Heat IntoleranceATHENANCT05678738
Acquiring and Targeting Heat Exposures Necessary for Action
A study testing Antioxidant Berry Supplementation and Acute and Chronic Exercise-Heat Stress in people with Heat Intolerance and Heat Stress, run by University of Connecticut at 1 site in United States.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Heat Intolerance, Heat Stress, Fatigue; Heat
- What is being tested?
- Antioxidant Berry Supplementation and Acute and Chronic Exercise-Heat Stress
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 108 participants
- Where
- 1 siteUnited States
- Study dates
- 16 Sep 2021to 17 Apr 2024
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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.
Who cannot join
- 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
Show all 19Show fewer
- 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
- history of allergic reactions to medical tape and/or latex
- currently participating in "non-traditional" diets including diets such as intermittent fasting, caloric restriction, highly limited consumption of large food classes (e.g., vegan)
- consumption of antioxidant supplementation on a regular, long-term basis outside of the aronia supplementation regime for the study
- limited decision-making ability
- inability to participate in extended physical activity on a treadmill (i.e., standing, running, jogging, walking)
- consumption of a non-traditional diet including diets such as intermittent fasting, caloric restriction, highly limited consumption of large food classes (e.g., vegan) (this includes individuals who are suffering with current diagnosed or undiagnosed eating disorder)
- allergy to povidone, ethyl chloride, lidocaine, or bacitracin
- pregnant or positive pregnancy test during DXA pre-procedures (see DXA SOP)
- allergy to aronia berries, monkfruit, or sham juice ingredients
Trial locations and contacts
1 site in 1 country.
United States1 site
Human Performance Laboratory at the University of Connecticut
Storrs, Connecticut, 06269
About this study
Official title: Enhancing Lethality by Targeting Cognitive and Physiological Mechanisms of Female Warfighter Resiliency to Consecutive Days of Intense Exercise in the Heat
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?
Read more
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.
- Conditions
- Heat Intolerance, Heat Stress, Fatigue; Heat
- Being tested
- Antioxidant Berry Supplementation, Acute and Chronic Exercise-Heat Stress, Placebo (non-juice) Supplementation
- Keywords
- Sex Differences, Physical Performance, Body Composition, Heat Acclimation
- Medical subject headings
- Heat Stress Disorders
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Antioxidant Berry SupplementationDietary supplement
Participants who opt-in will be instructed to consume 300mL of the bioactive (antioxidant berry) supplement every morning and afternoon during days of participation.
Acute and Chronic Exercise-Heat StressOther
All participants (male and female) will be exposed to repeated bouts of exercise-heat stress.
Placebo (non-juice) SupplementationDietary supplement
Participants who opt-in will be instructed to consume 300mL of the placebo (non-juice) supplement every morning and afternoon during days of participation.
| Study group | Role | What they receive |
|---|---|---|
| Acute and Chronic Exercise-Heat Stress | Experimental | All participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Receives: Other: Acute and Chronic Exercise-Heat Stress |
| Exercise-Heat Stress + Antioxidant Berry Supplementation | Active comparator | All participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Participants who opt-in may be randomly assigned to receive bioactive (antioxidant berry supplement) ingredient in addition to repeated bouts of exercise-heat stress. Receives: Dietary Supplement: Antioxidant Berry Supplementation; Other: Acute and Chronic Exercise-Heat Stress |
| Exercise-Heat Stress + Placebo (Non-juice) Supplementation | Placebo comparator | All participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Participants who opt-in may be randomly assigned to receive placebo (non-juice) ingredient in addition to repeated bouts of exercise-heat stress. Receives: Other: Acute and Chronic Exercise-Heat Stress; Dietary Supplement: Placebo (non-juice) Supplementation |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Rectal Temperature at Rest
Rectal thermometer will be self-inserted by participants to assess core temperature prior to exercise-heat stress bouts
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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)
Measured: 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
Measured: 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)
Measured: 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
Measured: 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
Measured: 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
Measured: Throughout study completion, an average of 14 days
Change in Circulatory RNA Content
Blood samples will be collected and assessed for intracellular RNA content
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: Throughout study completion, an average of 14 days
Secondary outcomes (12)
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)
Measured: 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)
Measured: 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
Measured: 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.
Measured: 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)
Measured: 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
Measured: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Estradiol
Blood plasma samples will be collected for the measurement of circulating estradiol
Measured: 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
Measured: 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
Measured: 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)
Measured: 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)
Measured: 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
Measured: Throughout study completion, an average of 14 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Jan 2023
- Study start16 Sep 2021
- Primary completion17 Apr 2024
- Study completion17 Apr 2024
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Heat IntoleranceStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Participants will consist of both male and female subjects who will be exposed to similar bouts of exertional heat stress. Analysis will be completed to assess for potential sex-based differences in outcomes measured (male vs. female). Participants (both male and female) who opt-in for antioxidant berry supplementation will be assigned to a subgroup parallel study model where subjects will be exposed to similar bouts of exertional heat stress while consuming either the antioxidant or placebo supplement.
