Respiratory muscle strength training in the myositis population

Idiopathic inflammatory myopathies (IIM), including inclusion body myositis (IBM), dermatomyositis (DM), and polymyositis (PM), are rare autoimmune disorders often associated with dysphagia and respiratory dysfunction. Respiratory muscle strength training (RMST) has demonstrated benefits in other neuromuscular conditions, but evidence in myositis is limited. The primary aim of this study was to examine the effects of expiratory muscle strength training (EMST) using the EMST150® device on expiratory function and self-reported swallowing in individuals with myositis. Nineteen participants (7 males, 12 females; mean age 62.7 years) completed 25 RMST repetitions per day, 5 days per week, for 5 weeks at 70% of maximum expiratory pressure (MEP). Outcome measures included the Eating Assessment Tool (EAT-10), peak expiratory flow (PEF), and MEP. Pre- and post-intervention changes were analyzed using paired-samples t-tests. Statistically significant improvements were observed for all outcomes. EAT-10 scores decreased from 17.95 (SD = 10.51) to 11.63 (SD = 9.03), p < .001. PEF increased from 297.63 L/min (SD = 83.39) to 338.16 L/min (SD = 107.56), p < .001. MEP increased from 81.26 cm H₂O (SD = 20.86) to 87.95 cm H₂O (SD = 18.46), p = .004. Exploratory correlations revealed a moderate, non-significant association between improvements in MEP and reductions in EAT-10 scores (r = –0.37, p = 0.13). Changes in PEF demonstrated a moderate-to-strong, statistically significant association with EAT-10 improvement (r = 0.53, p = 0.02), suggesting that enhanced expiratory airflow may relate to reduced dysphagia symptom burden. This pilot study provides preliminary evidence that expiratory muscle strength training may improve expiratory pressure generation, expiratory airflow, and self-reported swallowing symptoms in individuals with myositis. The significant relationship between PEF gains and reductions in EAT-10 scores suggests a potential functional link between expiratory airflow and perceived swallowing improvement. Although the MEP–EAT-10 association did not reach significance and the study was not powered for correlational inference, the observed patterns support further investigation of the respiratory–swallowing relationship in myositis. Larger, controlled studies incorporating instrumental swallowing measures are needed to confirm these findings and clarify underlying mechanisms.