Generalizability of the limits of stability test in the evaluation of dynamic balance among older adults

OBJECTIVE: Reliability of platform posturography tests is essential for the identification and treatment of balance-related disorders. The purposes of this study were to establish the reliability of the limits of stability (LOS) test and to determine the relative variance contributions from identified sources of measurement error. DESIGN: Generalizability theory was used to calculate (1) variance estimates and percentage of variation for the sources of measurement error, and (2) generalizability coefficients. Random effects repeated measures analysis of variance (RM ANOVA) was used to assess consistency of measurements across both days and targets. PARTICIPANTS: Thirty-eight community-dwelling older adults with no recent history of falls. MAIN OUTCOME MEASURES: Outcome measures derived from the LOS tests included movement velocity (MV), maximum center of gravity (COG) excursion (ME), end point COG excursion (EE), and directional control (DC). RESULTS: Estimated generalizability coefficients for 2 and 3 days of testing ranged from .69 to .91. Relative contributions of the day facet were minimal. The RM ANOVA results indicated that for three of the movement variables, no significant differences in scores were observed across days. CONCLUSIONS: The 75% and 100% LOS tests are reliable tests of dynamic balance when administered to healthy older adults with no recent history of falls. Dynamic balance measures were generally consistent across multiple evaluations.