Recruiting

Thermoregulation Study

Sponsor:

University of Ottawa

Code:

NCT07781605

Conditions

Body Temperature Changes

Heat Stress

Child Development

Heat

Physiological Stress

Eligibility Criteria

Sex: All

Age: 9 - 25

Healthy Volunteers: Accepted

Interventions

Exercise at 22°C

Exercise at 26°C

Exercise at 31°C

Exercise at 36°C

Study Details

Brief summary:

Little is known about how children and youth regulate body temperature during exercise across different environmental temperatures compared with young adults, including whether differences in whole-body heat exchange contribute to their responses. The goal of this clinical trial is to determine how ambient temperature affects thermoregulation during exercise in boys and girls aged 9-16 years compared with young adult men and women aged 20-25 years. Participants will complete four study visits at ambient temperatures of 22°C (Celsius; 72°F, Fahrenheit), 26°C (79°F), 31°C (88°F), and 36°C (97°F), while exercising at the same moderate-intensity metabolic heat production of 160 W/m² (W = watts, m = meters). During each visit, participants will complete four 15-minute periods of exercise (exercise bouts 1, 2, 3 and 4 respectively) separated by 15-minute rest periods. Testing will be performed in a whole-body air calorimeter, a specialized chamber that precisely measures heat lost through evaporation and dry heat exchange and the amount of heat stored in the body. These measurements, together with core temperature and heart rate, will allow researchers to determine how increasing ambient temperature affects the body's ability to lose heat and whether these responses differ between children and youth and young adults.

Conditions

Body Temperature Changes

Heat Stress

Child Development

Heat

Physiological Stress

Study ID

NCT07781605

Start date

Jul 19, 2026

Status verified date

Aug, 2026

Completion date

Jun 30, 2027

Anticipated

Primary completion date

Apr 30, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 9 - 25

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Healthy male or female.
  • Aged 9-16 years or 20-25 years.
  • Habitually active, defined as participating in regular physical activity at least 3 times per week for at least 20 minutes per session over the previous 6 months.
  • Able to understand and communicate in English or French.
  • For participants younger than 18 years, written parental or guardian consent and participant assent are required.

Exclusion Criteria:

  • Acute illness at the time of testing (e.g., cold, flu, or infection).
  • History of a chronic medical condition that may affect thermoregulation, cardiovascular function, or exercise capacity (e.g., cardiovascular disease, metabolic disorders, respiratory disease including asthma requiring regular medication, or neurological disorders).
  • Use of medications known to affect thermoregulation, hydration status, or cardiovascular responses.
  • History of heat-related illness (e.g., heat exhaustion or heat stroke).
  • Digestive abnormalities or gastrointestinal conditions that may contraindicate ingestion of a telemetry pill.
  • Any condition that, in the opinion of the investigators, would compromise participant safety or the integrity of the data.

Study Design

Enrollment

12 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Exercise at 22°C

Participants will complete intermittent moderate-intensity exercise at an ambient temperature of 22°C (celsius; 72°F, fahrenheit). Exercise will be performed at a metabolic heat production of 160 W/m² (W = watts, m = meters) and will consist of four 15-minute exercise periods separated by 15-minute rest periods. Exercise workload will be individually adjusted to achieve the prescribed metabolic heat production.

experimental: Exercise at 26°C

Participants will complete intermittent moderate-intensity exercise at an ambient temperature of 26°C (79°F). Exercise will be performed at a metabolic heat production of 160 W/m² and will consist of four 15-minute exercise periods separated by 15-minute rest periods. Exercise workload will be individually adjusted to achieve the prescribed metabolic heat production.

experimental: Exercise at 31°C

Participants will complete intermittent moderate-intensity exercise at an ambient temperature of 31°C (88°F). Exercise will be performed at a metabolic heat production of 160 W/m² and will consist of four 15-minute exercise periods separated by 15-minute rest periods. Exercise workload will be individually adjusted to achieve the prescribed metabolic heat production.

experimental: Exercise at 36°C

Participants will complete intermittent moderate-intensity exercise at an ambient temperature of 36°C (97°F). Exercise will be performed at a metabolic heat production of 160 W/m² and will consist of four 15-minute exercise periods separated by 15-minute rest periods. Exercise workload will be individually adjusted to achieve the prescribed metabolic heat production.

Interventions

Exercise at 22°C

Participants complete intermittent exercise at a metabolic heat production of 160 W/m² in an ambient temperature of 22°C (72°F).

Exercise at 26°C

Participants complete intermittent exercise at a metabolic heat production of 160 W/m² in an ambient temperature of 26°C (79°F).

Exercise at 31°C

Participants complete intermittent exercise at a metabolic heat production of 160 W/m² in an ambient temperature of 31°C (88°F).

Exercise at 36°C

Participants complete intermittent exercise at a metabolic heat production of 160 W/m² in an ambient temperature of 36°C (97°F).

Primary outcome measure

  • Core temperature [ Time Frame: End of each of the four 15 minutes exercise bouts (average of last 5 minutes) ]

Central Contacts and Locations

Central contacts

Glen P Kenny, PhD

6135625800gkenny@uottawa.ca

Locations

University of Ottawa

Recruiting

Ottawa, Ontario, Canada, K1N 6N5

Contacts

Glen P Kenny, PhD

613-562-5800gkenny@uottawa.ca

More Information

Sponsor

University of Ottawa

Last update posted

Aug 24, 2026

Last verified

Aug, 2026

Keywords

  • Thermoregulation
  • Heat loss
  • Heat tolerance
  • Heat strain
  • Physical activity

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of Ottawa on 2026-08-24.