthy male students of 19 to 21 years of age were divided into two equal groups of 16 each. One group (YG) practiced yoga (Yogasanas, YBM and meditation) for 40 minutes every day for 6 days per week for 3 months. YBM were progressively inducted by increasing practice duration throughout training Other group ( G) did not practice oga Their basal heart rate (HR) and respiratory rate (RR) were recorded in the morning in bed Predicted O2max was measured on them by Queen’s college step test. HR was recorded before, during and after exercise manually and with Polar sports tester. All the parameters were recorded at baseline, 6 th and 12 th week end of yoga training In G O2max improved from baseline (47.5±3.7 ml/kg/min) to 6 th week (49.4±3.3 ml/kg/min, P<0.001) and 12th week end (53.03±3.3ml/kg/min, P<0.0001). YG showed significant reduction in basal RR, HR and resting HR at 6 th and 12 th week end compared to their respective base line values

recorded at baseline, 6 th and 12 th week end of yoga training In G O2max improved from baseline (47.5±3.7 ml/kg/min) to 6 th week (49.4±3.3 ml/kg/min, P<0.001) and 12th week end (53.03±3.3ml/kg/min, P<0.0001). YG showed significant reduction in basal RR, HR and resting HR at 6 th and 12 th week end compared to their respective base line values G did not show such changes O2max was correlated to basal RR(r – 0 463 p 0 0009) HR (r -0 235 p 0 107) and resting HR (r -0 414 p 0 003) facilitated the improvement in O2max possibly by its effects on cardiovascular and respiratory systems. Keywords: Yoga, Physical fitness O2max, yoga breathing maneuvers. Copyright © 2020 The Author(s): This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC BY-NC 4.0) which permits unrestricted use, distribution, and reproduction in any medium for non-commercial use provided the original author and source are credited. INTRODUCTION Traditional Indian system of Yoga is increasingly getting popular as it has positive effects on both the physical and mental level of an individual [1- 3]. Yoga improves muscular endurance and strength [1, 4], body flexibility [1, 2, 5], anaerobic capacity [6] and physical performance without any exhaustive exercise as required in other form of exercise [7, 8]. Majority of studies on the effect of yoga on physical performance have observed performance improvement at submaximal level of dynamic exercise [2, 8, 9]. Only a few reported improvement in maximal oxygen uptake capacity [1, 7, 10] while other studies reported no improvement or changes like Carroll et al. [11]. The exercise physiologists are sceptical about the potential of yoga on the aerobic performance improvement as it does not generate sufficient exercise stimulus which is required to improve aerobic capacity as recommended by ACSM/AHM [12-14]. Apparently it looks justified as Ray et al 15 have shown that in yoga practice session exercise intensity remains maximum up to 26 5 of O2max and 2.19 MET. Thus, it remains within low to moderate intensity of exercise. So to improve aerobic capacity

generate sufficient exercise stimulus which is required to improve aerobic capacity as recommended by ACSM/AHM [12-14]. Apparently it looks justified as Ray et al 15 have shown that in yoga practice session exercise intensity remains maximum up to 26 5 of O2max and 2.19 MET. Thus, it remains within low to moderate intensity of exercise. So to improve aerobic capacity by yoga it has been suggested to incorporate in the training schedule the yoga practices which may have comparatively higher energy cost in some postures / poses or sequences to meet energy expenditure or exercise stimulus requirement according to ACSM/AHM guide line [14, 15]. Suryanamaskar, a combination of different yoga postures may have comparatively higher intensity of exercise stimulus in its faster form [16-18]. So its practice has also been recommended to meet ACSM/AHM guide line [14]. Apart from this conventional approach, to understand the mechanism for aerobic capacity improvement by yoga as shown by some studies 1 7 10 and also to bring about a training system requiring optimum time and energy for

