Introduction
Metabolic Syndrome (MetS) is a condition comprising ≥3 MetS risk factors including high waist circumference (WC), high blood pressure (BP), high triglycerides (TGs), high fasting blood glucose (FGL) and low high-density lipoprotein (HDL). Its presence dramatically raises the risk of type 2 diabetes (T2D) and cardiovascular illnesses, two of the world’s leading causes of mortality. It is noteworthy that MetS is reversible as is closely linked to an individual’s lifestyle choices and behaviour’s, such as excessive calorie intake, insufficient physical activity, and psychosocial stress (Huang, 2009; Kuo et al., 2019).
Globally, the COVID-19 epidemic reduced people’s lifestyles and behaviours. According to reports from the Department of Health in HK (Centre for Health Protection, 2021) in HK, (the consumption of food and physical activity) lifestyle and behaviour by individuals has drastically decreased as a result of COVID-19. According to Choi et al. (2020), this has led to higher levels of stress, anxiety, and depression prevalence. Since disturbed lifestyle behaviour and mental health increases the risk of MetS, this may have contributed to the increased prevalence of MetS in the post COVID-19 era.
The most recent Population Health Survey undertaken by the Department of Health in HK between 2014 and 2015 found that 20.1% of individuals aged 15 to 84 were overweight and 29.9% were obese (Surveillance and Epidemiology Branch Centre for Health Protection Department of Health, 2017). According to this survey, 27.7% of people between the ages of 15 and 84 had hypertension in combination with obesity (Surveillance and Epidemiology Branch Centre for Health Protection Department of Health, 2017). Moreover, prior to Covid-19, 50% of HK patients in our 2010–2013 study (Siu et al., 2015) had high systolic blood pressure and central adiposity, which were found to be the most common components of MetS. The possibility of contracting diabetes and cardiovascular disease is greatly increased by elevations in these two indicators. MetS was already elevated prior to Covid-19, and it was predicted that following the pandemic, the proportion of people with MetS would increase dramatically, necessitating immediate actions in the HK population.
Therapeutic techniques for controlling MetS include side effects. Thus, in order to prevent or delay the onset of T2D, intensive lifestyle treatments have been prioritized (Diabetes Prevention Program Research Group, 2002; Tuomilehto et al., 2001). However, maintaining lifestyle modifications that result in weight loss may be difficult to implement (Wadden et al., 2012). Therefore, long-term lifestyle adjustments are required. According to our previous research (Siu et al., 2015; Supriya et al., 2018) practicing hatha yoga, one of the generic forms of yoga, for a year reduces the number of diagnostic components of MetS, WC, and shows a decreasing trend in systolic BP with positive modulations of adipokines in adults with MetS in HK. A comprehensive review and meta-analysis investigating the effects of yoga in people with MetS was published in 2016. It included 794 participants from 7 trials. (Cramer et al., 2016, 2018). In terms of WC and systolic BP, yoga performed better than streching and under standard treatment (Cramer et al., 2016); Corey et al., 2014).
Restorative yoga is non-generic yoga, customized to a specific population or disease. “Restorative yoga,” uses props to sustain positions for extended periods of time to reduce stress eliminate all muscular effort, and encourage profound relaxation. Restorative yoga sets itself apart from conventional stretching exercises by primarily focusing on fostering deep relaxation, alleviating stress, and aiding in the healing process. This practice prioritizes soothing the nervous system and reestablishing balance within the body and mind. In contrast, the primary objective of stretching exercises is to enhance flexibility, broaden the range of motion, and prepare the muscles for various physical activities. Prior research based on restorative yoga were either comparative studies with control groups or compared other forms of exercises like stretching. For instance, a pilot and a definitive trial by a research team found that six months of restorative yoga improved the mental health and risk factors of individuals with MetS from the United States (US). Reductions in WC and BP was evident in their pilot trial (Cohen et al., 2008). However, their trial revealed that only FGL was reduced in the restorative yoga group verses stretching group (Kanaya et al., 2014). It’s interesting to note that the restorative yoga group showed greater adherence and persistence of outcome than the stretching group. Since the benefits of yoga practice can take up to a year or more to materialize, they discovered that the only significant between-group difference happened after a year, and many of the positive outcomes within the yoga group appeared after a year rather than at six months.
