Diabetes is one of the leading cause of death in general population as well as postmenopausal women in India[1]. It is expected to remain a substantial public health burden, with global rates exceeding 470 million by 2030[2].The prevalence of diabetes in Indian postmenopausal women varies from 31% to more than 60% in the different parts of country[3]. Estrogen deficiency, due to natural or surgical menopause has been suggested to have an effect on Insulin Resistance(IR)[4,5]. Homeostatis model assessment of IR (HOMA-IR) as a surrogate marker of IR based on measurement of fasting plasma glucose and insulin, has been widely used in research and epidemiology[6]. HOMA-IR has been reported to be significantly higher in postmenopausal women than in premenopausal women[7].The risk versus benefit profile of HRT in managing diabetes in postmenopausal women remains controversial8,9,10,11]. With growing evidence that psychological stressors are bidirectionally associated with IR, mind-body interventions are attracting increasing attention to address stress psychophysiology related to diabetes. In light of this knowledge, yoga is fast emerging as a complementary and attractive intervention for treatment of IR and diabetes. Yoga has been explained by Sage Patanjali as “Yogahchittavrittinirodhah”[12] and Sage Vasishta as “manahprashamanaupayahyogah”[13].It is one the most ancient Indian holistic art of living meant to quieten the mind and achieve its union with the divine intelligence of the universe[14,15,16].Yogic practice includes various asanas, kriyas, mudras, bandhas, and conscious physical relaxation for the body; concentration and meditation for the mind and Pranayama techniques to absorb “prana,” the life energy of the universe for the sustenance of life (Chandogya Upanishad)[17,18,19]. With improved healthcare system and prolongation of life span of human beings, the world postmenopausal women’s population continues to rise. Hence, there is pressing need for safe and effective intervention which can decrease the IR and morbidity and mortality associated with it without the adverse effects of HRT. We propose to study the influence of Yoga on IR in early postmenopausal women, an unchartered territory in the vast field of postmenopausal research.

Study settings and design The study is a prospective interventional study conducted in the Departments of Physiology, Biochemistry and Obstetrics and Gynaecology in Lady Hardinge Medical College and Associated Hospitals, New Delhi. Sampling strategy and sample size A convenient sample size of 67 subjects was taken due to constraints of duration of study and availability of patients willing to undertake Yogic practice. 67 women within 5 years of menopause between 45 and 60 years of age attending menopause clinic of Department of Gynaecology, Sucheta Kriplani Hospital were recruited as participants. Inclusion criteria for the participants were (1) diagnosis of menopause by a gynaecologist according to STRAWS[20] study criteria and menopausal for up to 5 years; (2) age group of 40–60 years, and (3) body mass index (BMI)<30[21]. Participants excluded from study were (1) patients with past or present history of diabetes, hypertension, coronary event or any other any known systemic illness; (2) on drugs that influence autonomic nerve system as antihypertensives, antianginals, antipsychotics, antidepressants or HRT; (3) already practising yoga or any known regular exercise regime or (4) who were unwilling to participate. After confirming inclusion criteria and explaining the objective and design of the study in detail, voluntary and informed signed consent of participants were obtained. Participants were divided into two groups on the basis of their willingness to join Yoga: Group 1[Yoga group(n = 37)] postmenopausal patients receiving routine management along with Yogic intervention and Group 2[Non-Yoga group (n = 30)] postmenopausal patients receiving routine management. No financial benefit/ compensation was offered to the participants as incentive to participate in the program. Measurements Baseline parameters After detailed history taking and general physical examination, major physiological parameters including anthropometric measurements[22] were measured and a semi structured proforma was filled with socio-demographic details. Participants were asked to report after an overnight fast of 12 hour after abstinence from caffeine, tea, coffee or nicotine for at least 24 h before the measurements to avoid known influences of these factors on autonomic nervous balance. The fasting blood samples and physiological parameters of subjects