Core TemperatureNCT05847712
Initial Stay Times and Heat Mitigation Controls for Uncompensable Occupational Heat Stress - Part I
A study testing Simulated work in the heat in people with Core Temperature and Heat Stress, Exertional, run by University of Ottawa at 1 site in Canada.
Trial summary
Workplaces rely on upper heat stress limits provided by the American Conference of Governmental Industrial Hygienists (ACGIH) to manage the health and safety of workers in hot environments. Read more about this study
- Who is it for?
- Ages 18 to 69 yearsHealthy volunteers can take part
- Conditions the study is for
- Core Temperature, Heat Stress, Exertional, Heat Fatigue
- What is being tested?
- Simulated work in the heat
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteCanada
- Study dates
- 8 Jun 2023to 12 Jul 2024
- 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 18 to 69 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- young (18-30 years) and older adults (50-69 years)
- habitually active, not endurance trained (<2 sessions per week, <150 minutes per week)
- non-smoking
- English or French speaking
- ability to provide informed consent
Who cannot join
- pre-existing health conditions (e.g., diabetes, hypertension)
- use of medication deemed to significantly modulate thermoregulatory function and heat tolerance (e.g., antidepressants, antihistamines, diuretics)
- engaged in jobs and/or activities that involve frequent exposure to hot environments (e.g., regular sauna use)
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Safe Maximum Work Times and the Effectiveness of Work-rest Allocations in Mitigating Increases in Core Temperature During and on the Day Following Prolonged Moderate-intensity Work in the Heat in Young and Older Workers
Workplaces rely on upper heat stress limits provided by the American Conference of Governmental Industrial Hygienists (ACGIH) to manage the health and safety of workers in hot environments. This is primarily achieved by interspersing work with rest periods, the length of which is dictated by environmental conditions and work intensity, to maintain core temperature at or below 38.0°C (equivalent to a 1°C increase in body core temperature above resting levels). However, these guidelines employ a "one size fits all" approach to exposure limits that does not consider individual variation between workers. Moreover, they fail to provide direction on the safe, initial stay times before these heat-mitigation controls should be employed (i.e., rest breaks) in conditions exceeding upper heat stress limits. While recent work has generated estimates of the initial stay times for young to older men before heat-mitigation controls are required for moderate-intensity work, this information is limited to a single work bout and does not consider a second work bout preceded by an extended rest period (e.g., lunch) or next day effects. This is a key consideration, as prolonged work in the heat has been shown to cause next-day impairments in heat dissipation in older men. Further, it remains unclear if the application of the prescribed ACGIH work-rest allocations thereafter would alleviate increases in core temperature for the duration of the work period (e.g., start of shift versus post-lunch period). This project will address these knowledge gaps by determining if refinements in initial stay times for moderate-intensity work (represents the average work effort of physically demanding occupations) in the heat (26°C wet-bulb globe temperature) may be required for young and older adults for i) a second work bout that is preceded by an extended rest period such as a lunch break, and ii) a work bout performed on the next day. This includes assessing the efficacy of the prescribed ACGIH work-rest allocations to mitigate increases in core temperature beyond safe limits (>38.0°C, equivalent to a >1°C increase in body core temperature above resting levels) during these work periods. Given the known sex-differences in heat loss that can modulate core temperature regulation during an exercise-heat stress, the investigators will conduct separate analysis to identify modulating effects of biological sex on the initial stay times and effectiveness of the work-rest allocation as a heat-alleviation control.
- Conditions
- Core Temperature, Heat Stress, Exertional, Heat Fatigue, Exercise
- Being tested
- Simulated work in the heat
- Keywords
- Heat exposure, Heat strain, Body temperature, Thermoregulation, Occupational heat stress, Uncompensable heat stress, Aging, Sex
- Medical subject headings
- Heat Stress Disorders, Motor Activity, Coitus
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Simulated work in the heatOther
Participants perform a continuous moderate-intensity work bout (metabolic rate of ~200 W/m2) until core temperature reaches 38.0°C (equivalent to a 1°C increase in body core temperature above resting levels), which is immediately followed by intermittent work using a 3:1 work-rest allocation, starting with a 15 min rest break followed by a 45 min work bout for a total work duration of ~240 min. The work protocol is performed in the morning of day 1, and repeated in a post-lunch work period (i.e., afternoon of day 1) and on the morning of the next day (i.e., morning of day 2).
| Study group | Role | What they receive |
|---|---|---|
| Younger adults | Experimental | Adults aged 18-30 years with no pre-existing health conditions Receives: Other: Simulated work in the heat |
| Older adults | Experimental | Adults aged 50-69 with no pre-existing health conditions Receives: Other: Simulated work in the heat |
What is being measured
The primary outcome is the main question the study is designed to answer.
