Heat StressNCT06842953
Influence of Indoor Humidity on Physiological Strain in Older Adults During a Simulated Heat Wave
A study testing Simulated indoor overheating in people with Heat Stress and Physiological Stress, run by University of Ottawa at 1 site in Canada.
Trial summary
Laboratory-based studies show that exposure to high humidity can worsen the effects of heat stress in young and older adults by impeding sweat evaporation - the main mechanism by which the human body cools itself. Read more about this study
- Who is it for?
- Ages 60 to 85 yearsHealthy volunteers can take part
- Conditions the study is for
- Heat Stress, Physiological Stress
- What is being tested?
- Simulated indoor overheating
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 10 participants
- Where
- 1 siteCanada
- Study dates
- 14 Mar 2025to 1 Sep 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
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 85 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
- with or without a) chronic hypertension (elevated resting blood pressure; as defined by Heart and Stroke Canada and Hypertension Canada), b) type 2 diabetes as defined by Diabetes Canada, with at least 5 years having elapsed since time of diagnosis
Who cannot join
- Episode(s) of severe hypoglycemia (requiring the assistance of another person) within the previous year, or inability to sense hypoglycemia (hypoglycemia unawareness).
- Serious complications related to diabetes (gastroparesis, renal disease, uncontrolled hypertension, severe autonomic neuropathy).
- Uncontrolled hypertension - BP >150 mmHg systolic or >95 mmHg diastolic in a sitting position.
- Restrictions in physical activity due to disease (e.g. intermittent claudication, renal impairment, active proliferative retinopathy, unstable cardiac or pulmonary disease, disabling stroke, severe arthritis, etc.).
- Use of or changes in medication judged by the patient or investigators to make participation in this study inadvisable.
- Cardiac abnormalities identified during screening
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
University of Ottawa
Ottawa, Ontario, K1N6N5
Glen P Kenny, PhD, 6135625800 ext. 4282, gkenny@uottawa.ca
About this study
Official title: Is an Adjustment in the Recommended Indoor Temperature Upper Limit of 26°C Required During Higher Levels of Humidity?
Laboratory-based studies show that exposure to high humidity can worsen the effects of heat stress in young and older adults by impeding sweat evaporation - the main mechanism by which the human body cools itself. At high levels of humidity, the efficiency of sweating decreases causing a greater rise core temperature and burden on the cardiovascular system. In this context, increasing temperatures and humidity with climate change thus pose a potential compound risk for human health. While humidity's role in heat-health outcomes could substantially alter projections of health burdens from climate change, the impact of humidity on physiological strain in vulnerable people in relation to the indoor environment has yet to be evaluated. In a recent study delineating the physiological effects of the proposed 26°C indoor upper limit (PMID: 38329752), relative humidity was set to 45% in all conditions based on indoor humidity standards by the American Society of Heating and Air-Conditioning Engineers. However, it is unknown whether a refinement of the recommended indoor temperature limit of 26°C is required in situations where humidity cannot be maintained at this level.
On separate occasions, the investigators will assess the change in body temperature and cardiovascular strain in older adults (65-85 years) exposed for 10 hours at the recommended indoor temperature limit of 26°C and 45% relative humidity (equivalent humidex of 29 (considered comfortable)) (experimental condition A), to 26°C with a relative humidity of 15% (equivalent humidex of 23 (considered comfortable); humidex is used to measure the perceived temperature taking into account the humidity)) (experimental condition B), to 26°C with a relative humidity of 85% (equivalent humidex of 37 (considered somewhat uncomfortable)) (experimental condition C), and to 31°C and 45% relative humidity with an equivalent humidex of 37 (considered somewhat uncomfortable) that is similar to experimental condition C. With this experimental design, investigators will assess the effects of indoor humidity in driving human heat strain and identify whether refinements in the recommended 26°C indoor temperature limit may be required. Further, by evaluating changes in relation to ambient conditions with a similar humidex, the investigators can assess how individuals perceive and respond to both heat and humidity.
