ExerciseNCT06872762
Effect of Exercise and Heat Stress on Acute Cardiometabolic Adaptations in Healthy Young Adults
A study testing Exercise and Heat strain in people with Exercise and Heat Strain, run by Northern Arizona University at 1 site in United States.
Trial summary
Life in space is completely void of physical and environmental stress. It is well known that living things need regular physical stress (e.g. exercise) to remain strong, functional and healthy. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Exercise, Heat Strain, Control Condition
- What is being tested?
- Exercise and Heat strain
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 15 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Mar 2025to 21 May 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- -regularly physically active as determined via ParQ+
Who cannot join
- smokers
- bronchial asthma
- chronic obstructive pulmonary disease
- obese
- alcoholism
- requiring daily medications that may effect responses to exercise,
Show all 12Show fewer
- anti-arrhythmogenics
- inhalers
- history of cardiovascular, respiratory, neurological, skeletal muscle disease
- irregular/absent menstrual cycle (females)
- unexpected responses to pre-experimental exercise tests
- previous diagnosis of heat stroke
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Northern Arizona University
Flagstaff, Arizona, 86011
TRAVIS GIBBONS, PhD, 928-523-4002, travis.gibbons@nau.edu
About this study
Official title: Does Heat Stress Improve the Acute Metabolic and Cardiovascular Adaptations to Exercise
Life in space is completely void of physical and environmental stress. It is well known that living things need regular physical stress (e.g. exercise) to remain strong, functional and healthy. More and more research is showing that regular environmental stress, for example heat and hypoxia, can further improve physical health. Astronauts aboard the international space station (ISS) exercise for 1-2 hours every day to avoid physical deconditioning that would otherwise cause them to age rapidly in space. Although physical exercise is very effective in remedying this deconditioning, today's astronauts still have physiological changes that indicate accelerated aging. This is a cause for concern given NASA's priority to travel to mars within the next decade; a mission that will require at least double the duration in space for our astronauts. The investigators think that the complete absence of environmental stress, i.e., heat, may be contributing to the accelerated aging that occurs during spaceflight. Our study will assess the health effects of adding heat stress to exercise that could be performed in space by astronauts. The goal is to inform best practice for astronauts to avoid physical deconditioning during long-duration spaceflight. This information will also be relevant to life on earth as spaceflight is a model of inactivity here on earth. Therefore, the potential benefits of adding heat stress will likely translate to life in space and on earth.
Read the detailed description
Experimental procedures:
Participants will visit the lab on seven occasions. Participants will be required to practice regular exercise and dietary habits that can be easily replicated in the 24 hours prior to every laboratory visit. Exercise and dietary patterns will be documented during the first visit and thereafter the participants will be reminded of these practices and instructed to match them as closely as possible in the 24 hours leading up to all subsequent visits. Participants will only be instructed to avoid heavy exercise in the 12 hours prior to testing sessions. On the first visit, participants will be introduced into the lab, where the investigators will give oral and written instruction detailing the procedures and associated risks related to participating. Details of the experimental visits are outlined below:
Familiarization Visit (1 hour):
- Familiarization and fitness test
- Lactate threshold and maximal aerobic power test on an upright cycle ergometer.
Experimental visit #1 (6 hours):
- Control exercise, heated exercise or control rest
- Rectal or esophageal thermistor will be inserted.
- Venous cannula will be inserted by trained phlebotomist (Chloe Gustafson, Dr Travis Gibbons).
- Cycling exercise for 90 minutes at 90% of lactate threshold with 2 pedestal fans to maximize heat loss and prevent core temperature increase to <1 ̊ C.
- 2.5 hours of resting recovery in semi-supine position.
- Vascular assessment.
- Glucose tolerance test (blood will be sampled for glucose and insulin 15, 30, 60 and 120 minutes after consuming a mixed macronutrient meal)
- Rectal thermistor and venous cannula will be removed and participant will leave.
Experimental visit #2 (6 hours):
- Control exercise, heated exercise or control rest
- Complete identical procedures as experimental visit #2 with the following exceptions:
- Cycling exercise for 90 minutes at 90% of lactate threshold.
- No fans will be used to maximal heat gain.
- Participants will wear a water impermeable jacket, pants and gloves, and wear a winter hat (beanie).
- Core temperature will be allowed to rise naturally but exercise will stop if core temperature reaches 40 ̊ C.
