Increased training load and the beta-adrenergic-receptor system on human lymphocytes

Increased training load and the beta-adrenergic-receptor system on human ly mphocytes. J. Appl. Physiol. 87(1): 317-324, 1999.-The influence of increas ed training on the sympathoadrenergic system was investigated. Moderately t rained male subjects (n = 15) increased their training within 10 wk by 60%; eight of the subjects increased their training volume, and seven increased their training intensity. Before and after the training, an exhaustive tre admill exercise was carried out. Acute treadmill exercise increased P-adren ergic receptor number on mononuclear lymphocytes, isoproternol-stimulated c AMP production, and plasma catecholamine concentration. The increase of rec eptor number can at least partially be explained by a changed lymphocyte co mposition at rest and after exercise. After training, the exercise-induced increase of P-adrenergic receptor number was significantly blunted, and the exercise-induced increase of the isoproternol-stimulated cAMP production p er beta-receptor was enhanced. Subjects who experienced increased symptoms of physical discomfort and/or mood changes showed an enhanced cAMP producti on after training. These findings point to an altered regulation of the rec eptor and postreceptor mechanisms as an effect of a 10-wk period of hard tr aining.