Trial Review

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Trial registered on ANZCTR


Registration number
ACTRN12623000913673
Ethics application status
Approved
Date submitted
1/08/2023
Date registered
25/08/2023
Date last updated
25/08/2023
Date data sharing statement initially provided
25/08/2023
Date results information initially provided
25/08/2023
Type of registration
Retrospectively registered

Titles & IDs
Public title
Effectiveness of Combined Breathwork and Cold Immersion for Psychological and Physiological Measures of Wellbeing and Performance
Scientific title
Effectiveness of Combined Breathwork and Cold Immersion for Psychological and Physiological Measures of Wellbeing and Performance Amongst Healthy Adults
Secondary ID [1] 310230 0
'Nil Known'
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Stress 330927 0
Depression 331085 0
Anxiety 331086 0
Sleep Disorders 331087 0
Fatigue 331088 0
Condition category
Condition code
Mental Health 327701 327701 0 0
Studies of normal psychology, cognitive function and behaviour
Cardiovascular 327702 327702 0 0
Normal development and function of the cardiovascular system

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Breathing and Cold Immersion Intervention (In-Person) and Breathing and Cold Immersion Intervention (Remote):

Participants in both the in-person and remote arms will engage in the combined breathwork and cold immersion interventions as described below. Both conditions will practice daily self-administered breathwork and cold immersion (shower). In-person participants (Sydney CBD knowledge workers) will be invited to attend a research-run ice bath session held in the Sydney CBD once per week for the 4-week intervention duration. Certified Wim Hof Method (WHM) instructors will be present to guide participants through this practice. For safety, we are not requesting the remote group to engage in a once-weekly ice bath as we cannot provide the same supervision and support.

Description - Breathing Component: Participants will engage in a daily breathwork practice, involving controlled hyperventilation followed by breath retention. The guided breathwork video was created by Wim Hof and follows the WHM breathing and retention techniques.

Frequency/Duration - Breathing Component: Daily practice for 29 days of the guided breathwork exercises for 15 minutes.

Mode of Administration - Breathing Component: Remote and in-person: Participants will receive guided instruction and supervised breathing practice via a live and recorded onboarding webinar with a certified WHM instructor. Additionally, participants will have access to a pre-recorded guided breathwork video link for their daily practice.

Administering the Intervention - Breathing Component: Certified WHM instructor via live and recorded onboarding webinar as well as via the pre-recorded Wim Hof guided breathwork video link.

Adherence Monitoring - Breathing Component: Participants will receive written instructions and engage in daily Qualtrics surveys accompanying the intervention videos. The surveys will include questions about adherence to the intervention, including recording the duration of participation in the breathwork exercises. Adherence data will be captured through Qualtrics survey analytics.

Description/ Frequency/Duration - Cold Immersion Component: Participants will be asked to engage in daily cold immersion in the shower during their daily morning shower routine. They will be asked to full submerge their bodies while engaging in controlled breathing. Participants will be provided with specific cold immersion timings listed below:
Week 1: 1 minute
Week 2: 1.5 minutes
Week 3: 2 minutes
Week 4: 2.5 minutes

Mode of Administration - Cold Immersion Component: In-Person: Participants will engage in cold showers and have the option to attend a weekly community ice bath session hosted by the research team. Remote: Participants will engage in cold showers only.

Administering the Intervention - Cold Immersion Component: In-Person: Research team members and certified instructors. Remote: Participants are only asked to engage in self-administered daily cold showers. They are not asked to participate in the additional once-weekly ice bath immersion, as the remote group may not be located conveniently to the research administered ice bath, and we cannot provide certified instructors outside of the research run ice baths.

Adherence Monitoring - Cold Immersion Component: In-Person: Attendance at weekly ice bath sessions and completion of the pre-post ice bath survey, which contains an executive function task and records the duration of the ice bath. Remote: Adherence to cold showers and increasing durations will be monitored through Qualtrics surveys.

