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Trial registered on ANZCTR


Registration number
ACTRN12616000867493
Ethics application status
Approved
Date submitted
29/06/2016
Date registered
4/07/2016
Date last updated
4/07/2016
Type of registration
Retrospectively registered

Titles & IDs
Public title
Effects of 16-week Bikram yoga program on heart rate variability and cardiovascular disease risk factors in sedentary, stressed adults.
Scientific title
A randomised controlled trial examining the effects of a 16-week Bikram yoga program on high frequency heart rate variability (HRV), additional HRV outcomes, and cardiovascular disease risk factors in sedentary, stressed adults compared to a no-treatment control group.
Secondary ID [1] 289548 0
Nil known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Stress 299268 0
Cardiovascular disease 299347 0
Obesity 299348 0
Condition category
Condition code
Alternative and Complementary Medicine 299271 299271 0 0
Other alternative and complementary medicine
Mental Health 299272 299272 0 0
Other mental health disorders
Cardiovascular 299273 299273 0 0
Other cardiovascular diseases

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Men and women aged between 18-64 were randomised into either the treatment group (yoga classes) or no-treatment control group. All participants were assessed at baseline (week 0) and completion (week 17) of the trial and were monitored weekly throughout the trial to record changes to lifestyle and/or health status. Baseline and completion assessments each included a 1.5 hour visit with the primary researcher to collect anthropometric, haemodynamic, fitness and psychological data, and a visit to a Capital Pathology collection centre in Canberra for a blood test. Participants were also required to complete a 7-day food diary prior to and after the trial to control for major changes to diet over the course of the trial.
Participants randomised to the treatment group were required to attend between 3 and 5 90-minute Bikram yoga classes per week for 16 weeks (participant could choose exact number of classes between 3-5 each week). Bikram yoga is a form of hatha yoga that takes place in a heated environment (40 degrees celsius, 38-40% humidity). The sequence of postures is the same every class and the class is led with an instructional dialogue. The classes were held at two Bikram yoga centres in the Australian Capital Territory. Participants attended classes with the current members of both studios and classes were taught by certified Bikram yoga instructors. All sessions were supervised. Participants were required to sign in for every class (attendance data was collected electronically).
Intervention code [1] 295143 0
Lifestyle
Comparator / control treatment
Participants randomised to the control group continued with their current lifestyle for the duration of the trial. Upon completion they were given a 10-class pass to use at either of the two centres partaking in the trial.
Control group
Active

Outcomes
Primary outcome [1] 298766 0
High frequency heart rate variability (HF HRV).HF HRV was assessed using ECG data produced by the SphygmoCor equipment and software (SphygmoCor, AtCor Medical Pty, Sydney, Australia).
Timepoint [1] 298766 0
Baseline (week 0) and after the 16-week intervention at completion (week 17)
Secondary outcome [1] 325142 0
Additional frequency and time domains of HRV - low frequency HRV, LF:HF, total power, and RMSSD, SDNN, triangular index, pNN50. These measures were also assessed using the SphygmoCor system (SphygmoCor, Atcor Medical Pty, Sydney, Australia).
Timepoint [1] 325142 0
Baseline (week 0) and after the 16-week intervention at completion (week 17)
Secondary outcome [2] 325256 0
Total cholesterol
Fasting bloods were collected by Capital Pathology (accredited by NATA, facility number 3448)
Timepoint [2] 325256 0
At baseline (week 0) and after the 16-week intervention (week 17)
Secondary outcome [3] 325258 0
HDL
Fasting bloods were collected by Capital Pathology (accredited by NATA, facility number 3448)
Timepoint [3] 325258 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)
Secondary outcome [4] 325259 0
LDL
Fasting bloods were collected by Capital Pathology (accredited by NATA, facility number 3448)
Timepoint [4] 325259 0
Baseline (week 0) and at completion after 16-week intervention (week 17)
Secondary outcome [5] 325260 0
Fasting blood glucose
Fasting bloods were collected by Capital Pathology (accredited by NATA, facility number 3448)
Timepoint [5] 325260 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)
Secondary outcome [6] 325261 0
C-reactive protein
Fasting bloods were collected by Capital Pathology (accredited by NATA, facility number 3448)
Timepoint [6] 325261 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)
Secondary outcome [7] 325262 0
Body fat percentage
Body composition data was collected at University of Canberra using DEXA technology (GE Lunar Prodigy)
Timepoint [7] 325262 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)
Secondary outcome [8] 325263 0
Waist circumference
Measured using soft tape measure according to American College of Sports Medicine guidelines.
Timepoint [8] 325263 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)
Secondary outcome [9] 325264 0
Cardiorespiratory fitness
VO2 was estimated from a sub maximal, modified Bruce treadmill protocol
Timepoint [9] 325264 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)
Secondary outcome [10] 325265 0
Perceived stress (measured by 10-item Perceived Stress Scale)

