HyperthermiaNCT05838612
Hot Water Immersion as a Heat Acclimation Strategy in Older Adults
A study testing Heat acclimation in people with Hyperthermia and Heat Exposure, run by University of Ottawa at 1 site in Canada.
Trial summary
Aging is associated with impairments in heat loss responses of skin blood flow and sweating leading to reductions in whole-body heat loss. Consequently, older adults store more body heat and experience greater elevations in core temperature during heat exposure at rest and during exercise. Read more about this study
- Who is it for?
- Ages 60 to 80 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Hyperthermia, Heat Exposure, Heat Stress
- What is being tested?
- Heat acclimation
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 12 participants
- Where
- 1 siteCanada
- Study dates
- 29 Apr 2022to 16 Feb 2023
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 60 to 80 years
- Men only
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Elderly (60-80 years), non-smoking adults.
- Not engaged in regular physical activity (>2 sessions/week for ≥20 minutes per session).
- Willing to provide informed consent.
- Healthy, no diagnosed health conditions.
- Body Mass index (BMI) <35 kg/m2.
Who cannot join
- Heat adapted due to repeated exposure to hot environments within the last 3 weeks (use sauna, recent travel to hot climates, other).
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Short-term Warm Water Immersion as a Heat Acclimation Strategy to Enhance Heat Dissipation in Older Adults: An Exploratory Study
Aging is associated with impairments in heat loss responses of skin blood flow and sweating leading to reductions in whole-body heat loss. Consequently, older adults store more body heat and experience greater elevations in core temperature during heat exposure at rest and during exercise. This maladaptive response occurs in adults as young as 40 years of age. Recently, heat acclimation associated with repeated bouts of exercise in the heat performed over 7 successive days has been shown to enhance whole-body heat loss in older adults, leading to a reduction in body heat storage. However, performing exercise in the heat may not be well tolerated or feasible for many older adults. Passive heat acclimation, such as the use of warm-water immersion may be an effective, alternative method to enhance heat-loss capacity in older adults. Thus, the following study aims to assess the effectiveness of a 7-day warm-water immersion (~40°C) protocol in enhancing whole-body heat loss in older adults. Warm-water immersion will consist of a one-hour immersion in warm water with core temperature clamped at 38.5°C. Improvements in whole-body heat loss will be assessed during an incremental exercise protocol performed in dry heat (i.e., 40°C, ~15% relative humidity) prior to and following the 7-day passive heat acclimation protocol. The incremental exercise protocol will consist of three 30 minute exercise bouts performed at increasing fixed rates of metabolic heat production (i.e., 150, 200, and 250 W/m2), each separated by 15-minutes of recovery, with exception final recovery will be 1-hour in duration) performed in a direct calorimeter (a device that provides a precise measurement of the heat dissipated by the human body).
- Conditions
- Hyperthermia, Heat Exposure, Heat Stress, Thermoregulation, Aging
- Being tested
- Heat acclimation
- Keywords
- Thermoregulation, Warm-water immersion, Heat acclimation, Aging
- Medical subject headings
- Hyperthermia, Heat Stress Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Heat acclimationOther
Participants will complete a 7-day passive heat acclimation protocol consisting of immersion in warm water (~40°C) for 1 hour over 7 consecutive days.
| Study group | Role | What they receive |
|---|---|---|
| Heat Acclimation | Experimental | Participants will undergo an exercise heat stress test prior to and following seven consecutive days of warm-water immersion (~40°C) of 1-hour duration with core temperature clamped at 38.5°C. During the exercise-heat stress test participants will perform three, successive 30-minute bouts of semi-recumbent cycling performed at increasing fixed loads of metabolic heat production of 150, 200 and 250 W/m2 (i.e., exercise bout 1, exercise bout 2 and exercise bout 3, respectively), each separated by 15-minute of rest break with the final recovery extended to 1-hour. Receives: Other: Heat acclimation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Evaporative heat loss
Evaporative heat loss as assessed using a direct air calorimeter.
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Evaporative heat loss
Evaporative heat loss as assessed using a direct air calorimeter.