Biometric Device Description- The biometric capture device employed in this study is the WHOOP (Boston, MA), a wrist-worn wearable technology designed to continuously monitor and record key physiological parameters. The device measures sleep duration, sleep stages, heart rate, heart rate variability (HRV), motion, skin conductance, and temperature. By capturing these metrics in real-time, the device provides a comprehensive understanding of participants' physiological responses to daily activities, stressors, and sleep patterns. The device pairs with a smartphone app which, once synced via Bluetooth, uploads and stores the participant physiological data. The device is charged with a remote battery pack which connects to the wrist worn device without the need to remove the device during charging. This device has been used in numerous field research studies and has been validated for collecting both sleep and cardiac metrics.

Biometric Device frequency- Participants wear the device 24/7 during both the 2-week baseline and 4-week intervention phases. Participants are also invited to continue to wear the device after the completion of the intervention phase so we can measure their physiology in conjunction with their 1, 2, 3 month follow up surveys.

Biometric Device Adherence Monitoring: The research team will monitor adherence to the biometric capture device through the device’s team portal. The portal provides information about which participants are offline (no data collection). This will enable prompt assistance if any participant experiences technical difficulties with their device.

Data Collection
Intervention Phase: Daily for 29 days (daily survey, intervention activities, cognitive tasks sent via Qualtrics link in-app or via email).
Intervention code [1] 326619 0
Treatment: Other
Comparator / control treatment
Control Condition (Mindful Awareness Meditation):

Description: Participants will engage in a daily mindful awareness meditation practice, focusing on present-moment awareness and relaxation. The pre-recorded mindful awareness meditation video was created by the research team and certified mindful meditation instructor to match the WHM breathwork guided video as much as possible. The active control condition will follow the exact same procedures as the two experimental conditions, with the exception of completing daily meditation practice in place of the breathwork and cold immersion. Participants will wear the exact same biometric capture device, with data uploaded to the device's smartphone app, as described above.

Engagement: Participants will access the guided mindful awareness meditation video through the daily surveys sent to them via the app or email.

Frequency/Duration: Daily mindful awareness meditation practice for 15 minutes over the 29 day intervention study.

Mode of Administration: Qualtrics survey links provided in email or via biometric device app access. Please refer to the information above regarding the biometric capture device and associated smartphone app, which is the same across all conditions.

Administering the Intervention: A certified mindful meditation instructor pre-recorded the mindful awareness meditation video following researcher’s specifications to match the WHM breathwork guided video.


Adherence Monitoring: Participants will engage in daily Qualtrics surveys accompanying the guided mindful awareness meditation practice sessions. The surveys will inquire about adherence to the intervention, including meditation duration. Adherence data will be captured through Qualtrics survey analytics.
Control group
Active

Outcomes
Primary outcome [1] 335504 0
State stress: measured using the single-item daily stress question and the Depression, Stress, Anxiety (DASS-21) scale.
Timepoint [1] 335504 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- Onboarding survey (Pre-intervention measures): staggered onboarding between study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)

2. Single-item momentary stress
- Measured pre and post-daily intervention (breath work and cold immersion/ or meditation).
Primary outcome [2] 335505 0
Anxiety: measured using the single-item daily anxiety question and the Depression, Stress, Anxiety (DASS-21) scale.
Timepoint [2] 335505 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- Onboarding survey (Pre-intervention measures): staggered onboarding between study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)


2. Single-item momentary anxiety
- Measured pre and post-daily intervention (breath work and cold immersion/ or meditation).
Primary outcome [3] 335721 0
Depression: measured using the Depression, Stress, Anxiety (DASS-21) scale.
Timepoint [3] 335721 0
1. Collected pre and post-study intervention in the onboarding and exit survey (only).

- Onboarding survey (Pre-intervention measures): staggered onboarding between study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [1] 424927 0
Sleep disorder as measured by the Mini Sleep Questionnaire (MSQ)
Timepoint [1] 424927 0
1. MSQ: Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [2] 425313 0
Executive Function Performance (working memory; N-back Task and inhibitory control; Stroop Task).
Timepoint [2] 425313 0
1. Baseline:
• completed daily for 7 days (daily survey and cognitive tasks only).
• Measured from Day -7 to Day 0 pre-intervention commencement.