Initial stay time
Total continuous work time to achieve an initial absolute increase in core temperature of 38°C (equivalent to a 1°C increase in body core temperature above resting levels) (note: in instances where a participant voluntarily terminates work prematurely before the absolute core temperature of ≥38°C (or relative increase of ≥1°C) is achieved or the absolute core temperature is <38°C (or relative increase of <1°C), the time of termination or end of the work bout will be taken as the initial stay time respectively).
Measured: End of first (morning day 1) continuous work bout
Initial stay time
Total continuous work time to achieve an initial absolute increase in core temperature of 38°C (equivalent to a 1°C increase in body core temperature above resting levels) (note: in instances where a participant voluntarily terminates work prematurely before the absolute core temperature of ≥38°C (or relative increase of ≥1°C) is achieved or the absolute core temperature is <38°C (or relative increase of <1°C), the time of termination or end of the work bout will be taken as the initial stay time respectively).
Measured: End of second (afternoon day 1) continuous work bout
Initial stay time
Total continuous work time to achieve an initial absolute increase in core temperature of 38°C (equivalent to a 1°C increase in body core temperature above resting levels) (note: in instances where a participant voluntarily terminates work prematurely before the absolute core temperature of ≥38°C (or relative increase of ≥1°C) is achieved or the absolute core temperature is <38°C (or relative increase of <1°C), the time of termination or end of the work bout will be taken as the initial stay time respectively).
Measured: End of third (morning day 2) continuous work bout
Average core temperature
Average core temperature over final 2-hours of each work bout
Measured: Period of work-rest allocations following initial stay time for morning day 1
Average core temperature
Average core temperature following initial stay time
Measured: Period of work-rest allocations following initial stay time for afternoon day 1
Average core temperature
Average core temperature following initial stay time
Measured: Period of work-rest allocations following initial stay time for morning day 2
Secondary outcomes (57)
Heart rate at initial stay time
Heart rate at the initial increase in absolute core temperature of 38°C (or relative increase of 1°C)
Measured: End of first (morning day 1) continuous work bout
Heart rate at initial stay time
Heart rate at the initial increase in absolute core temperature of 38°C (or relative increase of 1°C)
Measured: End of second (afternoon day 1) continuous work bout
Heart rate at initial stay time
Heart rate at the initial increase in absolute core temperature of 38°C (or relative increase of 1°C)
Measured: End of third (morning day 2) continuous work bout
Average heart rate
Average heart rate following initial stay time
Measured: Period of work-rest allocations following initial stay time for morning day 1
Average heart rate
Average heart rate following initial stay time
Measured: Period of work-rest allocations following initial stay time for afternoon day 1
Average heart rate
Average heart rate following initial stay time
Measured: Period of work-rest allocations following initial stay time for morning day 2
Skin temperature at initial stay time
Skin temperature (4 sites) measured at the initial increase in absolute core temperature of 38°C (or relative increase of 1°C)
Measured: End of first (morning day 1) continuous work bout
Skin temperature at initial stay time
Skin temperature (4 sites) measured at the initial increase in absolute core temperature of 38°C (or relative increase of 1°C)
Measured: End of second (afternoon day 1) continuous work bout
Skin temperature at initial stay time
Skin temperature (4 sites) measured at the initial increase in absolute core temperature of 38°C (or relative increase of 1°C)
Measured: End of third (morning day 2) continuous work bout
Average skin temperature
Average skin temperatures following initial stay time
Measured: Period of work-rest allocations following initial stay time for morning day 1
Average skin temperature
Average skin temperatures following initial stay time
Measured: Period of work-rest allocations following initial stay time for afternoon day 1
Average skin temperature
Average skin temperatures following initial stay time
Measured: Period of work-rest allocations following initial stay time for morning day 2
Systolic blood pressure
Arterial blood pressure measured via automated oscillometry
Measured: End of first (morning day 1) work period
Systolic blood pressure
Arterial blood pressure measured via automated oscillometry
Measured: End of second (afternoon day 1) work period
Systolic blood pressure
Arterial blood pressure measured via automated oscillometry
Measured: End of third (morning day 2) work period
Diastolic blood pressure
Arterial blood pressure measured via automated oscillometry