We aimed to assess the feasibility and acceptability of restorative yoga for addressing MetS risk factors in the adult population of HK. We intentionally chose not to include individuals with full-blown MetS, as this group is more vulnerable and we were uncertain about the effects of restorative yoga on this specific population. Instead, we focused on subjects with at least two MetS risk factors, who are not classified as having full-blown MetS but are more susceptible to developing it. By recruiting this population, we aim to evaluate the feasibility and acceptability of restorative yoga, as well as its potential impact, without putting a more vulnerable group at risk. The findings from the feasibility study can help refine intervention strategies, making them more effective and acceptable for individuals with three or more risk factors in subsequent trials.
Thus, this feasibility study aimed to explore the acceptability of conducting restorative yoga in HK adults with at least two MetS risk factors for a period of 6 months. This study also aimed to investigate the impact of six months of restorative yoga practice on the MetS risk factors and mental health in HK adults with at least two MetS risk factors.
Methods
Design and participants
A two arm, parallel RCT was adopted in this study. Subjects were assigned to a restorative yoga group or control group. Subjects participated in 2 measurement sessions at baseline (T1) and 6 months post-test (T2). The target population were HK community-dwelling adults. According to National Cholesterol Education Program (NCEP)-ATP III criteria, adults between the ages of 30 and 65 years who had at least 2 MetS were recruited. According to the US NCEP-ATP III diagnostic guidelines (National Cholesterol Education Program (NCEP) Expert Panel on Detection, 2002), a person with MetS must exhibit three or more of the following symptoms: 1) central obesity (WC greater than 90 cm for Asian men and 80 cm for Asian women), 2) hypertension (systolic pressure greater than 130 mmHg or diastolic pressure greater than 85 mmHg), 3) elevated blood sugar (fasting glucose level greater than 5.5 mmol/L [100 mg/dL]), and 4). Figure 1 shows the schematic research flowchart of subject recruitment.
Figure 1
Study flow chart.
Prior to the study, written informed consent was obtained on a voluntary basis. Both English and simplified Chinese version of consent forms were explained by the PI to participants and then were distributed for their approval. Participants were informed of the possible risks and advantages of their involvement. Participants between the ages of 30 and 65 years or who reported having dementia or a mental disorder, severe cardiovascular disease, a history of stroke, neuromusculoskeletal illness, major orthopaedic problems in the lower back, pelvis, or lower extremities, or who were immobile or use a wheelchair, on medication for metabolic abnormalities, or who were having symptoms of heart or lung disease were not eligible for the study. Regular smokers and participants who exercise regularly (three or more days per week with at least 30 minutes of moderate-to-vigorous activity) were also excluded from the study. Participants involved in other aerobic, or exercise programs were also excluded. The participants were asked to sign a consent form outlining that they did not participate in any health programs during the period of study. A computer program was used to complete subject randomization and trial group allocation. The public website of Life Management Yoga Centre (LMYC), its Facebook page was used to advertise for participant recruitment. We recruited more than 50 participants in just two waves, including approximately 25–30 participants per wave. Participants who were eligible had their seats booked for the briefing session by the principal investigator (PI) hosted by LMYC. The questionnaires were distributed on the briefing day to assess their awareness about MetS, their mental health, their demographics (Table 2), and inclusion and exclusion criteria. A WhatsApp group was created for making the appointments for clinical screening. Potential participants were asked to fast for at least 10 hours before the screening session, and they were asked to bring any current medications or dietary supplements. Standard methods to assess BP while seated, and height, weight measurements were performed in the clinic by certified clinical staff. WC was measured using inelastic measuring tape by the PI and research assistant. For the measurement of glucose, lipid panel, fasting blood samples were taken. Fulfilment of the MetS criteria ultimately determined research enrolment. HK Baptist University approved all experimental methods. Human research ethics (REC/22-23/0150) was obtained for HK adults with at least two MetS risk factors in October 2023.