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Evaporative heat loss
Evaporative heat loss as assessed using a direct air calorimeter.
Measured: End of 30 minute bout 3 (average of last 5 minutes).
Whole-body heat loss
The sum of evaporative and dry heat exchange will be quantified during each exercise period (i.e., 150, 200 and 250 W/m2).
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Whole-body heat loss
The sum of evaporative and dry heat exchange will be quantified during each exercise period (i.e., 150, 200 and 250 W/m2).
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Whole-body heat loss
The sum of evaporative and dry heat exchange will be quantified during each exercise period (i.e., 150, 200 and 250 W/m2).
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Secondary outcomes (33)
Body heat storage
Cumulative amount of heat stored within the body calculated as the temporal summation of metabolic heat production and net heat loss.
Measured: Change from start to end of 30 minute exercise bout 1
Body heat content
Cumulative amount of heat stored within the body calculated as the temporal summation of metabolic heat production and net heat loss.
Measured: Change from start to end of 30 minute exercise bout 2
Body heat storage
Cumulative amount of heat stored within the body calculated as the temporal summation of metabolic heat production and net heat loss.
Measured: Change from start to end of 30 minute exercise bout 3
Cumulative body heat storage
Cumulative amount of heat stored within the body calculated as the temporal summation of metabolic heat production and net heat loss.
Measured: Change from baseline resting to end of exercise bout 3
Dry heat loss
Dry heat loss as assessed using a direct air calorimeter.
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Dry heat loss
Dry heat loss as assessed using a direct air calorimeter.
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Dry heat loss
Dry heat loss as assessed using a direct air calorimeter.
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Core temperature
Core temperature indexed by rectal/visceral temperature
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Core temperature
Core temperature indexed by rectal/visceral temperature
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Core temperature
Core temperature indexed by rectal/visceral temperature
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Change in core temperature
Core temperature indexed by rectal/visceral temperature
Measured: Change from baseline resting to end of end of 30 minute exercise bout 3.
Skin temperature
Skin temperature measured at 4-sites (chest, upper arm, thigh, calf) with mean value calculated as weighted value of 4 sites - upper arm, 30%; chest, 30%; thigh, 20%; and calf, 20%.
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Skin temperature
Skin temperature measured at 4-sites (chest, upper arm, thigh, calf) with mean value calculated as weighted value of 4 sites - upper arm, 30%; chest, 30%; thigh, 20%; and calf, 20%.
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Skin temperature
Skin temperature measured at 4-sites (chest, upper arm, thigh, calf) with mean value calculated as weighted value of 4 sites - upper arm, 30%; chest, 30%; thigh, 20%; and calf, 20%.
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Change in skin temperature
Skin temperature measured at 4-sites (chest, upper arm, thigh, calf) with mean value calculated as weighted value of 4 sites - upper arm, 30%; chest, 30%; thigh, 20%; and calf, 20%.
Measured: Change from baseline resting to end of end of 30 minute exercise bout 3.
Heart rate
Measured continuously with chest-band device
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Heart rate
Measured continuously with chest-band device
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Heart rate
Measured continuously with chest-band device
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Heart rate variability
Measures of variability computed from the time, frequency, time-frequency, scale-invariant, entropy, and other nonlinear domains
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Heart rate variability
Measures of variability computed from the time, frequency, time-frequency, scale-invariant, entropy, and other nonlinear domains
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Heart rate variability
Measures of variability computed from the time, frequency, time-frequency, scale-invariant, entropy, and other nonlinear domains
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Thermal comfort scale
Thermal comfort assessed via a questionnaire using the ASHRAE 4-point scale ("1=comfortable to 4=very uncomfortable")
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Thermal comfort scale
Thermal comfort assessed via a questionnaire using the ASHRAE 4-point scale ("1=comfortable to 4=very uncomfortable")
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Thermal comfort scale
Thermal comfort assessed via a questionnaire using the ASHRAE 4-point scale ("1=comfortable to 4=very uncomfortable")
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Thermal sensation scale
Thermal sensation will be assessed using the ASHRAE 7-point scale ("0=neutral to 7=extremely hot")
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Thermal sensation scale
Thermal sensation will be assessed using the ASHRAE 7-point scale ("0=neutral to 7=extremely hot")
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Thermal sensation scale
Thermal sensation will be assessed using the ASHRAE 7-point scale ("0=neutral to 7=extremely hot")
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Thirst sensation scale
Thirst sensation will be quantified using a 9-point scale ("1=not thirsty at all to 9=very, very thirsty")
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Thirst sensation scale
Thirst sensation will be quantified using a 9-point scale ("1=not thirsty at all to 9=very, very thirsty")
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Thirst sensation scale
Thirst sensation will be quantified using a 9-point scale ("1=not thirsty at all to 9=very, very thirsty")
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Rating of perceived exertion
Rating of perceived exertion will be quantified using a 14-point scale ("6=no exertion at all to 20=maximal exertion")
Measured: End of 30 minute exercise bout 1 (average of last 5 minutes).
