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: 1. 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? 2. 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? 3. 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: 1. a heat acclimation protocol which includes the completion of 5 days of prescribed exercise-heat exposure 2. 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 3. 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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
108
Participants who opt-in will be instructed to consume 300mL of the bioactive (antioxidant berry) supplement every morning and afternoon during days of participation.
All participants (male and female) will be exposed to repeated bouts of exercise-heat stress.
Participants who opt-in will be instructed to consume 300mL of the placebo (non-juice) supplement every morning and afternoon during days of participation.
Human Performance Laboratory at the University of Connecticut
Storrs, Connecticut, United States
Change in Rectal Temperature at Rest
Rectal thermometer will be self-inserted by participants to assess core temperature prior to exercise-heat stress bouts
Time frame: Through study completion, an average of 14 days
Change in Rectal Temperature Rate of Rise
Rectal thermometer will be self-inserted by participants to assess core temperature during exercise-heat stress bouts
Time frame: Through study completion, an average of 14 days
Change in Rectal Temperature at Thermal Threshold (38.5C)
Rectal thermometer will be self-inserted by participants to assess core temperature during exercise-heat stress bouts at the thermal threshold of 38.5C
Time frame: Measured throughout 5 90-minute exercise-heat stress bouts (heat acclimation sessions)
Change in Mean Skin Temperature
Prior to start of exercise, participants will be instrumented with iButton skin temperature sensors on the chest, shoulder, abdomen, neck, back, thigh, and calf
Time frame: Through study completion, an average of 14 days
Change in Heart Rate
A heart rate monitor will be worn by participants throughout the exercise-heat stress bouts
Time frame: Through study completion, an average of 14 days
Change in Heart Rate at Thermal Threshold (38.5C)
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
Time frame: Measured throughout 5 90-minute exercise-heat stress bouts (heat acclimation sessions)
Change in Whole Body Sweat Rate
Difference in body weight measurement measured prior to and at the cessation of each exercise-heat stress bout
Time frame: Measured at the beginning and end of 5 90-minute exercise-heat stress bouts (heat acclimation sessions)
Change in Sweat Metabolite and Protein Expression
Sweat samples will be collected and assessed for metabolite and protein expression discovery via mass spectrometry
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)
Change in Cognitive Measures - Visual Vigilance
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
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
Change in Cognitive Measures - Psychomotor Vigilance
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
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
Change in Cognitive Measures - Four Choice Task
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
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
Change in Cognitive Measures - Match to Sample
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
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
Change in Cognitive Measures - Repeated Acquisition
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
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
Change in Cognitive Measures - Grammatical Reasoning
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
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
Change in Cognitive Measures - Profile of Mood States
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
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
Change in Cognitive Measures - Stroop Task
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
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
Change in Physical Performance - Anaerobic Performance
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
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
Change in Physical Performance - Agility Performance
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
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
Change in Physical Performance - Upper Body Strength Performance
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
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
Change in Physical Performance - Lower Body Power Performance
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
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
Change in Physical Performance - Lower Body Kinematic Performance
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
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
Change in Physical Performance - Balance Performance
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
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
Change in Musculoskeletal Gene and Protein Expression
Musculoskeletal tissue samples will be collected for analysis via RNA-seq
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
Change in Musculoskeletal Fiber-Typing
Musculoskeletal tissue samples will be collected for fiber-type analysis via immunohistochemical procedures
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
Change in Musculoskeletal Mitochondrial Function
Musculoskeletal tissue samples will be collected for analysis of 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
Change in Subcutaneous Abdominal Tissue (SCAAT) Lipolysis Rate