Measured: End of first (morning day 1) work period
Diastolic blood pressure
Arterial blood pressure measured via automated oscillometry
Measured: End of second (afternoon day 1) work period
Diastolic blood pressure
Arterial blood pressure measured via automated oscillometry
Measured: End of third (morning day 2) work period
Mean arterial blood pressure
Calculated as 1/3 * systolic blood pressure + 2/3 * diastolic blood pressure
Measured: End of first (morning day 1) work period
Mean arterial blood pressure
Calculated as 1/3 * systolic blood pressure + 2/3 * diastolic blood pressure
Measured: End of second (afternoon day 1) work period
Mean arterial blood pressure
Calculated as 1/3 * systolic blood pressure + 2/3 * diastolic blood pressure
Measured: End of third (morning day 2) work period
Rate pressure product
Calculated as systolic blood pressure * heart rate
Measured: End of first (morning day 1) work period
Rate pressure product
Calculated as systolic blood pressure * heart rate
Measured: End of second (afternoon day 1) work period
Rate pressure product
Calculated as systolic blood pressure * heart rate
Measured: End of third (morning day 2) work period
Fluid consumption
Cumulative fluid consumption calculated by weighing the participant's water intake
Measured: End of first (morning day 1) work period
Fluid consumption
Cumulative fluid consumption calculated by weighing the participant's water intake
Measured: End of second (afternoon day 1) work period
Fluid consumption
Cumulative fluid consumption calculated by weighing the participant's water intake
Measured: End of third (morning day 2) work period
Fluid loss
Fluid loss calculated as the change in body mass (corrected for food/fluid consumption).
Measured: End of first (morning day 1) work period
Fluid loss
Fluid loss calculated as the change in body mass (corrected for food/fluid consumption).
Measured: End of second (afternoon day 1) work period
Fluid loss
Fluid loss calculated as the change in body mass (corrected for food/fluid consumption).
Measured: End of third (morning day 2) work period
Change in plasma volume
Determined from venous blood samples
Measured: End of first (morning day 1) work period
Change in plasma volume
Determined from venous blood samples
Measured: End of second (afternoon day 1) work period
Change in plasma volume
Determined from venous blood samples
Measured: End of third (morning day 2) work period
Thermal comfort scale
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") (4: very uncomfortable to 1: comfortable)
Measured: End of first (morning day 1) continuous work bout
Thermal comfort scale
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") (4: very uncomfortable to 1: comfortable)
Measured: End of second (afternoon day 1) continuous work bout
Thermal comfort scale
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") (4: very uncomfortable to 1: comfortable)
Measured: End of third (morning day 2) continuous work bout
Thermal comfort scale
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") (4: very uncomfortable to 1: comfortable)
Measured: Period of work-rest allocations following initial stay time for morning day 1
Thermal comfort scale
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") (4: very uncomfortable to 1: comfortable)
Measured: Period of work-rest allocations following initial stay time for afternoon day 1
Thermal comfort scale
Thermal comfort assessed via a visual analog scale ("How comfortable does your body temperature feel?") (4: very uncomfortable to 1: comfortable)
Measured: Period of work-rest allocations following initial stay time for morning day 2
Thirst sensation scale
Assessed via a visual analog scale ("How thirsty are you?") (9: very, very thirsty to 1: Not thirsty at all)
Measured: End of first (morning day 1) continuous work bout
Thirst sensation scale
Assessed via a visual analog scale ("How thirsty are you?") (9: very, very thirsty to 1: Not thirsty at all)
Measured: End of second (afternoon day 1) continuous work bout
Thirst sensation scale
Assessed via a visual analog scale ("How thirsty are you?") (9: very, very thirsty to 1: Not thirsty at all)
Measured: End of third (morning day 2) continuous work bout
Thirst sensation scale
Assessed via a visual analog scale ("How thirsty are you?") (9: very, very thirsty to 1: Not thirsty at all)
Measured: Period of work-rest allocations following initial stay time for morning day 1
Thirst sensation scale
Assessed via a visual analog scale ("How thirsty are you?") (9: very, very thirsty to 1: Not thirsty at all)
Measured: Period of work-rest allocations following initial stay time for afternoon day 2
Thirst sensation scale
Assessed via a visual analog scale ("How thirsty are you?") (9: very, very thirsty to 1: Not thirsty at all)
Measured: Period of work-rest allocations following initial stay time for morning day 2
Rating of Perceived Exertion
Perceived exertion assessed via a self-report questionnaire upon verbal prompting (6: no exertion at all to 20: maximal exertion).