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 108 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Connecticut
- Sponsor type
- University, hospital or other
- Collaborators
- United States Department of Defense
- Responsible party
- Principal investigator, Elaine Choung-Hee Lee, University of Connecticut
- Investigators
- Douglas J Casa, PhD, Principal investigator, Korey Stringer Institute - UConn
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05678738
- Sponsor's protocol ID
- H21-0108
- Other IDs
- BA200299
- Acronym
- ATHENA
- Status last verified
- Sep 2025
- First submitted
- 16 Dec 2022
- Last updated
- 11 Sep 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Undecided
Study at a glance
From the registry record, last updated by the sponsor on 11 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Enhancing Lethality by Targeting Cognitive and Physiological Mechanisms of Female Warfighter Resiliency to Consecutive Days of Intense Exercise in the Heat
- ClinicalTrials.gov ID
- NCT05678738
- Acronym / sponsor ID
- ATHENA / H21-0108
- Conditions
- Heat Intolerance, Heat Stress, Fatigue; Heat
- Keywords
- Sex Differences, Physical Performance, Body Composition, Heat Acclimation
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 108 participants (actual)
- Lead sponsor
- University of ConnecticutUniversity, hospital or other
- Collaborators
- United States Department of Defense
- Study start
- 16 Sep 2021 (actual)
- Primary completion
- 17 Apr 2024 (actual)
- Study completion
- 17 Apr 2024 (actual)
- First posted
- 10 Jan 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 3
- Model description
- Participants will consist of both male and female subjects who will be exposed to similar bouts of exertional heat stress. Analysis will be completed to assess for potential sex-based differences in outcomes measured (male vs. female). Participants (both male and female) who opt-in for antioxidant berry supplementation will be assigned to a subgroup parallel study model where subjects will be exposed to similar bouts of exertional heat stress while consuming either the antioxidant or placebo supplement.
| Arm | Type | Receives |
|---|---|---|
| Acute and Chronic Exercise-Heat Stress | Experimental | Other: Acute and Chronic Exercise-Heat StressAll participants (male and female) will be exposed to repeated bouts of exercise-heat stress. |
| Exercise-Heat Stress + Antioxidant Berry Supplementation | Active comparator | Dietary Supplement: Antioxidant Berry Supplementation, Other: Acute and Chronic Exercise-Heat StressAll participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Participants who opt-in may be randomly assigned to receive bioactive (antioxidant berry supplement) ingredient in addition to repeated bouts of exercise-heat stress. |
| Exercise-Heat Stress + Placebo (Non-juice) Supplementation | Placebo comparator | Other: Acute and Chronic Exercise-Heat Stress, Dietary Supplement: Placebo (non-juice) SupplementationAll participants (male and female) will be exposed to repeated bouts of exercise-heat stress. Participants who opt-in may be randomly assigned to receive placebo (non-juice) ingredient in addition to repeated bouts of exercise-heat stress. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- 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.
Key exclusion criteria (19 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Antioxidant Berry SupplementationParticipants who opt-in will be instructed to consume 300mL of the bioactive (antioxidant berry) supplement every morning and afternoon during days of participation. | Dietary supplement | Exercise-Heat Stress + Antioxidant Berry Supplementation |
| Acute and Chronic Exercise-Heat StressAll participants (male and female) will be exposed to repeated bouts of exercise-heat stress. | Other | Acute and Chronic Exercise-Heat Stress, Exercise-Heat Stress + Antioxidant Berry Supplementation, Exercise-Heat Stress + Placebo (Non-juice) Supplementation |
| Placebo (non-juice) SupplementationParticipants who opt-in will be instructed to consume 300mL of the placebo (non-juice) supplement every morning and afternoon during days of participation. | Dietary supplement | Exercise-Heat Stress + Placebo (Non-juice) Supplementation |
Primary outcome
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 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 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 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 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 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 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 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 - 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 - 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 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 - 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 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 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 - 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 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 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 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 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 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 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 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 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 - 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 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 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 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 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 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 - 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
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 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 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 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
12 secondary outcomes
Change in Perception of Fatigue
Time frame: Throughout study completion, an average of 14 days
Change in Perception of Thirst
Time frame: Throughout study completion, an average of 14 days
Change in Environmental Perception
Time frame: Throughout study completion, an average of 14 days
Change in Rating of Perceived Exertion
Time frame: Throughout study completion, an average of 14 days
Change in Sleep Quality
Time frame: Throughout study completion, an average of 14 days
Change in Body Mass
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Estradiol
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Progesterone
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - Testosterone
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - LH
Time frame: Throughout study completion, an average of 14 days
Change in Reproductive Hormone State - FSH
Time frame: Throughout study completion, an average of 14 days
Change in Cardiovascular Response - Blood Pressure
Time frame: Throughout study completion, an average of 14 days
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Sep 2025.
- Individual participant dataSharing planned: Undecided
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Douglas J Casa, PhD principal investigator
Korey Stringer Institute - UConn
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Antioxidant Berry Supplementation and Acute and Chronic Exercise-Heat Stress in people with Heat Intolerance and Heat Stress, run by University of Connecticut at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 19 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 11 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Rectal Temperature at Rest (time frame: Through study completion, an average of 14 days). The study lists 41 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Sep 2025.