Persons with MS (PwMS) report weakness and walking difficulty as some of their most disabling symptoms. Lower limb (LL) weakness is prevalent in PwMS and is associated with more significant disability, impaired balance, and increased difficulty walking. However, limited research exists describing the relationship between strength of specific LL muscle groups and walking in the same cohort.
To determine the impact of dominant (D) and non-dominant (ND) LL strength on Patient Reported Outcomes (PROs) and objective walking outcome measures in PwMS.
A cross-sectional sample of PwMS (n = 137) derived from a larger, ongoing study was used. The following walking measures were collected at a single visit: 12-item MS Walking Scale (MSWS-12), Timed 25 foot walk (T25FW), and D and ND Stride Length (StrL), Step Length (SL), and Double Support Time (DStime). Isometric peak torque of Hip extension and flexion (HExt; Flex) Knee extension and flexion (KExt; Flex), Ankle plantar and dorsiflexion (APF; DF), and Hip abduction (HAbd) were also collected. Descriptive statistics were performed (age, gender, disease duration and disability level: Patient Determined Disease Steps; PDDS) and a correlational analysis was used to determine the strength of the association of walking to strength in muscle groups.
The MS cohort had a mean age of 51.4 yrs (range: 21-75), disease duration of 14.5 yrs (range: 0.3-40.0), and median PDDS of 2.5 (range: 0-7), with 74.1% being female. All muscle groups were correlated with SL and StrL, and inversely correlated with T25FW, MSWS-12, and DStime. Strong associations were observed between D HFlex and StrL (D: r=.621,p <0.001; and ND: r=.636,p <0.001), D HFlex and ND SL (r=.608,p <0.001), ND KFlex and StrL (D: r=.610,p <0.001; and ND: r=.622,p <0.001), ND HAbd and ND SL (r=.640,p <0.001) and ND HAbd and StrL (r=.605,p <0.001). Weak to moderate correlations (r = ± .190 to .599, p<0.05) were found for all remaining strength and walking measures assessed.
All LL muscle groups (HExt, HFlex, KExt, KFlex, APF, ADF, and HAbd) were associated with the PRO (MSWS-12) and objective walking variables (T25FW, gait parameters: StrL, SL, and DStime) collected. These findings suggest that strength training interventions of these muscles may improve walking in PwMS. Importantly, this study improves understanding of the relationship between different major LL muscle groups with both walking performance and perceived difficulty walking in PwMS.