Inclusion Criteria:  18 to 35 years old Body Mass Index between 18 and 27 kg/m2 Body weight ≥ 54 kg  Exclusion Criteria:  Presence or history of medical pathology (cardiological, renal, hepatic, cutaneous, intestinal, neurological...) Presence of a significant deviation from the normal values observed on the electrocardiogram History of heat stroke Known intolerance to heat (e.g. migraine sufferers) Presence of a contraindication to blood sampling, notably low venous capital, belonephobia Inability to ingest a capsule or refusal of the rectal probe Habitual consumption of caffeine > 500 mg per day Alcohol consumption greater than the equivalent of 3 glasses of wine per week Consumption of narcotics Smoking > 0.5 packet of cigarettes per day Undergoing habitual medication Pregnant or breastfeeding woman