Exertional Heat IllnessNCT04979455
Risk Factors for Exertional Heat Illness
An observational study of Exertional Heat Illness, run by Liverpool John Moores University at 1 site in United Kingdom.
Trial summary
The arduous nature of military training and operations require personnel to encounter high heat load, e.g., during intense physical exertion, particularly in the heat. These conditions reduce operational effectiveness and expose personnel to a risk of incapacitation and death from exertional heat illness (EHI). Read more about this study
- Who is it for?
- Ages 17 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Exertional Heat Illness
- What is being tested?
- Core temperature monitoring, Questionnaires and Heart rate monitoring
- Type of treatment
- Lifestyle or therapy programme
- How many people
- 790 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 11 Jun 2021to 8 Oct 2026
- Phase
- Observational
- 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 17 to 35 years
- All sexes
- Healthy volunteers accepted
- Child, Adult
Study population: Participants who experience and participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Who may be able to join
- Men and women aged 17-35 years enrolled in military training
Who cannot join
- Self-report as pregnant
Trial locations and contacts
1 site in 1 country.
United Kingdom1 site
Commando Training Centre Royal Marine
Lympstone, Devon, EX8 5AR
About this study
Official title: Prospective Investigation of Risk Factors for Exertional Heat Illness
The arduous nature of military training and operations require personnel to encounter high heat load, e.g., during intense physical exertion, particularly in the heat. These conditions reduce operational effectiveness and expose personnel to a risk of incapacitation and death from exertional heat illness (EHI).
The aim of this study is to examine traditional and novel risk factors that may increase thermal strain and EHI likelihood in military recruits undergoing strenuous physical exercise.
- Conditions
- Exertional Heat Illness
- Being tested
- Core temperature monitoring, Questionnaires, Heart rate monitoring, Urine collection, Sleep monitoring
- 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.
Core temperature monitoringOther
Core temperature will be monitored on the day of exercise
QuestionnairesBehavioural
Questionnaires will be completed at baseline and on the day of exercise
Heart rate monitoringOther
Heart rate will be monitored on the day of exercise
Urine collectionOther
Urine samples will be collected at baseline and on the day of exercise
Sleep monitoringOther
Sleep will be monitored at baseline and on the day of exercise
Blood collectionOther
Blood samples will be completed at baseline
Saliva collectionOther
Saliva samples will be collected at baseline and on the day of exercise
Throat swab collectionOther
Throat swab samples will be collected at baseline and on the day of exercise
Stool collectionOther
Stool samples will be collected at baseline and on the day of exercise
| Study group | Role | What they receive |
|---|---|---|
| Exertional heat illness | Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise. Receives: Other: Core temperature monitoring; Behavioral: Questionnaires; Other: Heart rate monitoring; Other: Urine collection; Other: Sleep monitoring; Other: Blood collection; Other: Saliva collection; Other: Throat swab collection; Other: Stool collection | |
| Control | Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise. Receives: Other: Core temperature monitoring; Behavioral: Questionnaires; Other: Heart rate monitoring; Other: Urine collection; Other: Sleep monitoring; Other: Blood collection; Other: Saliva collection; Other: Throat swab collection; Other: Stool collection |
What is being measured
The primary outcome is the main question the study is designed to answer.
