Comparing Exertional Heat Illness Risk Factors Between Patients and Controls
- Conditions
- Exertional Heat Illness
- Interventions
- Other: Heat Tolerance Assessment
- Registration Number
- NCT05303142
- Lead Sponsor
- University of Portsmouth
- 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 primary aim of this study is to compare putative 'chronic' EHI risk factors between a cohort who have suffered a history of EHI and a control cohort with no EHI history. The secondary aim is to examine the influence of these EHI risk factors on thermoregulation during a standard heat tolerance assessment.
- Detailed Description
Military training and operations present a risk of incapacitation and death from Exertional Heat Illness (EHI). However, widely accepted EHI risk factors are absent in almost half of all United Kingdom (UK) military EHI cases, indicating that a significant number of EHI cases in military personnel involve alternative risk factors. Risk factors for EHI can been classified along a spectrum ranging from acute (e.g. recent poor sleep) to chronic (e.g. low fitness), with the role of chronic risk factors supported by the observation that individuals who have suffered an EHI are at a substantially increased risk of subsequent EHI. The primary aim of this study is to compare putative 'chronic' EHI risk factors (e.g. composition of gastrointestinal (GI) microbiome, infection and inflammation, trait-like psychological factors) between a cohort who have suffered a history of EHI and a control cohort with no EHI history. The secondary aim is to examine the influence of these EHI risk factors on thermoregulation during a standard heat tolerance assessment.
Recruitment & Eligibility
- Status
- COMPLETED
- Sex
- All
- Target Recruitment
- 95
Individuals with a history of EHI:
- Previous EHI episode
- Normal resting ECG
- Male or female
- 18 - 40 years
Control participants:
- No previous history of EHI
- Normal resting ECG
- Male or female
- 18 - 40 years
Not provided
Study & Design
- Study Type
- OBSERVATIONAL
- Study Design
- Not specified
- Arm && Interventions
Group Intervention Description Control participants without a history of EHI Heat Tolerance Assessment Matched control participants with no history of EHI. They will be matched to the experimental group for parameters that are known to influence thermoregulatory responses to exercise heat-stress. 1. Relative aerobic fitness (V̇O2max; ml∙kg-1∙min-1) 2. Body mass (kg) 3. Body surface area (m2) 4. Age 5. Sex Individuals with a history of EHI Heat Tolerance Assessment Service personnel who have a history of EHI.
- Primary Outcome Measures
Name Time Method Circulating Zonulin Baseline Measured using ELISA
Diversity of gastrointestinal microbiota Baseline Measured in stool sample. Assessed by beta diversity score.
Circulating Interleukin 6 Post Heat Tolerance Assessment (within 15 minutes of test end) Measured using ELISA
Abundance of gastrointestinal microbiota Baseline Measured in stool sample. Assessed at level of phylum.
Detection of sexually transmitted pathogens Baseline Assessed from urine sample. Measured using cobas CT/NG assays.
Detection of respiratory pathogens Baseline Assessed from throat swab. Measured using Allplex assays.
Detection of gastrointestinal pathogens Baseline Assessed from stool swab. Measured using Allplex.
Circulating Claudin 3 Post Heat Tolerance Assessment (within 15 minutes of test end) Measured using ELISA
Circulating C-Reactive Protein Post Heat Tolerance Assessment (within 15 minutes of test end) Measured using ELISA
Circulating lipopolysaccharide binding protein Post Heat Tolerance Assessment (within 15 minutes of test end) Measured using ELISA
Circulating intestinal fatty acid binding protein Post Heat Tolerance Assessment (within 15 minutes of test end) Measured using ELISA
Gastrointestinal illness symptomology questionnaire Immediately post Heat Tolerance Assessment Visual analogue scale (0-10). Higher scores indicate worse symptomology
Respiratory illness symptomology, measured by Jackson common cold questionnaire Baseline Higher scores indicate worse symptomology
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index Baseline -3 days Higher scores indicate worse sleep
Motivation, measured by Motivation scale Baseline -3 days State-trait anxiety, measured by state-trait anxiety inventory form Y-2 Baseline -3 days Risk taking, measured by the risk-taking inventory Baseline -3 days Stress, measured by perceived stress scale Baseline -3 days Mental readiness Baseline Visual analogue scale (0-100). Higher scores indicate a lower state of mental readiness.
Stress Baseline Visual analogue scale (0-100). Higher scores indicate a greater state of stress.
Resilience, measured by the Connor-Davidson resilience scale Baseline -3 days Core temperature Rate of rise from 30 to 60 minutes (or test termination if earlier) of Heat Tolerance Assessment Measured using a rectal thermistor.
- Secondary Outcome Measures
Name Time Method Heat rate At 5 minute intervals during the Heat Tolerance Assessment Sweat rate During Heat Tolerance Assessment Determined from change in nude body mass during the heat tolerance assessment
Rating of Perceived Exertion At 15 minute intervals during Heat Tolerance Assessment 6-20 Borg scale. Higher scores indicate higher perceived exertion
Skin Temperature During Heat Tolerance Assessment Weighted mean skin temperature
Thermal comfort At 15 minute intervals during Heat Tolerance Assessment Modified 9 point Gagge scale. Higher scores indicate worse comfort.
Thermal sensation At 15 minute intervals during Heat Tolerance Assessment Modified 9 point Gagge scale. Higher scores indicate hotter sensation
Trial Locations
- Locations (1)
University of Portsmouth
🇬🇧Portsmouth, Hampshire, United Kingdom