Objective:The aim of the present study was 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:The subjects underwent an exercise challenge test (ECT) for bronchial provocation on a treadmill ergometer according to the guidelines of the American Thoracic Society (ATS). Before and after exercise heart rate (HR), forced expiratory volume in 1 sec. (FEV1), pH-values (pH) and lactate concentrations (Lac) were measured.
Results :After exercise in 56% of the examined subjects lactate concentrations were lower than 6mmol/l. Regarding pulmonary function, a highly-significant decrease in FEV1 (-4.41±1.5%) was found at concentrations of more than 6mmol/l, whereas at concentrations below 6.48mmol/l no test person showed an impairment of lung function with FEV1-values declining below 90%. In five subjects a bronchial obstruction was found, as shown by decreases in FEV1 of -10 to -47% after exercise. The lactate concentrations in these individuals were between 6.48 and 11.7mmol/l, indicating a predominantly anaerobic metabolic response to exercise.
Conclusion:These results demonstrate 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 therefore an exercise-induced hyperventilation. Consequently 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. Therefore a more precise protocol is required.
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