Background: Previous studies have experimentally investigated and simulated the effects of dynamic hyperinflation on respiratory system resistance variables in populations with different respiratory diseases. However, the acute effects of exercise on these parameters in healthy young adults are unknown; therefore, the objective of this study was to investigate the effects of a submaximal exercise test on the resistance of the respiratory system in healthy adult individuals. Methods: This is an observational study conducted with healthy adults. Fifty healthy volunteers were recruited, of both sexes, over the age of 18, with no previous uncontrolled respiratory diseases and normal spirometry, with an average age of 32.2 ± 11.6 years old and an average BMI of 24.3 ± 3.87 kg/m². The participants underwent an anamnesis, the Impulse Oscillometry Test (IOS) with the variables R5, R20, X5, Fres and AX, followed by the six-minute walk test (6MWT), another IOS measure, immediately after the 6MWT, finishing with a spirometry test. A paired t-test was used for the analyses. Results: Our results showed that the volunteers exhibited a decrease after the 6MWT in the oscillometry parameters R5 (0.35 to 0.32, p = 0.0001), R20 (0.33 to 0.30, p < 0.0001), X5 (−0.13 to −0.10, p < 0.0001), Fres (13.07 to 11.70, p = 0.0042) and AX (0.48 to 034, p = 0.01). In addition, the volunteers walked an average of 623.34 ± 42.6 m in the 6MWT, which represents around 96.6% of what was predicted for this group. Conclusions: Submaximal exercise, as assessed by the 6MWT, acutely reduces respiratory impedance in healthy individuals, which can facilitate moderate-intensity physical activity, preventing sedentary behavior.

Background: Bronchiectasis (BC) diagnosis is based on clinical findings, high-resolution computed tomography (HRCT), and by pulmonary function tests (PFT) as a complementary evaluation. When compared to spirometry, which is the most common used PFT, Impulse Oscilometry System (IOS) detects early changes in respiratory system both in central and peripheral airways. Objective: To correlate PFT, evaluated by spirometry and by IOS, with the area of the lumen obtained in HRCT in BC subjects. Methods: Thirty eight clinically stable non-cystic fibrosis BC subjects were evaluated by HRCT (area of the lumen measurements in the 3rd and 4th bronchial generations (AL3 and AL4)), spirometry (FVC% and FEV1%), and IOS (R5 and R20: airway resistance at 5 and 20 Hz). Results: AL3 showed significant correlation (p<0.05) only with IOS parameters, R5 (r=-0.52), R5% (r=-0.39), R20 (r=-0.54), R20% (r=-0.43); and AL4 was correlated with R5 (r=-0.33), R5% (r=-0.36), R20 (r=-0.36), R20% (r=-0.44), and the spirometry variables: FVC% (r=0.36) e FEV1% (r=0.35). Conclusion: The area of the lumen analysed by the HRCT shows a higher correlation with IOS than with spirometry parameters.