Severely disabled multiple sclerosis patients can achieve the performance of healthy subjects after expiratory muscle strength training

Abstract

Background: The efficacy of expiratory muscle strength training (EMST) in patients with multiple sclerosis (MS) is controversial. The current study's primary objective was to test the effects of a progressive and intensive 12 week home based EMST program on expiratory muscle strength and voluntary cough strength. The secondary objective was to determine the retention of EMST benefits.

Methods: Thirty-five severely disabled MS patients (relapsing-remitting MS, n = 15; primary progressive MS, n = 5; secondary progressive MS, n = 15) with Expanded Disability Status Scale (EDSS) 5.0 - 7.0 were included in the study. Within 36 weeks, patients completed 12 weeks of a non-training period, 12 weeks of EMST and 12 weeks of a detraining period. Maximal expiratory pressure (PEmax) and voluntary peak cough flow (vPCF) were assessed 4 times: at week 0 (baseline), week 12 (pre-training), week 24 (post-training), and week 36 (post-detraining). MS patients included in the study were compared to age- and sex-matched healthy subjects. In the healthy controls, the PEmax and vPCF were assessed once to obtain normative data.

Results: Twenty-six patients completed the training period (mean age 52.7 ± 10.2, EDSS 5.9 ± 0.6) and were compared to 26 sex- and age-matched healthy subjects (mean age 53.5 ± 5.8). Patients with MS had a lower PEmax (p = 0.002) and vPCF (p = 0.022) at baseline than the healthy control group. In training period, the PEmax and vPCF increased (p = 0.0000; effect size: d = 0.94 and p = 0.0036; d = 0.57 respectively) in comparison with the non-training period (p = 0.0692; d = -0.36 and p = 0.5810; d = 0.11 respectively). Following the 12 weeks detraining period, the PEmax and vPCF declined but remained 16.7% and 5.5% respectively above the pre-training values. No differences were observed in the PEmax and vPCF between the MS group at the post-training and post-detraining timepoint and the healthy control group normative values.

Conclusions: EMST improves expiratory muscle strength and voluntary cough strength in severely disabled MS patients.

Keywords: Expiratory muscle strength training; Multiple sclerosis; Respiratory muscles; Respiratory physiotherapy; Voluntary peak cough flow.