2. Intervention Phase:
• Daily surveys for 29 days (daily survey, intervention activities, cognitive tasks).
• Measured from Day 1 to Day 29.
Secondary outcome [3] 425314 0
Cardiovascular Recovery: heart rate variability (RMSSD) as measured by the wrist-worn physiological biometric capture device
Timepoint [3] 425314 0
Biometric capture: Measured 24/7 from Day -14 (2-week baseline) to Day 30 post-intervention commencement for all participants. Continuous monitoring will also occur daily from Day 30 to Day 120 post-intervention commencement for participants who are willing to provide these data.
Secondary outcome [4] 425315 0
Psychological well-being as measured by the (PWB-18)
Timepoint [4] 425315 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [5] 425316 0
Self-reported fatigue as measured by a modified version of the Multidimensional Daily Fatigue - Fibromyalgia-17.
Timepoint [5] 425316 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [6] 425317 0
Interoceptive sensitivity as measured by the Multidimensional Assessment of Interoceptive Awareness - MAIA-2
Timepoint [6] 425317 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [7] 425318 0
Self-reported Frustration Discomfort (Frustration Discomfort Scale - FDS)
Timepoint [7] 425318 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [8] 425319 0
Stress Mindset (Stress Mindset Measure - General - SMM-G)
Timepoint [8] 425319 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [9] 425320 0
Work Team Psychological safety from a modified Psychological Safety Scale.
Timepoint [9] 425320 0
1. Collected pre and post-study intervention in the onboarding and exit survey.

- study days -14 to -7 (with the start of the study intervention being day 1 of the study).
- Exit Survey (Post-intervention measures): Day 30 (baseline and endpoint)
Secondary outcome [10] 425321 0
State Mental Clarity from a 1-item scale.
Timepoint [10] 425321 0
Single-item momentary Mental Clarity
- Measured pre and post-daily intervention (breath work and cold immersion/ or meditation).
• Measured daily from Day 1 to Day 29 post-intervention commencement.
Secondary outcome [11] 425322 0
State Resilience from a 1-item scale.
Timepoint [11] 425322 0
Single-item momentary State Resilience
- Measured pre and post-daily intervention (breath work and cold immersion/ or meditation).
• Measured daily from Day 1 to Day 29 post-intervention commencement.
Secondary outcome [12] 425703 0
Sleep duration (mins) as measured by the wrist-worn physiological biometric capture device.
Timepoint [12] 425703 0
Biometric capture: •Measured 24/7 from Day -14 (2-week baseline) to Day 30 post-intervention commencement for all participants. Continuous monitoring will also occur daily from Day 30 to Day 120 post-intervention commencement for participants who are willing to provide these data.
Secondary outcome [13] 425704 0
Slow wave sleep (mins) as measured by the wrist-worn physiological biometric capture device
Timepoint [13] 425704 0
Biometric capture: •Measured 24/7 from Day -14 (2-week baseline) to Day 30 post-intervention commencement for all participants. Continuous monitoring will also occur daily from Day 30 to Day 120 post-intervention commencement for participants who are willing to provide these data.
Secondary outcome [14] 425705 0
Rapid Eye Movement Sleep as measured by the wrist-worn physiological biometric capture device
Timepoint [14] 425705 0
Biometric capture: •Measured 24/7 from Day -14 (2-week baseline) to Day 30 post-intervention commencement for all participants. Continuous monitoring will also occur daily from Day 30 to Day 120 post-intervention commencement for participants who are willing to provide these data.
Secondary outcome [15] 425706 0
Cardiovascular Recovery: nightly average heart rate (BPM) as measured by the wrist-worn physiological biometric capture device
Timepoint [15] 425706 0
Biometric capture: •Measured 24/7 from Day -14 (2-week baseline) to Day 30 post-intervention commencement for all participants. Continuous monitoring will also occur daily from Day 30 to Day 120 post-intervention commencement for participants who are willing to provide these data.

Eligibility
Key inclusion criteria
- Individuals living in Australia or New Zealand
- Individuals with or without the study's biometric capture device (devices will be supplied to those without)
- Individuals who are 18 years or older and speak English
- Individuals who are NOT currently engaging in or with extensive previous experience of any breathwork, meditation, or cold immersion practices.
Minimum age
18 Years
Maximum age
No limit
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
Participants who self-report moderate to severe psychiatric or medical conditions that may potentially worsen during study involvement will not be eligible to participate. These conditions include heart disease, respiratory difficulties, hypertension, diabetes, glaucoma, history of seizures, pregnancy, psychosis, suicidality, bipolar disorder, and substance use disorders. Additionally, we will not include participants with severe vision or hearing impairments, as these could hinder their ability to fully engage in study activities such as reading study materials and watching or listening to instructional videos for the interventions.