Experimental visit #3 (6 hours):
- Control exercise, heated exercise or control rest
- Complete identical procedures as experimental visit #2 with the following exceptions:
- Participant will rest comfortably in the semi-supine position for 90 minutes.
Follow-up assessments after experimental visits 1, 2, and 3 (1 hour):
- Rectal or esophageal thermistor will be inserted.
- Participant will lie comfortably for 10 minutes.
- Arterial stiffness assessment will be performed (3 minutes)
- A venous blood sample will be collected.
- Participant will complete 5-minute blood volume assessment via carbon monoxide rebreathing technique.
- A final blood draw will be performed.
- Conditions
- Exercise, Heat Strain, Control Condition
- Being tested
- Exercise, Heat strain
- Keywords
- exercise, heat strain, glucose tolerance test, arterial compliance
- Medical subject headings
- Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ExerciseBehavioural
Exercise for 90 minutes (cycling) while minimizing thermal strain
Heat strainBehavioural
Exercise for 90 minutes (cycling) while maximizing thermal strain
| Study group | Role | What they receive |
|---|---|---|
| Exercise | Experimental | Participants exercise for 90 minutes trying to remain cool with fans and limited clothing. Receives: Behavioral: Exercise; Behavioral: Heat strain |
| Heat strain | Experimental | Participants exercise for 90 minutes wearing winter and rain clothes to develop heat strain. Receives: Behavioral: Exercise; Behavioral: Heat strain |
| Control | Placebo comparator | Resting control for 90 minutes. Not allowed to exercise. Receives: Behavioral: Exercise; Behavioral: Heat strain |
What is being measured
The primary outcome is the main question the study is designed to answer.
Glucose tolerance
Glucose to insulin concentration ratio in serum.
Measured: 2 hours after intervention complete
Secondary outcomes (2)
Arterial compliance
Change in artery diameter (millimeter) assessed via ultrasound per change in artery pressure (mm Hg) assessed via tonometry.
Measured: 2 hours after intervention complete
Plasma volume expansion
Plasma volume change measured with carbon monoxide rebreathe
Measured: 24 hours after intervention
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted12 Mar 2025
- Study start1 Mar 2025
- Primary completion31 Dec 2025 (estimated)
- Study completion21 May 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ExerciseStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Random order, repeated measures, cross-over
- Masking
- Single blind
- Who is masked
- Investigator
- Enrolment
- 15 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Northern Arizona University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Travis Gibbons, Northern Arizona University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06872762
- Sponsor's protocol ID
- 2224584
- Status last verified
- Feb 2025
- First submitted
- 24 Feb 2025
- Last updated
- 12 Mar 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: I am concerned for privacy protection of our participants.
Study at a glance
From the registry record, last updated by the sponsor on 12 Mar 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Does Heat Stress Improve the Acute Metabolic and Cardiovascular Adaptations to Exercise
- ClinicalTrials.gov ID
- NCT06872762
- Acronym / sponsor ID
- 2224584
- Conditions
- Exercise, Heat Strain, Control Condition
- Keywords
- exercise, heat strain, glucose tolerance test, arterial compliance
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 15 participants (estimated)
- Lead sponsor
- Northern Arizona UniversityUniversity, hospital or other
- Study start
- 1 Mar 2025 (actual)
- Primary completion
- 31 Dec 2025 (estimated)
- Study completion
- 21 May 2026 (estimated)
- First posted
- 12 Mar 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Life in space is completely void of physical and environmental stress. It is well known that living things need regular physical stress (e.g. exercise) to remain strong, functional and healthy. More and more research is showing that regular environmental stress, for example heat and hypoxia, can further improve physical health. Astronauts aboard the international space station (ISS) exercise for 1-2 hours every day to avoid physical deconditioning that would otherwise cause them to age rapidly in space. Although physical exercise is very effective in remedying this deconditioning, today's astronauts still have physiological changes that indicate accelerated aging. This is a cause for concern given NASA's priority to travel to mars within the next decade; a mission that will require at least double the duration in space for our astronauts. The investigators think that the complete absence of environmental stress, i.e., heat, may be contributing to the accelerated aging that occurs during spaceflight. Our study will assess the health effects of adding heat stress to exercise that could be performed in space by astronauts. The goal is to inform best practice for astronauts to avoid physical deconditioning during long-duration spaceflight. This information will also be relevant to life on earth as spaceflight is a model of inactivity here on earth. Therefore, the potential benefits of adding heat stress will likely translate to life in space and on earth.