Intervention
We recruited eligible participants who met at least 2 MetS from the screened pool to take part in our feasibility study on yoga interventions. Using a computer program that generated random group names, the participants were divided into the yoga and control groups. The per protocol analysis did not include subjects from the yoga group who did not finish the training program with at least 70% attendance. All subjects were expected to carry out their regular daily dietary intake and other physical activities over the duration of the study. Additionally, because the majority of the subjects in both groups were domestic workers, 200HKD in cash was provided to them in order to guarantee the integrity of the intervention and lower the dropout rate.
Restorative Yoga intervention
For six months, participants were given one session per week. Pose variation from restorative yoga, which emphasizes relaxation and makes use of props to provide the body with all-encompassing support, were incorporated into the intervention. We cited a previous study in which four certified yoga instructors were brought together, and they had years of combined experience teaching yoga to individuals with various physical conditions and flexibility limitations. Based on individual limitations and requirements of participants, Yoga teachers of LMYC( HK) and The Yoga Institute (India) customized the protocols used in the sessions. The Yoga trainer, Miss Gan Zhi Li previously qualified for the degree of M. Sc Yoga and Naturopathy from Tamil Nadu Physical Education and Sports University (first class). She has completed 100 hours intensive hatha yoga teacher training certificate course (intermediate-advanced level) from International Yoga Academy which is an accredited school of yoga alliance (USA) Reg. No. RYS -ID 38733. She speaks English as well as Cantonese and Mandarin. Restorative yoga poses were the most feasible for this study population and would enhance the relaxation response, according to the expert panel. Every group yoga class began with a brief sequence of breathing and stretching exercises, then moved into ten positions that lasted five to ten minutes each. A variety of postures were done, including Child’s Pose, Supported Lying Down Bound Angle, Wall Hang, Seated Bound Angle, Seated Wide Angle, Reclining Twist, and Deep Relaxation Pose (Figures 2a and 2b). Each pose selected has an impact on metabolic parameters including obesity, glucose level, BP and mental health based on literature observations (Cohen et al., 2008). Whenever a subject expressed discomfort in their assigned posture, routine adjustments were made. According to Cohen et al. (2008), the participants in the yoga group were given a practice logbook and told to practice for at least half an hour three times a week at home.
Figure 2a
Restorative yoga postures with pictures (yoga trainer posed), poses name and time allotted by the trainer of LMYC.
Figure 2b
Participants performing restorative yoga sessions.
Waitlist control
Every two weeks, waitlist controls were contacted to inquire about their health. Moreover, during the intervention period, they were restricted from participating in any health programs or physical activities.
Outcome Measurements
MetS parameters and blood biochemistry
In the PHC lab, certified phlebotomists utilized an electronic BP monitor (Accutorr Plus, Datascope) to record systolic and diastolic BP. Using an inelastic measuring tape on bare skin, a skilled researcher measured WC midway between the superior border of the iliac crest and the lowest rib. The measurement was taken to the nearest 0.1 cm. The skin was not squeezed even though the tape is tightly wrapped around the abdomen and across the navel. The measurement was made after a normal expiration. PHC Medical Diagnostic Centre Ltd. accredited phlebotomists performed biochemical testing for FGL, cholesterol HDL, cholesterol LDL, TGs, and morning cortisol. A total of 2 millilitres of fluoridated blood and 5 millilitres of clotted blood were taken. Before bloodletting, the subjects had to fast for eight hours, although they were still permitted to drink water (Figure 3). The instruments used by medical laboratory to detect the levels of plasma glucose, TGs, and HDL cholesterol has been presented in Table 1. The removal of blood and all other procedures were carried out at the same time of day to minimize the impact of daily fluctuations under the careful supervision of two or more certified phlebotomists. To help the individuals feel at ease and attend to their physical and psychological requirements, a research assistant gave them fruit juices and snacks.
