tions posed by the military relative to monitoring the metabolic status of military personnel in training and operational situations, focusing on metabolic regulation during prolonged, exhaustive efforts (such as combat training or field operations), where nutrition/hydration and repair mechanisms may be mismatched to intakes and rest, or where specific metabolic derangements are present (e.g., following toxic chemical exposures or psychological threats). The committee was also asked to make a “blue sky” forecast for useful metabolic monitoring approaches and current research investments that may lead to revolutionary advances.

Biobehavioral research is among the most challenging of scientific endeavors as biological organisms display wide-ranging individual differences in physiology. A thorough exploration of biobehavioral responses requires the extensive study of individuals over time. In addition, the study of interactions between living systems and their environments has tested the limits of research methodologies and theoretical models. It is a truism in the biobehavioral sciences that no single measure or aspect of responding can adequately represent a complex latent construct; rather such constructs must be represented by an entire pattern of manifestations. In view of the prevalence and importance of rhythmicity in biological regulatory mechanisms, the inclusion of time-varying or temporal aspects of responding is crucial to accurately portray such activity. All recorded activity might be considered as relevant; functional relationships among ongoing physiological processes could then be extracted across observations.

In response to these various concerns, an alternative framework for research on monitoring the metabolic status of combat service members is suggested: a multivariate, systems perspective that emphasizes the study of individuals (combat service members). The three most important sources of variance (persons, occasions, and variables [or tests]) are present in nearly all experimental designs. Their relationship should be explicitly investigated, and the systematic variance associated with each should be accounted for before valid inferences can be drawn. The fact that such individualized, multivariate relationships have not been fully illuminated has seriously hampered the development of reliable monitoring strategies.

The overall physical status of service members in the field can be evaluated by analyzing either objective physiological measurements (e.g., energy expenditure, vital signs) or subjective measurements of self-assessments (or assessments by peers).