Measured: End of first (morning day 1) continuous work bout
Rating of Perceived Exertion
Perceived exertion assessed via a self-report questionnaire upon verbal prompting (6: no exertion at all to 20: maximal exertion).
Measured: End of second (afternoon day 1) continuous work bout
Rating of Perceived Exertion
Perceived exertion assessed via a self-report questionnaire upon verbal prompting (6: no exertion at all to 20: maximal exertion).
Measured: End of third (morning day 2) continuous work bout
Rating of Perceived Exertion
Perceived exertion assessed via a self-report questionnaire upon verbal prompting (6: no exertion at all to 20: maximal exertion).
Measured: Period of work-rest allocations following initial stay time for morning day 1
Rating of Perceived Exertion
Perceived exertion assessed via a self-report questionnaire upon verbal prompting (6: no exertion at all to 20: maximal exertion).
Measured: Period of work-rest allocations following initial stay time for afternoon day 2
Rating of Perceived Exertion
Perceived exertion assessed via a self-report questionnaire upon verbal prompting (6: no exertion at all to 20: maximal exertion).
Measured: Period of work-rest allocations following initial stay time for morning day 2
Orthostatic Intolerance Symptoms Assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance. 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: End of first (morning day 1) continuous work bout
Orthostatic Intolerance Symptoms Assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance. 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: End of second (afternoon day 1) continuous work bout
Orthostatic Intolerance Symptoms Assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance. 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: End of third (morning day 2) continuous work bout
Orthostatic Intolerance Symptoms Assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance. 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: Period of work-rest allocations following initial stay time for morning day 1
Orthostatic Intolerance Symptoms Assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance. 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: Period of work-rest allocations following initial stay time for afternoon day 1
Orthostatic Intolerance Symptoms Assessment
Cumulative sum of scores on 6 questions asking participant to rank symptoms associated with orthostatic intolerance. 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: Period of work-rest allocations following initial stay time for morning day 2
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 May 2023
- Study start8 Jun 2023
- Primary completion12 Jul 2024
- Study completion12 Jul 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Core TemperatureStudies 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
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 60 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
- NCT05847712
- Sponsor's protocol ID
- HEPRU 2023-03
- Status last verified
- Aug 2024
- First submitted
- 27 Apr 2023
- Last updated
- 6 Aug 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
Study at a glance
From the registry record, last updated by the sponsor on 6 Aug 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Safe Maximum Work Times and the Effectiveness of Work-rest Allocations in Mitigating Increases in Core Temperature During and on the Day Following Prolonged Moderate-intensity Work in the Heat in Young and Older Workers
- ClinicalTrials.gov ID
- NCT05847712
- Acronym / sponsor ID
- HEPRU 2023-03
- Conditions
- Core Temperature, Heat Stress, Exertional, Heat Fatigue, Exercise
- Keywords
- Heat exposure, Heat strain, Body temperature, Thermoregulation, Occupational heat stress, Uncompensable heat stress, Aging, Sex
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- University of OttawaUniversity, hospital or other
- Study start
- 8 Jun 2023 (actual)
- Primary completion
- 12 Jul 2024 (actual)
- Study completion
- 12 Jul 2024 (actual)
- First posted
- 8 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.