Timepoint [10] 325265 0
Baseline (week 0), midpoint (week 8) and at completion after the 16-week intervention (week 17)
Secondary outcome [11] 325266 0
Quality of life (measured by SF-36 questionnaire )
Timepoint [11] 325266 0
Baseline (week 0), midpoint (week 8) and at completion after the 16-week intervention (week 17)
Secondary outcome [12] 325267 0
Self-efficacy (General Self Efficacy and Exercise Self Efficacy questionnaires)
Timepoint [12] 325267 0
Baseline (week 0), midpoint (week 8) and at completion after the 16-week intervention (week 17)
Secondary outcome [13] 325268 0
Augmentation Index
Measured using SphygmoCor system with tonometer (SphygmoCor, Atcor Medical, Sydney, Australia)
Timepoint [13] 325268 0
Baseline (week 0) and at completion after the 16-week intervention (week 17)

Eligibility
Key inclusion criteria
Adult (>18 years); sedentary (<150min of continuous moderate-intensity exercise per week for at least 6 months); a score >7 on the stress component of the 21-item depression-anxiety-stress scale (DASS-21); waist circumference as a risk factor greater than 80cm (women) and greater than 94cm (men), able to attend 3-5 Bikram yoga classes per week for 16 weeks; no acute or chronic medical conditions which would make Bikram yoga potentially hazardous or primary outcomes impossible to assess (according to ACSM risk stratification guidelines); ability to communicate in English; willingness and cognitive ability to provide written informed consent to participate in the trial; access to internet and email.
Minimum age
18 Years
Maximum age
No limit
Gender
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Currently active; participation in Bikram yoga in the last 6 months or at any point consistently for >2 years; diagnosed chronic diseases (cardiovascular disease, blood pressure >140/90, uncontrolled diabetes or hyperlipidaemia); pregnancy; pacemaker.

Study design
Purpose of the study
Treatment
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
An investigator not involved in testing or the delivery of the intervention prepared the randomisation assignments, sealed them in opaque envelopes, and labeled them according to stratification in the order that they were to be handed out. Group assignments were delivered to participants in person in the sealed, opaque envelopes upon the completion of baseline testing. Participant opened envelope and showed primary researcher the assignment and then their group assignment was recorded.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants were randomised via a computer-generated list (www.randomization.com) stratified by sex and age (<50yr; >50yr).
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
Phase
Not Applicable
Type of endpoint(s)
Efficacy
Statistical methods / analysis
Data derived from an HRV and aerobic exercise intervention in an apparently healthy adult cohort was used to compute statistical power a priori using the non-commercial statistical power analysis program G*Power. With an alpha level of 0.05, approximately 56 participants (28 per group) were required to provide 80% power to detect a statistically significant difference between groups. Recruitment was inflated to 68 participants to enable a 20% participant attrition rate.
All analyses were carried out using SPSS (IBM, Registered Trademark, Version 23). Primary analysis was via intention-to-treat with all participants included regardless of dropout or level of adherence. Missing data at week 17 was imputed using the last observation carry forward method. Outcomes data is presented as the mean +/- standard deviation with effect size and 95% confidence intervals. Baseline characteristics were compared using t-tests and non-normally distributed data was transformed (Ln) prior to analysis with parametric methods. Chi square tests were used to assess normality of non-continuous, descriptive variables at baseline. Changes over time in all continuous outcome variables and covariates were determined by analysis of covariance (ANCOVA). Categorical variables will be analysed using logistic regression models. Linear and multivariate regression analyses will be used to analyse associations between variables of interest. A p value of <0.05 is considered indicative of statistical significance.

