PUB - Publikationen an der Universität Bielefeld

Objective: To determine if a heart rate-based protocol for bronchial provocation testing ensures sufficient exercise intensity for inducing exercise-induced bronchial obstruction. Participants: 100 clinically healthy non-asthmatic sports students. Design: Subjects underwent an exercise challenge test (ECT) on a treadmill ergometer for bronchial provocation according to the guidelines of the American Thoracic Society (ATS). Heart rate (HR), forced expiratory volume in 1 second (FEV1), pH (pH) and lactate concentration were measured before and after exercise. Results: After exercise in 56% of the examined subjects lactate concentrations were,6 mmol/l. A highly significant decrease in FEV1 (mean -4.41 (SD 1.5%)) was found at concentrations of >6 mmol/l, whereas at concentrations <6.48 mmol/l, no participant showed an impairment of lung function (FEV1 values <= 90%). In five subjects, a bronchial obstruction was found, as shown by decreases in FEV1 of 210 to 247% after exercise. The lactate concentrations in these individuals were between 6.48 and 11.7 mmol/l, indicating a predominantly anaerobic metabolic response to exercise. Conclusion: These results show that the ATS standard protocol, using a heart rate formula for assessing the exercise intensity, is not sufficient to cause predominantly anaerobic lactate metabolism and hence exercise-induced hyperventilation. Therefore, a potential bronchial obstruction could not be induced in 56% of the subjects. For a sensitive study design, exercise intensities demanding anaerobic lactate metabolism should always be ensured. A more precise protocol is required.