Enhancing Lethality by Targeting Cognitive and Physiological Mechanisms of Female Warfighter Resiliency to Consecutive Days of Intense Exercise in the Heat
Overview
- Phase
- Not Applicable
- Intervention
- Not specified
- Conditions
- Heat Intolerance
- Sponsor
- University of Connecticut
- Enrollment
- 108
- Locations
- 1
- Primary Endpoint
- Change in Rectal Temperature at Rest
- Status
- Completed
- Last Updated
- 7 months ago
Overview
Brief Summary
The purpose of this research study is to better understand ways that women and men differ physiologically, cognitively, physically, and cellularly to better prescribe helpful interventions that will prevent injury and risk of conditions like exertional heat illnesses or heatstroke. The main questions this project aims to answer are:
- What is the relative stress contributing to performance differences between women and men during intense exercise in extremely hot and humid environments in response to exertional heat stress?
- What is the relative contribution of responses in adipose tissue, cardiovascular tissue, gut microbiota, and musculoskeletal tissue on heat tolerance in women (vs. men) to exertional heat stress?
- What is the impact of adding an antioxidant juice consumption regime and will it assist in enhancing performance during an acute bout of exercise-heat stress before and after heat acclimation?
Subjects enrolled and approved for participation will perform:
- a heat acclimation protocol which includes the completion of 5 days of prescribed exercise-heat exposure
- two separate acute exercise-heat exposures for the assessment of thermotolerance and the investigation of potential enhancements in thermoregulatory performance that may occur after the completion of a 5-day heat acclimation protocol
- a subset of subjects enrolled and approved for participation who opt in to antioxidant berry supplement consumption will either consume the active or placebo product throughout their participation.
Investigators
Elaine Choung-Hee Lee
Professor
University of Connecticut
Eligibility Criteria
Inclusion Criteria
- •Participants will be healthy men and women, aged 18-50 years, who speak and read the English language fluently. This is required because some of the cognitive tests test grammatical reasoning and offer directional cues recorded as audio files in English. VO2max tests will provide evidence of level of aerobic fitness required to participate in this study. The investigators will use ≥45 ml·kg-1·min-1 for male participants, ≥40 ml·kg-1·min-1 for female participants as our threshold for inclusion.
- •The target composition of our subject sample is 50% men and 50% women.
- •No difficulties with vision, hearing, or ability to read a computer screen and operate a computer keyboard and mouse.
Exclusion Criteria
- •unable to visit the laboratory on the required, consistent schedule and consecutive required days (Days 2 and 3, Days 12 and 13)
- •any contraindications to participating in exercise lasting 60-120 minutes daily during a period of 2 consecutive days, 5 days within an 8-day period, and 2 additional days (if subjects elect to participate in the entire study, all options), screening will include resting blood pressure to exclude pre-hypertensive or hypertensive participants (resting BP \> 120 mmHg and 80mmHg systolic and diastolic, respectively)
- •any contraindications to exposure to exercise-heat stress (e.g., medications that affect thermoregulation, family or personal history of issues with anesthetics that indicate possible susceptibility to malignant hyperthermia, evidence of past heat intolerance)
- •tobacco use or electronic cigarettes (e-cigarettes) within the past 6 months
- •chronic illness (including diabetes, metabolic syndrome, thyroid disease, for example) or other chronic illnesses that make it unsafe for participants to participate in daily rigorous exercise in the heat
- •regular supplementation with blood thinners, including the use of aspirin
- •acute illness (e.g., influenza, head cold, gastrointestinal illness) during the week of scheduled testing
- •current positive COVID-test or infection and past COVID infection within past 6 months
- •contraindications to blood draw and if elected to be considered for participation with microdialysis and skeletal muscle biopsy procedures, contraindications to those individual procedures
- •for subjects who may not complete a DXA scan, history of claustrophobia
Outcomes
Primary Outcomes
Change in Rectal Temperature at Rest
Time Frame: Through study completion, an average of 14 days
Rectal thermometer will be self-inserted by participants to assess core temperature prior to exercise-heat stress bouts
Change in Mean Skin Temperature
Time Frame: Through study completion, an average of 14 days
Prior to start of exercise, participants will be instrumented with iButton skin temperature sensors on the chest, shoulder, abdomen, neck, back, thigh, and calf
Change in Whole Body Sweat Rate
Time Frame: Measured at the beginning and end of 5 90-minute exercise-heat stress bouts (heat acclimation sessions)
Difference in body weight measurement measured prior to and at the cessation of each exercise-heat stress bout
Change in Physical Performance - Anaerobic Performance
Time Frame: Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation
Participants will be assessed for anaerobic performance with the completion of a 400 meter sprint for time. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion
Change in Rectal Temperature at Thermal Threshold (38.5C)
Time Frame: Measured throughout 5 90-minute exercise-heat stress bouts (heat acclimation sessions)
Rectal thermometer will be self-inserted by participants to assess core temperature during exercise-heat stress bouts at the thermal threshold of 38.5C
Change in Cognitive Measures - Match to Sample
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of match to sample success through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Heart Rate at Thermal Threshold (38.5C)
Time Frame: Measured throughout 5 90-minute exercise-heat stress bouts (heat acclimation sessions)
A heart rate monitor will be worn by participants throughout the exercise-heat stress bouts to assess HR at the thermal threshold of 38.5C
Change in Cognitive Measures - Visual Vigilance
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of visual vigilance through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Cognitive Measures - Four Choice Task
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of four choice task success through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Cognitive Measures - Profile of Mood States
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of profile of mood states through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Cognitive Measures - Stroop Task
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of stroop task success through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Physical Performance - Agility Performance
Time Frame: Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation
Participants will be assessed for anaerobic performance with the completion of a quick feet agility test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion
Change in Musculoskeletal Mitochondrial Function
Time Frame: Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Musculoskeletal tissue samples will be collected for analysis of mitochondrial function
Change in Circulatory Indicators of Lipid Metabolism - NEFAs
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Non-Essential Fatty Acids (NEFAs)
Change in Circulatory Indicators of Lipid Metabolism - IGF-1
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Insulin Growth Factor-1 (IGF-1)
Change in Physical Performance - Balance Performance
Time Frame: Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation
Participants will be assessed for balance performance with the completion of the Balance Error Scoring System (BESS) Test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion
Change in Musculoskeletal Gene and Protein Expression
Time Frame: Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Musculoskeletal tissue samples will be collected for analysis via RNA-seq
Change in Rectal Temperature Rate of Rise
Time Frame: Through study completion, an average of 14 days
Rectal thermometer will be self-inserted by participants to assess core temperature during exercise-heat stress bouts
Change in Heart Rate
Time Frame: Through study completion, an average of 14 days
A heart rate monitor will be worn by participants throughout the exercise-heat stress bouts
Change in Cognitive Measures - Repeated Acquisition
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of repeated acquisition through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Cognitive Measures - Grammatical Reasoning
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of grammatical reasoning through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Subcutaneous Abdominal Tissue (SCAAT) Lipolysis Rate
Time Frame: Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
SCAAT lipolysis rate (interstitial glycerol and ethanol output:input) will be collected and assessed for fat mobilization and subcutaneous adipose tissue blood flow during exercise-heat stress bouts
Change in Circulatory Indicators of Stress - Epinephrine
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for the expression of physiological stress biomarker Epinephrine
Change in Sweat Metabolite and Protein Expression
Time Frame: Measurement completed during each exercise-heat stress bout (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation as well as the final heat acclimation session (HA5 - day 11)
Sweat samples will be collected and assessed for metabolite and protein expression discovery via mass spectrometry
Change in Cognitive Measures - Psychomotor Vigilance
Time Frame: Measurement completed immediately after one exercise-heat stress bout (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participants will perform an assessment of psychomotor vigilance through a validated computer programming system. The test is part of a larger Testing battery which should take approximately 30 minutes for completion
Change in Physical Performance - Upper Body Strength Performance
Time Frame: Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation
Participants will be assessed for upper body strength performance with the completion of a handgrip strength test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion
Change in Physical Performance - Lower Body Power Performance
