Respiratory muscle training in persons with spinal cord injury: a systematic review

The purpose of this paper was to review the effectiveness of respiratory muscle training (RMT) on respiratory muscle strength and endurance, pulmonary function, quality of life, respiratory complications and exercise performance in persons with spinal cord injury. A MEDLINE (National Library of Medicine, Bethesda, MD, USA) database was used for selection of the literature (from 1980 to November 2004), and relevant references from peer-reviewed articles were retrieved as well. Studies investigating the effects of RMT (i.e. resistive breathing weight lifting or normocapnic hyperpnea) in persons with spinal cord injury were selected. Two independent reviewers investigated controlled studies for methodological quality by using a modification of the framework for methodological quality. Methodological quality ranged between 15 and 29 (maximal feasible score=40). Twenty-three papers were retrieved and six controlled trials were kept for further analysis. A meta-analysis and calculation of effect-size of each individual study and weighted summary effect-size was intended. However, unreported data and heterogeneity in outcome variables did not allow performing a meta-analysis. From the systematic review it is concluded that RMT tended to improve expiratory muscle strength, vital capacity and residual volume. Insufficient data was available to make conclusions concerning the effects on inspiratory muscle strength, respiratory muscle endurance, quality of life, exercise performance and respiratory complications.