Rating of perceived exertion
Rating of perceived exertion will be quantified using a 14-point scale ("6=no exertion at all to 20=maximal exertion")
Measured: End of 30 minute exercise bout 2 (average of last 5 minutes).
Rating of perceived exertion
Rating of perceived exertion will be quantified using a 14-point scale ("6=no exertion at all to 20=maximal exertion")
Measured: End of 30 minute exercise bout 3 (average of last 5 minutes).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 May 2023
- Study start29 Apr 2022
- Primary completion16 Feb 2023
- Study completion16 Feb 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (3)Papers the sponsor has linked to this study.
- Other trials for HyperthermiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Each participant will complete seven consecutive experimental sessions consisting of a passive heat acclimation involving a one hour immersion in warm water (\~40°C) with core temperature clamped at 38.5°C. Prior to and following the passive heat acclimation protocol, study participants will perform an exercise-heat stress test (Days 0 and 8) to assess whole-body heat loss in a hot-dry environment (40°C, 15% relative humidity). The exercise protocol will consist of three successive 30-minute bouts of exercise performed at increasing rates of metabolic heat production (i.e., 150, 200 and 250 W/m2), each separated by a 15-minute rest break, with the final recovery 1-hour in duration.
- Masking
- None (open label)
- Enrolment
- 12 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Ottawa
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Glen P. Kenny, University of Ottawa
- Investigators
- Glen P Kenny, PhD., Principal investigator, University of Ottawa
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05838612
- Sponsor's protocol ID
- HEPRU-2023-02
- Status last verified
- Jul 2024
- First submitted
- 19 Apr 2023
- Last updated
- 11 Jul 2024
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Deidentified participant data will be made available with approved analysis plan and signed access agreement
Publications
Carrillo AE, Luomala RA, Janetos KT, McCormick JJ, O'Connor FK, Kirby NV, Herry CL, Seely AJE, Kenny GP. Heart Rate Variability During Exercise-Heat Stress Following Seven Days of Passive Heat Acclimation in Older Males: A Secondary Analysis. Med Sci Sports Exerc. 2026 Nov 1;58(11):2549-2557. doi: 10.1249/MSS.0000000000004079. Epub 2026 Jul 7.
PubMed 42406578Janetos K, O'Connor F, Morris N, Kenny G. The influence of heat acclimation on the relation and agreement between perceptual and physiological strain in older males during exercise-heat stress. Appl Physiol Nutr Metab. 2026 Jan 1;51:1-11. doi: 10.1139/apnm-2025-0360.
PubMed 41549363Janetos KT, O'Connor FK, Meade RD, Richards BJ, Koetje NJ, Kirby NV, McCormick JJ, Flouris AD, Kenny GP. Short-Term Warm Water Immersion for Improving Whole-Body Heat Loss in Older Men. Med Sci Sports Exerc. 2025 Jun 1;57(6):1137-1147. doi: 10.1249/MSS.0000000000003649. Epub 2025 Jan 17.
