Work of BreathingNCT07470086
The Role of Environmental Temperatures in Respiratory Control
A study testing Thermoneutral temperature environment, Cold temperature environment and Hot temperature environment in people with Work of Breathing, run by Indiana University at 1 site in United States.
Trial summary
Warfighters are frequently exposed to environments and life-support systems that increase breathing resistance and the work of breathing (WOB), such as aircraft on-board oxygen generation systems and underwater breathing apparatuses. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Work of Breathing
- What is being tested?
- Thermoneutral temperature environment, Cold temperature environment and Hot temperature environment
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 15 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Oct 2028to 31 Dec 2029
- 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 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Between the ages of 18-40 years old.
- English speaking and reading.
- Self-reported weekly activity of at least 120 minutes/week of high intensity exercise for the previous 2 years.
- Normal pulmonary function assessed by a resting forced expiratory volume in 1 second over forced vital capacity (FEV1/FVC) > 75% of predicted.
- Normal cognitive function assessed using the Montreal cognitive function test [18].
- Body mass index (BMI) ≤ 35 kg/m2.
- Females with a regular menstrual cycle that ranges from 21-35 days (eumenorrhea)
Who cannot join
- History of smoking or recreational smoking, cardiovascular disease, renal disease, pulmonary disease (including asthma or exercise-induced asthma), neurological disease, and metabolic disease.
- Are pregnant or could possibly be pregnant by self-report.
- Are color blind.
- Known allergy or hypersensitivity latex.
- Take selective serotonin reuptake inhibitors, stimulant medication, antibiotics, and chronically consume pain medication (Aleve, Tylenol, etc.).
- Resting blood pressure of > 130mmHg systolic or 90 mmHg diastolic and/or resting pulse rate of > 100 bpm.
- Females with irregular menstrual cycles (oligomenorrhea) that ranges from 36-90 days, and females with the absence of a menstrual cycle (amenorrhea).
- Taking birth control for the sole purpose of period cessation (eg., Mirena IUD)
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
Multidisciplinary Engineering and Sciences Hall (MESH)
Bloomington, Indiana, 47405
Scott M Clarke, 812-856-3244, scotclar@iu.edu
Zachary J Schalder, PhD, 812-855-6953, zschlade@iu.edu
About this study
Official title: Optimizing Mind-Body Interactions in Respiratory Control During Operationally Relevant Environmental Stressors
Warfighters are frequently exposed to environments and life-support systems that increase breathing resistance and the work of breathing (WOB), such as aircraft on-board oxygen generation systems and underwater breathing apparatuses. Elevated WOB increases the perception of breathing difficulty (dyspnea) and has been associated with impaired cognitive performance, including slower reaction time and reduced accuracy during attention-demanding tasks. These effects are particularly concerning in operational settings that require rapid decision-making and precise motor responses.
Despite growing recognition of this issue, critical gaps remain regarding strategies to mitigate the perceptual and cognitive consequences of elevated inspiratory resistance, especially under realistic operational stressors. The objective of this study is to determine whether exposing individuals to thermal stress alters breathing perception and cognitive performance during inspiratory resistance. Participants will perform inspiratory resistance breathing under thermoneutral, heat, and cold conditions to determine whether thermal stress amplifies WOB, breathing perception, and cognitive impairment.
Read the detailed description
Warfighters often face thermal stressors that increase the WOB, even with life-support systems in place. Both cold and heat stress elevate the WOB independently, without requiring increased inspiratory resistance. Cold stress stimulates ventilation and causes a biphasic bronchiolar response: inhaling cold air during hyperventilation leads to initial bronchodilation followed by bronchoconstriction, tightening the bronchioles and increasing airflow resistance, and thus the WOB. Warfighters are also exposed to extreme heat and hyperthermia-induced hyperventilation occurs when core body temperature reaches around 38.0°C, significantly correlating with increased WOB during heat stress. Warfighters frequently experience these environmental stressors alongside elevated breathing resistance, especially during underwater diving missions in varying temperatures or in high-performance aircraft with OBOGs exposed to extreme heat.
