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Risk Factors for Exertional Heat Illness

Prospective Investigation of Risk Factors for Exertional Heat Illness

Status
Completed
Phases
Unknown
Study type
Observational
Source
ClinicalTrials.gov
Registry ID
NCT04979455
Enrollment
790
Registered
2021-07-28
Start date
2021-06-11
Completion date
2026-10-08
Last updated
2026-10-14

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Exertional Heat Illness

Brief 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). 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.

Interventions

Core temperature will be monitored on the day of exercise

BEHAVIORALQuestionnaires

Questionnaires will be completed at baseline and on the day of exercise

Heart rate will be monitored on the day of exercise

OTHERUrine collection

Urine samples will be collected at baseline and on the day of exercise

Sleep will be monitored at baseline and on the day of exercise

OTHERBlood collection

Blood samples will be completed at baseline

OTHERSaliva collection

Saliva samples will be collected at baseline and on the day of exercise

OTHERThroat swab collection

Throat swab samples will be collected at baseline and on the day of exercise

OTHERStool collection

Stool samples will be collected at baseline and on the day of exercise

Sponsors

Liverpool John Moores University
Lead SponsorOTHER
Institute of Naval Medicine (UK)
CollaboratorUNKNOWN
CTCRM Lympstone (UK)
CollaboratorUNKNOWN
University of Portsmouth
CollaboratorOTHER
Public Health Wales
CollaboratorOTHER_GOV
Bangor University
CollaboratorOTHER
Headquarters Army Recruiting and Initial Training Command (UK)
CollaboratorUNKNOWN
Defence Science and Technology (UK)
CollaboratorUNKNOWN

Study design

Observational model
COHORT
Time perspective
PROSPECTIVE

Eligibility

Sex/Gender
ALL
Age
17 Years to 35 Years
Healthy volunteers
Yes

Inclusion criteria

* Men and women aged 17-35 years enrolled in military training

Exclusion criteria

* Self-report as pregnant

Design outcomes

Primary

MeasureTime frameDescription
Body mass index in EHI and control groupBaseline—
Fitness in EHI and control group - participants ranked by time to complete fitness testBaseline—
Core temperature in EHI and control group1 Day—
Heart rate in EHI and control group2 Hours—
Urine osmolality in EHI and control groupBaseline—
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index, in EHI and control groupThroughout study - up to 1 week0-21 Scale. Higher score indicates worse outcome
Sleep quality, measured by actigraphy, between EHI and control groupThroughout study - up to 1 week—
Sleep quantity, measured by actigraphy, between EHI and control groupThroughout study - up to 1 week—
Circulating Interleukin 6 in EHI and control groupBaseline—
Circulating C-Reactive Protein in EHI and control groupBaseline—
Circulating Creatine kinase in EHI and control groupBaseline—
Circulating Aspartate Aminotransferase in EHI and control groupBaseline—
Circulating Alanine Aminotransferase in EHI and control groupBaseline—
Circulating Claudin 3 in EHI and control groupBaseline—
Circulating Zonulin in EHI and control groupBaseline—
Circulating Lipopolysaccharide binding protein in EHI and control groupBaseline—
Circulating immunoglobulin E in EHI and control groupBaseline—
Salivary cortisol in EHI and control groupThroughout study - up to 1 week—
Detection of infectious pathogens in EHI and control groupsThroughout study - up to 1 week—
Respiratory illness symptomology, measured by Jackson common cold questionnaire, in EHI and control groupThroughout study - up to 1 week0-24 Scale. Higher score indicates worse outcome
Gastrointestinal illness symptomology, measured by gastrointestinal symptoms questionnaire, in EHI and control groupThroughout study - up to 1 week0-10 Scale per symptom. Higher score indicates worse outcome
Abundance and diversity of gastrointestinal microbiota in EHI and control groupBaseline—

Countries

United Kingdom

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Oct 15, 2026