Risk Factors for Exertional Heat Illness

Study Overview
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Brief Summary
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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.

Official Title
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Prospective Investigation of Risk Factors for Exertional Heat Illness

Conditions
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Exertional Heat Illness

Intervention / Treatment
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* 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


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women aged 17-35 years enrolled in military training Exclusion Criteria: Self-report as pregnant

Ages Eligible for Study
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Minimum Age: 17 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Exertional heat illness<br>Participants who experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise. | Other: Core temperature monitoring<br>* Core temperature will be monitored on the day of exercise<br>Behavioral: Questionnaires<br>* Questionnaires will be completed at baseline and on the day of exercise<br>Other: Heart rate monitoring<br>* Heart rate will be monitored on the day of exercise<br>Other: Urine collection<br>* Urine samples will be collected at baseline and on the day of exercise<br>Other: Sleep monitoring<br>* Sleep will be monitored at baseline and on the day of exercise<br>Other: Blood collection<br>* Blood samples will be completed at baseline<br>Other: Saliva collection<br>* Saliva samples will be collected at baseline and on the day of exercise<br>Other: Throat swab collection<br>* Throat swab samples will be collected at baseline and on the day of exercise<br>Other: Stool collection<br>* Stool samples will be collected at baseline and on the day of exercise<br>|
| Control<br>Participants who do not experience an atypical elevation in thermal strain or an EHI undergoing strenuous physical exercise. | Other: Core temperature monitoring<br>* Core temperature will be monitored on the day of exercise<br>Behavioral: Questionnaires<br>* Questionnaires will be completed at baseline and on the day of exercise<br>Other: Heart rate monitoring<br>* Heart rate will be monitored on the day of exercise<br>Other: Urine collection<br>* Urine samples will be collected at baseline and on the day of exercise<br>Other: Sleep monitoring<br>* Sleep will be monitored at baseline and on the day of exercise<br>Other: Blood collection<br>* Blood samples will be completed at baseline<br>Other: Saliva collection<br>* Saliva samples will be collected at baseline and on the day of exercise<br>Other: Throat swab collection<br>* Throat swab samples will be collected at baseline and on the day of exercise<br>Other: Stool collection<br>* Stool samples will be collected at baseline and on the day of exercise<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Body mass index in EHI and control group |  | Baseline | 
| Fitness in EHI and control group - participants ranked by time to complete fitness test |  | Baseline | 
| Core temperature in EHI and control group |  | 1 Day | 
| Heart rate in EHI and control group |  | 2 Hours | 
| Urine osmolality in EHI and control group |  | Baseline | 
| Sleep quality and quantity, measured by Pittsburgh Sleep Quality Index, in EHI and control group | 0-21 Scale. Higher score indicates worse outcome | Throughout study - up to 1 week | 
| Sleep quality, measured by actigraphy, between EHI and control group |  | Throughout study - up to 1 week | 
| 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 | 
| Circulating C-Reactive Protein in EHI and control group |  | Baseline | 
| Circulating Creatine kinase in EHI and control group |  | Baseline | 
| Circulating Aspartate Aminotransferase in EHI and control group |  | Baseline | 
| Circulating Alanine Aminotransferase in EHI and control group |  | Baseline | 
| Circulating Claudin 3 in EHI and control group |  | Baseline | 
| Circulating Zonulin in EHI and control group |  | Baseline | 
| Circulating Lipopolysaccharide binding protein in EHI and control group |  | Baseline | 
| Circulating immunoglobulin E in EHI and control group |  | Baseline | 
| Salivary cortisol in EHI and control group |  | Throughout study - up to 1 week | 
| 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 | 0-24 Scale. Higher score indicates worse outcome | 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 | Throughout study - up to 1 week | 
| Abundance and diversity of gastrointestinal microbiota in EHI and control group |  | Baseline |