Figure 3
MetS risk factor assessment.
Table 1
Blood test markers, its testing methods and instruments used for analysis.
| BLOOD TEST ITEM | BLOOD SPECIMEN USED | TESTING METHOD | INSTRUMENT USED FOR ANALYSIS | |
|---|---|---|---|---|
| 1. | Glucose, Fasting | 2 ml Fluoride Tube Blood × 1 | Chem – spectrophotometer | Abbott – Alinity C |
| 2. | Cholesterol, HDL | 5 ml Clotted Tube Blood × 1 | Chem – spectrophotometer | Abbott – Alinity C |
| 3. | Cholesterol, LDL (Direct Measure) | Chem – spectrophotometer | Abbott – Alinity C | |
| 4. | Triglycerides | Chem – spectrophotometer | Abbott – Alinity C | |
| 5. | Cortisol (a.m.) | Immunology – CMIA | Abbott – Alinity I |
Even though blood withdrawal was routine, the doctors at PHC Medical Diagnostics were scheduled to respond immediately in case of an emergency. One day before the blood withdrawal, the subjects were also contacted by a research assistant to help them relax psychologically.
Questionnaire measures
General demographic: We gathered demographic data, including chronic disease information, as well as data on gender, age, race/ethnicity, education, and marital status, mobile usage.
Mental Health
Adults measured their levels of stress, anxiety, and depression with the DASS-21 (Depression Anxiety Stress Scales), which has a high degree of internal consistency as well as discriminative, concurrent, and convergent validity. According to Yohannes et al. (2019), the test-retest and split-half reliability coefficient scores were.99 and.96, respectively. Three scales that measure the emotional states of stress, anxiety, and depression are part of this diagnostic tool. The depression scale measures general dissatisfaction, hopelessness, devaluation of life, self-criticism, lack of interest, inability to feel pleasure, and emotional states resistant to change. The autonomic arousal, muscle effects, situational anxiety, and subjective perceptions about anxious affect are all measured by the anxiety scale. An individual’s degree of calmness, anxiety, agitation, irritability, over-reactivity, and impatience are all measured by the stress scale.
Sleep quality and quantity
The self-administered Pittsburgh Sleep Quality Index (PSQI), which takes five to ten minutes to compile, was used. It is appropriate for people ages 24 to 83. The 19 self-reported items on the questionnaire fall into one of seven subcategories: daytime dysfunction, habitual sleep efficiency, subjective sleep quality, sleep latency, length, and interruptions. 5 questions relevant to respondent’s roommate will not be used. Buysse et al. (1989) reported that the assessment’s internal reliability was a = .83, its test-retest reliability for the global scale was.85, its sensitivity was 89.6%, and its specificity was 86.5%.
Physical activity and dietary record
International Physical Activity Questionnaire (IPAQ) short (Booth, 2000) was used. Subjects were also asked to provide details of a 3-day weighted dietary record (Yang et al., 2010) which includes two weekdays and one weekend day, at the Pre, Post and follow-up measurement sessions.
Qualitative interview
Following the study’s conclusion, individual face-to-face interviews with the yoga group were carried out exclusively. In order to reduce recall bias, interviews were conducted to learn more about the perspectives and experiences of adult HK participants in the yoga session one week after the intervention ended.
Feasibility and acceptability measures
The feasibility questionnaire focused on three important aspects of the intervention including i) Adaptation ii) Practicality and iii) Acceptability to seek participants feedback and suggestions for improvement. It was made clear that all materials and interventions were culturally appropriate and available in participant’s language to minimize barriers.