- Conditions
- Heat Stress, Physiological Stress
- Being tested
- Simulated indoor overheating
- Keywords
- Heat wave, Indoor overheating, Thermoregulation, Heat strain, Elderly, Heat vulnerability, Hyperthermia, Thermal comfort
- Medical subject headings
- Heat Stress Disorders, Hyperthermia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Simulated indoor overheatingOther
Older adults are exposed to a 10-hour simulated exposure
| Study group | Role | What they receive |
|---|---|---|
| Exposure to recommended indoor temperature limit with normal indoor humidity | Experimental | Participants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29). Receives: Other: Simulated indoor overheating |
| Exposure to recommended indoor temperature limit with low indoor humidity | Experimental | Participants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 15% relative humidity (humidex equivalent of 23). Receives: Other: Simulated indoor overheating |
| Exposure to recommended indoor temperature limit with high indoor humidity | Experimental | Participants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 85% relative humidity (humidex equivalent of 37). Receives: Other: Simulated indoor overheating |
| Exposure to high indoor temperature with normal indoor humidity | Experimental | Participants exposed daylong (10 hours) to an indoor temperature maintained at 31°C and 45% relative humidity (humidex equivalent of 37). Receives: Other: Simulated indoor overheating |
What is being measured
The primary outcome is the main question the study is designed to answer.
Core temperature (Peak) during daylong exposure to indoor overheating
Peak rectal temperature (15 min average) during exposure. Rectal temperature is measured continuously throughout the 10 hours of the simulated indoor overheating.
Measured: End of 10 hour daylong exposure
Core temperature (AUC) during daylong exposure to indoor overheating
Areas under the curve (AUC) of rectal temperature during the 10 hour simulate indoor overheating.
Measured: End of 10 hour daylong exposure
Heat rate (Peak) during daylong exposure to indoor overheating
Peak heart rate (15 min average) during exposure. Heart rate is measured continuously throughout the 10 hours of the simulated indoor overheating.
Measured: End of 10 hour daylong exposure
Heart rate (AUC) during daylong exposure to indoor overheating
Areas under the curve (AUC) of heart rate during the 10 hour simulate indoor overheating.
Measured: End of 10 hour daylong exposure
Cardiac response to standing from supine (30:15 Ratio) during daylong exposure to indoor overheating
Cardiac response to standing evaluated as the ratio between the highest R-wave to R-wave interval (lowest heart rate) measured at the 30th heart beat after standing from supine (+/- 5 beats) and the lowest R-wave to R-wave interval (highest heart rate) measured at the 15th heart beat after standing (+/- 5 beats). Cardiac response to standing will be evaluated twice, during two lying-to-standing tests (separated by 10 min of supine rest).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Systolic Response to Standing From Supine during daylong exposure to indoor overheating
Systolic blood pressure response to standing evaluated as the difference in blood pressure measured between the standing and supine. Standing systolic blood pressure will be taken as the lowest value of those measured after 60 and 120 seconds of standing. Systolic response to standing will be evaluated twice, during two lying-to-standing tests (separated by 10 min of supine rest).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Heart rate variability: RMSSD during daylong exposure to indoor overheating
Root mean squared standard deviation of normal-to-normal R-wave to R-wave intervals (RMSSD) measured during 5 minutes of paced breathing (15 breaths/min) with participants in the supine position. RMSSD will be evaluated twice, during two paced breathing periods (separated by 4 min of supine rest).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Heart rate variability: SDNN during daylong exposure to indoor overheating
Standard deviation of normal-to-normal R-wave to R-wave intervals (SDNN) measured during 5 minutes of paced breathing (15 breaths/min) with participants in the supine position. SDNN will be evaluated twice, during two paced breathing periods (separated by 4 min of supine rest).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Thermal comfort scale during daylong exposure to indoor overheating
Thermal comfort assessed via a visual analog scale ranging from extremely uncomfortable to extremely comfortable (midpoint: neutral).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Thirst sensation scale during daylong exposure to indoor overheating
Thermal sensation assessed via a visual analog scale ranging from extremely hot to neutral (midpoint: hot).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Arousal scale during daylong exposure to indoor overheating
Felt arousal scale assessed via a visual analog scale ("How worked up are you?") ranging from "high arousal" to "low arousal".
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Fluid loss during daylong exposure to indoor overheating
Average hourly fluid consumption calculated by weighing participant water intake at the start and end of each hour of exposure (normalized to the exposure duration).
Measured: At end of 10 hour daylong exposure
Changes in plasma volume during daylong exposure to indoor overheating
Change in plasma volume from baseline values calculated from duplicate measurements of hemoglobin and hematocrit at the start and end of each exposure using the technique by Dill and Costill
Measured: At end of 10 hour daylong exposur
Systolic blood pressure during daylong exposure to indoor overheating
Systolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures)
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Rate pressure product during daylong exposure to indoor overheating
Rate pressure product, an index of myocardial work and strain, calculated as systolic blood pressure x heart rate.
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Secondary outcomes (8)
Impulse control (cognitive function) during daylong exposure to indoor overheating
Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of impulse control. Participants will be asked to respond to both "go" and "no-go" visual cues. In response to the "go" cue, participants will initiate a movement of the device.