were taken between 9 a.m. and 12 noon to obviate any diurnal influences. HOMA-IR MEASUREMENTS After an overnight fast, blood samples for assays were drawn from the antecubital vein under aseptic conditions and collected in two tubes, with NaF for fasting blood sugar (FBS) measurement and plain serum vials for serum collection. The blood sample collected with NaF was sent for analysis of FBS by spectrophotometry by glucose oxidase method. Blood sample collected in plain vial was centrifuged at 1000 × g for 10-15 min to isolate serum. Serum sample thus obtained was immediately stored in aliquots at -70°C until measurement of S.F.Insulin levels by the chemiluminescence method. HOMA-IR calculation : HOMA-IR (Homeostasis Model of Assessment - IR) was calculated using the US Formula = Fasting Glucose(mg/dl) x Fasting Insulin(μU/mL) / 405(22). We preferred to use the U.S. formula for the calculation of HOMA-IR to the International formula for HOMA-IR as the FBS and S.F. Insulin measured in our lab could be directly employed in the U.S. formula[23]. Intervention The Group 1 participants received intervention in the form of Integrated Yoga module comprising asanas, pranayama, savasana, and OM chanting in addition to routine gynaecological management. The module was exclusively designed for postmenopausal women based on the concepts from Patanjali’s yoga sutras by trained Yoga physicians from AYUSH Department, LHMC. They were asked to attend Yoga clinic at a convenient time between 8 am and 1 pm and with a minimum of 2 hours of fasting. The uniform Yoga module was meticulously taught to them for a minimum of 7 days by trained Yoga instructors from AYUSH Department, LHMC. Participants were made familiar with the program which was introduced to them in a phased manner and standardized for all [Table 1]. They were instructed to practice it regularly at their respective houses for 1 h every day for at least 6 days in a week for a total duration of 12 weeks. Participants suffering from arthritis or those having undergone knee replacement surgery were advised to perform yoga manoeuvres seated on chairs. The Group 2 participants continued for 3 months with routine gynaecological management without Yogic intervention. No other interventions for blood sugar control were done in either group. The HOMA-IR measurements were done in both groups at the beginning and after 3 months of the study period. Outcome measurement A significant increase in HOMA-IR if observed indicates an increased probability of worsening of IR and development of diabetes against a decrease which suggests an improvement in IR and protection from diabetes. Ethics: The approval of the Institutional Ethics Committee for Human Research was sought and obtained for the complete experimental protocol. Statistics: 67 women within 5 years of menopause between 45 and 60 years of age attending menopause clinic of Department of Gynaecology, Sucheta Kriplani Hospital were recruited as participants. A convenient sample size of 67 subjects was taken due to constraints of duration of study and availability of patients willing to undertake Yogic practice. Participants were divided into two groups on the basis of their willingness to practice Yoga. The data were subjected to statistical evaluation using GraphPad Prism Version 5 software. After testing for normality of distribution of data with the Kolmogorov–Smirnov goodness of fit test, data were presented as mean values ± standard error of mean. Intergroup comparison between Group 1 and Group 2 for parametric data was done using unpaired “t” test and for nonparametric data was done using Mann–Whitney U test. Intragroup analysis after intervention was done using paired t test for normally distributed and Wilcoxon matched pair test for nonparametric data. Statistical significance was set up at P < 0.05.

Due to dedicated motivation and follow-up by the authors and the Yoga Department, the study did not register any dropout. Table 1 depicts the Yoga protocol designed by the trained Yoga physicians from AYUSH Department, LHMC based on the concepts of Patanjali’s Yoga Sutras and directed towards improving IR of the postmenopausal women and taught to them. Table 1: The yogic schedule I. ASANAS(30 min) A. Standing Series- Any 3 1. Katichakrasana 2. Tadasana 3. Ardhakatichakrasana 4. Ardhachakrasana B.Supine Series- Any 2 1. Uttanapadasana(30,45,90) 2. Pavanamuktasana 3. Setubandhasana 4. Shavasana with Quick Relaxation Technique-3 min. C. Prone Series- 1. Bhujangasana 2. Shalabhasana(single leg)/Balasana D. Sitting Series – Any 3 1. Gomukhasana 2. Vakrasana 3. Yogamudra 4. Pelvic Stretch 5. Ushtrasana 6. Pashchimotanasana II. PRANAYAMA(30 min.) 1. Kapalbhati-3 min. 2. Anulomvilom-7 min. 3. Bhramari-24 rounds-5 min. 4. If subject is willing-AUM chanting-24 rounds over agyachakra(eyebrow centre) 5. If subject is not willing – • Akara chanting-3 rounds • Ukara chanting-9 rounds • Mkara chanting-12 rounds 6. Shavasana with Deep Relaxation Technique-7 min.