The effect of physical training on the sympathoadrenal response to exercise.
The urinary excretion of catecholamines was measured in six healthy male volunteers at rest and during a fixed amount of work before and after physical training. It was found that, although training resulted in a significantly lower heart rate during exercise, the output of catecholamines was unaltered, indicating that the total activation of the sympathoadrenal system by exercise was similar before and after training. A similar heart rate study before and after training was also made during beta-adrenergic receptor blockade. Under these conditions the heart rate during exercise was not significantly changed by training. It is suggested that physical training reduces the sensitivity of the beta-receptors of the heart.
D000328:Adult; D001827:Body Height; D001835:Body Weight; D002986:Clinical Trials as Topic; D003404:Creatinine / Q000652:urine; D004231:Diuresis; D004837:Epinephrine / Q000652:urine; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D009638:Norepinephrine / Q000652:urine; D005082:Physical Exertion; D010809:Physical Fitness; D011433:Propranolol / Q000494:pharmacology; D013564:Sympathetic Nervous System / Q000502:physiology*
D011433:Propranolol; D003404:Creatinine; D009638:Norepinephrine; D004837:Epinephrine