An observational study in Exertional Heat Illness, sponsored by University of Portsmouth. Completed at 1 site in United Kingdom. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2023-05-22.
Sponsored by University of Portsmouth · Observational
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.
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.
111 studies on the registry are indexed under Heat Stress Disorders; 45 are open to participants now.
This study's enrollment of 95 is above the median of 55 across 13 observational studies indexed under Heat Stress Disorders.
Browse Heat Stress Disorders studies →University of Portsmouth is the lead sponsor of 32 studies on the registry; 6 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Individuals who have experienced a recent exertional heat illness and matched controls with no previous history of exertional heat illness
Inclusion Criteria:
Individuals with a history of EHI:
Control participants:
Service personnel who have a history of EHI.
Other: 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
Other: Heat Tolerance Assessment
60-90 minutes exercise in hot (34 °C; 45% R.H.) conditions at 60%VO2max
Core temperature
Measured using a rectal thermistor.
Time frame: At 60 minutes (or test termination if earlier) of Heat Tolerance Assessment
Core temperature
Measured using a rectal thermistor.
Time frame: Rate of rise from 30 to 60 minutes (or test termination if earlier) of Heat Tolerance Assessment
Diversity of gastrointestinal microbiota
Measured in stool sample. Assessed by alpha diversity score.
Time frame: Baseline
Diversity of gastrointestinal microbiota
Measured in stool sample. Assessed by beta diversity score.
Time frame: Baseline
Abundance of gastrointestinal microbiota
Measured in stool sample. Assessed at level of phylum.
Time frame: Baseline
Detection of sexually transmitted pathogens
Assessed from urine sample. Measured using cobas CT/NG assays.
Time frame: Baseline
Detection of respiratory pathogens
Assessed from throat swab. Measured using Allplex assays.
Time frame: Baseline
Detection of gastrointestinal pathogens
Assessed from stool swab. Measured using Allplex.
Time frame: Baseline
Circulating Interleukin 6
Measured using ELISA
Time frame: Baseline
Circulating Interleukin 6
Measured using ELISA
Time frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating C-Reactive Protein
Measured using ELISA
Time frame: Baseline
Circulating C-Reactive Protein
Measured using ELISA
Time frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating Claudin 3
Measured using ELISA
Time frame: Baseline
Circulating Claudin 3
Measured using ELISA
Time frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating Zonulin
Measured using ELISA
Time frame: Baseline
Circulating lipopolysaccharide binding protein
Measured using ELISA
Time frame: Baseline
Circulating lipopolysaccharide binding protein
Measured using ELISA
Time frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Circulating intestinal fatty acid binding protein
Measured using ELISA
Time frame: Baseline
Circulating intestinal fatty acid binding protein
Measured using ELISA
Time frame: Post Heat Tolerance Assessment (within 15 minutes of test end)
Gastrointestinal illness symptomology questionnaire
Visual analogue scale (0-10). Higher scores indicate worse symptomology
Time frame: Baseline
Gastrointestinal illness symptomology questionnaire
Visual analogue scale (0-10). Higher scores indicate worse symptomology
Time frame: Pre Heat Tolerance Assessment
Gastrointestinal illness symptomology questionnaire
Visual analogue scale (0-10). Higher scores indicate worse symptomology
Time frame: Immediately post Heat Tolerance Assessment
Respiratory illness symptomology, measured by Jackson common cold questionnaire
Higher scores indicate worse symptomology
Time frame: Baseline
Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index
Higher scores indicate worse sleep
Time frame: Baseline -3 days
Motivation, measured by Motivation scale
Time frame: Baseline -3 days
State-trait anxiety, measured by state-trait anxiety inventory form Y-2
Time frame: Baseline -3 days
Risk taking, measured by the risk-taking inventory
Time frame: Baseline -3 days
Resilience, measured by the Connor-Davidson resilience scale
Time frame: Baseline -3 days
Stress, measured by perceived stress scale
Time frame: Baseline -3 days
Mental readiness
Visual analogue scale (0-100). Higher scores indicate a lower state of mental readiness.
Time frame: Baseline
Stress
Visual analogue scale (0-100). Higher scores indicate a greater state of stress.
Time frame: Baseline
Heat rate
Time frame: At 5 minute intervals during the Heat Tolerance Assessment
Thermal comfort
Modified 9 point Gagge scale. Higher scores indicate worse comfort.
Time frame: At 15 minute intervals during Heat Tolerance Assessment
Thermal sensation
Modified 9 point Gagge scale. Higher scores indicate hotter sensation
Time frame: At 15 minute intervals during Heat Tolerance Assessment
Rating of Perceived Exertion
6-20 Borg scale. Higher scores indicate higher perceived exertion
Time frame: At 15 minute intervals during Heat Tolerance Assessment
Skin Temperature
Weighted mean skin temperature
Time frame: During Heat Tolerance Assessment
Sweat rate
Determined from change in nude body mass during the heat tolerance assessment
Time frame: During Heat Tolerance Assessment
Body mass
Time frame: Baseline
Relative maximal aerobic fitness
Highest value measured in ml.kg-1.min-1 during a treadmill graded exercise test.
Time frame: Baseline
Urine osmolality
Measured using freezing point depression
Time frame: Baseline
Plan to share: No
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University of Portsmouth