A critical gap in knowledge exists regarding whether high inspiratory resistance combined with thermal stress amplifies the WOB, altering the perception of breathing and cognitive and physiological responses. The study will investigate the WOB, breathing perception, cognitive function, and physiological responses under combined inspiratory resistance and thermal stress (thermoneutral, heat, and cold). It's hypothesized that WOB will increase during heat and cold stress, resulting in greater perceptions of breathing difficulty and decreased cognitive performance compared to thermoneutral conditions.
Participants will complete 4 study visits: a screening/familiarization visit (Study Day 0) followed by three experimental visits (Study Day 1, Day 2, and Day 3). Participants will be instructed to avoid caffeine, alcohol, stimulant medication, pain/anti-inflammatory medication, cannabis and cannabis related products, and vigorous exercise for at least 24 hours prior to experimental visits. On Study Day 0, participants will complete a short familiarization breathing task in which they will breathe for 10 minutes through an 8-10mm hole at the end of a customized device, generating a pre-determined inspiratory resistance of 6-9.5 centimeters of water per liter per second (cmH2O/L/s). During the breathing task, cerebral vascular, cardiovascular and autonomic activity responses will be measured. Every 5 minutes during the breathing test, participants will be asked to rate breathing intensity and unpleasantness, and perform an inspiratory capacity maneuver. Cognitive assessments will be administered every10 minutes. After the breathing task, participants will complete lung and respiratory muscle function tests.
Prior to the experimental visits, participants will be randomized to the order in which they are exposed to the interventional conditions (hot, cold, or thermoneutral). Upon arrival, an esophageal balloon will be placed to measure the pressure around the heart and lungs. Participants will then be placed into an environmental chamber (to control humidity) while wearing a special suit which allows different temperatures of water to be circulated through tubes which will expose them to the temperature conditions for roughly 30 minutes before starting the full-length breathing tasks. During thermoneutral conditions 34°C water will be perfused through special suit while participants resting the chamber set to 24°C and 40% room humidity. During the cold condition, 4°C water will be perfused through the special suit while participants rest in the chamber set to 4°C and 10% room humidity. The breathing task will commence when esophageal temperature reaches -1°C and -2°C relative to baseline esophageal temperature. During the hot condition, 50°C water will be perfused through the special suit while participants rest in the chamber set to 40°C and 40% room humidity. The breathing task will commence when esophageal temperature reaches +1°C and +2°C relative to baseline esophageal temperature. At each experimental visit, participants will complete a full-length breathing task, in which they inspire against a predetermined resistive load for 60 minutes. Biometric monitoring will be continuously performed, and cognitive assessments and participant ratings during the breathing tasks will be performed at 45- and 90-minutes of the condition exposure. A 7 day washout period will be observed between the experimental visits.
- Conditions
- Work of Breathing
- Being tested
- Thermoneutral temperature environment, Cold temperature environment, Hot temperature environment
- Keywords
- Inspiratory Resistance, Dyspnea Perception, Cognitive Performance, Thermal Stress
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Thermoneutral temperature environmentOther
During thermoneutral conditions 34°C water will be perfused through special suit while participants resting the chamber set to 24°C and 40% room humidity.
Cold temperature environmentOther
During the cold condition, 4°C water will be perfused through the special suit while participants rest in the chamber set to 4°C and 10% room humidity.
