Heat Stress, ExertionalAcute-XONCT07080853
Acute Exercise With Overdressing
A study testing Exercise with Overdressing in people with Heat Stress, Exertional and Heat Acclimation and Thermotolerance, run by United States Army Research Institute of Environmental Medicine at 1 site in United States.
Trial summary
The purpose of this study is to determine if exercise with extra clothing in a gym-like environment can increase body temperatures appropriately to help people adapt to the heat. Read more about this study
- Who is it for?
- Ages 18 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- Heat Stress, Exertional, Heat Acclimation and Thermotolerance
- What is being tested?
- Exercise with Overdressing
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 23 participants
- Where
- 1 siteUnited States
- Study dates
- 22 Jun 2023to 28 Apr 2025
- 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 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Male or female, age 18-45
- Females must be premenopausal
- Body mass index 18.5-30.0 kg m-2
- In good health as determined by the Office of Medical Support \& Oversight (OMSO) General Medical Clearance
- Performs aerobic exercise at least 2 times per week and capable of running 2 miles in under 16:00 (8 minute mile pace)
- Willing to abstain from exercise and alcoholic beverages for 24 hours before each study visit.
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- Willing to abstain from caffeine for 12 hours prior to all study visits.
- Willing to abstain from food for 2 hours prior to all study visits.
- Willing to abstain from nicotine/tobacco for at least 8 hours prior to all study visits.
- Have supervisor approval if permanent party military or a federal employee at U.S. Army Natick Soldier System Center
Who cannot join
- Females who are pregnant or planning to become pregnant during the study
- Taking dietary supplements, prescriptions, or over the counter medication, other than a contraceptive (unless approved by OMSO \& PI)
- Abnormal blood count during OMSO medical screening (For example: hemoglobin (Hb) outside of the typical normal values reported by LabCorp in accordance with OMSO (Normal [Hb] Males = 12.6-17.7 g/dL; Females = 11.1-15.9 g/dL) or hematocrit (Hct) outside of the normal ranges (Normal Hct Males = 37.5-51.0%; Females = 34.0-46.6%) levels, presence of abnormal blood chemicals (hemoglobin S or sickle cell traits)
- Any history of pulmonary or cardiovascular disease
- Any history of asthma
- Current or recent respiratory tract or sinus infections (< 1 month prior)
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- History of heat intolerance or orthostatic intolerance
- Diagnosed and/or treated for fluid/electrolyte imbalance within the last 30 days
- History of obstructive disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis.
- Scheduled MRI during testing
- Allergies to adhesives (e.g., medical tape).
Trial locations and contacts
1 site in 1 country.
United States1 site
US Army Research Institute of Environmental Medicine
Natick, Massachusetts, 01760
About this study
Official title: Efficacy of a Novel Exercise + Overdressing Protocol to Induce Targeted Heat Stress in Temperate Environments (Acute XO-Study)
The purpose of this study is to determine if exercise with extra clothing in a gym-like environment can increase body temperatures appropriately to help people adapt to the heat.
Read the detailed description
The purpose of the present study is to examine the influence of a novel 90-minute exercise + overdressing protocol on thermal responses in comparison to matched exercise in standard PT clothing. Sixteen healthy and fit adults (8 men and 8 women) will complete two 90-minute exercise sessions (randomized order) in a temperate environment (~20°C, ~50% relative humidity, and ~1 mph air velocity) involving a 30-minute run immediately followed by a 60-minute walk. Participants will wear standard physical training (PT) clothing (shorts, t-shirt) during one session and an overdressing ensemble in the other. The investigators hypothesize that 1) exercise + overdressing will elevate core temperature to between 38.3°C and 39.3°C for at least 45 minutes; and 2) elevations in core temperature, skin temperature, heart rate, and sweat rate will be substantially larger than observed with 90 minutes of matched exercise in standard PT clothing.
- Being tested
- Exercise with Overdressing, Control Exercise
- Keywords
- Heat acclimation, Overdressing
- Medical subject headings
- Heat Stress Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Exercise with OverdressingOther
Run for 30 minutes followed by walk for 60 minutes in a temperate (gym-like environment) wearing overdressing ensemble.
Control ExerciseOther
Run for 30 minutes followed by walk for 60 minutes in a temperate (gym-like environment) wearing control clothing ensemble.
| Study group | Role | What they receive |
|---|---|---|
| Exercise with Overdressing | Experimental | Exercise with overdressing clothing ensemble Receives: Other: Exercise with Overdressing |
| Control Exercise | Active comparator | Exercise with normal attire Receives: Other: Control Exercise |
What is being measured
The primary outcome is the main question the study is designed to answer.
