Effects of aminophylline upon the exercise performance of patients with stable chronic airflow obstruction.

To assess the effects of aminophylline upon the exercise performance of patients with chronic airflow obstruction (CAO), we performed ramp exercise tests (1 W/3 s) on six CAO subjects before and after intravenous aminophylline (6 mg X kg-1). The subjects had airflow obstruction (mean FEV1/FVC = 0.53) which did not improve following the inhalation of aerosolized isoetharine. After intravenous aminophylline, maximal oxygen uptake, maximal work rate and exercise duration increased (p less than 0.03) and the subjective dyspnea scores during exercise decreased (p less than 0.05). These changes were not accompanied by increases of FEV1 or peak expiratory flow rate, but maximal inspiratory pressure and peak inspiratory flow rate during exercise increased (p less than 0.05). These observations suggest that aminophylline acutely improves the maximal exercise performance of CAO subjects by mechanisms other than bronchodilation.