Mobility and cognitive correlates of dual task cost of walking in persons with multiple sclerosis.

BACKGROUND: Persons with multiple sclerosis (MS) often experience a decrease in walking performance while simultaneously performing a cognitive task. This decrease in walking performance is termed dual task cost (DTC). OBJECTIVE: To examine if mobility and cognitive function are correlates of DTC in persons with MS. METHODS: Participants were 96 persons with MS who had Expanded Disability Status Scale scores that ranged between 2.0 and 6.5. To determine DTC, participants walked at a self-selected pace with and without a cognitive task while gait velocity was recorded. The effect of the cognitive task was quantified as the percent change in walking velocity between conditions. Participants further completed the timed 25-foot walk (T25FW) and Symbol Digit Modalities Test (SDMT). Centered scores for the T25FW and SDMT, and the product of the center scores, were placed into a linear regression to determine the correlates of DTC. RESULTS: DTC averaged 12.5% (SD = 9.3) and ranged between -14.1 and 42.4%. Performance on the T25FW ranged between 3.1 and 24.5 s with an average of 6.8 s (SD = 3.1 s). SDMT scores ranged between 15 and 79 with an average of 45 items (SD = 12). Regression analysis revealed that age, disability, walking and cognitive performance explained 17% of the variance in DTC. The interaction between walking and cognition did not explain additional variance. CONCLUSIONS: Mobility and cognitive impairment were both independent predictors of DTC of walking in persons with MS. This raises the possibility that DTC could be reduced with modifications of either mobility or cognition.

Symptomatic correlates of six-minute walk performance in persons with multiple sclerosis.

BACKGROUND: The six-minute walk (6MW) test has been identified as a valid, reliable, and reproducible measure of endurance walking performance that differentiates persons with multiple sclerosis (MS) and controls and correlates with disability and walking impairment. AIM: This study examined symptoms of fatigue, pain, and depression as correlates of 6MW performance and the possibility that such symptoms would account for the difference in 6MW distance between persons with MS and controls. DESIGN: Observational. SETTING: Research laboratory. POPULATION: Sixty-six persons, 33 with MS and 33 controls matched on age, sex, height, and weight. METHODS. Participants completed the fatigue severity scale (FSS), short-form of the McGill pain questionnaire (SF-MPQ), and depression items of the hospital anxiety and depression scale (HADS-D) and then performed the six-minute walk (6MW) in a rectangular corridor. RESULTS: There were statistically significant differences between groups in 6MW distance (p = 0.0001) and FSS (P=0.0001) and SF-MPQ (P=0.025), but not HADS-D (P>0.05), scores. 6MW distance was significantly correlated with FSS (P=-0.66), SF-MPQ (P=-0.38), and HADS-D (P=-0.33) scores in the overall sample, but 6MW distance was significantly correlated with only FSS scores in the separate samples of those with MS (P=-0.46) and controls (P=-0.46). Only group (ß=0.32) and FSS scores (ß=-0.53) explained variance in overall 6MW distance in a hierarchical, linear regression analysis. CONCLUSION: This study provides new insight into the symptomatic correlates of 6MW performance and identifies fatigue as a possible target of interventions designed to improve walking endurance in MS. CLINICAL REHABILITATION IMPACT: Clinicians and practitioners might consider targeting fatigue as a method of managing compromised endurance walking in persons with MS.

Physical activity and multiple sclerosis: new insights regarding inactivity.

OBJECTIVES: There is increasing recognition that physical activity has beneficial consequences among persons with multiple sclerosis (MS), but there is concern regarding the current degree of physical inactivity in this population because of limitations with previous research and increased recognition of health behaviors in MS. This study compared physical activity levels between large samples of persons with mild MS and matched controls using validated measures of physical activity. MATERIALS AND METHODS: The sample included 77 cases of MS and 77 controls matched on age, height, weight, and gender. Physical activity was assessed using five measures, namely the Godin Leisure-Time Exercise Questionnaire (GLTEQ), International Physical Activity Questionnaire (IPAQ), and activity counts per day, step counts per day, and time spent in moderate-to-vigorous physical activity (MVPA) per day by accelerometry. RESULTS: There were statistically significant differences between groups in accelerometer activity counts (t = -3.87, P = 0.0001), accelerometer step counts (t = -4.29, P = 0.0001), time spent in MVPA (t = -2.39, P = 0.01), GLTEQ scores (t = -3.83, P = 0.0001), and IPAQ scores (t = -3.42, P = 0.0001). The average effect size across all five measures was d = -0.59 and indicated that persons with MS overall were moderately less physically active than the matched controls. CONCLUSIONS: The primary finding was a moderate reduction in physical activity among those with MS, but the magnitude was substantially smaller than reported in a published meta-analysis. Importantly, the degree of physical inactivity can likely be overcome through the delivery of behavioral interventions for increasing physical activity and this should translate into meaningful consequences for persons with MS.