Exercise-induced asthma in adult Nigerian asthma patients: a comparison of step test, free running, and bicycle ergometer

ABSTRACT

Exercise is not only a very common precipitant of acute asthmatic episodes but also a potent non-pharmacological test for diagnosis of asthma. Different exercise protocols have been used; however a simple exercise test would be valuable and helpful for detecting exerciseinduced asthma (EIA). The main goal of this study was to compare the exercise-inducing capacity of free running; step test; and cycle ergometer. Forty-eight asthma patients performed and completed the exercise tests reaching at least 80-85of the predicted maximal heat rate. The peak expiratory flow (PEF) values and heart rate (HR) were used to monitor pulmonary function post-exercise and the intensity of the exercise respectively. The PEF values were measured at baseline; immediately after the exercise then at 5-minute intervals up to 30 minutes. Subjects who reached the percentage fall in PEF 15were considered positive for EIA. Free running was found to be the most asthmagenic exercise followed by the step test and cycle ergometer 36 subjects (75) for free running versus 27 subjects (56) for step test; versus 24 subjects (50) for cycle ergometer. There is a strong and significant correlation between the percentage fall in PEF of cycle ergometer and step test (r=0.61; p0.001). Free running produced the most positive result. However; the step test is a safe; simple; portable; and readily available instrument which compares well with laboratory-based cycle ergometer. We conclude that the step-test is an inexpensive and responsive exercise protocol for assessing and evaluating asthmatics in low-income countries