None listed
Conditions
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.
Interventions
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.
Sponsors
University of Otago
Study design
Allocation
Randomised controlled trial
Primary purpose
Treatment
Eligibility
Sex/Gender
All
Age
18 Years to 65 Years
Healthy volunteers
Yes
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.
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.
Outcome results
None listed