Core temperature
Core temperature during exercise
Measured: Up to 90 minutes
Heart Rate
Heart rate during exercise
Measured: Up to 90 minutes
Skin temperature
Mean-weighted skin temperature during exercise
Measured: Up to 90 minutes
Whole-body sweat loss
Measured: 90 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Jul 2025
- Study start22 Jun 2023
- Primary completion28 Apr 2025
- Study completion28 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Heat Stress, ExertionalStudies 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
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 23 participants (actual)
Sponsor and investigators
- Lead sponsor
- United States Army Research Institute of Environmental Medicine
- Sponsor type
- US federal agency
- Responsible party
- Sponsor
- Investigators
- Benjamin J Ryan, PhD, Principal investigator, United States Army Research Institute of Environmental Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07080853
- Sponsor's protocol ID
- 23-14
- Acronym
- Acute-XO
- Status last verified
- Dec 2025
- First submitted
- 2 Jul 2025
- Last updated
- 24 Dec 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 24 Dec 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Efficacy of a Novel Exercise + Overdressing Protocol to Induce Targeted Heat Stress in Temperate Environments (Acute XO-Study)
- ClinicalTrials.gov ID
- NCT07080853
- Acronym / sponsor ID
- Acute-XO / 23-14
- Keywords
- Heat acclimation, Overdressing
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 23 participants (actual)
- Lead sponsor
- United States Army Research Institute of Environmental MedicineUS federal agency
- Study start
- 22 Jun 2023 (actual)
- Primary completion
- 28 Apr 2025 (actual)
- Study completion
- 28 Apr 2025 (actual)
- First posted
- 23 Jul 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.
The purpose of this study is to determine if exercise with extra clothing in a gym-like environment can increase body temperatures appropriately to help people adapt to the heat.
Detailed description
The purpose of the present study is to examine the influence of a novel 90-minute exercise + overdressing protocol on thermal responses in comparison to matched exercise in standard PT clothing. Sixteen healthy and fit adults (8 men and 8 women) will complete two 90-minute exercise sessions (randomized order) in a temperate environment (~20°C, ~50% relative humidity, and ~1 mph air velocity) involving a 30-minute run immediately followed by a 60-minute walk. Participants will wear standard physical training (PT) clothing (shorts, t-shirt) during one session and an overdressing ensemble in the other. The investigators hypothesize that 1) exercise + overdressing will elevate core temperature to between 38.3°C and 39.3°C for at least 45 minutes; and 2) elevations in core temperature, skin temperature, heart rate, and sweat rate will be substantially larger than observed with 90 minutes of matched exercise in standard PT clothing.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Exercise with Overdressing | Experimental | Other: Exercise with OverdressingExercise with overdressing clothing ensemble |
| Control Exercise | Active comparator | Other: Control ExerciseExercise with normal attire |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (10 listed)
- Male or female, age 18-45
- Females must be premenopausal
- Body mass index 18.5-30.0 kg m-2
- In good health as determined by the Office of Medical Support \& Oversight (OMSO) General Medical Clearance
- Performs aerobic exercise at least 2 times per week and capable of running 2 miles in under 16:00 (8 minute mile pace)
Key exclusion criteria (11 listed)
- Females who are pregnant or planning to become pregnant during the study
- Taking dietary supplements, prescriptions, or over the counter medication, other than a contraceptive (unless approved by OMSO \& PI)
- Abnormal blood count during OMSO medical screening (For example: hemoglobin (Hb) outside of the typical normal values reported by LabCorp in accordance with OMSO (Normal [Hb] Males = 12.6-17.7 g/dL; Females = 11.1-15.9 g/dL) or hematocrit (Hct) outside of the normal ranges (Normal Hct Males = 37.5-51.0%; Females = 34.0-46.6%) levels, presence of abnormal blood chemicals (hemoglobin S or sickle cell traits)
- Any history of pulmonary or cardiovascular disease
- Any history of asthma
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 |
|---|---|---|
| Exercise with OverdressingRun for 30 minutes followed by walk for 60 minutes in a temperate (gym-like environment) wearing overdressing ensemble. | Other | Exercise with Overdressing |
| Control ExerciseRun for 30 minutes followed by walk for 60 minutes in a temperate (gym-like environment) wearing control clothing ensemble. | Other | Control Exercise |
Primary outcome
Core temperature
Time frame: Up to 90 minutes
Core temperature during exercise
Heart Rate
Time frame: Up to 90 minutes
Heart rate during exercise
Skin temperature
Time frame: Up to 90 minutes
Mean-weighted skin temperature during exercise
Whole-body sweat loss
Time frame: 90 minutes
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 24 Dec 2025.
- Individual participant dataSharing planned: No
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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.
Benjamin J Ryan, PhD principal investigator
United States Army Research Institute of Environmental Medicine
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 with Overdressing in people with Heat Stress, Exertional and Heat Acclimation and Thermotolerance, run by United States Army Research Institute of Environmental Medicine 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 10 inclusion and 11 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: finished, as of the sponsor's last update on 24 Dec 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. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Core temperature (time frame: Up to 90 minutes). 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 24 Dec 2025.