Endocrine markers and anthropometric measures were degraded, and inflammatory mediators increased after an extended energy deficit. A short-term recovery of 2-6 weeks was sufficient to restore these mediators.

Missions conducted by the U.S. Military during combat involve a multitude of operational stressors that can cause deterioration in physical and military performance of soldiers. Physiological consequences of sustained operational stress include decrements in anabolic hormones, skeletal muscle mass, and loss of bone mineral density. The objective of this review is to examine the current literature and provide commanders with information on the physical and physiological decrements in soldiers conducting sustained operations. The intent is that this will provide commanders with insight on how to plan for missions to incorporate possible countermeasures to enhance or sustain warfighter performance.

Modern international military deployments in austere environments (i.e., Iraq and Afghanistan) place considerable physiological demands on soldiers. Significant physiological challenges exist: maintenance of physical fitness and body composition, rigors of external load carriage, environmental extremes (heat, cold, and altitude), medical illnesses, musculoskeletal injuries, traumatic brain injuries, post-traumatic stress disorder, and environmental exposure hazards (i.e., burn pits, vehicle exhaust, etc.). To date there is very little published research and no comprehensive reviews on the physiological effects of deployments. The purpose of this paper is to overview what is currently known from the literature related mainly to current military conflicts with regard to the challenges and consequences from deployments. Summary findings include: (1) aerobic capacity declines while muscle strength, power and muscular endurance appear to be maintained, (2) load carriage continues to tax the physical capacities of the Soldier, (3) musculoskeletal injuries comprise the highest proportion of all injury categories, (4) environmental insults occur from both terrestrial extremes and pollutant exposure, and (5) post-deployment concerns linger for traumatic brain injury and post-traumatic stress disorder. A full understanding of these responses will assist in identifying the most effective risk mitigation strategies to ensure deployment readiness and to assist in establishment of military employment standards.