ABSTRACT
Stress constitutes a sophisticated physiological response coordinated by the activation of the hypothalamic pituitary adrenal (HPA) axis and sympathetic nervous system (SNS). These primary mediators of the stress response act on peripheral tissues (liver, muscle, and adipose tissue) to mobilize energy stores and prepare the body for a “fight or flight” action. In today's society, stressors are more likely to be psychological than physical in nature, and are comprised of a variety of adverse forces including emotional, social, or professional. Psychological stress is viewed as a prolonged or chronic type of stress as the origin and termination of the stressor is most likely unclear. On the other hand, physical activity, a stressor in and of itself, provides beneficial adaptations rather than deleterious effects to the body in animals (Campbell et al., 2010) and in humans (Luger et al., 1987). Activation of both the HPA axis and SNS has profound effects on metabolism, cardiovascular function, immune function, and reproduction. Chronic stress is associated with a number of metabolic disturbances including heart disease, insulin resistance, and central obesity (De Kloet, Vreugdenhil, Oitzl, & Joels, 1998; Habib, Gold, & Chrousos, 2001; Miller & O'Callaghan, 2002; Seckl, Morton, Chapman, & Walker, 2004). In contrast, physical activity also increases mobilization of energy but reverses undesirable metabolic effects associated with chronic stress (Schmidt, Wijga, Von Zur Muhlen, Brabant, & Wagner, 1997). This chapter will highlight the dynamic physiological adaptations that occur in peripheral tissues in response to both physical activity and chronic psychological stress.
