Stress Resilience Study

Aging is associated with diminished stress resilience, as in reduced ability to manage or recover from acute changes in homeostasis. Increased oxidative damage to cells and tissues and dysregulation of stress hormones have been linked to age-associated chronic diseases including atherosclerosis, cancer, cardiovascular disease and Alzheimer's disease. Interventions to improve the body's resistance to stress, resulting in lower oxidative stress and better regulation of the stress hormones, may prevent or delay the onset of age-related diseases and improve quality of life. Oxidative stress is believed to be a key mechanism in the aging process, with free radicals also implicated in many pathological processes. Similarly, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis is thought to play a role in aging and is linked to the increased risk for age-related chronic disease. The hormesis theory suggests that a certain amount of stress can lead to better survival and reduced tissue damage following a subsequent, more severe stress. One way to stress the system is through acute exercise. Regular exercise training, however, results in adaptive responses that increase the tolerance for successive (exercise) stress. A relevant question is whether adaptations to regular exercise training translate to greater resilience to psychosocial stress and an increased capacity to resist acute oxidative stress, thereby providing increased protection from diseases associated with dysregulation of these systems. This study will investigate stress resilience in two areas related to aging: oxidative stress and the neuroendocrine response to psychosocial stress. The effects of physical fitness on oxidative stress compensation and neuroendocrine stress reactivity will be determined by comparing fit and unfit older men and women. The overall aim of this study is to provide enhanced understanding of the mechanisms by which physical fitness modifies stress resilience in older men and women.