Respiratory Muscle Strength and Endurance Cut-Offs in Multiple Sclerosis

Official title

Optimal Cut-off Points of Respiratory Muscle Strength and Endurance to Discriminate Disability Status in Multiple Sclerosis

Overview

Multiple sclerosis (MS) is a chronic and progressive autoimmune disease of the central nervous system characterized by inflammation, demyelination, and axonal degeneration. Depending on lesion localization and disease severity, individuals with MS may develop a wide range of neurological manifestations affecting motor and sensory functions. Current evidence indicates that pulmonary function impairments may occur in individuals with MS even in the absence of overt respiratory symptoms. Compared with healthy individuals, people with MS have been reported to exhibit significantly reduced values in several respiratory parameters, particularly respiratory muscle strength. Moreover, these reductions appear to become more pronounced in parallel with increasing Expanded Disability Status Scale (EDSS) scores, regardless of disease duration. Indeed, previous studies have demonstrated that even individuals with MS who have mild disability levels (EDSS 0-4.5) experience significant declines in respiratory muscle strength, pulmonary function, and functional exercise capacity compared with healthy controls. These findings suggest that the respiratory system may be affected not only in the advanced stages of MS but also during the early phases of the disease, with functional impairments emerging before clinically evident respiratory complaints arise. Despite this, the existing literature lacks studies that define clear, clinically applicable cut-off values for respiratory muscle strength and endurance that can discriminate disability levels in individuals with MS. This gap highlights the absence of objective criteria that clinicians can rely on for early detection and for planning targeted rehabilitation interventions. The present study aims to address this gap by identifying optimal cut-off points for respiratory muscle strength and endurance in individuals with MS to facilitate early and accurate discrimination of disability status. By doing so, this research seeks to make an original contribution to the literature. The findings are expected to support the standardization of respiratory assessment processes in clinical practice, thereby improving patient quality of life and enhancing the efficiency of healthcare services. Furthermore, the results will provide a strong scientific basis for integrating respiratory function assessments into MS follow-up protocols and will offer a methodological framework for future intervention-oriented studies.

Interventions

• Other Respiratory Muscle Strength and Endurance Assessment
  Participants will undergo a comprehensive assessment of respiratory muscle function, including respiratory muscle strength measured by maximal inspiratory and expiratory pressures and respiratory muscle endurance evaluated using an incremental threshold loading protocol. Pulmonary function will be assessed by spirometry. These assessments will be conducted to determine optimal cut-off values of respiratory muscle strength and endurance for discriminating disability status in individuals with mul

Primary outcome measures

• Respiratory Muscle Strength (Maximal Inspiratory and Expiratory Pressures) [Time frame: Baseline]
• Respiratory Muscle Endurance [Time frame: Baseline]

Secondary outcome measures (10)

• Expanded Disability Status Scale (EDSS) [Time frame: Baseline]
• Pulmonary Function: Forced Expiratory Volume in 1 Second (FEV₁) [Time frame: Baseline]
• Pulmonary Function: Forced Vital Capacity (FVC) [Time frame: Baseline]
• Pulmonary Function: FEV₁/FVC Ratio [Time frame: Baseline]
• Pulmonary Function: Peak Expiratory Flow (PEF) [Time frame: Baseline]
• Pulmonary Function: Forced Expiratory Flow at 25-75% of FVC (FEF₂₅-₇₅) [Time frame: Baseline]
• Walking Speed (Timed 25-Foot Walk Test) [Time frame: Baseline]
• Perceived Walking Ability (Multiple Sclerosis Walking Scale-12) [Time frame: Baseline]
• Fatigue (Modified Fatigue Impact Scale) [Time frame: Baseline]
• Quality of Life (Multiple Sclerosis International Quality of Life Questionnaire) [Time frame: Baseline]

Eligibility criteria

Inclusion criteria

• Diagnosed with multiple sclerosis,
• Aged 18 years or older,
• Able to communicate effectively (able to speak, understand, read, and comprehend Turkish),
• No relapse within the past three months,
• Clinically stable for at least the past one month,
• No participation in respiratory-based rehabilitation programs within the past six months,
• Voluntary participation in the study.

Exclusion criteria

• Presence of neurological disorders other than multiple sclerosis,
• Presence of autoimmune diseases other than multiple sclerosis (e.g., rheumatoid arthritis, type 1 diabetes mellitus, systemic lupus erythematosus),
• Presence of chronic cardiac or pulmonary diseases that may affect respiratory muscle strength or pulmonary function, such as chronic obstructive pulmonary disease (COPD), asthma, interstitial lung disease, or heart failure,
• Pregnancy or breastfeeding,
• Inability to comply with the testing procedures.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Other

Study locations

Turkey (Türkiye) · 1 center

• Selcuk University Faculty of Medicine Hospital MS Life Center — Konya

Publications

• Bosnak-Guclu M, Gunduz AG, Nazliel B, Irkec C. Comparison of functional exercise capacity, pulmonary function and respiratory muscle strength in patients with multiple sclerosis with different disability levels and healthy controls. J Rehabil Med. 2012 Jan;44(1):80-6. doi: 10.2340/16501977-0900. PMID 22234321
• Mutluay FK, Gurses HN, Saip S. Effects of multiple sclerosis on respiratory functions. Clin Rehabil. 2005 Jun;19(4):426-32. doi: 10.1191/0269215505cr782oa. PMID 15929512
• Altintas A, Demir T, Ikitimur HD, Yildirim N. Pulmonary function in multiple sclerosis without any respiratory complaints. Clin Neurol Neurosurg. 2007 Apr;109(3):242-6. doi: 10.1016/j.clineuro.2006.09.004. Epub 2006 Oct 13. PMID 17046152
• Brown TR, Kraft GH. Exercise and rehabilitation for individuals with multiple sclerosis. Phys Med Rehabil Clin N Am. 2005 May;16(2):513-55. doi: 10.1016/j.pmr.2005.01.005. PMID 15893685
• Bishop M, Rumrill PD. Multiple sclerosis: Etiology, symptoms, incidence and prevalence, and implications for community living and employment. Work. 2015;52(4):725-34. doi: 10.3233/WOR-152200. PMID 26639011
• Tremlett H, Paty D, Devonshire V. Disability progression in multiple sclerosis is slower than previously reported. Neurology. 2006 Jan 24;66(2):172-7. doi: 10.1212/01.wnl.0000194259.90286.fe. PMID 16434648
• Calabresi PA. Diagnosis and management of multiple sclerosis. Am Fam Physician. 2004 Nov 15;70(10):1935-44. PMID 15571060
• Centonze D, Leocani L, Feys P. Advances in physical rehabilitation of multiple sclerosis. Curr Opin Neurol. 2020 Jun;33(3):255-261. doi: 10.1097/WCO.0000000000000816. PMID 32304436

Identifiers

NCT: NCT07373704 · SelcukU_PT_MS_RESP_ENDURANCE_1

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