Gopinath Bhowmik Bhunia & Uday Sankar Ray; J Adv Sport Phys Edu, Nov., 2020; 3(11): 199-206 © 2020 |Published by Scholars Middle East Publishers, Dubai, United Arab Emirates 200 improvement in O2max, one needs to study the effect of yoga by considering different components of yoga i.e. Yogasanas, yoga breathing manuvers (Pranayama and Kriya) and meditation (Dhyana) with equal importance as those components have different as well as concerted effects on various physiological systems. Studies on Yoga breathing manuvers (YBM) have shown their direct effect on cardiac haemodynamic functions [19- 21] as well as on respiration [22]. For this, the design of yoga practice schedule in training is required to focus on any one of the component without ignoring other component. So, a different proportion of each of these components with their variations needs to be incorporated in yoga training for a scientific study. So far, no study was conducted where an experimental design had been made considering this fact. This study was an attempt in this direction where yoga breathing component was introduced on incremental way on different point of time in yoga training to observe its effect on aerobic capacity. MATERIAL AND METHODS Subjects The study was conducted on 32 healthy male volunteers. They were all undergraduate students of Ramakrishna Mission Vivekananda Educational and Research Institute, Belur Math, Howrah. The participants had no history of major cardio-pulmonary or metabolic disorders. They did not have any habit of smoking, taking alcohol and any other agents which affect performance. They did not have previous experience in hatha yoga practice. All of them were in the same hostel and had uniform pattern of daily routine activity and had same standard diet as used to be supplied from a common mess. Subjects were explained the purpose of the study in their mother tongue about yoga training and exercise tests to be conducted and risk factors involved. Their informed consent was obtained prior to the study. The experiments and training involved were conducted following the standard international norms/guidance for conducting experiments on human subjects. Approval of Institutional ethical committee was obtained. All the

were explained the purpose of the study in their mother tongue about yoga training and exercise tests to be conducted and risk factors involved. Their informed consent was obtained prior to the study. The experiments and training involved were conducted following the standard international norms/guidance for conducting experiments on human subjects. Approval of Institutional ethical committee was obtained. All the subjects did not practice any form of high intensity competitive athletics, games and heavy physical work during the 3 months period of this study. Subjects were divided into two groups i.e. Yoga and Control group with 16 subjects in each group. Here after, Yoga group and control group will be referred to as YG and CG respectively. oth groups’ height (cm) weight (kg) and body fat (%) were measured by body composition analyser (ioi353, Poland). Physical characteristics of the subjects are given in Table 1. Table-1: Physical characteristics of the subjects Yoga Group Age(yrs.) Height(cm) Body weight(kg) Body fat (%) Base line 20.3±1.3 167.5±5.27 55.2±6.09 13.31±2.33 6 th week 20.3±1.3 167.5±5.27 56.13±5.13 13.56±2.2 12 th week 20.3±1.3 167.5±5.27 56.7±5.10 13.74±1.74 Control Group Age(yrs.) Height(cm) Body weight(kg) Body fat (%) Base line 21.2±1.4 166.9±5.06 55.4±4.92 13.14±2.4 6 th week 21.2±1.4 166.9±5.06 56.06±5.09 13.42±2.07 12 th week 21.2±1.4 166.9±5.06 56.31±4.98 13.51±1.83 Design of experiment and yoga training YG was trained for yoga practices consisting of yogasanas, YBM and meditation for 45 minutes including free hand loosening exercises for 5 minutes, also meditation and OM chanting for 5 minutes every day for 6 days in a week for 3 months in the morning under the supervision of 2 qualified yoga instructors. Yogasanas as they practiced were: Shvasana, Makarasana, Sukhasana (Yoga relaxative postures) Tadasana, Trikonasana, Katichakrasana, Saral Bhujangasana, Ardhasalvasana, Salvaasana, Saral dhanurasana, Paschimottanasana, Janusirasana, Ardha matsyendrsana. YBM as practiced were: Kapalbhati (a Kriya in hatha yogic practice) and Anulom vilom, Bhastrika, Ujjai and Bhramari pranayamas. They followed specific yogic training schedule which was prepared to reveal the effect of YBM while keeping all major components of hatha yoga practice i.e. different yoga postures (yogasanas), YBM (Pranayamas and Kriya) and meditation (Dhyana) intact in the

Ardha matsyendrsana. YBM as practiced were: Kapalbhati (a Kriya in hatha yogic practice) and Anulom vilom, Bhastrika, Ujjai and Bhramari pranayamas. They followed specific yogic training schedule which was prepared to reveal the effect of YBM while keeping all major components of hatha yoga practice i.e. different yoga postures (yogasanas), YBM (Pranayamas and Kriya) and meditation (Dhyana) intact in the program. According to the principle of yoga practices the YBM should be introduced very slowly in the yoga program. Keeping that in mind as well as to observe the influence of YBM, only 2 YBM were introduced in the 1 st and 2 nd week. From 3 rd week duration of those YBM practices increased along with 1 more new YBM which was introduced in each week up to 6 th week as per their ability to perform those correctly. With this the duration of practicing yogasanas reduced. Like this, maximum 17 minutes they could devote for YBM (including rest pauses in relaxative postures like sukhasana or shavasana) and maximum time to practice yogasanas was for 18 minutes, which also included various relaxative yogasanas like Shavasana, Makarasana and Sukhasana. Subsequently, from the 7 th week onwards the duration of practice of YBM component was increased further up to the 12 th week, when maximum YBM practice duration was 25 minutes including relaxative postures, while the same for yogasana practice was for only 10 minutes which included yoga relaxative postures. The CG did not practice yoga during this period. The general physical activity pattern of both YG and CG was same from light to moderate intensity throughout the day during the study period as

