Impairment and Disability in Persons with MS: Do Functional Performance or Functional Limitations Matter?

Background: Persons with multiple sclerosis (MS) often demonstrate impairment in cardiorespiratory and musculoskeletal systems that may be associated with functional performance, functional limitations, and disability limitations.

Objectives: This study examined such relationships in persons with MS using Nagi’s disablement model and its subsequent conceptual modifications.

Methods: The sample included 63 persons with MS (75% relapsing-remitting MS, median EDSS = 4.0, mean MS duration = 13.1 years) who underwent measurements of aerobic fitness and muscular strength (i.e., impairment), functional performance, functional limitations, and disability limitations. The data were primarily examined using path analysis in Mplus 7.0.

Results: Our final model provided an excellent fit for the data (χ²=0.67, df=3, p=.88, SRMR=.01, CFI=1.00). The final model indicated that aerobic fitness and muscular strength were indirectly associated with disability limitations in persons with MS through a pathway that included functional limitations (indirect path coefficients of 0.29 and 0.20, respectively), but not functional performance.

Conclusions: Aerobic fitness and muscular strength may be important targets of exercise training interventions for improving perceived functional limitations and disability limitations in persons with MS.