Heat ExposureFemAdapt_HOTNCT06575985
Mechanisms Underlying Hypoxic, Heat and Cross-tolerance Adaptation in Women
A study testing Heat acclimation and exercise training and Thermo-neutral exercise training group in people with Heat Exposure and Exercise Training, run by Jozef Stefan Institute at 2 sites in Slovenia.
Trial summary
This study will consist of a parallel-groups design, with 30 healthy active female participants randomly assigned to either an experimental heat acclimation and exercise intervention, or a thermo-neutral exercise intervention control group. Read more about this study
- Who is it for?
- Ages 18 to 35 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Heat Exposure, Exercise Training
- What is being tested?
- Heat acclimation and exercise training and Thermo-neutral exercise training group
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 2 sitesSlovenia
- Study dates
- Oct 2024to Dec 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 35 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age: 18 - 35 years
- Body mass index: 18.5 - 25.0 kg/m^2
- Regular physical activity (at least 30 minutes of moderate-intensity activity, three times per week)
Who cannot join
- Habitual smoker within the past 5 years
- History of metabolic disorders or any medications deemed to pose an undue risk or introduce bias in any outcome measures
- Exposure to altitude > 2000 m above sea level within four weeks of scheduled participation
- Permanent residence at altitude > 1000 m above sea level
Trial locations and contacts
2 sites in 1 country.
Slovenia2 sites
Jozef Stefan Institute
Ljubljana, SI, 1000
Benjamin Narang, MSci, +38640569967, benjamin.narang@ijs.si
University of Ljubljana
Ljubljana, 1000
About this study
Official title: Investigating the Effects of a 10-day Heat Acclimation and Exercise Intervention on Physiological Adaptations and Cross-tolerance in Women
This study will consist of a parallel-groups design, with 30 healthy active female participants randomly assigned to either an experimental heat acclimation and exercise intervention, or a thermo-neutral exercise intervention control group. Interventions will be 10 days in duration, and consist of daily 60-minute exercise bouts under the appropriate environmental condition. Before and after each intervention, various tests will be conducted to establish exercise capacity under various environmental conditions, as well as underlying mechanisms of physiological adaptation induced by each intervention.
Read the detailed description
Most research on how the human body responds to different environmental conditions has primarily focused on men, leaving a gap in our understanding of how women adapt to these conditions. Heat exposure in particular is known to affect the well-being and performance of humans, as well as induce chronic adaptations through an acclimation/acclimatization process, which helps the body to better regulate core temperature. Moreover, contemporary research is beginning to explore the 'cross-tolerance' phenomenon; the notion that exposure (and acclimation/acclimatization) to one environmental stressor may affect the responses to another. In particular, both heat and hypoxia are known to activate common acclimatization pathways, with pulmonary, cardiovascular, hematological and muscular adaptations occurring to facilitate both oxygen transport and core body temperature regulation. In line with this background, the primary aim of this study is to investigate the effects of a heat acclimation and exercise intervention, relative to a thermo-neutral exercise control intervention, on exercise tolerance under various environmental conditions (heat, hypoxia, neutral) in healthy, active women. The secondary aim is to establish mechanisms of adaptation, by exploring the intervention-induced changes in pulmonary, cardiovascular, hematological and muscular factors, through various tests conducted at rest and during exercise.
To address these aims, 30 healthy active female participants, aged between 18 and 35 years, will be randomized to either an experimental (heat acclimation and exercise training) or control (thermo-neutral exercise training) group. The experimental group will complete a 10-day heat acclimation training intervention, exercising for 60 minutes per day in a climactic chamber set to 35°C and 50% relative humidity. The control group will complete a similar exercise intervention, but under thermo-neutral conditions (23°C and 50% relative humidity). Before and after the intervention period, both groups will complete a wide variety of tests, including exercise capacity measurements under each environmental condition (heat [35°C], hypoxia [Fraction of inspired oxygen = 0.135], neutral [23°C, FiO2 = 0.209]), body composition assessments, lung function testing, hemoglobin mass and blood volume quantification, skeletal muscle mitochondrial function and vascular responsiveness assessment, and venous blood sampling for a variety of sex hormone-, redox balance-, hematopoietic-, heat shock protein-, hypoxia-inducible factor- and genetic-related markers.
