title: Metabolic aspects of maximal exercise performance after slow release metoprolol and after atenolol.
abstract: Maximal exercise performance by eight healthy male subjects was tested after one week of medication with slow-release metoprolol 200 mg/d (metoprolol-SR), atenolol 200 mg/d or placebo, in a double blind crossover trial. The maximal working capacity was significantly decreased after atenolol and metoprolol-SR. Plasma glucose and FFA concentrations during the exercise test did not change: either after placebo therapy or after beta-blockade. The anerobic threshold did not change after beta-blockade, but the changes in lactate due to the exercise were less after beta-blockade. Neither beta-blocker affected the exercise-induced alteration in airway resistance. Both drugs caused a small but significant ventilatory depression at rest and at 75% of maximal exercise. It is concluded that the limiting factor in maximal exercise performance after beta 1-adrenergic blockade does not lie in oxygen transport to the working muscles via ventilation and the circulation, but is most probably due to anaerobic metabolism.
mesh_terms: D000328:Adult; D001262:Atenolol / Q000008:administration & dosage / Q000378:metabolism*; D003692:Delayed-Action Preparations; D004311:Double-Blind Method; D005080:Exercise Test; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage / Q000378:metabolism*; D010366:Peak Expiratory Flow Rate; D005082:Physical Exertion; D011412:Propanolamines / Q000378:metabolism*
chemical_list: D003692:Delayed-Action Preparations; D011412:Propanolamines; D001262:Atenolol; D008790:Metoprolol