Data Analyses
Data were expressed as mean ± standard deviation. Kolmogorov–Smirnov test of normality was used for checking distribution of the data before data analysis. Primary outcome measures included MetS risk factors (systolic and diastolic BP, WC, FGL, TGs, and HDL) and secondary outcomes included mental health (anxiety, depression, stress and morning cortisol levels in blood); and sleep behaviour (quality and quantity). Baseline pre data difference within group was tested using t test and significance was accepted in P < 0.01. The changes of measured parameters at Post and Pre in control and yoga groups were analysed using repeated t-test for independent assessment of effect of restorative yoga. Independent t test was performed to test difference between mean changes between control and yoga intervention group. Subjects with <70% attendance were used per protocol analysis. All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS) version 29 for Windows. Statistical significance was accepted at p < 0.05, two tailed. Physical activity level and caloric intake were also assessed and included in the covariate analyses.
Results
Baseline characteristics
Baseline characteristics of the participants are shown in Table 2. There were no observable baseline differences between the groups except systolic BP.
Table 2
Baseline characteristics.
| YOGA GROUP (n= 13) | CONTROL GROUP (n= 8) | |
|---|---|---|
| Mean age (SD), years | 55.45(4.67) | 51.62(10.22) |
| Women (%) | 77 | 63 |
| Men (%) | 23 | 37 |
| Hong Konger | 6 | 3 |
| Ethnic Minority | 7 | 5 |
| Waist circumference (SD) | 34.16(3.8) | 38.87(3.53) |
| Blood pressure(systolic) (SD) | 134.46(21.8) | 118.25(9.98) |
| High density lipoprotein (SD) | 1.81(0.29) | 1.4(0.27) |
| Low density lipoprotein (SD) | 3.54(0.88) | 2.74(0.77) |
| Triglycerides (SD) | 1.2(0.43) | 1.22(0.34) |
| Fasting glucose (SD) | 4.96(.34) | 6.15(1.78) |
| Body Mass Index (SD) | 23.69(4.04) | 28.25(4.65) |
[i] *SD is standard deviation and n is number of subjects.
We observed decreasing trends in MetS characteristics prevalence in post yoga compared to pre yoga in the intervention group (Table 3). High systolic BP was present in 43% of the participants before restorative yoga and was present in only 19% of the participants after yoga. Diastolic BP was high among 29% of the participants before restorative yoga which was later reduced to only 9% of the participants after yoga. There was only a slight reduction in prevalence percentage of high FGL after yoga from 24% to 23% of the population. Interestingly, low HDL prevalence percentage in the yoga group before was 19% and decreased to 4% after yoga. High TGs were present in 14% of the participants before restorative yoga and it was present in only 4% of the participants afters yoga. Furthermore, high WC prevalence percentage in yoga group before intervention was 67% and decreased to 61% after yoga.
Table 3
Mets components percentage.
| PRE-YOGA METS RISK FACTORS | PREVALENCE OF METS BASED ON NCEP-ATP III CRITERIA (NUMBER OF PARTICIPANTS) | TOTAL NUMBER OF PARTICIPANTS | PERCENTAGE PREVALENCE |
|---|---|---|---|
| Systolic-Blood Pressure | 9 | 21 | 43% |
| Diastolic-Blood Pressure | 6 | 21 | 29% |
| Fasting glucose level | 5 | 21 | 24% |
| High-density lipoprotein | 4 | 21 | 19% |
| Triglycerides | 3 | 21 | 14% |
| Waist circumference | 14 | 21 | 67% |
| Post-Yoga MetS risk factors | |||
| Systolic-Blood Pressure | 4 | 21 | 19% |
| Diastolic-Blood Pressure | 2 | 21 | 9% |
| Fasting glucose level | 5 | 21 | 23% |
| High-density lipoprotein | 1 | 21 | 4% |
| Triglycerides | 1 | 21 | 4% |
| Waist circumference | 13 | 21 | 61% |
Feasibility and retention
From October to May of 2023, persons in HK who had at least two MetS risk indicators were the subjects of this study. Two groups were randomly assigned into groups: Group 1 was given restorative yoga, while Group 2 was given waitlist control. 53 people signed up to participate in this study in total. 21 subjects (Group 1; n = 13) and Group 2; n = 8) ultimately finished the research after 45 had blood testing. Three participants had attendance of less than 70%, and 18 participants either did not show up after the blood test or did show up for one or two classes. In addition, 13 members of the intervention group completed the acceptability and feasibility questionnaire.
