Heat StressNCT07267598
Suitability of a 26 °C Indoor Environment for Mitigating Heat Strain in Young Adults
A study testing Simulated indoor temperature upper limit in people with Heat Stress and Physiological Stress, run by University of Ottawa at 1 site in Canada.
Trial summary
While an indoor upper temperature limit of 26 °C has been shown to protect heat-vulnerable older adults (DOI: 10.1289/EHP11651), this guideline has not been verified in young, habitually active adults. Read more about this study
- Who is it for?
- Ages 18 to 29 years
- Conditions the study is for
- Heat Stress, Physiological Stress, Cognitive Change
- What is being tested?
- Simulated indoor temperature upper limit
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 10 participants
- Where
- 1 siteCanada
- Study dates
- 7 Nov 2025to 30 Dec 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 18 to 29 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
- Healthy young adults without chronic disease (e.g., type 1 diabetes, hypertension)
Who cannot join
- Endurance trained (i.e., engaged in regular physical training activities more than 3 times a week for more than 1 hour per session).
- Undergoing passive heat exposures such as regular of saunas, warm-water immersion, other.
- Use of or changes in medication judged by the patient or investigators to make participation in this study inadvisable.
- Current pregnancy
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, K1N 6N5
Glen P Kenny, PhD, 613-562-5800 ext. 4282, gkenny@uottawa.ca
About this study
Official title: Evaluating the Effectiveness of a 26 °C Indoor Temperature Limit to Mitigate Physiological Strain in Young, Habitually Active Adults
While an indoor upper temperature limit of 26 °C has been shown to protect heat-vulnerable older adults (DOI: 10.1289/EHP11651), this guideline has not been verified in young, habitually active adults. Public health recommendations during hot weather typically emphasize staying in cool environments, avoiding strenuous activity, wearing lightweight clothing, and maintaining adequate hydration. However, young adults may be less likely to follow these guidelines. They often do not reduce their physical activity during extreme heat events and may overdress for fashion, cultural, or religious reasons. These behaviors can impose an additional thermoregulatory burden and lead to greater physiological strain during heat exposure, even though young adults generally have a higher capacity for heat dissipation than older individuals. Accordingly, it is important to evaluate whether an indoor temperature limit of 26 °C is sufficient to protect young, habitually active adults.
To address this gap, the investigators aim to assess changes in body temperature and cardiovascular strain in young, habitually active adults (18-29 years) during an 8-hour exposure to the recommended indoor upper temperature limit of 26 °C and 45% relative humidity (humidex of 29, considered comfortable). Participants will complete two conditions:
Read more
- seated rest while dressed in light clothing (T-shirt, shorts, and socks), and B) light exercise (stepping to simulate activities of daily living, 4-4.5 METs) performed once per hour (except for the lunch hour) while dressed in light clothing plus an additional insulating layer (sweatshirt and sweatpants).
This experimental design will allow investigators to determine the effects of added clothing insulation and light activity-representative of typical daily behaviors-on physiological strain in young adults, and to assess whether refinements to the recommended 26 °C indoor temperature limit are warranted for this population.
- Conditions
- Heat Stress, Physiological Stress, Cognitive Change
- Being tested
- Simulated indoor temperature upper limit
- Keywords
- Indoor overheating, Indoor temperatures, Heat wave, Thermoregulation, Heat strain, Heat vulnerability, Hyperthermia, Thermal comfort, Activities of daily living, Clothing insulation
- 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 temperature upper limitOther
Young adults exposed to an 8-hour simulated exposure.
| Study group | Role | What they receive |
|---|---|---|
| Exposure to indoor temperature upper limit without physical activity and added clothing. | Experimental | Participants, dressed in light clothing (t-shirt, shorts and socks), perform seated rest while exposed daylong (8 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29). Receives: Other: Simulated indoor temperature upper limit |
| Exposure to indoor temperature upper limit with physical activity and added clothing. | Experimental | Participants, dressed in light clothing (t-shirt, shorts and socks) and an added clothing layer (sweatshirt and sweatpants), perform light exercise (i.e., stepping, representing activities of daily living, 4-4.5 METS) every hour (with exception of lunch hour) while exposed daylong (8 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29). Receives: Other: Simulated indoor temperature upper limit |
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 temperature limit.
