Testing Simulated Occupational heat exposure for body temperature changes
Official title: Working in the Heat at Simulated Altitude: Effects of Normobaric Hypoxia on Physiological Strain
Effects of Normobaric Hypoxia on Initial Stay Time and Physiological Strain During Moderate-Intensity Work in the Heat in Young and Older Males
- 2 groups
- One site, in Ottawa
- Recruiting
Interventions
- Other intervention
Simulated Occupational heat exposure under normoxic conditions
Participants complete a simulated moderate-intensity occupational heat exposure protocol involving treadmill walking in a hot environment (37.5°C, 35% RH) under normoxic conditions (\~20.9% inspired oxygen). Participants walk until they reach their initial stay time, followed by prescribed work-rest cycles and seated recovery.
- Other intervention
Simulated Occupational heat exposure under hypoxic conditions
Participants complete a simulated moderate-intensity occupational heat exposure protocol involving treadmill walking in a hot environment (37.5°C, 35% RH) with an added hypoxic exposure equivalent to 14% inspired oxygen. Participants walk until they reach their initial stay time, followed by prescribed work-rest cycles and seated recovery.
Canadian Sites (1)
1 of 1 recruiting
- Recruiting
University of Ottawa
Ottawa, Ontario
Eligibility Criteria
See who this study is looking for13 criteria
The trial’s own eligibility text, word for word from the registry. Only the trial site can say who takes part.
Inclusion
- +English or French speaking.
- +Ability to provide informed consentInformed consentThe process of being told what taking part involves, then choosing freely.Read more →.
- +Are physically active (engage in exercise at least 2 times per week for ≥30 minutes)
- +Do not smoke or have been smoke free for at least 5 years.
Exclusion
- −Are regularly exposed to hot environments (e.g., occupational heat exposure)
- −Are regularly exposed to hypoxic environments (e.g., high altitudes)
- −Experience claustrophobia or discomfort in enclosed environments
- −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 screeningScreeningThe checks done before joining, to see whether a study fits.Read more →
In plain language
Assembled directly from this trial’s registry record. Every sentence traces to a field below — nothing here is generated or interpreted.
What this study is
This study is investigating how something functions in the body, rather than testing a treatment directly.
This study is not organised into the usual phase numbers — that is common for device, behavioural, and diagnostic research.
From the trial registry
Built from these fields:
- designModule.designInfo.primaryPurpose
- designModule.phases
Who receives what
There are 2 groups in this study.
Group A receives Simulated Occupational heat exposure under normoxic conditions.
Registry label: A: Normoxic exposure
Group B receives Simulated Occupational heat exposure under hypoxic conditions.
Registry label: B: Hypoxic exposure
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].label
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
How the study is run
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
One group of people involved — usually the participants — is not told which treatment is which.
From the trial registry
Built from these fields:
- designModule.designInfo.allocation
- designModule.designInfo.maskingInfo.masking
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
Built from these fields:
- armsInterventionsModule.armGroups[].type
- armsInterventionsModule.armGroups[].interventionNames
Who the study is looking for
The study lists an age range of 18 years to 70 years.
The study lists male participants only.
The study does not accept healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more →.
These are the criteria the study lists. Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part.
From the trial registry
Built from these fields:
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How big and how long
The study aims to enrol about 20 people.
The study is currently expected to finish around February 2027.
The main measurement is taken over: During the 240-minute work period.
From the trial registry
Built from these fields:
- designModule.enrollmentInfo.count
- statusModule.completionDateStruct.date
- outcomesModule.primaryOutcomes[].timeFrame
What the study measures
Total work volume — measured over During the 240-minute work period.
From the trial registry
Built from these fields:
- outcomesModule.primaryOutcomes[].measure
- outcomesModule.primaryOutcomes[].timeFrame
Source: NCT07664462 on ClinicalTrials.gov. The full registry text is further down this page — this summary never replaces it.
Not medical advice. What do these terms mean?
What is being tested — in plain terms
About Simulated Occupational heat exposure under normoxic conditionsOther
Participants complete a simulated moderate-intensity occupational heat exposure protocol involving treadmill walking in a hot environment (37.5°C, 35% RH) under normoxic conditions (\~20.9% inspired oxygen). Participants walk until they reach their initial stay time, followed by prescribed work-rest cycles and seated recovery.
From the trial registry — its own words, unedited.
What a other is here: An intervention the registry did not place in another category.
Read the full explanation → · in clinical review
About Simulated Occupational heat exposure under hypoxic conditionsOther
Participants complete a simulated moderate-intensity occupational heat exposure protocol involving treadmill walking in a hot environment (37.5°C, 35% RH) with an added hypoxic exposure equivalent to 14% inspired oxygen. Participants walk until they reach their initial stay time, followed by prescribed work-rest cycles and seated recovery.
From the trial registry — its own words, unedited.
What a other is here: An intervention the registry did not place in another category.
Read the full explanation → · in clinical review
Common questions
Answered from this trial’s registry record. Where the record doesn’t say, these answers say so rather than filling the gap.
Am I eligible for this trial?
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can decide whether someone can take part. Concord cannot make that determination, and neither can any tool that has not examined you.
What the study lists: an age range of 18 years to 70 years.
The full inclusionInclusion criteriaThe things you must have or be for a study to consider you.Read more → and exclusion criteriaExclusion criteriaThe things that would prevent someone from taking part.Read more → are published on this page, exactly as the study team wrote them.
The useful next step is to bring this trial to your doctor. Answering a few questions first gives them something concrete to review.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.eligibilityCriteria
Is there a placebo?
This study does not list a placeboPlaceboA dummy treatment with no active medicine, used for comparison.Read more → group.
From the trial registry
- armsInterventionsModule.armGroups[].type
Would I know which treatment I am getting?
One group of people involved — usually the participants — is not told which treatment is which.
Which group you would be placed in is decided by chance, like a coin flip — not by you and not by your doctor.
From the trial registry
- designModule.designInfo.maskingInfo.masking
- designModule.designInfo.allocation
Who can join?
The study lists an age range of 18 years to 70 years.
It lists male participants only.
It does not accept healthy volunteersHealthy volunteerSomeone without the condition being studied who takes part anyway.Read more →.
Only the trial siteTrial siteA hospital or clinic where a study is actually run.Read more → can confirm whether a particular person can take part.
From the trial registry
- eligibilityModule.minimumAge
- eligibilityModule.maximumAge
- eligibilityModule.sex
- eligibilityModule.healthyVolunteers
How long would this take?
The study's main measurement is taken over: During the 240-minute work period.
The study as a whole is currently expected to finish around 2027-02-28.
How long any one person takes part can differ from the study length. The study team can tell you what the schedule looks like in practice.
From the trial registry
- outcomesModule.primaryOutcomes[].timeFrame
- statusModule.completionDateStruct.date
How many people are taking part?
The study aims to enrol about 20 people.
From the trial registry
- designModule.enrollmentInfo.count
Where is this happening?
This study lists one location: Ottawa, Ontario, Canada.
Sites can open and close during a study, so confirm with the team before travelling.
From the trial registry
- trial_locations
About This Trial
Extreme heat events are becoming more frequent, intense, and prolonged, increasing the risk of heat-related illness among workers performing physically demanding work in hot environments. Occupational heat-stress guidelines use work-rest schedules to limit increases in core temperature and physiological strain, but they do not clearly define the safe maximum duration of continuous work before heat-mitigation controls should begin, known as the initial stay time. Recent work has generated initial stay time recommendations for young and older workers performing moderate-intensity work in the heat; however, these recommendations were developed under normoxic conditions. In many workplaces, heat may occur alongside additional stressors such as hypoxia, including work at altitude or in oxygen-reduced environments. Hypoxia can increase cardiovascular strain, reduce arterial oxygen saturation, and impair exercise tolerance, potentially compromising heat-stress guidance developed under normal oxygen conditions. Older workers may be especially vulnerable because of age-related reductions in thermoregulatory and cardiovascular function. It remains unclear whether hypoxia increases physiological strain during work in the heat or whether current initial stay time and recovery recommendations remain protective under combined heat and hypoxic stress. The primary objective of this study is to determine whether hypoxia increases physiological strain during moderate-intensity work in the heat in young and older males. Specifically, the study will assess whether normoxia-derived initial stay times and recovery recommendations for work at 29°C wet-bulb globe temperature (37.5°C, 35% RH) remain effective during exposure to 14% inspired oxygen, simulating approximately 3000 m altitude. Healthy young and older males will complete two simulated occupational heat exposures: heat alone and heat plus hypoxia. Participants will perform moderate-intensity treadmill work based on age-specific initial stay times, followed by prescribed work-rest cycles and seated recovery. Core temperature, cardiovascular strain, oxygen saturation, skin temperature, hydration status, perceptual responses, mood, environmental stress symptoms, and cognitive function will be assessed to determine whether hypoxia modifies responses to work in the heat. Findings will help determine whether occupational heat-stress guidance requires refinement for workers exposed to combined heat and hypoxic stress.
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See if this trial could fit youThis page is for informational purposes only and does not constitute medical advice. Clinical trial eligibility can only be determined by the trial site after proper screening. Trial information is sourced from ClinicalTrials.gov and may not reflect the most current status. Always consult your healthcare provider before making decisions about clinical trial participation.