Workplaces rely on upper heat stress limits provided by the American Conference of Governmental Industrial Hygienists (ACGIH) to manage the health and safety of workers in hot environments. This is primarily achieved by interspersing work with rest periods, the length of which is dictated by environmental conditions and work intensity, to maintain core temperature at or below 38.0°C (equivalent to a 1°C increase in body core temperature above resting levels). However, these guidelines employ a "one size fits all" approach to exposure limits that does not consider individual variation between workers. Moreover, they fail to provide direction on the safe, initial stay times before these heat-mitigation controls should be employed (i.e., rest breaks) in conditions exceeding upper heat stress limits. While recent work has generated estimates of the initial stay times for young to older men before heat-mitigation controls are required for moderate-intensity work, this information is limited to a single work bout and does not consider a second work bout preceded by an extended rest period (e.g., lunch) or next day effects. This is a key consideration, as prolonged work in the heat has been shown to cause next-day impairments in heat dissipation in older men. Further, it remains unclear if the application of the prescribed ACGIH work-rest allocations thereafter would alleviate increases in core temperature for the duration of the work period (e.g., start of shift versus post-lunch period). This project will address these knowledge gaps by determining if refinements in initial stay times for moderate-intensity work (represents the average work effort of physically demanding occupations) in the heat (26°C wet-bulb globe temperature) may be required for young and older adults for i) a second work bout that is preceded by an extended rest period such as a lunch break, and ii) a work bout performed on the next day. This includes assessing the efficacy of the prescribed ACGIH work-rest allocations to mitigate increases in core temperature beyond safe limits (>38.0°C, equivalent to a >1°C increase in body core temperature above resting levels) during these work periods. Given the known sex-differences in heat loss that can modulate core temperature regulation during an exercise-heat stress, the investigators will conduct separate analysis to identify modulating effects of biological sex on the initial stay times and effectiveness of the work-rest allocation as a heat-alleviation control.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Younger adults | Experimental | Other: Simulated work in the heatAdults aged 18-30 years with no pre-existing health conditions |
| Older adults | Experimental | Other: Simulated work in the heatAdults aged 50-69 with no pre-existing health conditions |
Who may qualify
- Ages
- 18 to 69 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- young (18-30 years) and older adults (50-69 years)
- habitually active, not endurance trained (<2 sessions per week, <150 minutes per week)
- non-smoking
- English or French speaking
- ability to provide informed consent
Key exclusion criteria (3 listed)
- pre-existing health conditions (e.g., diabetes, hypertension)
- use of medication deemed to significantly modulate thermoregulatory function and heat tolerance (e.g., antidepressants, antihistamines, diuretics)
- engaged in jobs and/or activities that involve frequent exposure to hot environments (e.g., regular sauna use)
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 work in the heatParticipants perform a continuous moderate-intensity work bout (metabolic rate of ~200 W/m2) until core temperature reaches 38.0°C (equivalent to a 1°C increase in body core temperature above resting levels), which is immediately followed by intermittent work using a 3:1 work-rest allocation, starting with a 15 min rest break followed by a 45 min work bout for a total work duration of ~240 min. The work protocol is performed in the morning of day 1, and repeated in a post-lunch work period (i.e., afternoon of day 1) and on the morning of the next day (i.e., morning of day 2). | Other | Older adults, Younger adults |
Primary outcome
Initial stay time
Time frame: End of first (morning day 1) continuous work bout
Total continuous work time to achieve an initial absolute increase in core temperature of 38°C (equivalent to a 1°C increase in body core temperature above resting levels) (note: in instances where a participant voluntarily terminates work prematurely before the absolute core temperature of ≥38°C (or relative increase of ≥1°C) is achieved or the absolute core temperature is <38°C (or relative increase of <1°C), the time of termination or end of the work bout will be taken as the initial stay time respectively).
Initial stay time
Time frame: End of second (afternoon day 1) continuous work bout
Total continuous work time to achieve an initial absolute increase in core temperature of 38°C (equivalent to a 1°C increase in body core temperature above resting levels) (note: in instances where a participant voluntarily terminates work prematurely before the absolute core temperature of ≥38°C (or relative increase of ≥1°C) is achieved or the absolute core temperature is <38°C (or relative increase of <1°C), the time of termination or end of the work bout will be taken as the initial stay time respectively).