(MAUNN i.e. Silence) Table 2 depicts measurement of the basic demographic profile of Group 1 and Group 2 prior to any intervention. There was no significant difference in age (years), duration of menopause (years), weight (kg), height (m), BMI (kg/m²), neck circumference (cm), waist circumference (cm), hip circumference (cm), body fat percentage (%) between the two groups. However, weight and BMI of the two groups are significantly different making them noncomparable. Hence, we decided to proceed with pre and post intervention intragroup study as the chosen method of analysis. Table 2: Baseline demographic profile of Group 1 and Group 2 [Mean± SEM values] PARAMETERS GROUP 1 (YOGA) (n=37) GROUP 2 (NON-YOGA) (n=30) p Value AGE(yrs) 51.78± 0.82 52.97± 0.72 NS Duration of Menopause(yrs) 3.02±0.23 3.43± 0.23 NS WEIGHT(kg) 66.52±1.50 60.58± 2.31 0.0294* HEIGHT(m) 1.545± 0.01 1.54±0.09 NS B.M.I(kg/m2) 27.88±0.62 25.34±0.82 0.0294* NECK CIRCUMFERENCE(cm) 33.03±0.35 33.03±0.44 NS WAIST CIRCUMFERENCE(cm) 95±2.68 93.83±2.23 NS HIP CIRCUMFERENCE(cm) 104.8± 1.34 102.1± 2.21 NS BODY FAT (%) 43.83± 1.43 42.03±1.76 NS Unpaired t-test; P>0.05 = Non-significant, *P<0.05 (Significant), **P<0.01 (Very significant),***P<0.001 = Highly significant.[25] NS = Nonsignificant, BMI = Body mass index Table 3 compares baseline physiological parameters of Group 1 and Group 2 prior to any intervention. It depicts no significant difference in resting heart rate (beats/min), respiratory rate (breaths/min) and systolic BP (mmHg) between the two groups under study. The diastolic BP (mmHg) of the two groups are however significantly different(p=0.0114). Hence, the two groups continue to remain non-comparable. Table 3: Baseline physiological parameters of Group 1 and Group 2 [Mean± SEM values] PARAMETER GROUP 1 (YOGA) (n=37) GROUP 2 (NON- YOGA) (n=30) P Value RESTING HEART RATE(beats/min) 74.46±2.04 77.47± 3.41 NS RESPIRATORY RATE(breaths/min) 13.95± 0.26 14.2±0.244 NS SYSTOLIC B.P.(mmHg) 127.2± 1.28 125.2±2.08 NS DIASTOLIC B.P.(mmHg) 84.72±0.74 80.77±1.41 0.0114* Unpaired t-test; P>0.05 = Non-significant, *P<0.05 (Significant), **P<0.01 (Very significant),***P<0.001 = Highly significant.[25] NS = Nonsignificant, B.P. = Blood pressure Table 4 represents IR status (HOMA-IR) of Group 1 and Group 2 pre and post intervention. It shows non-significant changes in Fasting Blood Sugar levels in both study groups after the study duration of 3 months. Serum Fasting Insulin levels (p=0.0066) and HOMA-IR measurements (p=0.0212) show a significant rise after 3 months in the Non-Yoga group. Unlike Group 2, there is a definite increase in Serum Fasting Insulin and HOMA-IR in Yoga group but it is non-significant, and hence, favourable to our study. Table 4: HOMA-IR parameters of Group 1 and Group 2 pre and post intervention PARAMETERS GROUP 1 (Yoga)(n=37) GROUP 2 (Non-Yoga)(n=30) PRE-YOGA POST-YOGA P Value PRE (At recruitment) POST (after 12 12 weeks) P Value Fasting Blood Sugar (mg/dl) 97.95±2.52 97.51±2.76 NS 106.9±5.13 105.7±4.70 NS Fasting Insulin(µU/ml) 6.52±0.49 7.41±0.52 NS 7.94±1.03 9.65±1.09 0.0066** HOMA-IR 1.56±0.11 1.76±0.12 NS 2.17±0.31 2.62±0.37 0.0212* Paired t-test; P>0.05 ‑ NS, *<0.05 ‑ significant, **<0.01 ‑ very significant, <0.001 ‑ highly significant, ***<0.0001 - highly significant. LF = Low frequency, HF = High frequency, VLF = Very low frequency, SDNN = Standard deviation of NN interval, RMSSD = Square root of the mean squared differences of successive NN interval, NS = Nonsignificant

To detect the association between Yoga and IR in early postmenopausal women, if any was the starting point and primary goal of our research undertaking. Previous studies have suggested positive influences of Yogic practices on IR in postmenopausal women as measured by HOMA-IR. Our data demonstrates significant deterioration in IR in early postmenopausal women not practicing Yoga and an increase of IR which was attenuated in the group practicing Yoga as an intervention. In the Non-Yoga group, S. F. Insulin (p=0.0066) and HOMA-IR (p=0.0212) showed an increase at the end of 3 months which was highly significant. The rise in S. F. Insulin and HOMA-IR in Yoga group also showed a trend towards increase but it was non-significant. This observation suggests and supports mitigating effect of Yoga on IR in postmenopausal women. Fasting Blood Sugar levels showed no significant changes in either groups after the study duration. A significant rise in these parameters in the Non-Yoga group suggests that early postmenopausal women not practicing Yoga showed greater tendency for worsening of IR over the observation period. Onset of diabetes after attainment of menopause in women is a much researched and established phenomenon. Our study is partly in concordance with prior studies by Chaya MS et al.