Obesity and Exercise-Induced Airway Obstruction Measured by Impulse Oscillometry
Background: the efficacy of impulse oscillometry (IOS) as an effortless technique for detection of different aspects of airway resistance in non-athlete obese men has not been fully appreciated. The objective was to evaluate concomitant airway responses induced by obesity and exercise pre and post an exercise bronchial provocation test and to recognize whether IOS variables relate to spirometry variables. Settings: 15 obese (BMI ≥ 35) and 13 lean (BMI ≤ 25) young men were enrolled in the study. Spirometry and IOS parameters were performed at baseline and for 20 mints after a treadmill exercise challenge of 8 minutes at 5-mint intervals. Heart rate (200 - 0.5 × age) was documented to verify exercise intensity. Obese subjects were screened based on the criteria of having a well-preserved FEV1/FVC ratio. Results: Correlations were found between resting FEV1 and IOS except for Ax (area of reactance) in the obese group. R5 at 5-min post-challenge was well correlated with the percent decrease in FEV1. Spirometry revealed significant differences in post-challenge percent changes only at 5-min after exercise; however, IOS identified differences in respiratory resistance at 5 and 10-min post-challenge time points. In obese group, sensitivity for X and R5 was 86% and 78%, respectively. Conclusions: obesity had no additive effects on proximal airway changes induced by exercise; however, IOS detected a difference in degree of small peripheral airway response to exercise in obese group, suggesting that IOS is a more sensitive measure of exercise-induced airway narrowing. IOS parameters, especially Ax may be more sensitive for detection of pulmonary function in obese people.