Initial stay time
Time frame: End of third (morning day 2) continuous work bout
Total continuous work time to achieve an initial absolute increase in core temperature of 38°C (equivalent to a 1°C increase in body core temperature above resting levels) (note: in instances where a participant voluntarily terminates work prematurely before the absolute core temperature of ≥38°C (or relative increase of ≥1°C) is achieved or the absolute core temperature is <38°C (or relative increase of <1°C), the time of termination or end of the work bout will be taken as the initial stay time respectively).
Average core temperature
Time frame: Period of work-rest allocations following initial stay time for morning day 1
Average core temperature over final 2-hours of each work bout
Average core temperature
Time frame: Period of work-rest allocations following initial stay time for afternoon day 1
Average core temperature following initial stay time
Average core temperature
Time frame: Period of work-rest allocations following initial stay time for morning day 2
Average core temperature following initial stay time
57 secondary outcomes
Heart rate at initial stay time
Time frame: End of first (morning day 1) continuous work bout
Heart rate at initial stay time
Time frame: End of second (afternoon day 1) continuous work bout
Heart rate at initial stay time
Time frame: End of third (morning day 2) continuous work bout
Average heart rate
Time frame: Period of work-rest allocations following initial stay time for morning day 1
Average heart rate
Time frame: Period of work-rest allocations following initial stay time for afternoon day 1
Average heart rate
Time frame: Period of work-rest allocations following initial stay time for morning day 2
Skin temperature at initial stay time
Time frame: End of first (morning day 1) continuous work bout
Skin temperature at initial stay time
Time frame: End of second (afternoon day 1) continuous work bout
Skin temperature at initial stay time
Time frame: End of third (morning day 2) continuous work bout
Average skin temperature
Time frame: Period of work-rest allocations following initial stay time for morning day 1
Average skin temperature
Time frame: Period of work-rest allocations following initial stay time for afternoon day 1
Average skin temperature
Time frame: Period of work-rest allocations following initial stay time for morning day 2
Systolic blood pressure
Time frame: End of first (morning day 1) work period
Systolic blood pressure
Time frame: End of second (afternoon day 1) work period
Systolic blood pressure
Time frame: End of third (morning day 2) work period
Diastolic blood pressure
Time frame: End of first (morning day 1) work period
Diastolic blood pressure
Time frame: End of second (afternoon day 1) work period
Diastolic blood pressure
Time frame: End of third (morning day 2) work period
Mean arterial blood pressure
Time frame: End of first (morning day 1) work period
Mean arterial blood pressure
Time frame: End of second (afternoon day 1) work period
Mean arterial blood pressure
Time frame: End of third (morning day 2) work period
Rate pressure product
Time frame: End of first (morning day 1) work period
Rate pressure product
Time frame: End of second (afternoon day 1) work period
Rate pressure product
Time frame: End of third (morning day 2) work period
Fluid consumption
Time frame: End of first (morning day 1) work period
Fluid consumption
Time frame: End of second (afternoon day 1) work period
Fluid consumption
Time frame: End of third (morning day 2) work period
Fluid loss
Time frame: End of first (morning day 1) work period
Fluid loss
Time frame: End of second (afternoon day 1) work period
Fluid loss
Time frame: End of third (morning day 2) work period
Change in plasma volume
Time frame: End of first (morning day 1) work period
Change in plasma volume
Time frame: End of second (afternoon day 1) work period
Change in plasma volume
Time frame: End of third (morning day 2) work period
Thermal comfort scale
Time frame: End of first (morning day 1) continuous work bout
Thermal comfort scale
Time frame: End of second (afternoon day 1) continuous work bout
Thermal comfort scale
Time frame: End of third (morning day 2) continuous work bout
Thermal comfort scale
Time frame: Period of work-rest allocations following initial stay time for morning day 1
Thermal comfort scale
Time frame: Period of work-rest allocations following initial stay time for afternoon day 1
Thermal comfort scale
Time frame: Period of work-rest allocations following initial stay time for morning day 2
Thirst sensation scale
Time frame: End of first (morning day 1) continuous work bout
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 6 Aug 2024.
- 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 Simulated work in the heat in people with Core Temperature and Heat Stress, Exertional, 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 3 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 6 Aug 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?
Initial stay time (time frame: End of first (morning day 1) continuous work bout). 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?
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 6 Aug 2024.