Abstract
BACKGROUND AND PURPOSE: Chronic Obstructive Pulmonary Disease (COPD) is a pulmonary condition characterized by airflow obstruction, which progresses with systemic alterations such as changes in muscle composition and metabolism, anticipating the activation of the inspiratory metaboreflex. This study aimed to analyze the acute effects of Inspiratory Muscle Training (IMT) on peripheral muscle metabolism in individuals with COPD, using near-infrared spectroscopy (NIRS). METHODS: This randomized, blinded, crossover study included 29 individuals with COPD who underwent three distinct sessions: high-load IMT (IMT-Strength, 60% of maximal inspiratory pressure-MIP), low-load IMT (IMT-Endurance, 30% of MIP), and a sham protocol. Tissue oxygenation of the gastrocnemius muscle was assessed using NIRS before and after each protocol. RESULTS: Differences in mean final tissue oxygen saturation were observed only during the IMT-Endurance protocol. The oxygen desaturation time was shorter during the IMT-Strength protocol compared with the other groups. Although not statistically significant, patients with more severe COPD (GOLD 3-4) exhibited an oxygen desaturation rate higher during the strength IMT compared with the endurance and sham protocols. CONCLUSIONS: Acute high-intensity IMT may accentuate the reduction in peripheral perfusion, especially in patients with advanced COPD, suggesting possible metaboreflex activation. Conversely, endurance IMT may improve peripheral perfusion. These findings reinforce the need for careful and individualized prescription of IMT in the COPD population. TRIAL REGISTRATION: Clinical Trials number: NCT06827379 https://clinicaltrials.gov/study/NCT06827379.