Hot temperature environmentOther
During the hot condition, 50°C water will be perfused through the special suit while participants rest in the chamber set to 40°C and 40% room humidity.
| Study group | Role | What they receive |
|---|---|---|
| Thermoneutral temperature, then Cold temperature, then Hot temperature | Active comparator | Participants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. Receives: Other: Thermoneutral temperature environment; Other: Cold temperature environment; Other: Hot temperature environment |
| Thermoneutral temperature, then Hold temperature, then Cot temperature | Active comparator | Participants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. Receives: Other: Thermoneutral temperature environment; Other: Cold temperature environment; Other: Hot temperature environment |
| Cold temperature, then Thermoneutral temperature, then Hot temperature | Active comparator | Participants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. Receives: Other: Thermoneutral temperature environment; Other: Cold temperature environment; Other: Hot temperature environment |
| Cold temperature, then Hot temperature, then Thermoneutral temperature | Active comparator | Participants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. Receives: Other: Thermoneutral temperature environment; Other: Cold temperature environment; Other: Hot temperature environment |
| Hot temperature, then Thermoneutral temperature, then Cold temperature | Active comparator | Participants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. Receives: Other: Thermoneutral temperature environment; Other: Cold temperature environment; Other: Hot temperature environment |
| Hot temperature, then Cold temperature, then Thermoneutral temperature | Active comparator | Participants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. Receives: Other: Thermoneutral temperature environment; Other: Cold temperature environment; Other: Hot temperature environment |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Stroop Color-Word Test Time Performance
Time performance on the Stroop Color-Word Test (min:sec) will be measured every 45 minutes during each experimental breathing task.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Stroop Color-Word Test Error Performance
The number of errors on the Stroop Color-Word Test will be measured every 45 minutes each experimental breathing task.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Perception of Dyspnea Intensity
Participants will rate perception of dyspnea (breathing) intensity on a visual analog scale (VAS) every 45 minutes during each breathing task. The participant will draw a vertical marker line on a horizontal line (100mm), indicating their breathing perception from "not noticeable" (0mm) to "maximal imaginable intensity" (100mm).
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Perception of Dyspnea Unpleasantness
Participants will rate perception of dyspnea (breathing) unpleasantness on a visual analog scale (VAS) every 45 minutes during each breathing task. The participant will draw a vertical marker line on a horizontal line(100mm), indicating their breathing perception from "not unpleasant"(0mm) to "maximal imaginable unpleasantness" (100mm).
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Secondary outcomes (8)
Change in Diaphragm Thickness
Diaphragm thickness will be measured via Doppler ultrasound of the10th/11th rib space during functional residual capacity (FRC; rest) and end-inspiration, as well as during the maximal inspiratory pressure (MIP)test from FRC before and after each condition.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Heart Rate Variability
Heart rate variability (beats per minute) will be measured continuously during each breathing task via 3-lead electrocardiograph (ECG).
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Peripheral Oxygen Saturation
Peripheral oxygen saturation will be measured continuously during each breathing task via pulse oximetry.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Blood Pressure - Brachial Artery
Blood pressure will be measured every 10 minutes during each breathing task via a standard blood pressure cuff and auscultation of the brachial artery.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Blood Pressure - Finger Photoplethysmography
Blood pressure will be measured continuously during each breathing task via finger photoplethysmography.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Heart Rate
Heart Rate will be measured continuously during each breathing task by 3-lead electrocardiograph (ECG).
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Cerebral Blood Oxygen Kinetics
Oxyhemoglobin and deoxyhemoglobin (uptake/extraction, uM) will be measured continuously via near-infrared spectroscopy (NIRS) of the pre-frontal cortex during each breathing task.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Cerebral Blood Velocity
Bilateral transcranial Doppler Ultrasound will be used to continuously measure middle and posterior cerebral artery blood velocity during each breathing task. The ultrasound transducers will be placed on both sides of the head at the temporal windows and the positions will be fixed using a transducer holder.
Measured: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted13 Mar 2026
- Study start1 Oct 2028 (estimated)
- Primary completion31 Dec 2029 (estimated)
- Study completion31 Dec 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Work of BreathingStudies of the same condition, open and under way.
- More trials run by Indiana UniversityThe sponsor's other registered studies.
