Altered exercise ventilatory responses by apparent propranolol-diminished glucose metabolism: implications concerning impaired physical training benefit in coronary patients.

The effect of a single oral 40 mg dose of propranolol on ventilatory responses to symptom-limited maximal exercise were studied in 14 coronary artery disease (CAD) patients and in four normal volunteers. In both groups, there was significant reduction of carbon dioxide production, minute ventilation, and respiratory exchange ratio at matched workloads. Propranolol did not affect oxygen uptake at matched workloads. A possible explanation of these findings was that propranolol, as a result of beta blockade, inhibited stimulation of glucose metabolism during exercise. Such an effect may diminish ability of CAD patients taking propranolol to obtain beneficial results of an exercise training program.