Time Frame: Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation
Participants will be assessed for lower body power performance with the completion of a vertical jump test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion
Change in Physical Performance - Lower Body Kinematic Performance
Time Frame: Measurements completed immediately after the cognitive battery performed during the Heat Tolerance Test 2 (days 6 and 13) both before and immediately after heat acclimation
Participants will be assessed for lower body kinematic performance with the completion of the Landing Error Scoring System (LESS) Test. This test is part of a larger physical performance battery test which should take approximately 30 minutes for completion
Change in Musculoskeletal Fiber-Typing
Time Frame: Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Musculoskeletal tissue samples will be collected for fiber-type analysis via immunohistochemical procedures
Change in Resting Energy Expenditure and Macronutrient Oxidation
Time Frame: Measurement completed after the performance of an exercise-heat stress bout and physical performance battery (Heat Tolerance Test 2 - days 6 and 13) both before and immediately after heat acclimation
Participant resting energy expenditure, fat oxidation, and carbohydrate oxidation will be assessed via indirect calorimetry for the measurement of respiratory quotient and respiratory exchange ratio
Change in Circulatory Indicators of Inflammation - IL-1B
Time Frame: Measurement completed during the completion of exercise-heat stress bouts (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation
Blood samples will be collected and assessed for the expression of inflammatory biomarker IL-1B
Change in Circulatory Indicators of Inflammation - IFN-gamma
Time Frame: Measurement completed during the completion of exercise-heat stress bouts (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation
Blood samples will be collected and assessed for the expression of inflammatory biomarker IFN-gamma
Change in Gut Microbiome Diversity
Time Frame: Measurement completed prior to the completion of an exercise-heat stress bout (Heat Tolerance Test 2) both before and after heat acclimation
Stool samples will be collected and assessed for the impact of gut microbiome diversity on heat intolerance
Change in Thermal Sensation
Time Frame: Through study completion, an average of 14 days
0-8 Scale (cold to hot) that indicated how cold or hot the participant feels. 0 = extremely cold, 8 = extremely hot
Change in Circulatory Indicators of Lipid Metabolism - Insulin
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Insulin
Change in Circulatory Indicators of Stress - Cortisol
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for the expression of physiological stress biomarker Cortisol
Change in Circulatory RNA Content
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for intracellular RNA content
Change in Saliva Metabolite Expression
Time Frame: Measurement completed during each exercise-heat stress bout (Heat Tolerance Tests 1 and 2) both before and after heat acclimation as well as the final heat acclimation session (HA5)
Saliva samples will be collected and assessed for metabolite expression
Change in Recovery
Time Frame: Throughout study completion, an average of 14 days
Participants will be provided a WHOOP strap after the completion of their baseline visit and will be instructed on how to download the associated application and use of the device. The WHOOP device will be used to provide data on sleep quality and quantity, strain, and recovery
Change in Circulatory Indicators of Stress - Norepinephrine
Time Frame: Throughout study completion, an average of 14 days
Blood samples will be collected and assessed for the expression of physiological stress biomarker Norepinephrine
Change in Circulatory Indicators of Inflammation - TNF-a
Time Frame: Measurement completed during the completion of exercise-heat stress bouts (Heat Tolerance Tests 1 [days 5 and 12] and 2 [days 6 and 13]) both before and immediately after heat acclimation
Blood samples will be collected and assessed for the expression of inflammatory biomarker TNF-a
Secondary Outcomes
- Change in Perception of Thirst(Throughout study completion, an average of 14 days)
- Change in Reproductive Hormone State - FSH(Throughout study completion, an average of 14 days)
- Change in Cardiovascular Response - Blood Pressure(Throughout study completion, an average of 14 days)
- Change in Environmental Perception(Throughout study completion, an average of 14 days)
- Change in Reproductive Hormone State - LH(Throughout study completion, an average of 14 days)
- Change in Perception of Fatigue(Throughout study completion, an average of 14 days)
- Change in Rating of Perceived Exertion(Throughout study completion, an average of 14 days)
- Change in Sleep Quality(Throughout study completion, an average of 14 days)
- Change in Reproductive Hormone State - Estradiol(Throughout study completion, an average of 14 days)
- Change in Reproductive Hormone State - Progesterone(Throughout study completion, an average of 14 days)
- Change in Body Mass(Throughout study completion, an average of 14 days)
- Change in Reproductive Hormone State - Testosterone(Throughout study completion, an average of 14 days)