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.