The prospects of recruiting participants for our study within the predicted time period was encouraging as more than the intended number of people (age = 35–65 years) were recruited only through LMYC official page on Facebook. A week was allotted for participant recruitment. The costs incurred were covered by the researchers, while LMYC already provided the facilities, equipment, and yoga instructors that were required to carry out the intervention. Every resource was made available in the allotted amount of time.
Clear objectives, time commitments, and potential dangers were communicated to participants in order to ensure retention. A customized strategy was started to address each participant’s unique wants and concerns in order to foster trust among the group. Before the intervention was finished, a 200 HK dollar financial incentive was promised. Throughout the intervention, participants were kept in regular contact with the PI via emails, WhatsApp, and in-person visits to the LMYC facility. The PI also addressed any concerns that the participants may have had.
Acceptability
91% percent of participants stated that they were adaptable to the specified intervention, to questions about whether they feel yoga has health advantages, and to whether they are prepared to adapt even in the absence of instruction. 92% of participants felt that the intervention was practical. Questions about practicality asked participants whether they thought the intervention was practical and if they would be glad if we raised the number of intervention sessions. Participants’ pleasure with yoga instruction and physical posture training was the focus of the acceptability portion, and 94% of them agreed to accept the intervention. Attendance served as a gauge for acceptance and compliance. 53 people signed up to participate in this study in total. 45 had blood tests, and 27 participants finally completed the study 4 participants had attendance of less than 70%, while 14 people did not return following the blood test. Additionally, 24 members of the intervention and control groups filled the questionnaire on acceptability and feasibility.
Metabolic syndrome risk factors outcomes
Effects of 6 months restorative yoga (1 hour/week) for 6 months on MetS risk factors in subjects with at least 2 MetS risk factor. Restorative yoga intervention showed a significant mean reduction in systolic BP = 16.69 ± 22.68 mm of Hg (P = 0.021), WC = 1.51 ± 1.49 inches (P = 0.003), TGs = 0.19 ± 0.32 mmol/dl (P = 0.05), FGL = 0.21 ± 0.31 mmol/dl (P = 0.03) and mental health = 12.7 ± 15.2 (P = 0.011) within group (Table 4). There were no significant changes in any of the MetS risk factors after 6 months in control group. We also observed between group significant difference in means of systolic BP (–17.81; CI –35.39, –0.24, P < 0.05) and WC (–1.38; CI –2.41, 0.35, P < 0.05) in restorative verses control group (Table 4).
Table 4
Means Changes in variables within group.
