Trial Review

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Trial registered on ANZCTR


Registration number
Help: Registration number
ACTRN12626001088336
Ethics application status
Help: Ethics application status
Approved
Date submitted
Help: Date submitted
21/08/2026
Date registered
Help: Date registered
3/09/2026
Date last updated
Help: Date last updated
3/09/2026
Date data sharing statement initially provided
Help: Data sharing statement date
3/09/2026
Type of registration
Help: Type of registration
Retrospectively registered

Titles & IDs
Public title
Effect of breathing protocols on heart health and mental well-being in those with elevated anxiety
Scientific title
Effect of breathing interventions on cardiac sympathetic drive and anxiety in moderate to highly anxious individuals
Additional trial identifiers [1] 317121 0
Nil
Universal Trial Number (UTN)
Trial acronym
Related trial records

Health condition
Health condition(s) studied:
Anxiety 341676 0
Condition category
Condition code
Mental Health 337766 337766 0 0
Anxiety
Cardiovascular 337767 337767 0 0
Normal development and function of the cardiovascular system

Intervention/exposure
Study type
Interventional
Description of the intervention or exposure
Measurement sessions before and after intervention:
All participants will attend a single in-person session located in the University of Otago Psychology Department lasting approximately 90 minutes. Each session will include completion of self-report questionnaires, baseline physiological measurements, a pre-intervention hypercapnia sensitivity test, one randomly assigned guided breathing intervention, and a post-intervention hypercapnia sensitivity test.
Physiological measurements include: heart rate (HR), heart rate variability (HRV), pre-ejection period (PEP), tidal volume (TV), minute ventilation (VE), and pressure of end tidal CO2 (PETCO2).
Pre and post-intervention questionnaires to assess mental well-being include the State-Trait Anxiety Questionnaire.
Measurements are taken by trained experimenters who hold a current certification in CPR.

Breathing intervention:
Participants will then be randomised into one of the four groups using a computer-generated sequence. All interventions will be standardised through pre-recorded video tutorials developed by Mr Fraser Beck. The videos will explain the theory behind each breathing exercise using both an indigenous Maori narrative and a Western-science explanation to represent the dual-narrative approach (approximately 4 minutes). The intervention will then be 10 minutes in duration followed by a further 5 minute monitoring of physiological signals.
The interventions include:
1. Resonant Breathing (RF)– slow rhythmic nasal breathing (~6 breaths per minute).
2. Physiological Sighs (PS) – two short nasal inhalations followed by an extended sigh breath exhalation.
3. Extended Exhalation with Humming (EEH) – prolonged exhalation (1:2 inhale to exhale ratio) combined with gentle humming.
4. Control – quiet rest
Physiological signals (HR, HRV, PEP, RR, VE, TV, PETCO2) will be collected throughout, and the participant will be supervised by a research staff member at all times to ensure adherence.
Intervention code [1] 333884 0
Treatment: Other
Description of the comparator or control
The control treatment for the study is described above, where individuals randomized into the control intervention will sit in quiet rest for 10 minutes instead of engaging in a breathing intervention protocol.
An additional cross-sectional control group of individuals with low anxiety will also be measured for comparison, who will also not undergo any intervention (i.e. quiet rest condition).
Control group
Active

Outcomes
Primary outcome [1] 345218 0
Participant state anxiety
Timepoint [1] 345218 0
Measures taken at baseline and immediately following intervention
Primary outcome [2] 345219 0
Participant pre-ejection period at rest
Timepoint [2] 345219 0
Measures taken at baseline and immediately following intervention
Primary outcome [3] 346629 0
Participant pre-ejection period response to hypercapnia
Timepoint [3] 346629 0
Measures taken at baseline and immediately following intervention
Secondary outcome [1] 460986 0
Participant heart rate variability at rest
Timepoint [1] 460986 0
Measures taken at baseline and immediately following intervention
Secondary outcome [2] 466789 0
Participant ventilation at rest
Timepoint [2] 466789 0
Measures taken at baseline and immediately following intervention
Secondary outcome [3] 466790 0
Participant heart rate responses to hypercapnia
Timepoint [3] 466790 0
Measures taken at baseline and immediately following intervention
Secondary outcome [4] 467027 0
Participant ventilatory responses to hypercapnia
Timepoint [4] 467027 0
Measures taken at baseline and immediately following intervention
Secondary outcome [5] 467028 0
Participant breathlessness perception responses to hypercapnia
Timepoint [5] 467028 0
Measures taken at baseline and immediately following intervention
Secondary outcome [6] 467029 0
Participant anxiety perception responses to hypercapnia
Timepoint [6] 467029 0
Measures taken at baseline and immediately following intervention

Eligibility
Key inclusion criteria
Aged between 18 and 45 years
Able to provide written informed consent
Able to adhere to all study procedures
Exhibit moderate trait anxiety (STAI-T at or above 40) OR low trait anxiety for the controls (STAI-T at or below 30)
Minimum age
18 Years
Maximum age
45 Years
Sex
Both males and females
Healthy volunteers
Yes
Key exclusion criteria
Current use of nicotine, illicit drugs, or psychoactive medication
Alcohol consumption within 24 hours of testing
History of cardiac or respiratory conditions, including asthma
History of psychosis, panic disorder, or other severe mental illness (i.e., severe mental illness is defined as clinically diagnosed conditions such as schizophrenia, bipolar disorder, or conditions requiring acute psychiatric care)
Diagnosis of any severe medical condition
Currently pregnant or breastfeeding
Elite athletes or those engaging in intense exercise within 4 hours of testing

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)
Permuted block randomisation
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
Power calculations indicate that a sample size of 64 participants would be required to detect a moderate effect size (f = 0.25) for 4 moderate anxiety groups with 90% power and a = 0.05 using a repeated-measures ANOVA design. A moderate effect size for cardiovascular (e.g. changes in HRV) and state anxiety outcome variables was chosen to ensure clinically relevant outcomes are targeted, with effect magnitudes large enough to be easily measurable feasible for development into feasible future interventions. To ensure adequate statistical power (80%) in the event of attrition (15–20%), the recruitment target has been increased to 80 moderate anxiety participants.

An additional power calculation indicates that a sample size of 34 participants would be required to detect a moderate effect size (f = 0.25) with 80% for 2 groups (i.e. 18 for each of the moderate and low anxiety controls) at 2 timepoints, with 80% power and a = 0.05. Therefore, we will measure 20 low anxiety controls to account for attrition.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
Actual
16/07/2026
Date of last participant enrolment
Anticipated
26/02/2027
Actual
Date of last data collection
Anticipated
5/03/2027
Actual
Sample size
Target
100
Accrual to date
8
Final
Recruitment outside Australia
Country [1] 28456 0
New Zealand
State/province [1] 28456 0
Otago

Funding & Sponsors
Funding source category [1] 321663 0
University
Name [1] 321663 0
Putahi Manawa Healthy Hearts Centre for Research Excellence
Country [1] 321663 0
New Zealand
Funding source category [2] 322802 0
University
Name [2] 322802 0
University of Otago
Country [2] 322802 0
New Zealand
Primary sponsor type
University
Name
University of Otago
Address
Country
New Zealand
Secondary sponsor category [1] 325731 0
None
Name [1] 325731 0
Address [1] 325731 0
Country [1] 325731 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 320196 0
University of Otago Human Ethics Committee (Health)
Ethics committee address [1] 320196 0
Ethics committee country [1] 320196 0
New Zealand
Date submitted for ethics approval [1] 320196 0
16/02/2026
Approval date [1] 320196 0
02/06/2026
Ethics approval number [1] 320196 0
H25/0578

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 149730 0
A/Prof Olivia Harrison
Address 149730 0
Department of Psychology, University of Otago, William James Building 275 Leith Walk, Dunedin North, Dunedin 9016
Country 149730 0
New Zealand
Phone 149730 0
+64 221629673
Fax 149730 0
Email 149730 0
[email protected]
Contact person for public queries
Name 149731 0
Olivia Harrison
Address 149731 0
Department of Psychology, University of Otago, William James Building 275 Leith Walk, Dunedin North, Dunedin 9016
Country 149731 0
New Zealand
Phone 149731 0
+64 221629673
Fax 149731 0
Email 149731 0
[email protected]
Contact person for scientific queries
Name 149732 0
Olivia Harrison
Address 149732 0
Department of Psychology, University of Otago, William James Building 275 Leith Walk, Dunedin North, Dunedin 9016
Country 149732 0
New Zealand
Phone 149732 0
+64 221629673
Fax 149732 0
Email 149732 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
Yes
Will there be any conditions when requesting access to individual participant data?
Persons/groups eligible to request access:
• Researchers
Conditions for requesting access:
• Yes, conditions apply:
• Requires review on a case-by-case basis by the trial custodian, sponsor or data sharing committee
• Requires a scientifically sound proposal or protocol
• Requires approval by an ethics committee
• Requires a data sharing agreement between data requester and trial custodian or sponsor
What individual participant data might be shared?
• De-identified individual participant data:
• All outcomes data
• Published results
• Primary outcome(s)
What types of analyses could be done with individual participant data?
• Any type of analysis (i.e. no restrictions on data re-use)
When can requests for individual participant data be made (start and end dates)?
From:
At the end of the study
To:
Not yet decided
Where can requests to access individual participant data be made, or data be obtained directly?
• Email of trial custodian, sponsor or committee: [email protected]

Are there extra considerations when requesting access to individual participant data?
No


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.