acquiring and targeting heat exposures necessary for action

Conditions: Heat Intolerance; Heat Stress; Fatigue; Heat

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: 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.


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 * 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

Keywords: sex differences physical performance body composition heat acclimation