Inclusion Criteria:  male or female between the ages of 18-45 years females only: taking monophasic birth control pill this is to maintain applicability to a large portion of the female population that take birth control and limit the influence of varying estrogen and progesterone levels throughout the menstrual cycle. during the informational session researchers will have this list of brands of monophasic birth control pill brands to determine if the participant is eligible Brevicon Modicon Wera Balziva Gildagia Philith Zenchent Estarylla Previfem Sprintec Ocella Yasmin Zarah Yaz Safyral Beyaz Cryselle Elinest Ogestrel Apri Desogen Juleber Reclipsen Solia Levora Altavera Daysee Lessina Lybrel Amethia Jolessa all trials will only be conducted during the days the participant is on the hormone pill (not on the days during which they are taking the placebo pill) been cleared by the medical monitor for this study VO2max > 45ml/kg/min (measure obtained only from the VO2max test performed on the treadmill on Visit 1) Aerobically active (at least 30 minutes of aerobic exercise 4-5 days per week)  Exclusion Criteria:  Have a current musculoskeletal injury that would limit their physical activity or preclude the participant from walking, jogging, running, sprinting, or cutting. Chronic health problems that affect your ability to thermoregulate (disorders affecting the liver, kidneys or the ability to sweat normally) Fever or current illness at the time of testing History of cardiovascular, metabolic, or respiratory disease A family member died for no apparent reason, had a heart attack, died from heart problems, or sudden death before the age of 50 Currently taking a medication that is known to influence body temperature (amphetamines, antihypertensives, anticholinergics, acetaminophen, diuretics, NSAIDs, aspirin) Have a history of heat related illness Have any allergies or adverse reactions to the cold (e.g. Cold Uticaria, Raynauds -Phenomenon/Disease, or Cryoglobulinanemia) Have claustrophobia or feelings of discomfort towards sitting in a small, enclosed area Have allergies to medical and/or adhesive tape Have eating disorders History of COVID-19 unless cleared by a physician for exercise at the level exercise required to participate in this study. The physician must be made aware of what is required to participate in this study.