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)
'Allocation is not concealed'
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Stratified randomisation based on the average temperature of participants' location in August (active participation month of the study).
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Parallel
Other design features
In this semi-randomized control trial, we have three study conditions: (1) Breathwork and Cold Immersion (in-person), (2) Breathwork and Cold Immersion (remote), or (3) Active control Mindful Awareness Meditation (remote). We will randomly assign participants to the two online conditions: Breathwork and Cold Immersion (remote), or Mindful Awareness Meditation (remote). We will recruit participants directly into the third condition: Breathwork and Cold Immersion (in-person). For logistical reasons, we require these participants to work in Sydney CBD to be able to attend in-person weekly ice-bath sessions (on a weekday, at lunchtime).
Phase
Not Applicable
Type of endpoint/s
Efficacy
Statistical methods / analysis
As power calculations in Intensive Longitudinal Methods (ILM) depend on at least two sample sizes (participants and number of measurements or time-occasions), ILM power models suggest that a sample size of 125 participants with 16 total measurement observations is adequate to achieve 80% power (Bolger and Laurenceau., 2013). By these recommendations, the current study’s sample size will be sufficient to achieve 80% power with the current sampling size aims and measurement count (estimated 65 measurements per participant).

Recruitment sample size aims
Experimental Condition 1: Breathwork and cold immersion (in-person n= 145)
Experimental Condition 2: Breathwork and cold immersion (remote n= 300)
Active Control Condition 3: Mindful awareness meditation (remote n= 300)

Current Analysis Plan
Due to the nested nature of our data (measures nested within participants and participants nested within conditions), we will use multilevel models to test hypothesis 2, 3, and 4 . For our daily momentary sampling data, the goal of the statistical analyses is to create a series of multilevel regression models to assess the relevant hypotheses presented above. We will use the lme4 package in R to conduct these analyses, we will calculate p-values with lmerTest, which will be used to make inferences about the data, and use bobyqa optimizer with 250k iterations. Including the bobyqa optimizer will aid convergence without changing the fixed effects in the model. We will begin with models including random intercepts for participant and random slopes of all time-varying continuous variables included in the model (unless otherwise stated below). If the model does not converge, we will remove the random slope(s) with the least variance until we reach convergence. Time-varying continuous predictors will be person-mean centred so that they represent within-person effects (change across time regardless of individual global scores) and time-invariant predictors will be grand-mean centred. Sensitivity/ exploratory analyses will include control variables and the outcome variable listed above.

Hypothesis 2:
1. Testing Pre- and Post-Intervention Scores Within Each Condition:
For each of the 3 intervention conditions, we will perform a pairwise t-test (or Wilcoxon signed-rank test for non-parametric data) to compare the average daily post-scores to the average daily pre-scores within each group to determine if there is a significant change in daily momentary scores post-intervention within each condition.
2. Mixed-Effects Model to Compare Changes Between Conditions:
To investigate if there is a significant difference in the change in daily pre/post intervention momentary measures between different intervention conditions, we will run a multilevel mixed-effects model. In this analysis, we will account for the number of completed intervention days per participant. We will calculate daily change scores by subtracting pre-daily intervention scores from post-daily intervention scores for each participant.

Hypothesis 3 and 4: three-level multilevel model analyses
To investigate hypothesis 3 (daily cognitive performance) and hypothesis 4 (daily physiological recovery) we will employ a three-level multilevel model (MLM), with daily measures (cognitive performance/ physiological recovery metrics) nested within participants, participants nested within conditions.

