The effects of physical conditioning and propranolol on physical work capacity

The effects of propranolol on several physiological responses to orthostatic and exercise stress were examined in 11 men, both before and after physical conditioning. The heart rate response to orthostatic stress was significantly lower with propranolol following the conditioning program. Blood pressure responses were unaffected by the drug. The mean heart rates at several levels of exercise were significantly lower with propranolol, both before and after conditioning. Similar results were observed for minute ventilation. Maximal oxygen uptake and mean endurance times were significantly increased after conditioning. There were no significant effects of propranolol on either the oxygen uptake or the endurance times. The plasma FFA levels were lower with propranolol although the differences were not statistically significant. The findings suggested that the exercise capacity of normal subjects is neither impaired nor enhanced by propranolol and that the effects of propranolol and physical conditiining are not additive.