Ambient Temperature and Thermoregulation During Exercise in Children and Youth

NCT07781605 | Recruiting

• 1 other identifier: HEPRU-2026-08B
• Study Type: interventional
• Target: 12
• Locations: 1 country
• Sites: 1

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

Keywords

Thermoregulation; Heat loss; Heat tolerance; Heat strain; Physical activity

Outcome Measures

Primary Outcomes (1)

• Core temperature

  Core temperature indexed by visceral (telemetry pill) temperature

  End of each of the four 15 minutes exercise bouts (average of last 5 minutes)

Secondary Outcomes (8)

• Evaporative heat loss

  End of each of the four 15 minutes exercise bouts (average of last 5 minutes)

• Dry heat loss

  End of each of the four 15 minutes exercise bouts (average of last 5 minutes)

• Whole-body total heat loss

  End of each of the four 15 minutes exercise bouts (average of last 5 minutes)

• Body heat storage

  Change from start to end of exercise for each of the four 15 minutes exercise bouts

• Skin temperature

  End of each of the four 15 minutes exercise bouts (average of last 5 minutes)

Study Arms (4)

Exercise at 22°C

EXPERIMENTAL

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.

Other: Exercise at 22°C

Exercise at 26°C

EXPERIMENTAL

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.

Other: Exercise at 26°C

Exercise at 31°C

EXPERIMENTAL

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.

Other: Exercise at 31°C

Exercise at 36°C

EXPERIMENTAL

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.

Other: Exercise at 36°C

Interventions

Exercise at 22°C OTHER

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

Exercise at 22°C

Exercise at 26°C OTHER

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

Exercise at 26°C

Exercise at 31°C OTHER

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

Exercise at 31°C

Exercise at 36°C OTHER

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

Exercise at 36°C

Eligibility Criteria

• Age: 9 Years - 25 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Child (0-17), Adult (18-64)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• University of Ottawa: lead

Study Sites (1)

University of Ottawa

Ottawa, Ontario, K1N 6N5, Canada

RECRUITING

MeSH Terms

Conditions

Body Temperature Changes; Heat Stress Disorders; Motor Activity

Condition Hierarchy (Ancestors)

Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Wounds and Injuries; Behavior

Central Study Contacts

Glen P Kenny, PhD

CONTACT

6135625800; gkenny@uottawa.ca

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Full Professor

Study Record Dates

• First Submitted: August 18, 2026
• First Posted: August 24, 2026
• Study Start: July 19, 2026
• Primary Completion (Estimated): April 30, 2027
• Study Completion (Estimated): June 30, 2027
• Last Updated: August 24, 2026

Record last verified: 2026-08

Locations

CA (1)