Neuroendocrine, Metabolic and Cardiovascular Responses to Exercise Differ Among Healthy Men
Abstract
This dissertation shows that healthy, moderately trained males (19-42) may be divided into two groups based upon their unique endocrine and metabolic responses to a physiologic stressor, high-intensity treadmill exercise. Individuals exhibiting enhanced exercise-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis that was resistant to glucocorticoid suppression were designated as high-responders (= 36% of each population sample studied) and those showing normal exercise-induced HPA activation that was completely suppressed by glucocorticoid pretreatment were termed low-responders. Specifically, in phase I of this project, high-responders (n=4) exhibited a significant increase in exercise-induced plasma adrenocorticotropin (ACTH) concentrations following pretreatment with 4 mg of dexamethasone (DEX), a synthetic glucocorticoid. In contrast, the exercise-induced plasma ACTH response of low-responders (n=7) was completely suppressed by DEX administration. High-responders also showed significantly greater exercise-induced increases in heart rate and circulating concentrations of plasma ACTH, cortisol, lactate and glucose with placebo as compared to low-responders (p < 0.05). lnterestingly, high-responders exhibited a markedly enhanced plasma arginine vasopressin (AVP) response to exercise that was not attenuated by DEX pretreatment. Phase II of this project confirmed and extended these findings to include: an examination of equipotent doses of DEX (4 mg) and hydrocortisone (100 mg) on exercise-induced HPA activation; determination of individualanaerobic thresholds and pituitary-adrenal responses to both exogenous AVP stimulation and a 1 mg dexamethasone suppression test (DST). In addition,individuals underwent assessments of trait behavior.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 20, 1995
- Accession Number
- AD1011456
Entities
People
- John Petrides
Organizations
- Uniformed Services University of the Health Sciences