Suitability of a 26 °C Indoor Environment for Mitigating Heat Strain in Young Adults
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Simulated indoor temperature upper limit.
- Who it may be relevant to
- Registry conditions: Heat Stress, Physiological Stress, Cognitive Change. Basic parameters: 18 years — 29 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Canada
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Official title
Evaluating the Effectiveness of a 26 °C Indoor Temperature Limit to Mitigate Physiological Strain in Young, Habitually Active Adults
Overview
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: A) 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.
Interventions
- Other Simulated indoor temperature upper limit
Young adults exposed to an 8-hour simulated exposure.
Primary outcome measures
- Core temperature (Peak) during daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Core temperature (AUC) during daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Core temperature end of daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Mean skin temperature (Peak) during daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Mean skin temperature (AUC) during daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Mean skin temperature end of daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Heat rate (Peak) during daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Heart rate (AUC) during daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- Heart rate end of daylong exposure to indoor temperature limit. [Time frame: End of 8 hour daylong exposure]
- 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]
Secondary outcome measures (3)
- 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.]
Eligibility criteria
Inclusion criteria
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
- Healthy young adults without chronic disease (e.g., type 1 diabetes, hypertension)
Exclusion criteria
- 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
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Single blind
- Primary purpose
- Basic science
Study locations
Canada · 1 center
- University of Ottawa — Ottawa
Identifiers
NCT: NCT07267598 · HEPRU-2025-10B