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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.

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.