Military personnel are called upon to serve in hot, dry or humid climates, which places great demands on their ability to tolerate heat. Induced heat stress can impair performance and lead to pathologies. Faced with the challenges of global warming, this issue is becoming increasingly important in the practice of sport. While hyperthermia is known to impair endurance performance, the underlying thermophysiological responses and regulatory mechanisms during prolonged exercise remain poorly understood. The effects of hyperthermia on mental performance raise questions about the degradation of interoceptive capacities and the deleterious impact on behavioral regulation, an important component of thermal risk management in ultra-endurance exercise. What's more, despite the muscular and hydromineral consequences (rhabdomyolysis, renal failure, dehydration) of prolonged exercise, few data are available on recovery kinetics. A better understanding of the factors conditioning recovery quality could help limit the deleterious consequences of ultra-endurance exercise.

Inclusion Criteria:

• Healthy individuals
• BMI between 18 and 25 kg/m2
• Weight ≥ 51 kg
• Minimum training volume 6 days/7, aerobic
• Participation in a running competition ≥ 6hours
• Having given informed consent

Exclusion Criteria:

• Presence or history of medical pathology
• Presence of significant deviation from normal electrocardiogram values
• History of heat stroke
• Known intolerance to heat
• Inability to swallow a capsule or refusal of rectal probe
• Alcohol consumption exceeding the equivalent of 3 glasses of wine per week
• Consumption of narcotics
• Smoking > 0.5 pack of cigarettes per day
• On usual medication
• Pregnant or breast-feeding women
• Protected adult, under legal protection, guardianship or curatorship, or unable to give personal written consent

The study population will be composed of healthy young athletes.