Predictors of positive outcomes following resistive inspiratory muscle training in non-ambulatory persons with advanced multiple sclerosis.

Background: Inspiratory muscle training (IMT) using a threshold device improves inspiratory muscle strength. What factors influence the IMT outcome has not been examined. Objective: To identify predictors of the positive outcome following IMT in persons with advanced multiple sclerosis (PwAMS). Methods: Inclusion criteria were non-ambulatory PwAMS, Expanded Disability Status Scale (EDSS) ≥6.5, age >18 years, no acute medical conditions, current non-smokers, and ability to consent. Participants (n = 38) performed daily inspiratory exercises using a resistive threshold device for 10 weeks. Baseline measurements included age, sex, body mass index, year post multiple sclerosis diagnosis, comorbidities, EDSS, Modified Fatigue Impact Scale-5, and oral Symbol Digit Modality Test. The percentage of completed prescribed exercise trials (Trials%) during the 10-week intervention was calculated. Age- and sex-adjusted predicted values of maximum inspiratory pressure (MIP%pred) and maximum expiratory pressure (MEP%pred) were obtained before and after the 10-week intervention. Backward multivariable regression analyses for the primary outcome (MIP%pred) were conducted. Results: After controlling for the initial MIP%pred, perceived fatigue at the baseline and Trial% were significant and independent predictors of MIP%pred after IMT. Conclusion: Less fatigue at the baseline and higher adherence to the prescribed exercise repetitions were positive predictors of the positive outcome following IMT in PwAMS.

Predictors of static balance in ambulatory persons with multiple sclerosis.

People with multiple sclerosis (MS) experience a high rate of falls and have decreased static and dynamic balance. The purpose of this study was to determine best predictors of static standing balance, as measured by a single limb stance (SLS) timed test, in ambulatory persons with MS (PwMS) from among commonly used medical and rehabilitation clinical tests. Ambulatory PwMS participated in a single test session. Medical exam data gathered included the Function System (FS) neurologic exam and Expanded Disability Status Score (EDSS). A variety of commonly administered rehabilitation clinical tests addressing static balance, dynamic balance, gait endurance, functional lower extremity strength, abdominal and respiratory muscle strength were completed. Descriptive statistics, Pearson product moment correlations, and forward step-wise linear regressions were calculated. Twenty-eight ambulatory PwMS completed this study. Mean age was 54.74 years. Mean SLS score was 14.6 s. Pyramidal, sensory, bowel/bladder, and visual FS scores and the EDSS were significantly correlated with SLS. Maximal step length scores were significantly correlated with SLS at P less than 0.05 and the Functional Stair Test (FST) and 6-min walk test were correlated with SLS at P less than 0.10. Medical exam data EDSS and FS sensory explain 72.1% of the variance in SLS scores. Rehabilitation exam data FS sensory and FST explain 68.8% of the variance. The FS sensory, EDSS, and FST together explain 73.3% of the variance.

Core muscle strength and endurance measures in ambulatory persons with multiple sclerosis: validity and reliability.

This study examined the test-retest reliability and validity of three core muscle strength tests in individuals with multiple sclerosis (MS). Twenty-one ambulatory individuals with MS completed the curl-up, flexor endurance, and pelvic tilt stabilization tests of core muscle strength. They were retested 1-2 weeks after the first test. The sit-to-stand (STS) test was also conducted on the first test. Descriptive statistics, intraclass correlation coefficients, SEM, and minimal detectable change (MDC) were calculated for each test. Pearson's correlations were calculated between all variables for the first test date. The curl-up test demonstrated excellent test-retest reliability (intraclass correlation coefficient=0.995), requiring 3.4 additional repetitions in 60 s to demonstrate a detectable change. The curl-up test was moderately correlated with the STS. The flexor endurance and pelvic tilt stabilization tests demonstrated moderate test-retest reliability, with relatively large SEMs and MDCs and only a low correlation with the STS. The curl-up test is recommended as a valid and reliable test of core muscle strength in individuals with MS. The flexor endurance test and the pelvic tilt stabilization test of core muscle strength are not recommended due to large SEM and MDC scores. Further study of core muscle strength and endurance measures is indicated to seek additional tests that are valid and reliable in the MS population.