Peak rectal temperature (15 min average) during exposure. Rectal temperature is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Measured: End of 8 hour daylong exposure
Core temperature (AUC) during daylong exposure to indoor temperature limit.
Areas under the curve (AUC) of rectal temperature during the 8 hour exposure to the simulate indoor temperature upper limit.
Measured: End of 8 hour daylong exposure
Core temperature end of daylong exposure to indoor temperature limit.
Rectal temperature measured at hour 8 of exposure to indoor temperature limit (15-min average).
Measured: End of 8 hour daylong exposure
Mean skin temperature (Peak) during daylong exposure to indoor temperature limit.
Peak mean skin temperature (15 min average) during exposure. Mean skin temperature as calculated from skin temperature measured across 7 body regions is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Measured: End of 8 hour daylong exposure
Mean skin temperature (AUC) during daylong exposure to indoor temperature limit.
Areas under the curve (AUC) of mean skin temperature as calculated over 7 body regions during the 8 hour exposure to the simulate indoor temperature upper limit.
Measured: End of 8 hour daylong exposure
Mean skin temperature end of daylong exposure to indoor temperature limit.
Mean skin temperature measured over 7 body regions at hour 8 of exposure to indoor temperature limit (15-min average).
Measured: End of 8 hour daylong exposure
Heat rate (Peak) during daylong exposure to indoor temperature limit.
Peak heart rate (15 min average) during exposure. Heart rate is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Measured: End of 8 hour daylong exposure
Heart rate (AUC) during daylong exposure to indoor temperature limit.
Areas under the curve (AUC) of heart rate during the 8 hour exposure to the simulate indoor temperature upper limit.
Measured: End of 8 hour daylong exposure
Heart rate end of daylong exposure to indoor temperature limit.
Heart rate measured at hour 8 of exposure to indoor temperature limit (15-min average).
Measured: End of 8 hour daylong exposure
Heart rate variability: RMSSD during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Heart rate variability: SDNN during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Cardiac response to standing from supine (30:15 ratio) during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Systolic response to standing from supine during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Systolic blood pressure during daylong exposure to indoor temperature limit.
Systolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures).
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Diastolic blood pressure during daylong exposure to indoor temperature limit.
Diastolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures).
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Rate pressure product during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Reaction time during daylong exposure to indoor temperature limit (cognitive function).
Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of reaction time. Participants will be asked to initiate a movement of the device in response to a visual cue.
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Impulse control during daylong exposure to indoor temperature limit (cognitive function).
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 8 hour daylong exposure
CDC 4-Stage Balance Test during daylong exposure to indoor temperature limit (postural stability).
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 8 hour daylong exposure
BTrackS Balance Assessment during daylong exposure to indoor temperature limit (postural stability).
To assess postural stability, participants will be asked to stand on a BTracks force plate with their feet spread out to shoulder width while looking straight ahead. The assessment will comprise of one trial lasting 120 seconds in length. 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 8 hour daylong exposure
Fluid consumption during daylong exposure to indoor temperature limit.
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: End of 8 hour daylong exposure
Fluid loss during daylong exposure to indoor temperature limit.
Fluid loss calculated as the change in body mass during each exposure presented as a percentage of baseline body mass (corrected for food consumption).
Measured: End of 8 hour daylong exposure
Change in plasma volume during daylong exposure to indoor temperature limit.
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: End of 8 hour daylong exposure
Thermal comfort scale during daylong exposure to indoor temperature limit.
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") ranging from "very uncomfortable" to "comfortable".
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Thirst sensation scale during daylong exposure to indoor temperature limit.
Thirst sensation assessed via a visual analog scale ranging from "very, very thirsty" to "not thirsty at all".
