Does Aerobic Exercise Training Improve Inspiratory Muscle Function in Individuals with Chronic Obstructive Pulmonary Disease? A Systematic Review

ABSTRACT Purpose: To determine whether aerobic exercise training improves inspiratory muscle strength and/or endurance in adults with stable chronic obstructive pulmonary disease (COPD). Methods: A systematic review was conducted according to the Cochrane Collaboration protocol. MEDLINE, EMBASE, and CINAHL electronic databases were searched to December 2005. Articles were independently reviewed by 2 reviewers to determine inclusion. Criteria included: randomized control trials, adults with stable COPD, comparing aerobic exercise to another comparison group that measured outcomes of inspiratory muscle strength and/or endurance, and published in English. Standardized procedures were used to abstract data from included articles. Methodological quality was assessed. Results: One hundred fifty six (156) articles were retrieved. Nine met inclusion criteria. Participants were predominately male, with moderate to severe COPD and mean age from 49 to 72 years. Meta-analyses were performed for outcomes of inspiratory muscle strength (maximum inspiratory pressure - Pimax) and endurance (respiratory muscle endurance time - RMET). Results showed no effect of aerobic exercise training on Pimax (p=0.55) and RMET (p=0.59) as compared to control. Conclusions: Based on this review, aerobic exercise alone, performed at least 3 times per week for at least 6 weeks in individuals with stable COPD does not improve inspiratory muscle function. If improvement in inspiratory muscle strength or endurance is desired, additional modalities such as inspiratory muscle training could be considered.