Symmetry in vertical ground reaction force is not related to walking and balance difficulties in people with multiple sclerosis

Analysis of vertical ground reaction force (GRF) symmetry may benefit people with multiple sclerosis (PwMS) since it can detect important differences in gait mechanics which have not previously been discussed in the related literature. Therefore, the primary objective of the current study was to determine whether symmetry of the vertical GRF during gait is associated with validated gait and balance tests in PwMS. Additionally, we examined whether the symmetry of the vertical GRF differs between MS fallers, non-fallers and between neurological disability levels. Gait and balance data were collected from 402 PwMS (249 women) with a mean age of 42.1 (S.D = 14.1) years. Vertical GRF parameters were obtained using the Zebris FDM-T Treadmill (Zebris Medical GmbH, Germany). Clinical gait and balance tests included the 2 and 6-min Walk Test, Timed Up and Go Test, Timed 25 Foot Walk, Four Square Step Test, Multiple Sclerosis Walking Scale questionnaire, Modified Fatigue Impact Scale and the Falls Efficacy Scale International questionnaire. The vertical GRF symmetry index score of the total sample was 3.7 (SD = 3.1). In terms of fall status, non-significant differences were observed between the fallers and non-faller groups and between the neurological disability subgroups. Non-significant correlation scores were found between the vertical GRF symmetry index, all clinical walking and balance tests and self-reported questionnaires. We suggest clinicians, especially those involved in physical rehabilitation, accord low priority to this gait phenomenon in the MS population.