Body mass index in EHI and control group
Measured: Baseline
Fitness in EHI and control group - participants ranked by time to complete fitness test
Measured: Baseline
Core temperature in EHI and control group
Measured: 1 Day
Heart rate in EHI and control group
Measured: 2 Hours
Urine osmolality in EHI and control group
Measured: Baseline
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index, in EHI and control group
0-21 Scale. Higher score indicates worse outcome
Measured: Throughout study - up to 1 week
Sleep quality, measured by actigraphy, between EHI and control group
Measured: Throughout study - up to 1 week
Sleep quantity, measured by actigraphy, between EHI and control group
Measured: Throughout study - up to 1 week
Circulating Interleukin 6 in EHI and control group
Measured: Baseline
Circulating C-Reactive Protein in EHI and control group
Measured: Baseline
Circulating Creatine kinase in EHI and control group
Measured: Baseline
Circulating Aspartate Aminotransferase in EHI and control group
Measured: Baseline
Circulating Alanine Aminotransferase in EHI and control group
Measured: Baseline
Circulating Claudin 3 in EHI and control group
Measured: Baseline
Circulating Zonulin in EHI and control group
Measured: Baseline
Circulating Lipopolysaccharide binding protein in EHI and control group
Measured: Baseline
Circulating immunoglobulin E in EHI and control group
Measured: Baseline
Salivary cortisol in EHI and control group
Measured: Throughout study - up to 1 week
Detection of infectious pathogens in EHI and control groups
Measured: Throughout study - up to 1 week
Respiratory illness symptomology, measured by Jackson common cold questionnaire, in EHI and control group
0-24 Scale. Higher score indicates worse outcome
Measured: Throughout study - up to 1 week
Gastrointestinal illness symptomology, measured by gastrointestinal symptoms questionnaire, in EHI and control group
0-10 Scale per symptom. Higher score indicates worse outcome
Measured: Throughout study - up to 1 week
Abundance and diversity of gastrointestinal microbiota in EHI and control group
Measured: Baseline
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Jul 2021
- Study start11 Jun 2021
- Primary completion22 Jul 2024
- Study completion8 Oct 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for Exertional Heat IllnessStudies 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 790 participants (actual)
Sponsor and investigators
- Lead sponsor
- Liverpool John Moores University
- Sponsor type
- University, hospital or other
- Collaborators
- Institute of Naval Medicine (UK), CTCRM Lympstone (UK), University of Portsmouth, Public Health Wales, Bangor University, Headquarters Army Recruiting and Initial Training Command (UK), Defence Science and Technology (UK)
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04979455
- Sponsor's protocol ID
- 2029/MODREC/21
- Status last verified
- Oct 2026
- First submitted
- 28 May 2021
- Last updated
- 14 Oct 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
Tyson HC, Zurawlew MJ, Robinson MR, Hemingway R, Corbett JO, Tipton MJ, Gould AAM, Moore C, Jones R, Pheasant K, Rawcliffe AJ, Izard RM, Roberts AJ, Walsh NP. Infection as an Exertional Heat Illness Risk Factor: A Prospective Cohort Study. Med Sci Sports Exerc. 2026 Sep 1;58(9):2101-2110. doi: 10.1249/MSS.0000000000004012. Epub 2026 Apr 23.
PubMed 42023778
Study at a glance
From the registry record, last updated by the sponsor on 14 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Prospective Investigation of Risk Factors for Exertional Heat Illness
- ClinicalTrials.gov ID
- NCT04979455
- Acronym / sponsor ID
- 2029/MODREC/21
- Conditions
- Exertional Heat Illness
- Study type
- Observational
- Recruitment status
- Completed
- Enrolment
- 790 participants (actual)
- Lead sponsor
- Liverpool John Moores UniversityUniversity, hospital or other
- Collaborators
- Institute of Naval Medicine (UK), CTCRM Lympstone (UK), University of Portsmouth, Public Health Wales, Bangor University, Headquarters Army Recruiting and Initial Training Command (UK), Defence Science and Technology (UK)
- Study start
- 11 Jun 2021 (actual)
- Primary completion
- 22 Jul 2024 (actual)
- Study completion
- 8 Oct 2026 (actual)
- First posted
- 28 Jul 2021 (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 arduous nature of military training and operations require personnel to encounter high heat load, e.g., during intense physical exertion, particularly in the heat. These conditions reduce operational effectiveness and expose personnel to a risk of incapacitation and death from exertional heat illness (EHI).
