Five times sit-to-stand following stroke: Relationship with strength and balance

Background: Rising from a chair is an important functional measure after stroke. Originally developed as a measure of lower-limb strength, the five times sit-to-stand test has shown associations with other measures of impairment, such as balance ability. We aimed to compare strength and balance in their relationship with the five times sit-to-stand test following stroke. Methods: Sixty-one participants following stroke were recruited from two hospitals in this cross-sectional observational study. Participants underwent assessment of the five times sit-to-stand (measured with a stopwatch), bilateral lower-limb muscle strength of seven individual muscle groups (hand-held dynamometry), and standing balance (computerised posturography). Partial correlations (controlling for body mass and height) were used to examine bivariate associations. Regression models with partial F-tests (including pertinent covariates) compared the contribution of strength (both limbs) and balance to five times sit-to-stand time. Results: The strength of the majority of lower-limb muscle groups (6/7) on the paretic side had a significant (P < 0.05) partial correlation with five times sit-to-stand time (r = -0.34 to -0.47) as did all balance measures (r = -0.27 to -0.56). In our regression models, knee extensor strength, total path length, and anteroposterior path velocity provided the largest contribution to five times sit-to-stand over covariates amongst strength and balance measures (R-2 = 16.6 to 17.9 %). Partial F-tests revealed that both lower-limb strength and balance contribute to five times sit-to-stand time independent of each other. A regression model containing knee extensor strength and anteroposterior path velocity accounted for 25.5 % of the variance in five times sit-to-stand time over covariates. Conclusions: The strength of the knee extensor muscle group along with measures of standing balance ability (total path length and anteroposterior path velocity) both independently contribute to five times sit-to-stand time. Further research is required to examine how other important impairments post stroke impact five times sit-to-stand performance.