Model human core thermoregulation, metabolic glycogen debt, dehydration, and cognitive resistance under severe survival and evasion stress.
Thermoregulation is calculated through metabolic heat production ($M$), convective/radiative losses via insulation ($R+C$), respiratory cooling ($E_{res}$), and evaporative perspiration ($E_{sk}$). Shivering triggers automatically when heat debt exceeds 180 kJ.
Sustained tactical movements draw on muscle glycogen (~450g / 1800 kcal stored) and adipose fat oxidation. Once glycogen depletes past 85%, muscular coordination degrades and involuntary shivering power drops by up to 40%.
In SERE resistance scenarios, intermittent brief bursts of isometric contraction, maintaining dry core layers, and rationing fluid intake to match insensible perspiration prevent rapid cognitive collapse under interrogator duress.