The Detection of Heat Stress by Assessing Individual Body Responses to Heat (Heat Strain) in Young and Healthy Non-athlete Participants

• This study investigates and compares the within and in-between variances of the body responses to different heat stressors in a controlled lab-setting. The participants will be exposed to different heat sources while a variety of physiological heat strain reactions such as heartrate, sweat rate, and core body temperature are recorded using on- and in-body devices. For the participant monitoring during the study, medical grade devices such as a certified ECG and a swallowable sensor-pill to continuously monitor the core body temperature will be applied. A one-for-all wearable device is additionally applied for physiological validation. Further, sweat will be collected to assess (i) the local sweat rate and (ii) the appearance of different heat stress associated molecular markers in this non-invasively collectable biofluid. As a secondary aim, a model will be developed that will enable to predict the different heat stress sources out of the heat strain measurements.

Inclusion Criteria:Healthy participant, able to give consentAge 18-40 yearsNon-athlete (<4h sport/week)BMI<30 (non-obese)German speaking, or fluent in GermanExclusion Criteria:Pregnancy (urine pregnancy test), and breastfeedingRegular medication intake (excluding birth control pill)Intake of drugs and/or daily alcohol consumptionFever or symptoms of an acute infection (cough, shortness of breath, sore throat, taste loss)Active smoking or history of smoking <9 months agoMobility impairmentTraveled (<1 month ago) to a warm/hot temperature zone and stayed for >6 daysAny chronic conditions such as: high blood pressure, diabetes mellitus, immuno-deficiencies, sweat disorders such as anhidrosisColor blindness (STROOP test)Weight <40 kg (e-Celsius pill)Diverticulum or obstructions of the gastrointestinal tract (including motility disorders, swallowing disorders) as well as major abdominal surgery (e-Celsius pill)Need of exposure to strong electromagnetic fields during study participation, above all MRI examinations (e-Celsius pill)