Six-minute walk test for persons with mild or moderate disability from multiple sclerosis: performance and explanatory factors.

PURPOSE: The primary purpose of this study was to determine the extent to which health factors, functional measures, and pulmonary impairment explain performance on 6-Minute Walk Test (6MWT) distance in ambulatory persons with multiple sclerosis (MS). Another purpose was to determine the effect of disability and age on 6MWT performance and explanatory factors. METHODS: A cross-sectional study design was used to evaluate factors that explain performance on the 6MWT in 64 community-dwelling persons with MS-related disability (Expanded Disability Status Scale [EDSS] 3.8±1.6). Of the 64 participants, 43 (67.2%) exhibited mild disability (EDSS <4.0) and 21 (32.8%) had moderate disability (EDSS 4.0-6.5). A regression analysis compared 6MWT performance to measures of health factors (EDSS, number of medications, number of comorbidities, resting HR, systolic and diastolic blood pressure [BP]); physical performance (functional stair test [FST], sit-to-stand test [SST], static standing balance [BAL], Fatigue Severity Scale [FSS], Activities-specific Balance Confidence [ABC] Scale); and pulmonary function (forced expiratory volume in 1 second [FEV(1)], forced vital capacity [FVC], maximal voluntary ventilation [MVV], maximal inspiratory pressure [MIP], maximal expiratory pressure [MEP]). RESULTS: EDSS, ABC, FST, SST, BAL, MVV, MIP, and MEP were significantly associated with 6MWT distance after adjusting for age. Multiple step-wise linear regression analysis revealed that ABC, FST, and BAL were significant and independent explanatory factors of 6MWT distance. ABC and FST explained 75% of the variance in 6MWT performance (R(2)=0.75). Curvilinear regression analysis revealed that the FST is the most significant explanatory factor for 6MWT distance, explaining 79% of the variance (R(2)=0.79). CONCLUSIONS: 6MWT performance in persons with MS was explained by balance confidence (ABC) and stair-climbing ability (FST). The ABC and FST may be practical clinical measures for explaining walking ability and determining risk for disablement in persons with MS.

Randomized control trial of effects of a 10-week inspiratory muscle training program on measures of pulmonary function in persons with multiple sclerosis.

Pulmonary impairments have long been recognized as major causes of morbidity and mortality in individuals with advanced multiple sclerosis (MS). This study was designed to determine if a 10-week home exercise inspiratory training program in community-dwelling persons with MS improves pulmonary muscle strength and endurance. Forty-six ambulatory individuals with clinically diagnosed MS [Expanded Disability Status Scale (EDSS) 2.0-6.5, intervention group mean = 3.96 and control group mean = 3.36] were randomly assigned to an intervention group that received 10 weeks of inspiratory muscle strength training (IMT) or a nontreatment control group. Twenty-one subjects in the control group and 20 subjects in the intervention group completed the study. The intervention group demonstrated significantly greater improvement than the control group in maximal inspiratory pressure (P < 0.001). When compared to the control group, no significant differences were noted for maximal expiratory pressure or maximal ventilation volume after training in the intervention group. Baseline and postexercise training comparison of secondary pulmonary expiratory outcomes were significant in the intervention group for forced expiratory volume at one second (FEV1) (P = 0.014), forced vital capacity (FVC) (P = 0.041), and midexpiratory flow rate(FEF(25-75%)) (P = 0.011). No significant changes were noted for the control group. Thus, IMT significantly increased inspiratory muscle strength and resulted in generalized improvements in expiratory pulmonary function in persons with MS who have minimal to moderate disability. Future studies are needed that focus on the long-term effects of IMT with increased resistance and the impact it has on increasing pulmonary function and functional performance.