Maximal Expiratory Pressure and Its Link With Cough Airflow Before and After Expiratory Muscle Strength Training in Parkinson's Disease

Expiratory muscle strength training (EMST) improves maximal expiratory pressure (MEP), and several researchers have reported improvements to voluntary cough airflow in people with Parkinson's disease (PD). However, the link between the change in MEP and cough and whether patient-specific factors impact the training response is not well understood. Therefore, study aims were to examine (a) the relationship between MEP and cough pre- and post-EMST, (b) the associations between the change in MEP and change in cough, and (c) if patient-specific factors predict the change MEP. This is a secondary analysis of data from 30 people with PD who completed MEP and voluntary and reflex cough testing via spirometry pre– and post–5 weeks of EMST. Pearson's r correlations were used for Aims 1 and 2. Multivariable linear regression was used for Aim 3. Pre-EMST correlations between MEP and cough as well as correlations between the change in MEP and change in cough were nonsignificant. Post-EMST, MEP was correlated with voluntary cough expired volume (CEV, r = .58 , p < .001), peak expiratory flow rate (PEFR, r = .56 , p = .001), and cough volume acceleration ( r = .47 , p = .009 ) , as well as reflex CEV ( r = .5, p = .005). Patient-specific factors did not predict the change in MEP. This study showed that there was a larger correlation between expiratory muscle strength and cough airflow post-EMST than pre-EMST for voluntary and reflex cough in PD; however, the correlation between the change was small. Future research is needed to identify additional physiologic changes that are impacting cough airflow after EMST. https://doi.org/10.23641/asha.24602565