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Trial registered on ANZCTR


Registration number
ACTRN12623001302640
Ethics application status
Approved
Date submitted
22/11/2023
Date registered
14/12/2023
Date last updated
14/12/2023
Date data sharing statement initially provided
14/12/2023
Type of registration
Prospectively registered

Titles & IDs
Public title
Blood pressure response to differing modes of hot-water immersion
Scientific title
Blood pressure response to differing modes of hot-water immersion in healthy adults
Secondary ID [1] 311009 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Hypertension 332119 0
Condition category
Condition code
Cardiovascular 328848 328848 0 0
Hypertension

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
All participants will complete 3 water immersion sessions and a control session (in a randomised order): 1) 30-min whole-body hot-water immersion (40°C; chest depth), 2) 30-min waist deep hot-water immersion (40°C), 3) 30-min lower-limb hot-water immersion (~40°C; below knee depth).

There will be a 4-day washout between exposures.

1. 30-min whole-body hot-water immersion (40°C)
Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the primary investigator (PI) or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately nipple level.
Duration: 30 min.

2. 30-min waist-deep hot-water immersion (40°C)
Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately waist deep level.
Duration: 30 min.

3. 30-min lower-limb hot-water immersion (40°C)
Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min hot water immersion session in 40 °C water. Participants will be seated upright with water approximately at below knee level.
Duration: 30 min.
Intervention code [1] 327448 0
Treatment: Other
Comparator / control treatment
30-min control (no exposure).

Location: School of Physical Education, Sport and Exercise Sciences Aquatic Facility (University of Otago, Dunedin).
Supervision: This session will be supervised by an American College of Sports Medicine (ACSM) registered clinical exercise physiologist (CEP), and the PI or a research assistant; all supervising researchers are first aid trained. Attendance and session particulars (e.g., physiological indices etc.) will be recorded at each session by the supervising researcher.
Exposure: Participants will complete a single 30-min resting session (i.e., no exposure/water immersion). Participants will be seated upright in a chair.
Duration: 30 min.
Control group
Active

Outcomes
Primary outcome [1] 336644 0
Blood pressure
Timepoint [1] 336644 0
Pre-exposure, during exposure (every 10 mins), immediately post-completion of exposure and every hour across 24-h post-completion of exposure.
Secondary outcome [1] 429145 0
Physical activity
Timepoint [1] 429145 0
Across the 24-h post-completion of exposure
Secondary outcome [2] 429146 0
Heart rate
Timepoint [2] 429146 0
Pre-exposure, during exposure (e.g., every 10 mins) and immediately post-completion of exposure.
Secondary outcome [3] 429150 0
Core temperature
Timepoint [3] 429150 0
Pre-exposure, during exposure (every 10mins) and immediately post-completion of exposure

Eligibility
Key inclusion criteria
- 18-65 years old;
- Either sex or any gender;
- Any ethnicity;
- Healthy;
- Patient gives written consent;
- Patient is able to travel to the study centre to complete all sessions.
Minimum age
18 Years
Maximum age
65 Years
Sex
Both males and females
Can healthy volunteers participate?
Yes
Key exclusion criteria
- Be hypertensive when at seated rest (Stage 2: systolic or diastolic blood pressure >130 mm Hg or >90 mm Hg, respectively);
- A “yes” response to the follow-up questions on the Physical Activity Readiness Questionnaire
- Contraindication to maximal exercise testing;
- Angina;
- Recent myocardial infarction (< 3 months ago);
- Implanted cardiac device (i.e. ICD, pacemaker etc.);
- Heat intolerance;
- Pregnancy;
- History of large blood pressure decreases or fainting;
- Any other medical condition deemed a significant risk to study participation.

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 will not be concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Who is / are masked / blinded?



Intervention assignment
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
18/12/2023
Actual
Date of last participant enrolment
Anticipated
Actual
Date of last data collection
Anticipated
Actual
Sample size
Target
10
Accrual to date
Final
Recruitment outside Australia
Country [1] 25981 0
New Zealand
State/province [1] 25981 0

Funding & Sponsors
Funding source category [1] 315273 0
University
Name [1] 315273 0
University of Otago
Country [1] 315273 0
New Zealand
Primary sponsor type
University
Name
University of Otago
Address
362 Leith Street Dunedin North Dunedin 9016
Country
New Zealand
Secondary sponsor category [1] 317308 0
None
Name [1] 317308 0
Address [1] 317308 0
Country [1] 317308 0

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 314192 0
University of Otago Human Ethics Committee - Health
Ethics committee address [1] 314192 0
362 Leith Street Dunedin North Dunedin 9016
Ethics committee country [1] 314192 0
New Zealand
Date submitted for ethics approval [1] 314192 0
06/11/2023
Approval date [1] 314192 0
20/11/2023
Ethics approval number [1] 314192 0

Summary
Brief summary
This 4x4 randomised crossover study will aim to recruit 10 healthy participants. Participants will complete 4 sessions: 1) 30-min whole-body (chest deep) hot-water immersion (40°C), 2) 30-min waist deep hot-water immersion (40°C), 3) 30-min lower-limb (knee deep in 40°C), and 4) 30-min control (no exposure). The order for the four exposures will be randomised using a 4x4 Latin square design. Physiological measures will be taken during each exposure to characterise the stimulus (e.g., beat-to-beat blood pressure, heart rate, core temperature). Following each exposure participants will be fitted with an ambulatory blood pressure monitor (and accelerometer to confirm standardisation of activity levels) for the following 24 h to quantify the magnitude and duration of post-session hypotension.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 130738 0
Dr Brendon Roxburgh
Address 130738 0
Department of Surgical Sciences Level 4, Dunedin Public Hospital 201 Great King Street, Central Dunedin, Dunedin 9016
Country 130738 0
New Zealand
Phone 130738 0
+64 274632376
Fax 130738 0
Email 130738 0
brendon.roxburgh@otago.ac.nz
Contact person for public queries
Name 130739 0
Dr Brendon Roxburgh
Address 130739 0
Department of Surgical Sciences Level 4, Dunedin Public Hospital 201 Great King Street, Central Dunedin, Dunedin 9016
Country 130739 0
New Zealand
Phone 130739 0
+64 274632376
Fax 130739 0
Email 130739 0
brendon.roxburgh@otago.ac.nz
Contact person for scientific queries
Name 130740 0
Dr Brendon Roxburgh
Address 130740 0
Department of Surgical Sciences Level 4, Dunedin Public Hospital 201 Great King Street, Central Dunedin, Dunedin 9016
Country 130740 0
New Zealand
Phone 130740 0
+64 274632376
Fax 130740 0
Email 130740 0
brendon.roxburgh@otago.ac.nz

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.