- 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
- Crossover
- Masking
- None (open label)
- Enrolment
- 15 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Indiana University
- Sponsor type
- University, hospital or other
- Collaborators
- United States Department of Defense
- Responsible party
- Principal investigator, Tim Mickleborough, Indiana University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07470086
- Sponsor's protocol ID
- 28381 - Aim 3
- Other IDs
- FOAAFRLAFOSR20240007
- Status last verified
- Mar 2026
- First submitted
- 10 Mar 2026
- Last updated
- 13 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: The plan to share individual participant data (IPD) is still unknown. However, if other researchers request IPD, we will evaluate that request and determine to share IPD.
Study at a glance
From the registry record, last updated by the sponsor on 13 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Optimizing Mind-Body Interactions in Respiratory Control During Operationally Relevant Environmental Stressors
- ClinicalTrials.gov ID
- NCT07470086
- Acronym / sponsor ID
- 28381 - Aim 3
- Conditions
- Work of Breathing
- Keywords
- Inspiratory Resistance, Dyspnea Perception, Cognitive Performance, Thermal Stress
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 15 participants (estimated)
- Lead sponsor
- Indiana UniversityUniversity, hospital or other
- Collaborators
- United States Department of Defense
- Study start
- 1 Oct 2028 (estimated)
- Primary completion
- 31 Dec 2029 (estimated)
- Study completion
- 31 Dec 2029 (estimated)
- First posted
- 13 Mar 2026 (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.
Warfighters are frequently exposed to environments and life-support systems that increase breathing resistance and the work of breathing (WOB), such as aircraft on-board oxygen generation systems and underwater breathing apparatuses. Elevated WOB increases the perception of breathing difficulty (dyspnea) and has been associated with impaired cognitive performance, including slower reaction time and reduced accuracy during attention-demanding tasks. These effects are particularly concerning in operational settings that require rapid decision-making and precise motor responses.
Despite growing recognition of this issue, critical gaps remain regarding strategies to mitigate the perceptual and cognitive consequences of elevated inspiratory resistance, especially under realistic operational stressors. The objective of this study is to determine whether exposing individuals to thermal stress alters breathing perception and cognitive performance during inspiratory resistance. Participants will perform inspiratory resistance breathing under thermoneutral, heat, and cold conditions to determine whether thermal stress amplifies WOB, breathing perception, and cognitive impairment.
Detailed description
Warfighters often face thermal stressors that increase the WOB, even with life-support systems in place. Both cold and heat stress elevate the WOB independently, without requiring increased inspiratory resistance. Cold stress stimulates ventilation and causes a biphasic bronchiolar response: inhaling cold air during hyperventilation leads to initial bronchodilation followed by bronchoconstriction, tightening the bronchioles and increasing airflow resistance, and thus the WOB. Warfighters are also exposed to extreme heat and hyperthermia-induced hyperventilation occurs when core body temperature reaches around 38.0°C, significantly correlating with increased WOB during heat stress. Warfighters frequently experience these environmental stressors alongside elevated breathing resistance, especially during underwater diving missions in varying temperatures or in high-performance aircraft with OBOGs exposed to extreme heat.
A critical gap in knowledge exists regarding whether high inspiratory resistance combined with thermal stress amplifies the WOB, altering the perception of breathing and cognitive and physiological responses. The study will investigate the WOB, breathing perception, cognitive function, and physiological responses under combined inspiratory resistance and thermal stress (thermoneutral, heat, and cold). It's hypothesized that WOB will increase during heat and cold stress, resulting in greater perceptions of breathing difficulty and decreased cognitive performance compared to thermoneutral conditions.
Participants will complete 4 study visits: a screening/familiarization visit (Study Day 0) followed by three experimental visits (Study Day 1, Day 2, and Day 3). Participants will be instructed to avoid caffeine, alcohol, stimulant medication, pain/anti-inflammatory medication, cannabis and cannabis related products, and vigorous exercise for at least 24 hours prior to experimental visits. On Study Day 0, participants will complete a short familiarization breathing task in which they will breathe for 10 minutes through an 8-10mm hole at the end of a customized device, generating a pre-determined inspiratory resistance of 6-9.5 centimeters of water per liter per second (cmH2O/L/s). During the breathing task, cerebral vascular, cardiovascular and autonomic activity responses will be measured. Every 5 minutes during the breathing test, participants will be asked to rate breathing intensity and unpleasantness, and perform an inspiratory capacity maneuver. Cognitive assessments will be administered every10 minutes. After the breathing task, participants will complete lung and respiratory muscle function tests.
