|| Checking for direct PDF access through Ovid
Strikingly consistent individual responses and significant mean elevations of plasma cortisol levels (5 to 9 μ g%) and plasma norepinephrine levels (2.0 to 2.5 μ g/1) were observed during a 20-min interval prior to onset of the first exhausting exercise (70% max VO2) session in eight normal young men. No detectable plasma epinephrine response was observed. Such consistent anticipatory psychoendocrine responses were not found prior to subsequent exercise sessions involving milder degrees of muscular exercise. Psychoendocrine reactions to intravenous catheterization were also observed in some individual subjects, suggesting the need for precautions to minimize the possible effects of this variable in exercise experiments. Some implications of this study for psychoendocrine research are also discussed.