Validation of a Talking Pedometer for Adults with Visual Impairment ELIZABETH ACKLEY HOLBROOK 1 , SANDY L. STEVENS 2 , MINSOO KANG 2 , and DON W. MORGAN 2 1 Department of Health and Human Performance, Roanoke College, Salem, VA; and 2 Department of Health and Human Performance, Middle Tennessee State University, Murfreesboro, TN ABSTRACT HOLBROOK, E. A., S. L. STEVENS, M. KANG, and D. W. MORGAN. Validation of a Talking Pedometer for Adults with Visual Impairment. Med. Sci. Sports Exerc., Vol. 43, No. 6, pp. 1094–1099, 2011. 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 T 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 G3%). APE values did not differ across environmental conditions (P 9 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. Key Words: PHYSICAL ACTIVITY, MOBILITY AID, ENVIRONMENTAL FAMILIARITY A lthough vision-related disability affects 21 million Americans and ranks as the fourth-leading class of disability in the United States (33), the relatively low prevalence of severe visual impairment belies the sig- nificant health-related needs of persons with vision loss. Despite a higher incidence of functional limitations (35), comorbid conditions (6–8), obesity (15,27,34), depression (22), and mortality (6), public health efforts aimed at pro- moting the health status of persons with visual impairment are generally nonexistent. Given the efficacy of pedometer- based walking interventions in promoting physical activity and improving health among large groups of clinical sub- populations (1,4,12,30–32), previous investigators have considered establishing validity evidence for talking pedom- eters as a preliminary step toward promoting ambulatory activity in persons with vision loss (3,21). Before physical activity interventions can be conducted, however, unique characteristics that are inherent to persons with visual im- pairment, but have not been addressed in previous validation studies, should be considered. Several factors have been identified in the measurement literature as having the potential to affect pedometer accu- racy, including walking speed (2,14,20), mounting position (2,14), and the morphological and ambulatory character- istics of the individual wearing the pedometer (9,14,23). The validity of a pedometer can also be influenced by the inter- nal counting mechanism within the device. Piezoelectric pedometers, for instance, tend to be more accurate than spring-levered models at slow walking speeds (2,20,23) and when worn by overweight individuals (9,23). It is possible, however, that in addition to the factors that are known to influence pedometer accuracy in the general population, other characteristics may need to be considered when vali- dating a pedometer for use in special populations. The locomotor patterns of individuals with visual impair- ment have previously been described as being mechanically inefficient (5,16,17). Even among blind athletes, Ferro et al. (11) observed higher stride rates, shorter stride lengths, and longer contact times (e.g., shorter flight phases) when com- pared with individuals without vision loss. Moreover, alter- ations in gait and long-cane mechanics have been observed in persons with visual impairment in response to changes in the environment, leading to a decrease in hip flexion velocity Address for correspondence: Elizabeth Ackley Holbrook, Ph.D., Depart- ment of Health and Human Performance, Roanoke College, 221 College Lane, Salem, VA 24153; E-mail: holbrook@roanoke.edu. Submitted for publication August 2010. Accepted for publication November 2010. 0195-9131/11/4306-1094/0 MEDICINE & SCIENCE IN SPORTS & EXERCISE Ò Copyright Ó 2011 by the American College of Sports Medicine DOI: 10.1249/MSS.0b013e318205e2d6 1094 APPLIED SCIENCES Copyright © 2011 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.