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Arousal scale during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Thermal sensation scale during daylong exposure to indoor temperature limit.
Thermal sensation assessed via a visual analog scale ("How hot do you feel?") ranging from "extremely hot" to "neutral"(midpoint: hot)
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Thermal sensation 2 scale during daylong exposure to indoor temperature limit.
Thermal sensation assessed via a visual analog scale ("How do you feel?") ranging from "hot" to "cold"(midpoint: neutral)
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Orthostatic intolerance symptoms assessment during daylong exposure to indoor temperature limit.
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance during the lying to standing tests. All symptoms scored on a scale from 0 (none) to 10 (worst possible) and include feelings of: (1) "dizziness, lightheadedness, feeling faint, or feeling like you might black out"; (2) "Problems with vision (blurring, seeing spots, tunnel vision, etc.)"; (3) "Weakness"; (4) "Fatigue"; (5) "Trouble concentrating"; and (6) "Head and neck discomfort".
Measured: At end of 8 hour daylong exposure
Feel good scale during daylong exposure to indoor temperature limit.
Feel good assessed via a visual analog scale ("How good do you feel?") ranging from "very good" to "very bad"(midpoint: neutral).
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Perceived exertion scale during daylong exposure to indoor temperature limit.
Perceived exertional assessed via a visual analog scale ("How hard are you working?") ranging from "no exertional at all" to "maximal exertion".
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Hydration status during daylong exposure to indoor overheating
Hydration status measured via assessing the urine specific gravity of a urine sample.
Measured: At the start (hour 0) and end of 8 hour daylong exposure
Activity levels during daylong exposure to indoor overheating
Activity levels assessed via a wearable monitor (Actical) containing an accelerometer worn on the wrist and hip.
Measured: End of 8 hour daylong exposure
Secondary outcomes (3)
Profiles of Mood States (POMS) during daylong exposure to indoor temperature limit.
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. 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 8 hour daylong exposure
Environmental Symptoms Questionnaire (ESQ) during daylong exposure to indoor temperature limit.
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 8 hour daylong exposure
Sleep quality and quantify assessment during daylong exposure to indoor temperature limit.
The Pittsburgh Sleep Quality Index (PSQI) is a self-report questionnaire that works by asking 19 questions about a person's sleep habits over the past month. It is scored by evaluating seven components: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. Each component is scored from 0 to 3, and these are summed to create a global score from 0 to 21, where a higher score indicates poorer sleep quality.
Measured: At the start of 8 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 posted5 Dec 2025
- Study start7 Nov 2025
- Primary completion25 Jan 2026
- Study completion30 Dec 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
- Participant
- 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
- Investigators
- Glen P Kenny, PhD, Principal investigator, University of Ottawa
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07267598
- Sponsor's protocol ID
- HEPRU-2025-10B
- Status last verified
- Jun 2026
- First submitted
- 21 Nov 2025
- Last updated
- 16 Jun 2026
- 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 16 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Evaluating the Effectiveness of a 26 °C Indoor Temperature Limit to Mitigate Physiological Strain in Young, Habitually Active Adults
- ClinicalTrials.gov ID
- NCT07267598
- Acronym / sponsor ID
- HEPRU-2025-10B
- Conditions
- Heat Stress, Physiological Stress, Cognitive Change
- Keywords
- Indoor overheating, Indoor temperatures, Heat wave, Thermoregulation, Heat strain, 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
- 7 Nov 2025 (actual)
- Primary completion
- 25 Jan 2026 (actual)
- Study completion
- 30 Dec 2026 (estimated)
- First posted
- 5 Dec 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.