- Conditions
- Heat Exposure, Exercise Training
- Being tested
- Heat acclimation and exercise training, Thermo-neutral exercise training group
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Heat acclimation and exercise trainingOther
10-day intervention consisting of daily 60-min exercise sessions aimed to induce increases in core body temperature, conducted in a climactic chamber set to 35°C and 50% relative humidity.
Thermo-neutral exercise training groupOther
10-day intervention consisting of daily 60-min exercise sessions conducted in a climactic chamber set to 23°C and 50% relative humidity.
| Study group | Role | What they receive |
|---|---|---|
| Heat acclimation and exercise group | Experimental | Experimental group who will complete an exercise training intervention under hot conditions Receives: Other: Heat acclimation and exercise training |
| Thermo-neutral exercise training group | Active comparator | Control group who will complete an exercise training intervention under thermo-neutral conditions Receives: Other: Thermo-neutral exercise training group |
What is being measured
The primary outcome is the main question the study is designed to answer.
Exercise capacity under thermo-neutral normoxic conditions
Results of an incremental exercise test to exhaustion conducted at 23°C and an FiO2 of 0.209, quantified using maximal oxygen uptake
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Exercise capacity under hot normoxic conditions
Results of an incremental exercise test to exhaustion conducted at 35°C and an FiO2 of 0.209, quantified using maximal oxygen uptake
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Exercise capacity under thermo-neutral hypoxic conditions
Results of an incremental exercise test to exhaustion conducted at 23°C and an FiO2 of 0.135, quantified using maximal oxygen uptake
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Secondary outcomes (20)
Core body temperature regulation during exercise
Core body temperature measured throughout the incremental exercise tests using a rectal temperature probe.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Skin temperature regulation during exercise
Skin temperature measured throughout the incremental exercise tests using temperature probes attached to the calf, thigh, chest and arm, from which weighted averages are calculated.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Sweat rates during exercise
Sweat rate measured throughout the incremental exercise tests using a sensor attached to the forehead.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hemo-dynamic activity during exercise
Cardiac output measured throughout the incremental exercise tests by bio-electrical impedance cardiography.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Pulmonary ventilation during exercise
Pulmonary ventilation measured throughout the incremental exercise tests using flow measurements as recorded by metabolic cart.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Gas exchange during exercise
Balance of oxygen uptake and carbon dioxide production measured throughout the incremental exercise tests using gas composition sensors recorded by metabolic cart.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Muscle oxygenation during exercise
Vastus lateralis oxygenation measured throughout the incremental exercise tests using near-infrared spectroscopy.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Brain oxygenation during exercise
Cerebral oxygenation measured at the left pre-frontal cortex throughout the incremental exercise tests using near-infrared spectroscopy.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Pulse oxygen saturation during exercise
Capillary oxygen saturation measured on the right earlobe throughout the incremental exercise tests using pulse oximetry.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Body composition
Body mass measured using standard weighing scales, with body fat percentage estimated using a standardized eight-site skinfold measurement protocol with associated equation.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Lung function
Standard spirometry procedure to assess lung function using forced expiratory volume
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hemoglobin mass
Hemoglobin mass estimation using the carbon monoxide re-breathing method
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Blood/plasma volume
Blood/plasma volume estimation using the carbon monoxide re-breathing method
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Skeletal muscle mitochondrial function
Skeletal muscle mitochondrial function quantified using a peripheral vascular occlusion test, with the rate of decrease in muscle oxygenation used to estimate mitochondrial function.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Skeletal muscle vascular responsiveness
Skeletal muscle vascular responsiveness quantified using a peripheral vascular occlusion test, with the rate of increase in muscle oxygenation during re-perfusion, and the oxygenation overshoot relative to pre-occlusion baseline, used to estimate vascular responsiveness.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Blood viscosity
Blood viscosity will be measured by obtaining venous blood samples from the participants, extracting plasma, and using a cone/plate viscometer to quantify viscosity and varying shear rates.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Oxidative stress marker
Venous blood samples will be obtained to quantify redox balance from the extracted plasma.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hematopoiesis
Venous blood samples will be obtained to measure various markers of hematopoiesis from the extracted plasma, serum and/or whole blood.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Heat shock proteins
Venous blood samples will be obtained to measure heat shock proteins in the extracted plasma and serum.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hypoxia-inducible factor 1α
Venous blood samples will be obtained to measure hypoxia-inducible factor 1α in the extracted plasma and serum.