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Memory recall (cognitive function) during daylong exposure to indoor overheating
Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of memory recall. Participants complete both a delayed recall test and a working memory test.
Measured: At the start (hour 0) and end of 10 hour daylong exposure
CDC 4-Stage Balance Test (Postural stability) during daylong exposure to indoor overheating
To assess postural stability, participants hold a tablet to their chest, then auditory cues guide participants through four consecutive stances, feet side by side, instep of one foot touching the big toe of the other foot, tandem stand with one foot in front of the other, heel touching toe, and stand on one foot. The balance assessment will be evaluated based on movement detected by an accelerometer integrated into the hardware of the tablet device (Sway Medical Inc).
Measured: At the start (hour 0) and end of 10 hour daylong exposure
BTrackS Balance Assessment (Postural stability) during daylong exposure to indoor overheating
To assess postural stability, participants will be asked to stand on a BTracks force plate with their feet spread out to shoulder width, hand on their hips and eyes closed. The assessment will comprise of four trials (one practice trial) lasting 20 seconds in length and 20 seconds between trials. Center of pressure (COP) vector data along vertical (y) and horizontal (x) axes will be summed for the total path excursion length (cm) during each trial.
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Profiles of Mood States (POMS) during daylong exposure to indoor overheating
Potential changes in mood (7 subscales of mood: tension, anger, depression, fatigue, confusion, vigor and esteem-related affect). The POMS-40 is a validated, self-administered questionnaire that examines seven distinct aspects of mood state across two positive subscales (Esteem-Related Affect, and Vigor) and five negative subscales (Fatigue, Tension, Confusion, Anger, and Depression), which are described across 40 distinct adjectives (reference). For each individual item, participants were asked to describe "how you feel right now" by responding using a 5-point Likert scale (0 = "Not at all", 1 = "A little", 2 = "Moderately", 3 = "Quite a lot", or 4 = "Extremely"). The values of items associated with a specific subscale (e.g., Fatigue) were summed to calculate its score.
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Environmental Symptoms Questionnaire (ESQ) during daylong exposure to indoor overheating
Self-reported environmental reactions and medical symptomatology associated with prolonged heat exposure. The ESQ-IV is a validated 68-item, self-administered questionnaire that has been used successfully in identifying symptomatology during exposure to a wide variety of environmental conditions, including heat exposure [24, 25]. Participants are asked to assess and described "how you have been feeling today" by responding to each item using a 6-point Likert scale (0 = "Not at all", 1 = "Slight", 2 = "Somewhat", 3 = "Moderate", 4 = "Quite a bit", or 5 = "Extreme"). Total Symptom Score was calculated from this data by taking the sum of the intensity ratings from all 68 individual items using reverse scores for the three positive items from the list ("I Felt Good", "I Felt Alert", and "I Felt Wide Awake").
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Sleepiness during daylong exposure to indoor overheating A
Karolinska sleepiness scale measures the subjective level of sleepiness at a particular time
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Sleepiness during daylong exposure to indoor overheating B
Stanford sleepiness scale consists of only one item, where participant must identify one of seven statements that best represents their level of perceived sleepiness. It employs a scale of 1 to 7 with 1 = feeling wide awake and 7 = sleep onset soon
Measured: At the start (hour 0) and end of 10 hour daylong exposure
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Feb 2025
- Study start14 Mar 2025
- Primary completion31 Mar 2026 (estimated)
- Study completion1 Sep 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Heat StressStudies 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
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 10 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Ottawa
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Glen P. Kenny, University of Ottawa
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06842953
- Sponsor's protocol ID
- HEPRU-2025-02-A
- Status last verified
- Jun 2025
- First submitted
- 17 Feb 2025
- Last updated
- 15 Jun 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 15 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Is an Adjustment in the Recommended Indoor Temperature Upper Limit of 26°C Required During Higher Levels of Humidity?
- ClinicalTrials.gov ID
- NCT06842953
- Acronym / sponsor ID
- HEPRU-2025-02-A
- Conditions
- Heat Stress, Physiological Stress
- Keywords
- Heat wave, Indoor overheating, Thermoregulation, Heat strain, Elderly, Heat vulnerability, Hyperthermia, Thermal comfort
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 10 participants (estimated)
- Lead sponsor
- University of OttawaUniversity, hospital or other
- Study start
- 14 Mar 2025 (actual)
- Primary completion
- 31 Mar 2026 (estimated)
- Study completion
- 1 Sep 2026 (estimated)
- First posted
- 24 Feb 2025 (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.