Prior to the experimental visits, participants will be randomized to the order in which they are exposed to the interventional conditions (hot, cold, or thermoneutral). Upon arrival, an esophageal balloon will be placed to measure the pressure around the heart and lungs. Participants will then be placed into an environmental chamber (to control humidity) while wearing a special suit which allows different temperatures of water to be circulated through tubes which will expose them to the temperature conditions for roughly 30 minutes before starting the full-length breathing tasks. During thermoneutral conditions 34°C water will be perfused through special suit while participants resting the chamber set to 24°C and 40% room humidity. During the cold condition, 4°C water will be perfused through the special suit while participants rest in the chamber set to 4°C and 10% room humidity. The breathing task will commence when esophageal temperature reaches -1°C and -2°C relative to baseline esophageal temperature. During the hot condition, 50°C water will be perfused through the special suit while participants rest in the chamber set to 40°C and 40% room humidity. The breathing task will commence when esophageal temperature reaches +1°C and +2°C relative to baseline esophageal temperature. At each experimental visit, participants will complete a full-length breathing task, in which they inspire against a predetermined resistive load for 60 minutes. Biometric monitoring will be continuously performed, and cognitive assessments and participant ratings during the breathing tasks will be performed at 45- and 90-minutes of the condition exposure. A 7 day washout period will be observed between the experimental visits.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 6
| Arm | Type | Receives |
|---|---|---|
| Thermoneutral temperature, then Cold temperature, then Hot temperature | Active comparator | Other: Thermoneutral temperature environment, Other: Cold temperature environment, Other: Hot temperature environmentParticipants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. |
| Thermoneutral temperature, then Hold temperature, then Cot temperature | Active comparator | Other: Thermoneutral temperature environment, Other: Cold temperature environment, Other: Hot temperature environmentParticipants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. |
| Cold temperature, then Thermoneutral temperature, then Hot temperature | Active comparator | Other: Thermoneutral temperature environment, Other: Cold temperature environment, Other: Hot temperature environmentParticipants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. |
| Cold temperature, then Hot temperature, then Thermoneutral temperature | Active comparator | Other: Thermoneutral temperature environment, Other: Cold temperature environment, Other: Hot temperature environmentParticipants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. |
| Hot temperature, then Thermoneutral temperature, then Cold temperature | Active comparator | Other: Thermoneutral temperature environment, Other: Cold temperature environment, Other: Hot temperature environmentParticipants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. |
| Hot temperature, then Cold temperature, then Thermoneutral temperature | Active comparator | Other: Thermoneutral temperature environment, Other: Cold temperature environment, Other: Hot temperature environmentParticipants will complete 3 experimental visits at which they will complete a breathing task under an assigned temperature condition. The order of condition exposure will be assigned via randomization. |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (7 listed)
- Between the ages of 18-40 years old.
- English speaking and reading.
- Self-reported weekly activity of at least 120 minutes/week of high intensity exercise for the previous 2 years.
- Normal pulmonary function assessed by a resting forced expiratory volume in 1 second over forced vital capacity (FEV1/FVC) > 75% of predicted.
- Normal cognitive function assessed using the Montreal cognitive function test [18].
Key exclusion criteria (8 listed)
- History of smoking or recreational smoking, cardiovascular disease, renal disease, pulmonary disease (including asthma or exercise-induced asthma), neurological disease, and metabolic disease.
- Are pregnant or could possibly be pregnant by self-report.
- Are color blind.
- Known allergy or hypersensitivity latex.
