Clinical trial NCT06670339: Effect of Pre-cooling on Whole-body Heat Loss During Exercise-heat Stress
Official title: Effect of Pre-cooling the Body on Whole-body Heat Exchange in Young Males During Exercise in the Heat
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Thermoregulation
Cold Exposure
Heat Stress
Exercise
Keywords: Cold Stress
Heat Stress
Heat Dissipation
Physical Activity
Performance
Athletes
Workers
Lead sponsor: University of Ottawa
Sponsor class: OTHER
First posted: 2024-11-01
Enrollment: 10
Sex: MALE
Minimum age (years): 18
Maximum age (years): 30
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: BASIC_SCIENCE

Brief summary: Endurance exercise performance declines in hot environments as core body temperature increases. To enhance performance, body pre-cooling strategies, such as cold-water immersion have been employed to lower resting core temperature thereby increasing the body's heat storage capacity. In turn, the increase in body core temperature associated with exercise in the heat is blunted, allowing the individual to exercise at higher intensity and or for a longer period of time. However, the mechanisms by which pre-cooling impacts heat exchange during exercise remain unclear. While existing research has focused on the performance benefits of pre-cooling the body, relatively little is known about the impacts of pre-cooling on whole-body heat exchange during an exercise-heat stress. Investigators will therefore evaluate whole-body heat exchange (dry ± evaporative heat loss as assessed using a direct air calorimeter) during a prolonged (1-hour) moderate-intensity cycling bout in the heat (wet-bulb globe temperature of 29°C; equivalent to 37.5°C, 35% relative humidity) performed with and without pre-cooling by cool-water (\~17°C) immersion.


Eligibility criteria: Inclusion Criteria:

* Healthy young males (18-30 years)
* Non-smoking
* English or French speaking
* Ability to provide informed consent

Exclusion Criteria:

* Presence of chronic diseases (e.g., hypertension, diabetes)
* Acute illness (e.g., flu, COVID-19)
* Physical restriction limiting physical activity
* Use of medication judged by the patient or investigators to make participation in this study inadvisable.
* Sedentary

Primary outcomes:
measure: Evaporative heat loss at end exercise
timeFrame: Final 15 minutes of the 60 minutes exercise bout
measure: Dry heat loss at end exercise
timeFrame: Final 15 minutes of the 60 minutes exercise bout
measure: Total heal loss at end exercise
timeFrame: Final 15 minutes of the 60 minutes exercise bout
measure: Body heat storage during the 60-minute exercise bout
timeFrame: Over the 60 minute exercise bout
measure: Core temperature at end of exercise
timeFrame: Final 15 minutes of exercise
measure: Relative change in core temperature at end of exercise
timeFrame: Change over the 60-minute exercise bout
measure: Heart rate at end exercise
timeFrame: Final 15 minutes of exercise
measure: Mean skin temperature at end of exercise
timeFrame: Final 15 minutes of exercise
measure: Relative change in skin temperature at end of exercise
timeFrame: Change over the 60-minute exercise bout
measure: Thermal sensation A at end exercise
timeFrame: Final 15 minutes of exercise
measure: Thermal sensation B at end exercise
timeFrame: Final 15 minutes of exercise
measure: Thermal comfort at end exercise
timeFrame: Final 15 minutes of exercise
measure: Thirst sensation at end exercise
timeFrame: Final 15 minutes of exercise
measure: Rating of perceived exertion
timeFrame: Final 15 minutes of exercise
Secondary outcomes:
measure: Heart rate variability at end of exercise
timeFrame: Final 15 minutes of exercise
Other outcomes:
Locations:
city: Ottawa
country: Canada
facility: University of Ottawa
state: Ontario
Study officials:
affiliation: University of Ottawa
name: Glen P Kenny, PhD
role: PRINCIPAL_INVESTIGATOR
References: