The biomechanical investigation of the relationship between balance and muscular strength in people with chronic stroke: a pilot cross-sectional study

Background: Impaired balance and weak muscle strength are common deficits associated with stroke. Limited research has examined the relationship between balance and strength in people post-stroke.Objective: To investigate the association between balance and muscular strength in people post-stroke.Methods: A total of 11 people with chronic stroke, who were community dwelling and ambulatory, completed balance and strength assessments. A computerized dynamic posturography system was used for Limits of Stability (LOS) test, Sit-to-Stand (STS) test, and the Modified Clinical Test of Sensory Interaction on Balance (mCTSIB). Additionally, a computerized dynamometer was used to assess the isometric muscle strength of flexion/extension in the core (the trunk) and the leg (the hip, knee, and ankle). Pearson correlation analysis was used to investigate the relationship between balance and muscle strength measurements.Results: Endpoint excursion (EPE) (r =.646; p <0.032) and maximum excursion (MXE) (r =.613; p <0.045) of LOS test were positively correlated with core and leg strength (C&L). Specifically, both EPE (r =-.792; p <0.004) and MXE (r =-.623; p <0.041) in backward direction had strong correlations with C&L. Core strength also showed a positive correlation with EPE of LOS test (r =.636; p <0.035) while the composite leg strength did not. Lastly, STS and mCTSIB tests did not demonstrate significant associations with muscle strength.Conclusions: The results indicate that the C&L have a strong relationship with the ability to shift body weight in multiple directions, particularly backward, among people post-stroke. However, static balance and STS performance do not appear to be related to muscle strength.