Validation of a talking pedometer for adults with visual impairment.

UNLABELLED: Alterations in gait mechanics and mobility aid (MA) use have been observed in persons with visual impairment (VI) in response to environmental changes, yet the influence of these modifications on the accuracy of an adaptive pedometer has not been documented.

PURPOSE: The purpose of this study was to establish validity evidence for the Centrios talking pedometer relative to environmental familiarity and MA use in adults with VI.

METHODS: Thirteen adults with VI (age = 38 ± 14 yr) completed two walking trials over an unfamiliar, quarter-mile course while wearing a Centrios talking pedometer at the right and left sides of the hip. Walking speed, pedometer-determined steps, and actual steps were recorded during the first session, reflecting walking in an "unfamiliar environment." After a series of additional walks over the same course, outcome measures were reassessed during a second trial, reflecting walking in a "familiar environment." Absolute percent error (APE) scores were calculated between actual and pedometer-determined steps. Paired t-tests were used to assess differences in APE relative to mounting position across environmental settings.

RESULTS: During unfamiliar trials, the pedometer accurately reported steps when mounted at the hip opposite the user's MA (APE = 2.1%) but was significantly less accurate when mounted at the hip on the user's MA side (APE = 11.1%). In the familiar setting, the pedometer accurately reported steps when mounted at the left hip and the hip opposite the user's MA (APE <3%). APE values did not differ across environmental conditions (P > 0.05).

CONCLUSIONS: In unfamiliar and familiar walking conditions, the Centrios pedometer accurately monitors step-based activity in adults with VI when mounted at the hip opposite the user's MA.