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NCT Number: NCT07781605

Ambient Temperature and Thermoregulation During Exercise in Children and Youth

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.

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Key information

Age range

9 year–25 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University of Ottawa

Ottawa, Ontario, K1N 6N5, Canada

Location status: Recruiting

Location contact

Glen P Kenny, PhD

CONTACT

[email protected]

613-562-5800 ext. 4282

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

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 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 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 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).

Primary outcomes

  1. Core temperature

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

    Core temperature indexed by visceral (telemetry pill) temperature

Secondary outcomes

  1. Evaporative heat loss

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

    Evaporative heat loss as assessed using a direct air calorimeter

  2. Dry heat loss

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

    Dry heat loss as assessed using a direct air calorimeter

  3. Whole-body total heat loss

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

    Total heat loss (evaporative + dry) as assessed using a direct air calorimeter

  4. Body heat storage

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

    Heat stored in the body for each of the exercise bouts

  5. Skin temperature

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

    Skin temperature measured at 8-sites (forehead, chest, scapula, upper arm, forearm, hand, thigh, calf) with mean value calculated as weighted values of 8 sites - forehead 7%, chest 17.5%, scapula 17.5%, upper arm 7%, forearm 7%, hand 5%, thigh 19%, and calf 20%.

  6. Change in skin temperature

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

    Skin temperature measured at 8-sites (forehead, chest, scapula, upper arm, forearm, hand, thigh, calf) with mean value calculated as weighted values of 8 sites - forehead 7%, chest 17.5%, scapula 17.5%, upper arm 7%, forearm 7%, hand 5%, thigh 19%, and calf 20%.

  7. Heart rate

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

    Heart rate measured continuously with chest-band telemetric device

  8. Thermal sensation

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

    Thermal sensation will be assessed using the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 7-point scale ("0=neutral to 7=extremely hot")

Study contacts

Contact information is provided by the study sponsor or research team.

Glen P Kenny, PhD

CONTACT

[email protected]

6135625800 ext. 4282

Sponsors and collaborators

Lead sponsor

University of Ottawa

Other

Registry information

Official study title

Ambient Temperature and Thermoregulation During Moderate-Intensity Exercise in Children and Youth

Important dates

Study start
2026
Primary completion
2027
Study completion
2027
First posted
Aug 24, 2026
Registry last updated
Aug 24, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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