Inspiratory Muscle Training Using Tapered Flow Resistive Loading to Enhance Pulmonary Function in Smokers: A Randomized Controlled Trial

Background: Smoking is a leading cause of respiratory muscle weakness and diminished lung function. Inspiratory Muscle Training (IMT), particularly with Tapered Flow Resistive Loading (TFRL), is a promising non-pharmacological intervention aimed at enhancing respiratory muscle strength. This randomized controlled trial (RCT) aims to evaluate whether IMT with TFRL can significantly improve respiratory muscle strength and lung function in smokers. Methodology: The study enrolled 60 adult smokers aged 18-60 years, with a smoking history of at least five years and mild to moderate lung impairment, defined by a baseline Forced Expiratory Volume in one second (FEV1) between 40% and 80% of the predicted value. Participants were randomly assigned to either the intervention group, which underwent an eight-week IMT program with TFRL, or the control group, which received general smoking cessation advice and no respiratory muscle training. The primary outcome measure is maximum inspiratory pressure (MIP), assessed using a handheld portable manometer. Secondary outcomes include pulmonary function tests (FEV1, FVC, and PEFR), perceived dyspnea via the Modified Borg Scale, and changes in smoking behavior. All the outcomes were recorded at baseline and after eight weeks.  Results: Statistical analyses revealed that the intervention group showed significant improvements in respiratory muscle strength and pulmonary function compared to the control group. The two-way repeated measures ANOVA confirmed significant group-by-time interactions for MIP and pulmonary function tests, indicating that the changes over time differed between the intervention and control groups. Conclusion: IMT with TFRL may offer a valuable therapeutic approach for smokers suffering from lung impairment, particularly in non-pharmacological rehabilitation programs aimed at enhancing pulmonary function and reducing dyspnea.