Gopinath Bhowmik Bhunia & Uday Sankar Ray; J Adv Sport Phys Edu, Nov., 2020; 3(11): 199-206 © 2020 |Published by Scholars Middle East Publishers, Dubai, United Arab Emirates 201 they used to be involved mostly in their academic schedule. Recordings of different parameters Recordings of basal and resting heart rate (HR), respiratory rate (RR) and predicted O2max were taken on both YG and CG at base line, immediately before the commencement of yoga training for YG, at the end of the 6 th week and at the end of 12 th week. HR and RR were manually taken respectively by palpation of radial pulse and by observing the movement of chest in the morning when they were in bed. Predicted O2max was measured by Queen’s college step test 23 The validity and applicability of the Queen’s college step test for the population with the same ethnicity among students was tested by Chatterjee et al. [24]. The step test was conducted in the forenoon. There was a gap of at least 2 hours after the last meal and the test. After a brief warm up and adequate rest for minimum ½ hour to achieve resting HR in the laboratory the test was started. The step test was performed on a stool of 41.3 cm height. Duration of stepping was 3 minutes and 24 cycle steps per minute which was set by metronome. Just before, during and after exercise HR was measured by Polar Heart rate monitor V800 (Polar Electro Oy, Finland). After completion of 3 minutes of exercise their heart beat was monitored from 5 th to 20 th seconds of the recovery period The 15 seconds’ total pulse / heart beat was also noted with the help of the software of the heart rate monitor Then same was multiplied by 4 to obtain heart beat for one minute The following equation was used to calculate the predicted O2max (24)  P O2max (ml/Kg/min) = 111.33 – (0.42 × HR in beats/min)  Here after predicted O2max will be expressed as O2max only. The whole experiment was performed in a room

of the heart rate monitor Then same was multiplied by 4 to obtain heart beat for one minute The following equation was used to calculate the predicted O2max (24)  P O2max (ml/Kg/min) = 111.33 – (0.42 × HR in beats/min)  Here after predicted O2max will be expressed as O2max only. The whole experiment was performed in a room temperature varying from 25 to 28°C with relative humidity in the range between 70 % - 85%. STATISTICAL ANALYSIS Purposive sampling was adopted from the university student community. Normality of continuous variables was evaluated by Shapiro-Wilk test. Data were summarized using means and standard deviation (SD). The means obtained from different data sets were compared by one way repeated measures of analysis of variance test (ANOVA), followed by Bonferroni test. Inter group comparison was done by unpaired t test. A value of p<0.05 was considered as statistically significant. The statistical analyses were performed using statistical software Graph pad prism (Version 5, 2007, Sandiego, CA, USA) and SPSS (Version 25). RESULTS In oga group the pre training base line mean value of O2max was 47.5±3.7 ml/kg/min. It increased to 49.4±3.3 ml/kg/min with statistical significance (P<0.001) at 6 th week end. At 12 th week end, it further increased with a significantly higher value of 53.03±3.3 ml/kg/min (P<0.0001) as compared to baseline (Fig: 1A). In CG, baseline value of VO2max was 49.4±4.0 ml/kg/min which did not change significantly at the 6 th and 12 th week end (Fig:2A). Basal resting HR which was recorded in the morning gradually decreased in YG from 65.6±9.8 bpm at base line to 63.7±9.0 bpm at 6 th week end (P<0.0001). At the 12 th week end it further reduced to 58.2±6.3 bpm with very high level of significance (P<0.0001) as compared to base line value (Fig: 1C). CG did not show any reduction in the mean basal HR values both at the 6 th and 12 th week of study period (Fig: 2C). Resting HR values before exercise test as recorded in the laboratory in YG also followed the similar trend like basal HR. It gradually

of significance (P<0.0001) as compared to base line value (Fig: 1C). CG did not show any reduction in the mean basal HR values both at the 6 th and 12 th week of study period (Fig: 2C). Resting HR values before exercise test as recorded in the laboratory in YG also followed the similar trend like basal HR. It gradually reduced from base line value of 66.9±7.9 bpm to 60.6±4.7 bpm at 12th week end which had highly significant (P<0.0001) difference (Fig: 1D) but CG did not show such reduction (Fig: 2D). Mean base line RR was15.8±2.7 per minute reduced significantly (P<0.001) to 14±1.7 at 6th week end. It further reduced with high significance (P<0.0001) to 12.8±1.2 per minute at the12th week end (Fig: 1B). In case of CG, there was no such reduction both at the 6 th and 12 th week end (Fig: 2B).