The aim of this study is to examine traditional and novel risk factors that may increase thermal strain and EHI likelihood in military recruits undergoing strenuous physical exercise.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Exertional heat illness | – | Other: Core temperature monitoring, Behavioral: Questionnaires, Other: Heart rate monitoring, Other: Urine collection, Other: Sleep monitoring, Other: Blood collection, Other: Saliva collection, Other: Throat swab collection, Other: Stool collectionParticipants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise. |
| Control | – | Other: Core temperature monitoring, Behavioral: Questionnaires, Other: Heart rate monitoring, Other: Urine collection, Other: Sleep monitoring, Other: Blood collection, Other: Saliva collection, Other: Throat swab collection, Other: Stool collectionParticipants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise. |
Who may qualify
- Ages
- 17 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child, Adult
- Study population
- Participants who experience and participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Key inclusion criteria (1 listed)
- Men and women aged 17-35 years enrolled in military training
Key exclusion criteria (1 listed)
- Self-report as pregnant
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 |
|---|---|---|
| Core temperature monitoringCore temperature will be monitored on the day of exercise | Other | Control, Exertional heat illness |
| QuestionnairesQuestionnaires will be completed at baseline and on the day of exercise | Behavioural | Control, Exertional heat illness |
| Heart rate monitoringHeart rate will be monitored on the day of exercise | Other | Control, Exertional heat illness |
| Urine collectionUrine samples will be collected at baseline and on the day of exercise | Other | Control, Exertional heat illness |
| Sleep monitoringSleep will be monitored at baseline and on the day of exercise | Other | Control, Exertional heat illness |
| Blood collectionBlood samples will be completed at baseline | Other | Control, Exertional heat illness |
| Saliva collectionSaliva samples will be collected at baseline and on the day of exercise | Other | Control, Exertional heat illness |
| Throat swab collectionThroat swab samples will be collected at baseline and on the day of exercise | Other | Control, Exertional heat illness |
| Stool collectionStool samples will be collected at baseline and on the day of exercise | Other | Control, Exertional heat illness |
Primary outcome
Body mass index in EHI and control group
Time frame: Baseline
Fitness in EHI and control group - participants ranked by time to complete fitness test
Time frame: Baseline
Core temperature in EHI and control group
Time frame: 1 Day
Heart rate in EHI and control group
Time frame: 2 Hours
Urine osmolality in EHI and control group
Time frame: Baseline
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index, in EHI and control group
Time frame: Throughout study - up to 1 week
0-21 Scale. Higher score indicates worse outcome
Sleep quality, measured by actigraphy, between EHI and control group
Time frame: Throughout study - up to 1 week
Sleep quantity, measured by actigraphy, between EHI and control group
Time frame: Throughout study - up to 1 week
Circulating Interleukin 6 in EHI and control group
Time frame: Baseline
Circulating C-Reactive Protein in EHI and control group
Time frame: Baseline
Circulating Creatine kinase in EHI and control group
Time frame: Baseline
Circulating Aspartate Aminotransferase in EHI and control group
Time frame: Baseline
Circulating Alanine Aminotransferase in EHI and control group
Time frame: Baseline
Circulating Claudin 3 in EHI and control group
Time frame: Baseline
Circulating Zonulin in EHI and control group
Time frame: Baseline
Circulating Lipopolysaccharide binding protein in EHI and control group
Time frame: Baseline
Circulating immunoglobulin E in EHI and control group
Time frame: Baseline
Salivary cortisol in EHI and control group
Time frame: Throughout study - up to 1 week
Detection of infectious pathogens in EHI and control groups
Time frame: Throughout study - up to 1 week
Respiratory illness symptomology, measured by Jackson common cold questionnaire, in EHI and control group
Time frame: Throughout study - up to 1 week
0-24 Scale. Higher score indicates worse outcome
Gastrointestinal illness symptomology, measured by gastrointestinal symptoms questionnaire, in EHI and control group
Time frame: Throughout study - up to 1 week
0-10 Scale per symptom. Higher score indicates worse outcome
Abundance and diversity of gastrointestinal microbiota in EHI and control group
Time frame: Baseline
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 14 Oct 2026.
- Derived from this study: PubMed 42023778Tyson HC, Zurawlew MJ, Robinson MR, Hemingway R, Corbett JO, Tipton MJ, Gould AAM, Moore C, Jones R, Pheasant K, Rawcliffe AJ, Izard RM, Roberts AJ, Walsh NP. Infection as an Exertional Heat Illness Risk Factor: A Prospective Cohort Study. Med Sci Sports Exerc. 2026 Sep 1;58(9):2101-2110. doi: 10.1249/MSS.0000000000004012. Epub 2026 Apr 23.
- 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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Exertional Heat Illness, run by Liverpool John Moores University at 1 site in United Kingdom.
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 1 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 14 Oct 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 Kingdom. 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?
Body mass index in EHI and control group (time frame: Baseline). The study lists 22 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04979455, which also lists 1 linked publication.
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 14 Oct 2026.