Effects of expiratory muscle strength training on maximal respiratory pressure and swallow-related quality of life in individuals with multiple sclerosis

BACKGROUND Weakening and dyscoordination of expiratory muscles in multiple sclerosis (MS) can impair respiratory and swallow function. OBJECTIVE The objective of this paper is to test a novel expiratory muscle strength training (EMST) device on expiratory pressure, swallow function, and swallow-related quality-of-life (SWAL-QOL) in individuals with MS. METHODS Participants with MS were randomized to a five-week breathing practice of either positive pressure load (EMST) or near-zero pressure (sham). We compared baseline to post-treatment data according to maximum expiratory pressure (MEP), abnormal airway penetration and aspiration (PAS), and SWAL-QOL. RESULTS Both groups improved in MEP (p < 0.001). Forty percent of the EMST group improved on PAS, and 15% worsened; conversely, 21.4% of the sham group worsened and 14.3% improved. There was no group difference in overall SWAL-QOL; but the EMST group had significantly greater gain versus sham on the Burden (p = 0.014) and Pharyngeal Swallow (p = 0.022) domains. Both groups improved in SWAL-QOL domains of Fear, Burden Mental Health, but only the EMST group improved in the SWAL-QOL and domains of Pharyngeal Swallow function, and Saliva management. CONCLUSION Results suggest that strengthening of expiratory muscles can occur with repetition of focused breathing practice in the absence of high resistance. Conversely, results from the PAS and SWAL-QOL domains suggest that the high resistance of the EMST was required in order to improve the functional safety (reduced penetration/aspiration) and coordination of swallowing, specifically pharyngeal function and saliva management.