While an indoor upper temperature limit of 26 °C has been shown to protect heat-vulnerable older adults (DOI: 10.1289/EHP11651), this guideline has not been verified in young, habitually active adults. Public health recommendations during hot weather typically emphasize staying in cool environments, avoiding strenuous activity, wearing lightweight clothing, and maintaining adequate hydration. However, young adults may be less likely to follow these guidelines. They often do not reduce their physical activity during extreme heat events and may overdress for fashion, cultural, or religious reasons. These behaviors can impose an additional thermoregulatory burden and lead to greater physiological strain during heat exposure, even though young adults generally have a higher capacity for heat dissipation than older individuals. Accordingly, it is important to evaluate whether an indoor temperature limit of 26 °C is sufficient to protect young, habitually active adults.
To address this gap, the investigators aim to assess changes in body temperature and cardiovascular strain in young, habitually active adults (18-29 years) during an 8-hour exposure to the recommended indoor upper temperature limit of 26 °C and 45% relative humidity (humidex of 29, considered comfortable). Participants will complete two conditions:
- seated rest while dressed in light clothing (T-shirt, shorts, and socks), and B) light exercise (stepping to simulate activities of daily living, 4-4.5 METs) performed once per hour (except for the lunch hour) while dressed in light clothing plus an additional insulating layer (sweatshirt and sweatpants).
This experimental design will allow investigators to determine the effects of added clothing insulation and light activity-representative of typical daily behaviors-on physiological strain in young adults, and to assess whether refinements to the recommended 26 °C indoor temperature limit are warranted for this population.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Exposure to indoor temperature upper limit without physical activity and added clothing. | Experimental | Other: Simulated indoor temperature upper limitParticipants, dressed in light clothing (t-shirt, shorts and socks), perform seated rest while exposed daylong (8 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29). |
| Exposure to indoor temperature upper limit with physical activity and added clothing. | Experimental | Other: Simulated indoor temperature upper limitParticipants, dressed in light clothing (t-shirt, shorts and socks) and an added clothing layer (sweatshirt and sweatpants), perform light exercise (i.e., stepping, representing activities of daily living, 4-4.5 METS) every hour (with exception of lunch hour) while exposed daylong (8 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29). |
Who may qualify
- Ages
- 18 to 29 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
- Healthy young adults without chronic disease (e.g., type 1 diabetes, hypertension)
Key exclusion criteria (4 listed)
- Endurance trained (i.e., engaged in regular physical training activities more than 3 times a week for more than 1 hour per session).
- Undergoing passive heat exposures such as regular of saunas, warm-water immersion, other.
- Use of or changes in medication judged by the patient or investigators to make participation in this study inadvisable.
- Current pregnancy
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 temperature upper limitYoung adults exposed to an 8-hour simulated exposure. | Other | Exposure to indoor temperature upper limit with physical activity and added clothing., Exposure to indoor temperature upper limit without physical activity and added clothing. |
Primary outcome
Core temperature (Peak) during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Peak rectal temperature (15 min average) during exposure. Rectal temperature is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Core temperature (AUC) during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Areas under the curve (AUC) of rectal temperature during the 8 hour exposure to the simulate indoor temperature upper limit.
Core temperature end of daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Rectal temperature measured at hour 8 of exposure to indoor temperature limit (15-min average).
Mean skin temperature (Peak) during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Peak mean skin temperature (15 min average) during exposure. Mean skin temperature as calculated from skin temperature measured across 7 body regions is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Mean skin temperature (AUC) during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Areas under the curve (AUC) of mean skin temperature as calculated over 7 body regions during the 8 hour exposure to the simulate indoor temperature upper limit.
Mean skin temperature end of daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Mean skin temperature measured over 7 body regions at hour 8 of exposure to indoor temperature limit (15-min average).
Heat rate (Peak) during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Peak heart rate (15 min average) during exposure. Heart rate is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Heart rate (AUC) during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Areas under the curve (AUC) of heart rate during the 8 hour exposure to the simulate indoor temperature upper limit.
Heart rate end of daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Heart rate measured at hour 8 of exposure to indoor temperature limit (15-min average).
Heart rate variability: RMSSD during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 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 temperature limit.
Time frame: At the start (hour 0) and end of 8 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).
Cardiac response to standing from supine (30:15 ratio) during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 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 temperature limit.