PubMed 39820413
Study at a glance
From the registry record, last updated by the sponsor on 11 Jul 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Short-term Warm Water Immersion as a Heat Acclimation Strategy to Enhance Heat Dissipation in Older Adults: An Exploratory Study
- ClinicalTrials.gov ID
- NCT05838612
- Acronym / sponsor ID
- HEPRU-2023-02
- Conditions
- Hyperthermia, Heat Exposure, Heat Stress, Thermoregulation, Aging
- Keywords
- Thermoregulation, Warm-water immersion, Heat acclimation, Aging
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 12 participants (actual)
- Lead sponsor
- University of OttawaUniversity, hospital or other
- Study start
- 29 Apr 2022 (actual)
- Primary completion
- 16 Feb 2023 (actual)
- Study completion
- 16 Feb 2023 (actual)
- First posted
- 1 May 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Aging is associated with impairments in heat loss responses of skin blood flow and sweating leading to reductions in whole-body heat loss. Consequently, older adults store more body heat and experience greater elevations in core temperature during heat exposure at rest and during exercise. This maladaptive response occurs in adults as young as 40 years of age. Recently, heat acclimation associated with repeated bouts of exercise in the heat performed over 7 successive days has been shown to enhance whole-body heat loss in older adults, leading to a reduction in body heat storage. However, performing exercise in the heat may not be well tolerated or feasible for many older adults. Passive heat acclimation, such as the use of warm-water immersion may be an effective, alternative method to enhance heat-loss capacity in older adults. Thus, the following study aims to assess the effectiveness of a 7-day warm-water immersion (~40°C) protocol in enhancing whole-body heat loss in older adults. Warm-water immersion will consist of a one-hour immersion in warm water with core temperature clamped at 38.5°C. Improvements in whole-body heat loss will be assessed during an incremental exercise protocol performed in dry heat (i.e., 40°C, ~15% relative humidity) prior to and following the 7-day passive heat acclimation protocol. The incremental exercise protocol will consist of three 30 minute exercise bouts performed at increasing fixed rates of metabolic heat production (i.e., 150, 200, and 250 W/m2), each separated by 15-minutes of recovery, with exception final recovery will be 1-hour in duration) performed in a direct calorimeter (a device that provides a precise measurement of the heat dissipated by the human body).
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Each participant will complete seven consecutive experimental sessions consisting of a passive heat acclimation involving a one hour immersion in warm water (~40°C) with core temperature clamped at 38.5°C. Prior to and following the passive heat acclimation protocol, study participants will perform an exercise-heat stress test (Days 0 and 8) to assess whole-body heat loss in a hot-dry environment (40°C, 15% relative humidity). The exercise protocol will consist of three successive 30-minute bouts of exercise performed at increasing rates of metabolic heat production (i.e., 150, 200 and 250 W/m2), each separated by a 15-minute rest break, with the final recovery 1-hour in duration.
| Arm | Type | Receives |
|---|---|---|
| Heat Acclimation | Experimental | Other: Heat acclimationParticipants will undergo an exercise heat stress test prior to and following seven consecutive days of warm-water immersion (~40°C) of 1-hour duration with core temperature clamped at 38.5°C. During the exercise-heat stress test participants will perform three, successive 30-minute bouts of semi-recumbent cycling performed at increasing fixed loads of metabolic heat production of 150, 200 and 250 W/m2 (i.e., exercise bout 1, exercise bout 2 and exercise bout 3, respectively), each separated by 15-minute of rest break with the final recovery extended to 1-hour. |
Who may qualify
- Ages
- 60 to 80 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Elderly (60-80 years), non-smoking adults.
- Not engaged in regular physical activity (>2 sessions/week for ≥20 minutes per session).
- Willing to provide informed consent.
- Healthy, no diagnosed health conditions.
- Body Mass index (BMI) <35 kg/m2.
Key exclusion criteria (1 listed)
- Heat adapted due to repeated exposure to hot environments within the last 3 weeks (use sauna, recent travel to hot climates, other).
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Heat acclimationParticipants will complete a 7-day passive heat acclimation protocol consisting of immersion in warm water (~40°C) for 1 hour over 7 consecutive days. | Other | Heat Acclimation |
Primary outcome
Evaporative heat loss
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Evaporative heat loss as assessed using a direct air calorimeter.