| VARIABLE | MEAN (std. DEVIATION) | t VALUE | p VALUE |
|---|---|---|---|
| INTERVENETION | |||
| Systolic-Blood Pressure | 16.69(22.68) | 2.653 | 0.021 |
| Diastolic-Blood Pressure | 1.07(12.39) | .313 | >0.05 |
| Fasting blood glucose | .207(.309) | 2.420 | 0.032 |
| High density lipoprotein | .046(.156) | 1.066 | >0.05 |
| Low density lipoprotein | –.073(.379) | –.702 | >0.05 |
| Triglycerides | .19(.317) | 2.184 | 0.050 |
| Cortisol | .569(2.24) | .914 | >0.05 |
| Body Mass Index | –.153(.98) | –.562 | >0.05 |
| Mental Health | 12.69(15.2) | 3.005 | 0.011 |
| Waist circumference | 1.50(1.48) | 3.65 | 0.003 |
| CONTROL | |||
| Systolic-Blood Pressure | –1.13(8.14) | –0.39 | >0.05 |
| Diastolic-Blood Pressure | 1.25(4.3) | 0.82 | >0.05 |
| Fasting blood glucose | 0.31(1.1) | 0.80 | >0.05 |
| High density lipoprotein | –0.06(0.177) | –1.0 | >0.05 |
| Low density lipoprotein | –0.29(0.49) | –1.6 | >0.05 |
| Triglycerides | 0.16(0.27) | 1.7 | >0.05 |
| Cortisol | 1.72(3.2) | 1.5 | >0.05 |
| Body Mass Index | –0.375(1.06) | –1.0 | >0.05 |
| Mental Health | 5(10.88) | 1.3 | >0.05 |
| Waist circumference | 0.13(0.75) | 0.48 | >0.05 |
Sleep behaviour
There were no changes in sleep behaviour after 6 months in the restorative yoga group or control group.
Metabolic syndrome awareness
No one was aware of MetS.
Perception of participants
In qualitative interviews we asked about the impact of this form of yoga on their health wellness, stress relief and spiritual connection. They reported that this form of yoga improved flexibility, strength, and overall fitness and helped positively in mental well-being and some reported that they discovered deeper aspects of themselves and fostering a sense of inner peace. However, only one participant reported improvement in sleep pattern. Women represented a larger demographic in yoga classes, leading to perceptions of yoga as a feminine activity however, males negated this perception. Elderly as well as young adults both were comfortable in doing restorative yoga and found it simpler than generic form or walking or any form of exercises. We also asked a few questions to explore barriers to participation including time constraints, accessibility and evolving trends of delivery mode. Many of the participants were domestic help employees. In HK, domestic helpers are given only one day off in a week on a Sunday. Even though they want to attend 3 session per week yoga for effective results they had no options to attend. In terms of accessibility their perception was that yoga classes are expensive or that they cater primarily to a specific demographic, which may deter broader participation. Online Platforms: Participants were asked if they would/could attend 3 times/ week online training. They were not interested in online sessions.
Discussion
Our findings show that recruiting subjects with at least 2 MetS risk factors for a randomized study involving restorative yoga is practical. The participants complied with the restorative yoga poses and were able to complete a few postures related to stretching at home. The intervention study group had outstanding attendance at study visits. Furthermore, we had high participant satisfaction rates and strong participant retention in the trial.
We observed between group significant differences in means of changes in pre-post systolic BP (–17.81; CI –35.39, –0.24, P < 0.05) and WC (–1.38; CI –2.41, 0.35, P < 0.05) in restorative verses control group which agrees with another pilot study that clearly reflected reductions in BP and WC (Cohen et al., 2008). Similar to Cohen et al., we also didn’t observe significant changes in other MetS risk factors. Seep behaviours and cortisol levels were also not improved by restorative yoga compared to control. Pre and post results of restorative yoga intervention showed a significant mean reduction in systolic BP = 16.69 ± 22.68 mm of Hg (P = 0.021), WC = 1.51 ± 1.49 inches (P = 0.003), TGs = 0.19 ± 0.32 mmol/dl (P = 0.05), FGL = 0.21 ± 0.31 mmol/dl (P = 0.03) and mental health = 12.7 ± 15.2 (P = 0.011) within group. There were no significant changes in any of the MetS risk factors after 6 months in the control group. These results indicate that this form of yoga is MetS specific and has impact on MetS risk factors more than the generic form of yoga like hatha yoga. As our previous team study revealed that only waist circumference was significantly improved after the 1-year yoga intervention and a trend towards a decrease in systolic BP was observed following hatha yoga intervention (Siu et al., 2015).
