Combined administration of atropine and propranolol during heavy exercise reduced maximal oxygen uptake by 6%, whereas individual drugs did not alter it despite wide variations in heart rate.
Healthy subjects performed submaximal and maximal bicycle exercise under 1) control conditions, and after injection of 2) atropine (2.0–2.5 mg i.v.), 3) propranolol (10 mg i.v.), 4) both these drugs. Lowest heart rate was noticed after propranolol and at any level of exercise the average heart rate was about 40 beats/min lower than after injection of atropine. The maximal oxygen uptake was, however, unchanged except after both drugs (6 % reduction). Maximal work time and cardiac output were significantly reduced after injection of propranolol. Thus, a remarkably efficient arterial oxygen transport can be maintained during heavy exercise despite a wide variation in heart rate.
Ekblom et al. (Sat,) conducted a other in Healthy subjects. Atropine, propranolol, or both vs. Control conditions was evaluated on Maximal oxygen uptake. Combined administration of atropine and propranolol during heavy exercise reduced maximal oxygen uptake by 6%, whereas individual drugs did not alter it despite wide variations in heart rate.