Measured: Measured once before (pre) and once up to 1 week after (post) the intervention period
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Aug 2024
- Study startOct 2024 (estimated)
- Primary completionDec 2024 (estimated)
- Study completionDec 2024 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Heat ExposureStudies 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Jozef Stefan Institute
- Sponsor type
- University, hospital or other
- Collaborators
- University of Ljubljana, University of Ljubljana, Faculty of Medicine
- Responsible party
- Principal investigator, Tadej Debevec, Jozef Stefan Institute
- Investigators
- Tadej Debevec, PhD, Principal investigator, University of Ljubljana
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06575985
- Sponsor's protocol ID
- FemAdapt_HEAT
- Other IDs
- J5-50180
- Acronym
- FemAdapt_HOT
- Status last verified
- Aug 2024
- First submitted
- 21 Aug 2024
- Last updated
- 28 Aug 2024
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: All of the individual participant data collected during the study, after de-identification, will be made publicly available using an online data repository.
Study at a glance
From the registry record, last updated by the sponsor on 28 Aug 2024. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Investigating the Effects of a 10-day Heat Acclimation and Exercise Intervention on Physiological Adaptations and Cross-tolerance in Women
- ClinicalTrials.gov ID
- NCT06575985
- Acronym / sponsor ID
- FemAdapt_HOT / FemAdapt_HEAT
- Conditions
- Heat Exposure, Exercise Training
- Study type
- Interventional
- Recruitment status
- Unknown status
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Jozef Stefan InstituteUniversity, hospital or other
- Collaborators
- University of Ljubljana, University of Ljubljana, Faculty of Medicine
- Study start
- Oct 2024 (estimated)
- Primary completion
- Dec 2024 (estimated)
- Study completion
- Dec 2024 (estimated)
- First posted
- 28 Aug 2024 (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.
This study will consist of a parallel-groups design, with 30 healthy active female participants randomly assigned to either an experimental heat acclimation and exercise intervention, or a thermo-neutral exercise intervention control group. Interventions will be 10 days in duration, and consist of daily 60-minute exercise bouts under the appropriate environmental condition. Before and after each intervention, various tests will be conducted to establish exercise capacity under various environmental conditions, as well as underlying mechanisms of physiological adaptation induced by each intervention.
Detailed description
Most research on how the human body responds to different environmental conditions has primarily focused on men, leaving a gap in our understanding of how women adapt to these conditions. Heat exposure in particular is known to affect the well-being and performance of humans, as well as induce chronic adaptations through an acclimation/acclimatization process, which helps the body to better regulate core temperature. Moreover, contemporary research is beginning to explore the 'cross-tolerance' phenomenon; the notion that exposure (and acclimation/acclimatization) to one environmental stressor may affect the responses to another. In particular, both heat and hypoxia are known to activate common acclimatization pathways, with pulmonary, cardiovascular, hematological and muscular adaptations occurring to facilitate both oxygen transport and core body temperature regulation. In line with this background, the primary aim of this study is to investigate the effects of a heat acclimation and exercise intervention, relative to a thermo-neutral exercise control intervention, on exercise tolerance under various environmental conditions (heat, hypoxia, neutral) in healthy, active women. The secondary aim is to establish mechanisms of adaptation, by exploring the intervention-induced changes in pulmonary, cardiovascular, hematological and muscular factors, through various tests conducted at rest and during exercise.
