Effect of Inspiratory Muscle Training on Muscle Strength and Quality of Life in Patients With Chronic Airflow Limitation: a Randomized Controlled Trial

OBJECTIVE: Chronic airflow limitation (CAL) is a significant cause of illness and death. Inspiratory muscle training has been described as a technique for managing CAL. The aim of the present study was to evaluate the effectiveness of inspiratory muscle training on improving physiological and functional variables. PATIENTS AND METHODS: Randomized controlled trial in which 35 patients with CAL were assigned to receive either an experimental (n=17) or control (n=18) intervention. The experimental intervention consisted of 2 months of inspiratory muscle training using a device that administered a resistive load of 40% of maximal static inspiratory mouth pressure (PI max ). Inspiratory muscle strength, exercise tolerance, respiratory function, and quality of life were assessed. RESULTS: Significant improvement in inspiratory muscle strength was observed in the experimental training group (P=.02). All patients improved over time in both groups (P<.001). PI max increased by 8.9 cm H 2 O per month of training. Likewise, the health-related quality of life scores improved by 0.56 points. CONCLUSION: Use of a threshold loading device is effective for strengthening inspiratory muscles as measured by PI max after the first month of training in patients with CAL. The long-term effectiveness of such training and its impact on quality of life should be studied in a larger number of patients.