Gopinath Bhowmik Bhunia & Uday Sankar Ray; J Adv Sport Phys Edu, Nov., 2020; 3(11): 199-206 © 2020 |Published by Scholars Middle East Publishers, Dubai, United Arab Emirates 202 A B C D ig- showing 2max (A), basal RR (B), basal HR (C) and resting HR (D) at baseline before, at 6 th week end and at 12 th end of yoga training As co pared to ase line ax has significantly i proved oth at the th week and 12 th week end while basal RR and HR, resting HR have reduced significantly both at 6 th and 12 th week A B C D ig- showing 2max (A), basal RR (B), basal HR (C) and resting HR (D) at baseline before, at 6 th week end and at 12 th end. As compared to their respective base line values all the parameters show no significant difference both at the 6 th and 12 th week end

Gopinath Bhowmik Bhunia & Uday Sankar Ray; J Adv Sport Phys Edu, Nov., 2020; 3(11): 199-206 © 2020 |Published by Scholars Middle East Publishers, Dubai, United Arab Emirates 203 As compared to G mean value of O2max in YG was higher at the 6 th and 12 th week end. But, compared to CG, mean value of RR, basal HR and resting HR in YG were lower at the 6 th and 12 th week end Inter group comparison showed significantly higher value (p 0 01) in O2max in YG as compared to CG at the 12 th week end. RR showed significantly lower value in YG as compared to CG both at 6 th week end (p<0.05) and 12 th week end (p<0.001). Basal HR and resting HR before exercise in YG were lower compared to those of CG at the significance level of p<0.02 and p<0.01 respectively at the12 th week end. As given in Fig-3 O2max was negatively correlated with respect to basal RR (Fig-3A), basal HR (Fig-3B) and resting HR before exercise (Fig-3C),were r= - 0.463 (p=0.0009), r= -0.235 (p=0.107) and r= - 0.414 (p=0.003) respectively. ig- orrelation etween 2max with respect to asal A asal and resting efore exercise showing that oth asal and resting are highly correlated with 2max DISCUSSION Present study clearly indicates significant improvement in aerobic capacity even after 6 weeks of yoga training with progressive incorporation of As both the groups have similar activity pattern except the G practicing yoga the improvement in O2max may be attributed to yoga practice. To the best of our knowledge no other previous study has shown improvement in aerobic capacity with one and half months of yoga training. From 7 th week onwards of yoga training after increasing the practice of YBM in greater proportion i.e. almost 50% of the total time of yoga practice O2max improves further in very highly significant way. Again to the best of our knowledge no study has so far demonstrated the role of YBM in the improvement of aerobic capacity within this much time period of yoga training. The

training after increasing the practice of YBM in greater proportion i.e. almost 50% of the total time of yoga practice O2max improves further in very highly significant way. Again to the best of our knowledge no study has so far demonstrated the role of YBM in the improvement of aerobic capacity within this much time period of yoga training. The reason for this improvement is possibly the better cardiovascular conditioning by yoga and this has been facilitated by YBM. Through indirect evidence, 17% improvement in cardiac output after YBM (Ujjayi pranayama) was shown by Mesian and Bhole [19] in a single subject by using radioactive isotope method. Ray et al. [20] reported significantly greater mean value of stroke volume (134.3±11.4 ml/beat) and cardiac output (12±0.99 l/min) during the actual practice of Kapalbhati (YBM, Kriya), than comfortable sitting (Sukhasana) posture in a study on 20 young subjects by using impedance cardiograph. Similarly in other YBM also they saw a significantly higher value of stroke volume and cardiac output. The reason for this has been attributed to improved venous return to the heart due to reduced intrathoracic pressure during YBM practice. This in turn would increase end-diastolic volume leading to greater stroke volume due to Frank Starling mechanism; consequently cardiac output would also increase. So the practice of YBM repeatedly for days together helps to have a better cardiovascular conditioning with improved cardiac reserve. Udupa et al. [21] in their young healthy subjects, after 3 months practice of different pranayamas (types of YBM), have found reduced Rate Pressor Product (RPP) indicating reduction in cardiac load with significant changes in systolic time interval (increased QST2, PEP and PEP/ LVET), an indirect evidence of changes in cardiac haemodynamics [25]. They attributed this better ventricular performance to decreased sympathetic and increased parasympathetic activity due to pranayama practice. In study [26], YBM training on elderly persons has shown better sympathovagal balance in heart along with improvement in respiratory function. Yoga also helps in the improvement of cardiovascular function among persons with cardiovascular abnormalities. Yogasanas and slow breathing and relaxation through meditation for long duration reduces HR