To address these aims, 30 healthy active female participants, aged between 18 and 35 years, will be randomized to either an experimental (heat acclimation and exercise training) or control (thermo-neutral exercise training) group. The experimental group will complete a 10-day heat acclimation training intervention, exercising for 60 minutes per day in a climactic chamber set to 35°C and 50% relative humidity. The control group will complete a similar exercise intervention, but under thermo-neutral conditions (23°C and 50% relative humidity). Before and after the intervention period, both groups will complete a wide variety of tests, including exercise capacity measurements under each environmental condition (heat [35°C], hypoxia [Fraction of inspired oxygen = 0.135], neutral [23°C, FiO2 = 0.209]), body composition assessments, lung function testing, hemoglobin mass and blood volume quantification, skeletal muscle mitochondrial function and vascular responsiveness assessment, and venous blood sampling for a variety of sex hormone-, redox balance-, hematopoietic-, heat shock protein-, hypoxia-inducible factor- and genetic-related markers.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Heat acclimation and exercise group | Experimental | Other: Heat acclimation and exercise trainingExperimental group who will complete an exercise training intervention under hot conditions |
| Thermo-neutral exercise training group | Active comparator | Other: Thermo-neutral exercise training groupControl group who will complete an exercise training intervention under thermo-neutral conditions |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Age: 18 - 35 years
- Body mass index: 18.5 - 25.0 kg/m^2
- Regular physical activity (at least 30 minutes of moderate-intensity activity, three times per week)
Key exclusion criteria (4 listed)
- Habitual smoker within the past 5 years
- History of metabolic disorders or any medications deemed to pose an undue risk or introduce bias in any outcome measures
- Exposure to altitude > 2000 m above sea level within four weeks of scheduled participation
- Permanent residence at altitude > 1000 m above sea level
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 |
|---|---|---|
| Heat acclimation and exercise training10-day intervention consisting of daily 60-min exercise sessions aimed to induce increases in core body temperature, conducted in a climactic chamber set to 35°C and 50% relative humidity. | Other | Heat acclimation and exercise group |
| Thermo-neutral exercise training group10-day intervention consisting of daily 60-min exercise sessions conducted in a climactic chamber set to 23°C and 50% relative humidity. | Other | Thermo-neutral exercise training group |
Primary outcome
Exercise capacity under thermo-neutral normoxic conditions
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Results of an incremental exercise test to exhaustion conducted at 23°C and an FiO2 of 0.209, quantified using maximal oxygen uptake
Exercise capacity under hot normoxic conditions
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Results of an incremental exercise test to exhaustion conducted at 35°C and an FiO2 of 0.209, quantified using maximal oxygen uptake
Exercise capacity under thermo-neutral hypoxic conditions
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Results of an incremental exercise test to exhaustion conducted at 23°C and an FiO2 of 0.135, quantified using maximal oxygen uptake
20 secondary outcomes
Core body temperature regulation during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Skin temperature regulation during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Sweat rates during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hemo-dynamic activity during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Pulmonary ventilation during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Gas exchange during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Muscle oxygenation during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Brain oxygenation during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Pulse oxygen saturation during exercise
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Body composition
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Lung function
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hemoglobin mass
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Blood/plasma volume
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Skeletal muscle mitochondrial function
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Skeletal muscle vascular responsiveness
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Blood viscosity
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Oxidative stress marker
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hematopoiesis
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Heat shock proteins
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Hypoxia-inducible factor 1α
Time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Aug 2024.
- Individual participant dataSharing planned: Yes. All of the individual participant data collected during the study, after de-identification, will be made publicly available using an online data repository.
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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. This study is not recruiting at the moment.
Tadej Debevec, PhD principal investigator
University of Ljubljana
2 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Heat acclimation and exercise training and Thermo-neutral exercise training group in people with Heat Exposure and Exercise Training, run by Jozef Stefan Institute at 2 sites in Slovenia.
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 3 inclusion and 4 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: status not confirmed, as of the sponsor's last update on 28 Aug 2024. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 2 sites in Slovenia. 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. 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?
Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
Contact Tadej Debevec, PhD (+38615207726, tadej.debevec@fsp.uni-lj.si), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Exercise capacity under thermo-neutral normoxic conditions (time frame: Measured once before (pre) and once up to 1 week after (post) the intervention period). The study lists 3 primary outcomes in all. 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 28 Aug 2024.