[24], Rani M.R et al. [25], Lee J A et al.[26], Bhavanani et al.[17], Innes et al.[15] Madanmohan et al.[27], and Innes and Vincent et al.[28] which suggest positive influences of Yogic practices on IR and type 2 DM in various populations. However, some employed a lesser number of patients[24,27], some were of shorter duration than ours[27] and some were without controls[27] making our methodology more rigorous and fastidious. Our study supports by scientific evidence that Yoga has attenuating effect on IR in postmenopausal women, as is proposed by the abovementioned studies and is in concordance with them. A significant reason for our observations regarding IR which didnot achieve significance like these studies could be a shorter duration of study and a smaller sample size. All these studies have been done on postmenopausal women belonging to all ages. Our study focusses on early postmenopausal women which has not been undertaken till date making it novel. Insulin resistance increases with onset of menopause and interventions such as hormonal therapy has benefits if started in early menopause rather than established menopause where it has shown to have no effect or detrimental effect on glucose homeostatis and insulin sensitivity[29]. Past researches on Yoga amply elucidate our observations. In the Yogic tradition, voluntary slow control of breathing has long been used to foster self awareness and reduce unnecessary autonomic reactivity, due to the known reciprocal relation between breath and visceral and mental functioning[16]. Yoga is known to enhance vagal activity and reduce sympathetic activity. This balancing of ANS is believed to control insulin secretion by pancreatic islet cells as well as increase glucose disposal at cellular levels by decreasing the resistance to glucose uptake in cells[30].Yogic practices have been associated with an increase in lean body mass and decrease in body fat percentage. Reduction in free fatty acid levels reduces lipotoxicity, which has a significant effect on beta cell function, improvement in insulin sensitivity and reduction in IR[31]. Therefore it is reasonable to postulate that beneficial effects of yoga on insulin kinetics and lipid metabolism prevents beta cell exhaustion thereby preventing development of IR[32]. Yoga practice increases the release of an adipocyte-derived hormone called adiponectin which decreases IR by decreasing triglyceride content in muscle and the liver[26]. In addition, research has suggested that yoga’s contribution to stress reduction actually may moderate the impact of diabetes. High levels of stress hormones have been shown to raise blood glucose levels, promote overeating, lead to the accumulation of intra-abdominal fat, IR and boost heart attack risk. By reducing stress hormone levels, yoga can minimize these side effects[33]. Yoga has no appreciable side effects and imparts multiple collateral benefits to its practitioners. It is safe and simple to learn and can be practiced by even ill, elderly or disabled individuals[28]. If started early, Yoga has the potential to prevent progression of the DM and maybe even effect a cure[34]. Our study helps to explain the causative etiopathology of many of the adverse health events associated with menopause and creates avenues for researchers to take up the cause of postmenopausal health. It further substantiates the already growing evidence for efficacy of Yoga in preventing and ameliorating health adversities faced by postmenopausal women. Regular practice of yoga could be a powerful tool to attenuate the IR brought about by hormonal imbalances in early postmenopausal women and thereby help prevent and decrease morbidity and mortality associated with IR and type-II DM in these subjects. Our study puts things in order for clinically important implications for Yoga as a non- clinical, cost-effective and safe lifestyle intervention for the prevention and treatment of type-II DM in postmenopausal women and holds much promise in promoting health in postmenopausal women.

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