Evaporative heat loss
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Evaporative heat loss as assessed using a direct air calorimeter.
Evaporative heat loss
Time frame: End of 30 minute bout 3 (average of last 5 minutes).
Evaporative heat loss as assessed using a direct air calorimeter.
Whole-body heat loss
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
The sum of evaporative and dry heat exchange will be quantified during each exercise period (i.e., 150, 200 and 250 W/m2).
Whole-body heat loss
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
The sum of evaporative and dry heat exchange will be quantified during each exercise period (i.e., 150, 200 and 250 W/m2).
Whole-body heat loss
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
The sum of evaporative and dry heat exchange will be quantified during each exercise period (i.e., 150, 200 and 250 W/m2).
33 secondary outcomes
Body heat storage
Time frame: Change from start to end of 30 minute exercise bout 1
Body heat content
Time frame: Change from start to end of 30 minute exercise bout 2
Body heat storage
Time frame: Change from start to end of 30 minute exercise bout 3
Cumulative body heat storage
Time frame: Change from baseline resting to end of exercise bout 3
Dry heat loss
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Dry heat loss
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Dry heat loss
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Core temperature
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Core temperature
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Core temperature
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Change in core temperature
Time frame: Change from baseline resting to end of end of 30 minute exercise bout 3.
Skin temperature
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Skin temperature
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Skin temperature
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Change in skin temperature
Time frame: Change from baseline resting to end of end of 30 minute exercise bout 3.
Heart rate
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Heart rate
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Heart rate
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Heart rate variability
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Heart rate variability
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Heart rate variability
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Thermal comfort scale
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Thermal comfort scale
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Thermal comfort scale
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Thermal sensation scale
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Thermal sensation scale
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Thermal sensation scale
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Thirst sensation scale
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Thirst sensation scale
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Thirst sensation scale
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Rating of perceived exertion
Time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).
Rating of perceived exertion
Time frame: End of 30 minute exercise bout 2 (average of last 5 minutes).
Rating of perceived exertion
Time frame: End of 30 minute exercise bout 3 (average of last 5 minutes).
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Jul 2024.
- Derived from this study: PubMed 42406578Carrillo AE, Luomala RA, Janetos KT, McCormick JJ, O'Connor FK, Kirby NV, Herry CL, Seely AJE, Kenny GP. Heart Rate Variability During Exercise-Heat Stress Following Seven Days of Passive Heat Acclimation in Older Males: A Secondary Analysis. Med Sci Sports Exerc. 2026 Nov 1;58(11):2549-2557. doi: 10.1249/MSS.0000000000004079. Epub 2026 Jul 7.
- Derived from this study: PubMed 41549363Janetos K, O'Connor F, Morris N, Kenny G. The influence of heat acclimation on the relation and agreement between perceptual and physiological strain in older males during exercise-heat stress. Appl Physiol Nutr Metab. 2026 Jan 1;51:1-11. doi: 10.1139/apnm-2025-0360.
- Derived from this study: PubMed 39820413Janetos KT, O'Connor FK, Meade RD, Richards BJ, Koetje NJ, Kirby NV, McCormick JJ, Flouris AD, Kenny GP. Short-Term Warm Water Immersion for Improving Whole-Body Heat Loss in Older Men. Med Sci Sports Exerc. 2025 Jun 1;57(6):1137-1147. doi: 10.1249/MSS.0000000000003649. Epub 2025 Jan 17.
- Individual participant dataSharing planned: Yes. Deidentified participant data will be made available with approved analysis plan and signed access agreement
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Glen P Kenny, PhD. principal investigator
University of Ottawa
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Heat acclimation in people with Hyperthermia and Heat Exposure, run by University of Ottawa at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 11 Jul 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Evaporative heat loss (time frame: End of 30 minute exercise bout 1 (average of last 5 minutes).). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05838612, which also lists 3 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Jul 2024; AzTrials last refreshed its copy on 6 Nov 2026.