Laboratory-based studies show that exposure to high humidity can worsen the effects of heat stress in young and older adults by impeding sweat evaporation - the main mechanism by which the human body cools itself. At high levels of humidity, the efficiency of sweating decreases causing a greater rise core temperature and burden on the cardiovascular system. In this context, increasing temperatures and humidity with climate change thus pose a potential compound risk for human health. While humidity's role in heat-health outcomes could substantially alter projections of health burdens from climate change, the impact of humidity on physiological strain in vulnerable people in relation to the indoor environment has yet to be evaluated. In a recent study delineating the physiological effects of the proposed 26°C indoor upper limit (PMID: 38329752), relative humidity was set to 45% in all conditions based on indoor humidity standards by the American Society of Heating and Air-Conditioning Engineers. However, it is unknown whether a refinement of the recommended indoor temperature limit of 26°C is required in situations where humidity cannot be maintained at this level.
On separate occasions, the investigators will assess the change in body temperature and cardiovascular strain in older adults (65-85 years) exposed for 10 hours at the recommended indoor temperature limit of 26°C and 45% relative humidity (equivalent humidex of 29 (considered comfortable)) (experimental condition A), to 26°C with a relative humidity of 15% (equivalent humidex of 23 (considered comfortable); humidex is used to measure the perceived temperature taking into account the humidity)) (experimental condition B), to 26°C with a relative humidity of 85% (equivalent humidex of 37 (considered somewhat uncomfortable)) (experimental condition C), and to 31°C and 45% relative humidity with an equivalent humidex of 37 (considered somewhat uncomfortable) that is similar to experimental condition C. With this experimental design, investigators will assess the effects of indoor humidity in driving human heat strain and identify whether refinements in the recommended 26°C indoor temperature limit may be required. Further, by evaluating changes in relation to ambient conditions with a similar humidex, the investigators can assess how individuals perceive and respond to both heat and humidity.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 4
| Arm | Type | Receives |
|---|---|---|
| Exposure to recommended indoor temperature limit with normal indoor humidity | Experimental | Other: Simulated indoor overheatingParticipants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29). |
| Exposure to recommended indoor temperature limit with low indoor humidity | Experimental | Other: Simulated indoor overheatingParticipants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 15% relative humidity (humidex equivalent of 23). |
| Exposure to recommended indoor temperature limit with high indoor humidity | Experimental | Other: Simulated indoor overheatingParticipants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 85% relative humidity (humidex equivalent of 37). |
| Exposure to high indoor temperature with normal indoor humidity | Experimental | Other: Simulated indoor overheatingParticipants exposed daylong (10 hours) to an indoor temperature maintained at 31°C and 45% relative humidity (humidex equivalent of 37). |
Who may qualify
- Ages
- 60 to 85 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
- with or without a) chronic hypertension (elevated resting blood pressure; as defined by Heart and Stroke Canada and Hypertension Canada), b) type 2 diabetes as defined by Diabetes Canada, with at least 5 years having elapsed since time of diagnosis
Key exclusion criteria (6 listed)
- Episode(s) of severe hypoglycemia (requiring the assistance of another person) within the previous year, or inability to sense hypoglycemia (hypoglycemia unawareness).
- Serious complications related to diabetes (gastroparesis, renal disease, uncontrolled hypertension, severe autonomic neuropathy).
- Uncontrolled hypertension - BP >150 mmHg systolic or >95 mmHg diastolic in a sitting position.
- Restrictions in physical activity due to disease (e.g. intermittent claudication, renal impairment, active proliferative retinopathy, unstable cardiac or pulmonary disease, disabling stroke, severe arthritis, etc.).
- Use of or changes in medication judged by the patient or investigators to make participation in this study inadvisable.
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 |
|---|---|---|
| Simulated indoor overheatingOlder adults are exposed to a 10-hour simulated exposure | Other | Exposure to high indoor temperature with normal indoor humidity, Exposure to recommended indoor temperature limit with high indoor humidity, Exposure to recommended indoor temperature limit with low indoor humidity, Exposure to recommended indoor temperature limit with normal indoor humidity |
Primary outcome
Core temperature (Peak) during daylong exposure to indoor overheating
Time frame: End of 10 hour daylong exposure
Peak rectal temperature (15 min average) during exposure. Rectal temperature is measured continuously throughout the 10 hours of the simulated indoor overheating.
Core temperature (AUC) during daylong exposure to indoor overheating
Time frame: End of 10 hour daylong exposure
Areas under the curve (AUC) of rectal temperature during the 10 hour simulate indoor overheating.