Recruitment
Recruitment status
Completed
Date of first participant enrolment
Anticipated
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
ACT

Funding & Sponsors
Funding source category [1] 293949 0
University
Name [1] 293949 0
Western Sydney University
Address [1] 293949 0
Western Sydney University
Locked Bag 1797
Penrith NSW 2751
Country [1] 293949 0
Australia
Funding source category [2] 293950 0
Commercial sector/Industry
Name [2] 293950 0
Bikram Yoga Canberra
Address [2] 293950 0
6/56 Hoskins Street
Mitchell ACT
2911
Country [2] 293950 0
Australia
Funding source category [3] 293951 0
Commercial sector/Industry
Name [3] 293951 0
Bikram Yoga Kingston
Address [3] 293951 0
27-29 Eyre St
Kingston ACT
2604
Country [3] 293951 0
Australia
Funding source category [4] 293952 0
Commercial sector/Industry
Name [4] 293952 0
Capital Pathology
Address [4] 293952 0
PO Box 20
Woden ACT
2605
Country [4] 293952 0
Australia
Primary sponsor type
Individual
Name
Miss Zoe Hewett
Address
School of Science and Health
University of Western Sydney
Locked Bag 1797
Penrith South NSW 2751
Country
Australia
Secondary sponsor category [1] 292771 0
University
Name [1] 292771 0
Western Sydney University
Address [1] 292771 0
University of Western Sydney
Locked Bag 1797
Penrith South NSW 2751
Country [1] 292771 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 295373 0
Western Sydney University Human Research Ethics Committee
Ethics committee address [1] 295373 0
Locked bag 1797
Penrith NSW
2751
Ethics committee country [1] 295373 0
Australia
Date submitted for ethics approval [1] 295373 0
24/02/2014
Approval date [1] 295373 0
16/05/2014
Ethics approval number [1] 295373 0
H10549
Ethics committee name [2] 295374 0
University of Canberra Human Research Ethics Committee
Ethics committee address [2] 295374 0
Research Services Office
Locked Bag 1
University of Canberra
ACT 2601
Ethics committee country [2] 295374 0
Australia
Date submitted for ethics approval [2] 295374 0
13/06/2014
Approval date [2] 295374 0
20/06/2014
Ethics approval number [2] 295374 0
H10549 14/009174

Summary
Brief summary
The purpose of this parallel-arm RCT was to investigate the effects of a 16-week Bikram yoga program on the high frequency (HF) component of HRV and secondary related outcomes (i.e., additional HRV measures, anthopometric, haemodynamic, haematological, and psychological measures) in a population of sedentary, stressed adults. We hypothesised that engaging in 16 weeks of Bikram yoga, 3-5 times per week, would improve HF HRV, secondary measures of HRV, and associated CVD risk factors when compared with a no-treatment control group.
Participants were recruited via word of mouth, flyers, and social media and were screened via email/phone/in person for eligibility to participate. Sixty-three participants were enrolled in the trial with 34 in the control group and 29 in the experimental group. The experimental group was required to attend 3-5 Bikram yoga classes each week for 16 weeks, whereas the control group was asked to continue with their current lifestyle. Both groups were asked not to change their diet and exercise habits (aside from the intervention) throughout the trial period. Baseline measures and completion measures were assessed at week 0 and week 17 respectively. Body composition, waist circumference, HRV, blood pressure and psychological questionnaires were done at a 1.5 hour appointment at University of Canberra with the primary investigator. Blood tests were done at various Capital Pathology collection centres in Canberra. Both testing sessions took place in a fasted state in the morning and were done on separate days to one another.
All participants were followed up with weekly via email/phone/in person to record changes in health status or lifestyle throughout the trial. Upon completion of the trial, participants had the option to fill out an exit survey to gain a better understanding of their experience as a participant.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 66946 0
Miss Zoe Hewett
Address 66946 0
School of Science and Health
University of Western Sydney
Locked Bag 1797
Penrith South 2751
NSW
Country 66946 0
Australia
Phone 66946 0
+61421786333
Fax 66946 0
Email 66946 0
13521266@student.westernsydney.edu.au
Contact person for public queries
Name 66947 0
Miss Zoe Hewett
Address 66947 0
School of Science and Health
University of Western Sydney
Locked Bag 1797
Penrith South 2751
NSW
Country 66947 0
Australia
Phone 66947 0
+61421786333
Fax 66947 0
Email 66947 0
13521266@student.westernsydney.edu.au
Contact person for scientific queries
Name 66948 0
Miss Zoe Hewett
Address 66948 0
School of Science and Health
University of Western Sydney
Locked Bag 1797
Penrith South 2751
NSW
Country 66948 0
Australia
Phone 66948 0
+61421786333
Fax 66948 0
Email 66948 0
13521266@student.westernsydney.edu.au

No information has been provided regarding IPD availability
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary