Mauro Prosperi was a police officer and resistance runner, Prosperi took part in 1994 at the Marathon des Sables, an ultramarathon held in Morocco, then lost his way due to a sand storm, and remained several hours without eating or drinking.
Stress and contraction muscle converts chemical energy into mechanical energy. ATP (adenosine triphosphate) is essential for muscle contraction; the problem is that the stock of ATP must be constantly renewed as it is weak and largely solicited by effort.
In an endurance sport (as Mauro practiced), the recycling of ADP into ATP is mainly through cellular respiration and it is the type I fibers that intervene, which allowed it to survive and maintain its energy capital.