Lifestyle physical activity and walking impairment over time in relapsing-remitting multiple sclerosis: results from a panel study.

OBJECTIVE: There is currently no published evidence from longitudinal or intervention studies of an association between lifestyle physical activity and walking impairment in persons with multiple sclerosis. This panel study tested the hypothesis that a change in lifestyle physical activity would be inversely associated with change in walking impairment over a 6-mo period in persons with relapsing-remitting multiple sclerosis.
DESIGN: Participants with a confirmed diagnosis of relapsing-remitting multiple sclerosis completed a battery of measures at baseline (n = 269) and at 6-mo follow-up (n = 263) in the absence of an intervention. The data were analyzed using linear panel analysis and covariance modeling in Mplus 3.0.
RESULTS: The panel model fit the data (χ(2) = 25.23; df = 12; P = 0.01; standardized root-mean-squared residual, 0.04; comparative fit index, 0.98) and, as expected, identified the direct effects between baseline physical activity and walking impairment (path coefficient, -0.31) and follow-up physical activity and walking impairment (path coefficient, -0.16). The second path coefficient indicated that a standard deviation unit change of 1 in physical activity was associated with a standard deviation unit residual change of 0.16 in walking impairment.
CONCLUSIONS: The finding supports the possible importance of targeting free-living physical activity as a behavioral approach for forestalling walking impairments in adults with relapsing-remitting multiple sclerosis.