Time frame: At the start (hour 0) and end of 8 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).
Systolic blood pressure during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Systolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures).
Diastolic blood pressure during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Diastolic blood pressure measured in triplicate via automated oscillometry (~60 seconds between measures).
Rate pressure product during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Rate pressure product, an index of myocardial work and strain, calculated as systolic blood pressure x heart rate.
Reaction time during daylong exposure to indoor temperature limit (cognitive function).
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Participants will be provided with a tablet device with the Sway Medical testing platform for the assessment of reaction time. Participants will be asked to initiate a movement of the device in response to a visual cue.
Impulse control during daylong exposure to indoor temperature limit (cognitive function).
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
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.
CDC 4-Stage Balance Test during daylong exposure to indoor temperature limit (postural stability).
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
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).
BTrackS Balance Assessment during daylong exposure to indoor temperature limit (postural stability).
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
To assess postural stability, participants will be asked to stand on a BTracks force plate with their feet spread out to shoulder width while looking straight ahead. The assessment will comprise of one trial lasting 120 seconds in length. 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.
Fluid consumption during daylong exposure to indoor temperature limit.
Time frame: End of 8 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).
Fluid loss during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
Fluid loss calculated as the change in body mass during each exposure presented as a percentage of baseline body mass (corrected for food consumption).
Change in plasma volume during daylong exposure to indoor temperature limit.
Time frame: End of 8 hour daylong exposure
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.
Thermal comfort scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") ranging from "very uncomfortable" to "comfortable".
Thirst sensation scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Thirst sensation assessed via a visual analog scale ranging from "very, very thirsty" to "not thirsty at all".
Arousal scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Felt arousal scale assessed via a visual analog scale ("How worked up are you?") ranging from "high arousal" to "low arousal".
Thermal sensation scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Thermal sensation assessed via a visual analog scale ("How hot do you feel?") ranging from "extremely hot" to "neutral"(midpoint: hot)
Thermal sensation 2 scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Thermal sensation assessed via a visual analog scale ("How do you feel?") ranging from "hot" to "cold"(midpoint: neutral)
Orthostatic intolerance symptoms assessment during daylong exposure to indoor temperature limit.
Time frame: At end of 8 hour daylong exposure
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance during the lying to standing tests. All symptoms scored on a scale from 0 (none) to 10 (worst possible) and include feelings of: (1) "dizziness, lightheadedness, feeling faint, or feeling like you might black out"; (2) "Problems with vision (blurring, seeing spots, tunnel vision, etc.)"; (3) "Weakness"; (4) "Fatigue"; (5) "Trouble concentrating"; and (6) "Head and neck discomfort".
Feel good scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Feel good assessed via a visual analog scale ("How good do you feel?") ranging from "very good" to "very bad"(midpoint: neutral).
Perceived exertion scale during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Perceived exertional assessed via a visual analog scale ("How hard are you working?") ranging from "no exertional at all" to "maximal exertion".
Hydration status during daylong exposure to indoor overheating
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Hydration status measured via assessing the urine specific gravity of a urine sample.
Activity levels during daylong exposure to indoor overheating
Time frame: End of 8 hour daylong exposure
Activity levels assessed via a wearable monitor (Actical) containing an accelerometer worn on the wrist and hip.
3 secondary outcomes
Profiles of Mood States (POMS) during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Environmental Symptoms Questionnaire (ESQ) during daylong exposure to indoor temperature limit.
Time frame: At the start (hour 0) and end of 8 hour daylong exposure
Sleep quality and quantify assessment during daylong exposure to indoor temperature limit.
Time frame: At the start of 8 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 16 Jun 2026.
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.
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 Simulated indoor temperature upper limit 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 4 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 16 Jun 2026. 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 (6133029267 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 temperature limit. (time frame: End of 8 hour daylong exposure). The study lists 33 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 16 Jun 2026; AzTrials last refreshed its copy on 7 Nov 2026.