This study is investigating the efficacy of CORE™ devices in calculating core body temperature in athletes under varying environmental conditions.

As athletes exercise, their core body temperature rises, which can affect their performance. Additionally, repeated mild to moderate heat stress, heat acclimation, can be used to improve exercise tolerance and performance. Thus, an athlete can gain performance benefits through monitoring their heat loading while training. The aim of this study is to compare the CORE™ body temperatures recorded during exercise in two different environmental conditions in which the investigators will get a separation of core temperature and skin temperature. The investigators will accomplish this by recruiting trained and elite athletes, ages 18-59, to participate in two exercise sessions in the heat at low (10-20%) and high (80-100%) relative humidity. The investigators will compare the CORE™ temperature estimates against an FDA approved ingestible temperature monitoring device to assess the accuracy of the CORE™ devices.

Inclusion Criteria:

• Highly trained or elite athlete
• Nonsmokers
• Able to read and speak English
• No underlying cardiovascular limitations

Exclusion Criteria:

• Currently or previously a habitual smoker (nicotine/cannabis)
• Pregnant, breast feeding, trying to conceive, undergoing treatment to increase sperm count
• Those taking medications that affect cardiovascular function, with the exception of oral contraceptives
• History of stroke, clotting disorders or venous thrombosis
• A history of heat illness or heat injury
• History of obstructive diseases of the gastrointestinal tract including diverticulosis, diverticulitis, inflammatory bowel disease, peptic ulcer disease, Chron's disease, ulcerative colitis, or previous GI surgery