Reliability and comparison of weight-bearing ability during standing tasks for individuals with chronic stroke

Abstract

Objectives: To determine the test-retest reliability over 2 separate days for weight-bearing ability during standing tasks in individuals with chronic stroke and to compare the weight-bearing ability among 5 standing tasks for the paretic and nonparetic limbs.

Design: Prospective study using a convenient sample.

Setting: Free-standing tertiary rehabilitation center.

Participants: Fifteen community-dwelling stroke individuals with moderate motor deficits; volunteer sample.

Interventions: Not applicable.

Main outcome measures: Weight-bearing ability as measured by the vertical ground reaction force during 5 standing tasks (rising from a chair, quiet standing, weight-shifting forward, backward, laterally).

Results: The weight-bearing ability was less for the paretic limb compared with the nonparetic limb, but the intraclass correlation coefficients were high (.95-.99) for both limbs between the 2 sessions for all 5 tasks. The forward weight-shifting ability was particularly low in magnitude on the paretic side compared with the other weight-shifting tasks. In addition, the forward weight-shift ability of the nonparetic limb was also impaired but to a lesser extent. Large asymmetry was evident when rising from a chair, with the paretic limb bearing a mean 296N and the nonparetic side bearing a mean 458N. The weight-bearing ability during all 5 tasks correlated with one another (r range,.56-.94).

Conclusions: Weight-bearing ability can be reliably measured and may serve as a useful outcome measure in individuals with stroke. We suggest that impairments of the hemiparetic side during forward weight shifting and sit-to-stand tasks presents a challenge to the motor systems of individuals with stroke, which may account for the poor balance that is often observed in these individuals.

Figure 1

Figures A-H depict a top-down schematic view of the feet placement with respect to the forceplate location during the five tasks. The shaded foot represents the direction of maximal weight shifting during the unilateral tasks of lateral, forward, and backwards weight shifting. For the bilateral tasks, quiet standing and rising from a chair, both feet are shaded grey, as the task requires the individual to bear weight through both feet as equally as possible. The following figures depict the task and corresponding foot orientation: a) Quiet Standing, b) rising from a chair (4 legs of the chair are represented as black filled circles with subject’s feet on F2 and F3), c) lateral weight shift to the left foot, d) lateral weight shift to the right foot, e) forward weight shift to the right foot, f) backwards weight shift to the left foot, g) forwards weight shift to the left foot, and h) backwards weight shift to the right foot.