Ambient Temperature and Thermoregulation During Exercise in Children and Youth
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age9-25
SponsorUniversity of Ottawa
About this trial
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.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
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.
Disqualifiers
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).
Trial design
Design model
Crossover
Treatments tested in this trial
Exercise at 22°C
Other interventionParticipants 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 interventionParticipants 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 interventionParticipants 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 interventionParticipants complete intermittent exercise at a metabolic heat production of 160 W/m² in an ambient temperature of 36°C (97°F).
Treatment groups
12 Participants
are divided into 4 treatment groupsGroup A: Exercise at 22°CExperimental treatment 1 intervention
Group B: Exercise at 26°CExperimental treatment 1 intervention
Group C: Exercise at 31°CExperimental treatment 1 intervention
Group D: Exercise at 36°CExperimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Core temperature
Core temperature indexed by visceral (telemetry pill) temperature
Time frame
End of each of the four 15 minutes exercise bouts (average of last 5 minutes)Secondary outcomes
1
Evaporative heat loss
Evaporative heat loss as assessed using a direct air calorimeter
Time frame
End of each of the four 15 minutes exercise bouts (average of last 5 minutes)2
Dry heat loss
Dry heat loss as assessed using a direct air calorimeter
Time frame
End of each of the four 15 minutes exercise bouts (average of last 5 minutes)3
Whole-body total heat loss
Total heat loss (evaporative + dry) as assessed using a direct air calorimeter
Time frame
End of each of the four 15 minutes exercise bouts (average of last 5 minutes)4
Body heat storage
Heat stored in the body for each of the exercise bouts
Time frame
Change from start to end of exercise for each of the four 15 minutes exercise boutsSponsors and contacts
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Source ClinicalTrials.gov