Allostasis & Allostatic Load
These are two terms I want every firefighter to become familiar with.

Allostasis: This is our body’s adaptive responses to external challenges…maintaining stability through change. Our body actively copes with challenges by expending energy and attempting to return to its initial state (homeostasis). Allostasis is an extension of the concept of homeostasis and represents the adaptation process of complex physiological systems to the physical, psychosocial, and environmental challenges associated with stress.

Allostatic Load: When the physiological systems involved in allostasis do not shut off when not needed, or do not become active when needed. AL is the resulting cumulative effect on the body of either being overwhelmed by too many challenges or meeting challenges less efficiently. High AL leads to dysregulation of major physiological systems and ultimately to disease onset and mortality.

The Firefighter Allostatic Load Test
Stress can, and often does, act as the trigger mechanism for allostasis. Research on multisystem impacts of stress on the firefighter’s body has established allostasis as an appropriate conceptual base to which measurements of cumulative stress can be referred. Allostatic Load, is a recently documented diagnostic measure that provides statistically significant predictions of a firefighters future morbidity and mortality.