Recruitment
Recruitment status
Active, not recruiting
Date of first participant enrolment
Anticipated
Actual
22/06/2023
Date of last participant enrolment
Anticipated
Actual
1/08/2023
Date of last data collection
Anticipated
30/11/2023
Actual
Sample size
Target
745
Accrual to date
Final
556
Recruitment in Australia
Recruitment state(s)
ACT,NSW,QLD,SA,TAS,WA,VIC
Recruitment outside Australia
Country [1] 25673 0
New Zealand
State/province [1] 25673 0

Funding & Sponsors
Funding source category [1] 314389 0
Commercial sector/Industry
Name [1] 314389 0
Wilson Asset Management
Country [1] 314389 0
Australia
Primary sponsor type
University
Name
The University of Queensland
Address
280-284 Sir Fred Schonell Dr, St Lucia QLD 4067, Australia
Country
Australia
Secondary sponsor category [1] 316398 0
Other
Name [1] 316398 0
BioPsychAnalytics
Address [1] 316398 0
25 Vivian Street Tennyson QLD 4105
Country [1] 316398 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 313483 0
University of Queensland Human Research Ethics Committee A
Ethics committee address [1] 313483 0
The University of Queensland
312 McElwain Building Sir Fred Schonell Dr, St Lucia QLD 4067
Ethics committee country [1] 313483 0
Australia
Date submitted for ethics approval [1] 313483 0
09/06/2023
Approval date [1] 313483 0
20/06/2023
Ethics approval number [1] 313483 0
2023/HE000736

Summary
Brief summary
This semi-randomised control trial aims to investigate the effectiveness of the Wim Hof breathing method and cold immersion (compared to an active control condition) for promoting stress reduction, resilience, recovery, cognitive functioning, and overall mental health and well-being. The present research combines 24/7 physiological biometric capture, daily experience sampling, and survey measurements across the study period (including a 2-week baseline, 4-week intervention period, and 3-month follow-up period). By measuring physiological, cognitive, and subjective measures, and continuing to monitor participants post-intervention, we aim to contribute to the growing body of knowledge concerning the potential benefits of the Wim Hof Method. In particular, assessing whether it is a suitable and effective strategy for stress reduction, performance optimisation, and mental health enhancement.

Hypothesis 1: Onboarding/Exit Measures (Pre/post the 4-week study intervention)
We hypothesize that there will be an improvement in post-intervention scores compared to pre-intervention baseline scores across all three conditions. We expect Condition 1 to show greater improvements than Conditions 2 and 3, and Condition 2 to show greater improvement than Condition 3 in the post-intervention outcome measures.

Hypothesis 2: Daily Momentary Measures (Pre/post daily intervention)
We hypothesise that there will be an improvement in post-daily intervention scores compared to pre-intervention daily scores across all three conditions. We anticipate the improvement to be greater in Conditions 1 and 2, relative to Condition 3, for the momentary outcome measures.

Hypothesis 3: Daily Measures (Post daily intervention)
We predict better Stroop task scores (lower Stroop interference effect, faster reaction times, and greater accuracy) and N-back task scores (greater accuracy and faster reaction times) in the daily post-intervention cognitive tasks in Conditions 1 and 2, relative to Condition 3.

Hypothesis 4: Daily Physiological Recovery (Nightly post-intervention)
We predict improved average nightly physiological recovery (greater sleep: quantity (duration) and quality (slow wave sleep and rapid eye movement sleep), and cardiovascular functioning: higher heart rate variability, and lower resting heart rate and respiratory rate) in Condition 1 compared to Condition 2 and 3, and greater recovery in Condition 2 than condition 3.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 128326 0
Dr Jemma King
Address 128326 0
University of Queensland Sir Fred Schonell Dr, St Lucia QLD 4067
Country 128326 0
Australia
Phone 128326 0
+61 414597555
Fax 128326 0
Email 128326 0
jemma@bio-pa.com
Contact person for public queries
Name 128327 0
Dr Jemma King
Address 128327 0
University of Queensland Sir Fred Schonell Dr, St Lucia QLD 4067
Country 128327 0
Australia
Phone 128327 0
+61 414597555
Fax 128327 0
Email 128327 0
jemma@bio-pa.com
Contact person for scientific queries
Name 128328 0
Ms Nadia Fox
Address 128328 0
University of Queensland Sir Fred Schonell Dr, St Lucia QLD 4067
Country 128328 0
Australia
Phone 128328 0
+61478800085
Fax 128328 0
Email 128328 0
nadia.fox@uq.net.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.