- Take selective serotonin reuptake inhibitors, stimulant medication, antibiotics, and chronically consume pain medication (Aleve, Tylenol, etc.).
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 |
|---|---|---|
| Thermoneutral temperature environmentDuring thermoneutral conditions 34°C water will be perfused through special suit while participants resting the chamber set to 24°C and 40% room humidity. | Other | Cold temperature, then Hot temperature, then Thermoneutral temperature, Cold temperature, then Thermoneutral temperature, then Hot temperature, Hot temperature, then Cold temperature, then Thermoneutral temperature, Hot temperature, then Thermoneutral temperature, then Cold temperature, Thermoneutral temperature, then Cold temperature, then Hot temperature, Thermoneutral temperature, then Hold temperature, then Cot temperature |
| Cold temperature environmentDuring the cold condition, 4°C water will be perfused through the special suit while participants rest in the chamber set to 4°C and 10% room humidity. | Other | Cold temperature, then Hot temperature, then Thermoneutral temperature, Cold temperature, then Thermoneutral temperature, then Hot temperature, Hot temperature, then Cold temperature, then Thermoneutral temperature, Hot temperature, then Thermoneutral temperature, then Cold temperature, Thermoneutral temperature, then Cold temperature, then Hot temperature, Thermoneutral temperature, then Hold temperature, then Cot temperature |
| Hot temperature environmentDuring the hot condition, 50°C water will be perfused through the special suit while participants rest in the chamber set to 40°C and 40% room humidity. | Other | Cold temperature, then Hot temperature, then Thermoneutral temperature, Cold temperature, then Thermoneutral temperature, then Hot temperature, Hot temperature, then Cold temperature, then Thermoneutral temperature, Hot temperature, then Thermoneutral temperature, then Cold temperature, Thermoneutral temperature, then Cold temperature, then Hot temperature, Thermoneutral temperature, then Hold temperature, then Cot temperature |
Primary outcome
Change in Stroop Color-Word Test Time Performance
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Time performance on the Stroop Color-Word Test (min:sec) will be measured every 45 minutes during each experimental breathing task.
Change in Stroop Color-Word Test Error Performance
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
The number of errors on the Stroop Color-Word Test will be measured every 45 minutes each experimental breathing task.
Change in Perception of Dyspnea Intensity
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Participants will rate perception of dyspnea (breathing) intensity on a visual analog scale (VAS) every 45 minutes during each breathing task. The participant will draw a vertical marker line on a horizontal line (100mm), indicating their breathing perception from "not noticeable" (0mm) to "maximal imaginable intensity" (100mm).
Change in Perception of Dyspnea Unpleasantness
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Participants will rate perception of dyspnea (breathing) unpleasantness on a visual analog scale (VAS) every 45 minutes during each breathing task. The participant will draw a vertical marker line on a horizontal line(100mm), indicating their breathing perception from "not unpleasant"(0mm) to "maximal imaginable unpleasantness" (100mm).
8 secondary outcomes
Change in Diaphragm Thickness
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Heart Rate Variability
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Peripheral Oxygen Saturation
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Blood Pressure - Brachial Artery
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Blood Pressure - Finger Photoplethysmography
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Heart Rate
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Cerebral Blood Oxygen Kinetics
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
Change in Cerebral Blood Velocity
Time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)
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 13 Mar 2026.
- Individual participant dataSharing planned: No. The plan to share individual participant data (IPD) is still unknown. However, if other researchers request IPD, we will evaluate that request and determine to share IPD.
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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 Thermoneutral temperature environment, Cold temperature environment and Hot temperature environment in people with Work of Breathing, run by Indiana 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 7 inclusion and 8 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: opening soon, as of the sponsor's last update on 13 Mar 2026. 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. 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 Timothy D Mickleborough, PhD (812-855-0753, tmickleb@iu.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Stroop Color-Word Test Time Performance (time frame: Before and after each breathing task on Days 1, 2, 3 (each approximately 90 minutes in duration)). The study lists 4 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 13 Mar 2026.