Expiratory muscle strength training in persons with multiple sclerosis having mild to moderate disability: effect on maximal expiratory pressure, pulmonary function, and maximal voluntary cough

Abstract

Objective: To determine the effect of expiratory muscle strength training (EMST) on maximal expiratory strength, pulmonary function, and maximal voluntary cough in persons with multiple sclerosis (MS) having mild to moderate disability.

Design: Before-after trial.

Setting: Assessments were completed in the privacy of the subject's home or exercise physiology laboratory.

Participants: Seventeen persons with MS were age- and sex-matched to 14 healthy controls.

Intervention: Eight weeks of EMST and 4 weeks of detraining.

Main outcome measures: Maximal respiratory pressures, pulmonary function, and maximal voluntary cough were assessed 3 times (pretraining, posttraining, detraining). Maximal expiratory pressure (MEP) was assessed weekly and training intensity adjusted based on the new measurement.

Results: Subjects with MS had lower MEP, decreased pulmonary function, and weaker maximal voluntary cough at each assessment. EMST increased MEP and peak expiratory flow. However, improvement in maximal voluntary cough only occurred in subjects with a moderate level of disability when the MS group was subdivided into mild and moderate disability levels based on the Expanded Disability Status Scale.

Conclusions: EMST is a viable tool to enhance the strength of the respiratory muscles. However, further work is needed to determine the best parameters to assess change in cough following EMST.

Fig 1

(A) Labeled phases of cough wave: inspiratory phase, compression phase (minimal flow phase), and expiratory phase. (B) Measured components of cough wave: 1, rise-time (from the end of compression phase to the peak of expiratory flow during the expiratory phase); 2, cough expiratory airflow peak amplitude.

Fig 2

Change in MEP from pretrain through to detrain. Significant difference was found between the MS (○) and healthy (▲) groups and across assessments: pretrain to posttrain (*) and pretrain to detrain (†). Significant at P<.05.

Fig 3

Change in PEF from pretrain through to detrain. Significant difference was found between the MS (○) and healthy (▲) groups and across assessments: pretrain to posttrain (*) and pretrain to detrain (†). Significant at P<.05.