Risk Factors for Exertional Heat Illness

Active, not recruiting

• Conditions: Exertional Heat Illness
• Interventions: 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

• Registration Number: NCT04979455
• Lead Sponsor: Liverpool John Moores University

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.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2021-05-28
• Study Start: 2021-06-11
• Study First Submitted QC: 2021-07-16
• Study First Posted: 2021-07-28
• Primary Completion: 2024-07-22
• Status Verified: 2024-10
• Last Update Submitted: 2025-03-17
• Last Update Posted: 2025-03-19
• Study Completion: 2025-07

Recruitment & Eligibility

• Status: ACTIVE_NOT_RECRUITING
• Sex: All
• Target Recruitment: 783

Inclusion Criteria

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

Exclusion Criteria

• Self-report as pregnant

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Exertional heat illness	Core temperature monitoring	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Saliva collection	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Core temperature monitoring	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Stool collection	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Sleep monitoring	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Sleep monitoring	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Blood collection	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Throat swab collection	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Blood collection	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Saliva collection	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Throat swab collection	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Stool collection	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Questionnaires	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Urine collection	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Heart rate monitoring	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Exertional heat illness	Heart rate monitoring	Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Questionnaires	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.
Control	Urine collection	Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise.

Primary Outcome Measures

Name	Time	Method
Heart rate in EHI and control group	2 Hours
Sleep quality, measured by actigraphy, between EHI and control group	Throughout study - up to 1 week
Circulating C-Reactive Protein in EHI and control group	Baseline
Circulating Aspartate Aminotransferase in EHI and control group	Baseline
Circulating Claudin 3 in EHI and control group	Baseline
Gastrointestinal illness symptomology, measured by gastrointestinal symptoms questionnaire, in EHI and control group	Throughout study - up to 1 week	0-10 Scale per symptom. Higher score indicates worse outcome
Urine osmolality in EHI and control group	Baseline
Circulating Creatine kinase in EHI and control group	Baseline
Circulating Lipopolysaccharide binding protein in EHI and control group	Baseline
Salivary cortisol in EHI and control group	Throughout study - up to 1 week
Abundance and diversity of gastrointestinal microbiota in EHI and control group	Baseline
Core temperature in EHI and control group	1 Day
Sleep quantity, measured by actigraphy, between EHI and control group	Throughout study - up to 1 week
Circulating Interleukin 6 in EHI and control group	Baseline
Detection of infectious pathogens in EHI and control groups	Throughout study - up to 1 week
Respiratory illness symptomology, measured by Jackson common cold questionnaire, in EHI and control group	Throughout study - up to 1 week	0-24 Scale. Higher score indicates worse outcome
Fitness in EHI and control group - participants ranked by time to complete fitness test	Baseline
Circulating Zonulin in EHI and control group	Baseline
Circulating immunoglobulin E in EHI and control group	Baseline
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index, in EHI and control group	Throughout study - up to 1 week	0-21 Scale. Higher score indicates worse outcome
Circulating Alanine Aminotransferase in EHI and control group	Baseline
Body mass index in EHI and control group	Baseline

Trial Locations

Locations (1)

Commando Training Centre Royal Marine; 🇬🇧 Lympstone, Devon, United Kingdom