Compared to the control group, the yoga group had significantly improved trends toward improved mental health (psychological well-being and perceived stress). Compared to conventional exercise programs targeted at enhancing aspects of the metabolic syndrome, our restorative yoga intervention is unique. In restorative yoga positions, you will spend many minutes at a time lying down with your body supported. Participants were told to relax and concentrate on their breathing while in these poses. Reduction of tension and relaxation is probably the method by which this type of yoga reduces metabolic risk factors. Several previous research articles have addressed the mechanism of metabolic improvement, even if we were not able to investigate this in this pilot trial due to lack of resources or power. Stress hormones like cortisol, norepinephrine, and epinephrine that are generated by the sympathetic nervous system interfere with insulin’s function and can cause hyperglycemia and insulin resistance (Rosmond et. al., 2003). Moreover, visceral obesity, elevated blood pressure, and dyslipidemia are associated with elevated cortisol levels (Whitworth JA., et. al., 2005), higher morbidity and mortality in people with cardiovascular disease (CVD) (Nolan et. al., 1998) and higher complications in people with diabetes are linked to impaired autonomic function, which is characterized by increased sympathetic and decreased parasympathetic nervous system activity (Gottsäter A et al., 2006 & Kudat, H., et. al., 2006). Small studies have revealed a correlation between yoga and decreased cortisol and sympathetic hormone levels (Damodaran, A. et. al., 2002 & Schell, F. J., et. al., 1994).
Due to the small sample size in this pilot study and the inability to blind participants to the intervention, the conclusions of our research are restricted. Our capacity to show notable metabolic alterations may have been hampered by the small sample size and short follow-up period.
In summary, we discovered that a restorative yoga intervention was practical and acceptable by a group of adults in HK with at least 2 MetS. Our participant satisfaction and retention percentages were really high in the intervention group. While the size and duration of this trial were insufficient to assess the effectiveness of yoga in treating MetS, we did observe positive changes in BP, WC, psychological health. These outcomes, as well as the processes via which yoga may act, should be examined in a larger randomized controlled experiment.
Limitations
We conducted yoga sessions only once a week for an hour in person however they were asked to do the practice every day. They were encouraged to engage in home practice by providing resources such as guided videos, written instructions at least 3 times /week. This might have helped participants continue their practice outside of scheduled sessions and foster habit formation. Still, this could be a limitation of the study. In our main trial along with integration of home practice we will increase the session duration.
Conclusion
In conclusion, this study demonstrates that restorative yoga is both a feasible and acceptable intervention for adults in HK with at least two metabolic syndrome criteria. The positive feedback from participants regarding the adaptability and perceived health benefits of the yoga sessions highlights its potential as a beneficial practice in this population. Notably, the restorative yoga intervention led to significant improvements in various metabolic parameters, including reductions in systolic BP, WC, TGs, and FGL, as well as enhancements in mental health. In contrast, the control group showed no significant changes in these metrics. Given these promising findings, further investigation through a larger randomized controlled trial is warranted to fully assess the efficacy of restorative yoga in improving metabolic health among individuals with MetS.
Acknowledgements
We gratefully acknowledge The Yoga Institute (India) and the Life Management Yoga Center (Hong Kong) for their invaluable contributions to the research. We also extend our gratitude to PHC Medical Diagnostic Centre Limited for conducting the diagnostic tests. Lastly, we sincerely thank all the participants for their involvement in the study.
Funding information
This project was funded by Start -up grants by Research Committee of Hong Kong Baptist University “RC STARTUP/22-23/22”.
Competing Interests
Julien S. Baker is an Editorial Board Member for [Physical Activity and health] and was not involved in the editorial review or the decision to publish this article.
Author Contributions
RS designed the study and written the paper, KPS was involved in data collection and writting paper, AS and JSB provided comments and suggestions throughout the study.