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
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
Change in Resting Energy Expenditure and Macronutrient Oxidation
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
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
Change in Circulatory Indicators of Lipid Metabolism - NEFAs
Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Non-Essential Fatty Acids (NEFAs)
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory Indicators of Lipid Metabolism - Insulin
Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Insulin
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory Indicators of Lipid Metabolism - IGF-1
Blood samples will be collected and assessed for the expression of lipid metabolism biomarker Insulin Growth Factor-1 (IGF-1)
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory Indicators of Stress - Epinephrine
Blood samples will be collected and assessed for the expression of physiological stress biomarker Epinephrine
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory Indicators of Stress - Norepinephrine
Blood samples will be collected and assessed for the expression of physiological stress biomarker Norepinephrine
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory Indicators of Stress - Cortisol
Blood samples will be collected and assessed for the expression of physiological stress biomarker Cortisol
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory RNA Content
Blood samples will be collected and assessed for intracellular RNA content
Time frame: Throughout study completion, an average of 14 days
Change in Circulatory Indicators of Inflammation - IL-1B
Blood samples will be collected and assessed for the expression of inflammatory biomarker 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
Change in Circulatory Indicators of Inflammation - TNF-a
Blood samples will be collected and assessed for the expression of inflammatory biomarker 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
Change in Circulatory Indicators of Inflammation - IFN-gamma
Blood samples will be collected and assessed for the expression of inflammatory biomarker 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
Change in Gut Microbiome Diversity
Stool samples will be collected and assessed for the impact of gut microbiome diversity on heat intolerance
Time frame: Measurement completed prior to the completion of an exercise-heat stress bout (Heat Tolerance Test 2) both before and after heat acclimation
Change in Saliva Metabolite Expression
Saliva samples will be collected and assessed for 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)
Change in Thermal Sensation
0-8 Scale (cold to hot) that indicated how cold or hot the participant feels. 0 = extremely cold, 8 = extremely hot
Time frame: Through study completion, an average of 14 days
Change in Recovery
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
Time frame: Throughout study completion, an average of 14 days
Change in Perception of Fatigue
0-10 (no fatigue to extreme fatigue), scale indicates how fatigued the participant feels. High score indicates more fatigue (negative outcome)
Time frame: Throughout study completion, an average of 14 days
Change in Perception of Thirst
0-9 (no thirst to extreme thirst), scale that indicates how thirsty the subject feels, a higher score is considered a negative outcome (more thirsty)
Time frame: Throughout study completion, an average of 14 days
Change in Environmental Perception
Scale to assess participant perception of the environmental conditions, measurement scale identified as the modified environmental symptoms questionnaire (ESQ) which includes a minimum scale of "Not at all" and a maximum scale of "Extreme". Outcomes are considered worse when associated with greater extremes in documented answers
Time frame: Throughout study completion, an average of 14 days
Change in Rating of Perceived Exertion
6-20 scale to assess participant perceived exertion levels (how hard they are working) during exercise-heat stress bouts. A greater score indicates greater levels of exertion.
Time frame: Throughout study completion, an average of 14 days
Change in Sleep Quality
Scale to assess participant sleep habits including quantity and quality, measurement scale identified as the Kalinska sleep diary (KSD) which is a 9-point scale with increasing severity from 1 (extremely alert) to 9 (extremely sleepy - fighting sleep)
Time frame: Throughout study completion, an average of 14 days
Change in Body Mass
Participants will have nude body weight (kg) assessed at the beginning and end of each testing session
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Estradiol
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Blood plasma samples will be collected for the measurement of circulating estradiol
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Progesterone
Blood plasma samples will be collected for the measurement of circulating progesterone
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Testosterone
Blood plasma samples will be collected for the measurement of circulating testosterone
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - LH
Blood plasma samples will be collected for the measurement of circulating luteinizing hormone (LH)
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - FSH
Blood plasma samples will be collected for the measurement of circulating follicle stimulating hormone (FSH)
Time frame: Throughout study completion, an average of 14 days
Change in Cardiovascular Response - Blood Pressure
Blood pressure will be measured manually prior to each testing session with the documentation of systolic and diastolic measurements
Time frame: Throughout study completion, an average of 14 days