Detailed description
Experimental procedures:
Participants will visit the lab on seven occasions. Participants will be required to practice regular exercise and dietary habits that can be easily replicated in the 24 hours prior to every laboratory visit. Exercise and dietary patterns will be documented during the first visit and thereafter the participants will be reminded of these practices and instructed to match them as closely as possible in the 24 hours leading up to all subsequent visits. Participants will only be instructed to avoid heavy exercise in the 12 hours prior to testing sessions. On the first visit, participants will be introduced into the lab, where the investigators will give oral and written instruction detailing the procedures and associated risks related to participating. Details of the experimental visits are outlined below:
Familiarization Visit (1 hour):
- Familiarization and fitness test
- Lactate threshold and maximal aerobic power test on an upright cycle ergometer.
Experimental visit #1 (6 hours):
- Control exercise, heated exercise or control rest
- Rectal or esophageal thermistor will be inserted.
- Venous cannula will be inserted by trained phlebotomist (Chloe Gustafson, Dr Travis Gibbons).
- Cycling exercise for 90 minutes at 90% of lactate threshold with 2 pedestal fans to maximize heat loss and prevent core temperature increase to <1 ̊ C.
- 2.5 hours of resting recovery in semi-supine position.
- Vascular assessment.
- Glucose tolerance test (blood will be sampled for glucose and insulin 15, 30, 60 and 120 minutes after consuming a mixed macronutrient meal)
- Rectal thermistor and venous cannula will be removed and participant will leave.
Experimental visit #2 (6 hours):
- Control exercise, heated exercise or control rest
- Complete identical procedures as experimental visit #2 with the following exceptions:
- Cycling exercise for 90 minutes at 90% of lactate threshold.
- No fans will be used to maximal heat gain.
- Participants will wear a water impermeable jacket, pants and gloves, and wear a winter hat (beanie).
- Core temperature will be allowed to rise naturally but exercise will stop if core temperature reaches 40 ̊ C.
Experimental visit #3 (6 hours):
- Control exercise, heated exercise or control rest
- Complete identical procedures as experimental visit #2 with the following exceptions:
- Participant will rest comfortably in the semi-supine position for 90 minutes.
Follow-up assessments after experimental visits 1, 2, and 3 (1 hour):
- Rectal or esophageal thermistor will be inserted.
- Participant will lie comfortably for 10 minutes.
- Arterial stiffness assessment will be performed (3 minutes)
- A venous blood sample will be collected.
- Participant will complete 5-minute blood volume assessment via carbon monoxide rebreathing technique.
- A final blood draw will be performed.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Single blind (investigator)
- Number of arms
- 3
- Model description
- Random order, repeated measures, cross-over
| Arm | Type | Receives |
|---|---|---|
| Exercise | Experimental | Behavioral: Exercise, Behavioral: Heat strainParticipants exercise for 90 minutes trying to remain cool with fans and limited clothing. |
| Heat strain | Experimental | Behavioral: Exercise, Behavioral: Heat strainParticipants exercise for 90 minutes wearing winter and rain clothes to develop heat strain. |
| Control | Placebo comparator | Behavioral: Exercise, Behavioral: Heat strainResting control for 90 minutes. Not allowed to exercise. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- -regularly physically active as determined via ParQ+
Key exclusion criteria (12 listed)
- smokers
- bronchial asthma
- chronic obstructive pulmonary disease
- obese
- alcoholism
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ExerciseExercise for 90 minutes (cycling) while minimizing thermal strain | Behavioural | Control, Exercise, Heat strain |
| Heat strainExercise for 90 minutes (cycling) while maximizing thermal strain | Behavioural | Control, Exercise, Heat strain |
Primary outcome
Glucose tolerance
Time frame: 2 hours after intervention complete
Glucose to insulin concentration ratio in serum.
2 secondary outcomes
Arterial compliance
Time frame: 2 hours after intervention complete
Plasma volume expansion
Time frame: 24 hours after intervention
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 12 Mar 2025.
- Individual participant dataSharing planned: No. I am concerned for privacy protection of our participants.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Exercise and Heat strain in people with Exercise and Heat Strain, run by Northern Arizona University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 12 Mar 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Travis Gibbons, PhD (928-523-4002, travis.gibbons@nau.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Glucose tolerance (time frame: 2 hours after intervention complete). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Mar 2025.