NCT07656519 Consecutive Occupational Heat Exposure With and Without Overnight Cooling
| NCT ID | NCT07656519 |
| Status | Recruiting |
| Phase | — |
| Sponsor | University of Ottawa |
| Condition | Body Temperature Changes |
| Study Type | INTERVENTIONAL |
| Enrollment | 10 participants |
| Start Date | 2026-06-24 |
| Primary Completion | 2027-06-30 |
Eligibility & Interventions
Eligibility Fast-Check
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What to Expect as a Participant
You will actively receive the study intervention — which may be a drug, biologic, device, or procedure.
This trial targets 10 participants in total. It began in 2026-06-24 with a primary completion date of 2027-06-30.
⚠ This information is for research awareness only. Always consult your physician before joining any clinical trial. Participation is voluntary and you may withdraw at any time.
Brief Summary
Extreme heat events are becoming more frequent, intense, and prolonged, increasing the risk of heat-related illness among workers exposed to hot environments. Current occupational heat-stress guidelines are designed to limit excessive increases in core body temperature and physiological strain during work in the heat through the use of work-rest schedules. However, these guidelines are largely based on single-day heat exposures and assume that workers recover in cool indoor environments between shifts. During heat events, many workers may instead recover in homes or accommodations that remain overheated, particularly in the absence of air conditioning. Inadequate overnight cooling may impair the body's ability to dissipate heat, increase physiological strain, and reduce tolerance to heat exposure on subsequent workdays. Older adults may be especially vulnerable due to age-related impairments in heat-loss capacity. To date, the effects of recovering in an overheated indoor environment on physiological strain and thermoregulatory function during repeated occupational heat exposure remain poorly understood, limiting the development of evidence-based recommendations to protect workers during prolonged heat events. The primary objective of this study is to determine whether overnight recovery in an overheated indoor environment increases physiological strain during repeated occupational heat exposure in older adults. Specifically, investigators will assess whether recovery at the recently proposed upper indoor temperature limit of 26°C and 45% relative humidity (RH) (PMID: 38329752) is sufficient to attenuate elevations in core temperature during subsequent work in the heat compared with recovery in an overheated indoor environment (31°C, 45% RH) representative of conditions commonly experienced during extreme heat events. Healthy older adults will complete two consecutive days and nights of simulated moderate-intensity occupational heat exposure, with overnight recovery occurring in either the 26°C or 31°C condition. Measures of core temperature, cardiovascular strain, heat-loss capacity, hydration status, sleep quality, cognitive function, mood, and perceptual responses will be assessed to determine the impact of overnight recovery conditions on responses to repeated heat exposure. Whole-body heat-loss capacity will also be evaluated before and after the exposure protocol as assessed during incremental, intermittent exercise protocol performed in an air calorimeter.
Eligibility Criteria
Inclusion Criteria: * Are male. * Do not smoke or have been smoke free for at least 5 years. * English or French speaking. * Ability to provide informed consent. * Are physically active (engage in exercise at least 2 times per week for ≥30 minutes) Exclusion Criteria: * Are regularly exposed to hot environments (e.g., occupational heat exposure) * 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 screening
Contact & Investigator
Frequently Asked Questions
Who can join the NCT07656519 clinical trial?
This trial is open to male participants only, aged 50 Years or older, up to 70 Years, studying Body Temperature Changes. Full inclusion and exclusion criteria are listed in the Eligibility Criteria section. Always confirm your eligibility with the research team before applying.
Is NCT07656519 currently recruiting?
Yes, NCT07656519 is actively recruiting participants. Contact the research team at gkenny@uottawa.ca for enrollment information.
Where is the NCT07656519 trial being conducted?
This trial is being conducted at Ottawa, Canada.
Who is sponsoring the NCT07656519 clinical trial?
NCT07656519 is sponsored by University of Ottawa. The trial plans to enroll 10 participants.