Plasma catecholamines in stress and exercise

A technique was devised to monitor plasma catecholamines in a minimally obtrusive fashion in subjects going about their working activities. There was a disparity between plasma norepinephrine and epinephrine levels in different situations. During public speaking, epinephrine levels increase twofold, whereas during physical exercise, norepinephrine levels increase threefold. It seemed that while exercise induces a response of the sympathetic nervous system, psychological stress induces primarily an adrenal response.