Heat rate (Peak) during daylong exposure to indoor overheating
Time frame: End of 10 hour daylong exposure
Peak heart rate (15 min average) during exposure. Heart rate is measured continuously throughout the 10 hours of the simulated indoor overheating.
Heart rate (AUC) during daylong exposure to indoor overheating
Time frame: End of 10 hour daylong exposure
Areas under the curve (AUC) of heart rate during the 10 hour simulate indoor overheating.
Cardiac response to standing from supine (30:15 Ratio) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Cardiac response to standing evaluated as the ratio between the highest R-wave to R-wave interval (lowest heart rate) measured at the 30th heart beat after standing from supine (+/- 5 beats) and the lowest R-wave to R-wave interval (highest heart rate) measured at the 15th heart beat after standing (+/- 5 beats). Cardiac response to standing will be evaluated twice, during two lying-to-standing tests (separated by 10 min of supine rest).
Systolic Response to Standing From Supine during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Systolic blood pressure response to standing evaluated as the difference in blood pressure measured between the standing and supine. Standing systolic blood pressure will be taken as the lowest value of those measured after 60 and 120 seconds of standing. Systolic response to standing will be evaluated twice, during two lying-to-standing tests (separated by 10 min of supine rest).
Heart rate variability: RMSSD during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Root mean squared standard deviation of normal-to-normal R-wave to R-wave intervals (RMSSD) measured during 5 minutes of paced breathing (15 breaths/min) with participants in the supine position. RMSSD will be evaluated twice, during two paced breathing periods (separated by 4 min of supine rest).
Heart rate variability: SDNN during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Standard deviation of normal-to-normal R-wave to R-wave intervals (SDNN) measured during 5 minutes of paced breathing (15 breaths/min) with participants in the supine position. SDNN will be evaluated twice, during two paced breathing periods (separated by 4 min of supine rest).
Thermal comfort scale during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Thermal comfort assessed via a visual analog scale ranging from extremely uncomfortable to extremely comfortable (midpoint: neutral).
Thirst sensation scale during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Thermal sensation assessed via a visual analog scale ranging from extremely hot to neutral (midpoint: hot).
Arousal scale during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Felt arousal scale assessed via a visual analog scale ("How worked up are you?") ranging from "high arousal" to "low arousal".
Fluid loss during daylong exposure to indoor overheating
Time frame: At end of 10 hour daylong exposure
Average hourly fluid consumption calculated by weighing participant water intake at the start and end of each hour of exposure (normalized to the exposure duration).
Changes in plasma volume during daylong exposure to indoor overheating
Time frame: At end of 10 hour daylong exposur
Change in plasma volume from baseline values calculated from duplicate measurements of hemoglobin and hematocrit at the start and end of each exposure using the technique by Dill and Costill
Systolic blood pressure during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Systolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures)
Rate pressure product during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Rate pressure product, an index of myocardial work and strain, calculated as systolic blood pressure x heart rate.
8 secondary outcomes
Impulse control (cognitive function) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Memory recall (cognitive function) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
CDC 4-Stage Balance Test (Postural stability) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
BTrackS Balance Assessment (Postural stability) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Profiles of Mood States (POMS) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Environmental Symptoms Questionnaire (ESQ) during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Sleepiness during daylong exposure to indoor overheating A
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Sleepiness during daylong exposure to indoor overheating B
Time frame: At the start (hour 0) and end of 10 hour daylong exposure
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Jun 2025.
Related trials for Heat Stress
Not yet recruiting
Rapid Cool: Heat Stroke Treatment
Hyperthermia
Recruiting
Heat and Mental Health - PART 2
Depressed Mood, Young Adults
Recruiting
Thermal Therapies in the Treatment of Muscle Injuries
Hamstring Injuries, Hamstring Muscle Repair
Recruiting
Structural Heat Adaptation and Education in Urban Setting
Heat Illness, Quality of Life
RecruitingObservational study
Electrosurgical Patterns and Learning Curve in Elective Laparoscopic Cholecystectomy
Cholelithiasis
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.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Simulated indoor overheating in people with Heat Stress and Physiological Stress, 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 4 inclusion and 6 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: looking for participants now, as of the sponsor's last update on 15 Jun 2025. 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?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Glen P Kenny, PhD (6135625800 ext. 4282, gkenny@uottawa.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Core temperature (Peak) during daylong exposure to indoor overheating (time frame: End of 10 hour daylong exposure). The study lists 15 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 15 Jun 2025.