We investigated physiological responses and exercise capacity in sedentary young smokers during sub-maximal and maximal test and its impact on dyspnea and exercise intolerance. Fifty sedentary male smokers and non-smokers (age: 24 ± 1 years., weight: 71 ± 9 kg, height: 177.3 ± 4.8 cm, body mass index: 22.6 ± 2.5 kg/m²) underwent two visits with pulmonary function tests, breathing pattern, and inspiratory capacity measurement at rest and during sub-maximal and maximal exercise. Smokers show reduced exercise capacity during six minutes walk test (6-MWT) with decreased walked distance (p < 0.001) and inspiratory capacity (p < 0.05). During cardiopulmonary exercise test (CPET), smokers had higher minute ventilation VE for a given submaximal intensity (p < 0.05) and lower minute ventilation at maximal exercise (p < 0.001). End expiratory lung volume was significantly lower in sedentary smokers at rest (p < 0.05), at ventilatory threshold during exercise (p < 0.05), but not during peak exercise. End inspiratory lung volume was significantly lower in smokers at rest (p < 0.05) and ventilatory threshold (p < 0.05). Cigarette smoking alters lung function during submaximal and maximal exercise. This alteration is manifested by the development of dynamic hyperinflation contributing to exercise capacity limitation.

Background and Objectives: Pediatric pulmonary medicine relies heavily on accurate lung function assessment, yet conventional spirometry presents challenges in children due to cooperation requirements. In this context, the interrupter resistance technique (Rint), a method used in pediatric pulmonology, offers a potentially more feasible alternative for evaluating airway resistance in younger populations. This study aimed to assess the feasibility and clinical concordance between expiratory interrupter resistance (Rint(e)) and standard spirometry in healthy children under 8 years, thus contributing to the development of age-appropriate pulmonary function testing in pediatric medicine. Materials and Methods: A cross-sectional study was conducted on 200 healthy children (aged 2–8 years) in Tunisia. Pulmonary measurements were taken using a handheld device for both Rint(e) and spirometry. Feasibility rates were calculated, and correlations between the techniques were statistically analyzed. Results: Rint(e) showed significantly higher feasibility than spirometry (82.5% vs. 34.5%, p < 0.05). While older children had higher success rates with both techniques, feasibility was independent of sex, BMI, and passive smoking exposure. Moderate negative correlations were found between log Rint(e) and FEV1/FVC indices. Conclusions: In pediatric pulmonary assessment, Rint(e) demonstrated higher feasibility than spirometry among young children, making it a practical complementary method in clinical settings. However, due to only moderate correlation with spirometric indices, Rint(e) cannot yet replace spirometry in diagnostic use. Its integration into pediatric medicine may help address the gap in functional respiratory evaluation for children under the age of 8.