IntroductionBalance and gait problems in older adults are often associated with the occurrence of falls (Lipsitz et al., 1991; Tinetti et al., 1988) and fear of falling (Tinetti et al., 1994). In this study we investigated the relation between two different balance assessments, the Berg Balance Scale (Berg et al, 1992) and the Equitest computerized dynamic posturography system (NeuroCom, 1991) and we examined how scores obtained from these assessments related to the performance of older women on a number of different common gait activities, including stair ascent, stair descent, walking normally and walking over obstacles. These tasks were chosen to simulate common activities in which older individuals might be at risk for a fall.MethodParticipants: Sixty women between the ages of 57 and 86 (Mean = 72.3, SD = 7.3) participated in this study. Subjects reported a history of relatively low levels of physical activity or exercise (Mean days per week of exercise = 2.3, SD = 2.2, Mean length of exercise session = 12 minutes, SD = 8 minutes) with the most frequent form of exercise being walking.Procedures.Gait Tasks: Two observers assessed the gait speed of the participants as they completed 11 different gait tasks. The tasks included walking down and up a flight of 15 stairs, walking across a simulated street, walking across a 7 meter long pathway first with no obstacle and then with obstacles of 2.5 cm (similar in height to a threshold), 20 cm (approximately curb or step height) and 40 cm. The final four gait conditions involved repeating the gait tasks using the 7 meter pathway while performing a secondary task (carrying a tray with a mug). The simulated street consisted of two 20 cm high platforms separated by a distance of 9.75 meters. In all of the gait tasks participants were instructed to walk at their normal pace. During the stair ascent and descent participants were told that they could use the handrail if so desired. All of the tasks were completed twice.Balance Assessments: Balance was first assessed using the Berg Balance Scale (Berg et al., 1992), an easily administered 14 item assessment involving common everyday movements. For each item participants were given a score of zero (unable to complete item) to 4 (item easily completed). Scores are then summed across items to obtain an overall score (maximum = 56). Balance was then assessed using the NeuroCom Equitest computerized dynamic posturography system (Nashner, 1993: NeuroCom, 1991). Each of the participants were tested in all six conditions of the Sensory Organization Test (SOT) following standard testing procedures. For each condition subjects receive an equilibrium score which compares their peak sway in the anterior-posterior direction with the theoretical limits of their stability (based on their height). Scores range from zero (loss of balance) to 100% indicating very little AP sway. A composite equilibrium score is then derived from a weighted average of the individual conditions, with conditions 3 through 6 (the more difficult conditions) weighted more heavily (Nashner, 1993).ResultsA 2 (task: walking normally, walking with the tray) 4 (condition: no obstacle, 2.5 cm obstacle, 20 cm obstacle, 40 cm obstacle) repeated measures ANOVA revealed that the women walked more slowly as the obstacle height increased (F(3, 162) = 45.3, p < .001), and while carrying the tray (F(1,54) = 4.5, p < .05). In addition, the influence of the secondary task had a greater impact on gait speed when the women were walking over the two highest obstacles compared to the other gait conditions (F(3, 162) = 10.7, p < .001).Performance on the Berg Balance Scale was generally high with subjects obtaining a mean score of 52.7 (SD = 5.1, range 25 - 56) out of a possible 56. In contrast, the mean composite equilibrium score obtained from the EquiTest was 64.8 (SD = 12.3) out of a maximum of 100. Performance on the two balance assessments was found to be significantly correlated (r = .69, p < .001) and both measures were significantly correlated with the age of the participants (r = -.37, p <.005 for the Berg, r = -.41, p < .001 for the EquiTest).To examine the relation between the balance and gait measures correlations were computed controlling for subject height because gait speed and height have been found to be correlated (Himann et al, 1988; Woo et al, 1995). Both balance measures were found to be significantly correlated with gait speed during the simulated street task, stair ascent and descent, and walking normally and over the obstacles. In general the correlations were higher between the Berg score and the gait measures (rs = -.56 to -.88, ps < .01 for the Berg) than between the composite Equitest score and the gait measures (rs = -.37 to -.63,p s < .05. Similar results were obtained for the correlations between the balance measures and the gait tasks involving the secondary task, though these correlations tended to be lower.In order to determine which balance assessment was most predictive of performance on the various gait tasks a series of hierarchical multiple regression analyses were conducted. In each of these analyses subject age and height were controlled by entering them first. The Berg Balance Scale accounted for significant variance in gait speed in all cases. In contrast, the Equitest only accounted for significant portion of the variance in gait speed when it was entered prior to the Berg.DiscussionOlder women who performed well on the Balance Scale and Equitest were found to have significantly faster gait speeds across a wide variety of gait tasks at different levels of difficulty compared to older women with relatively low scores on either the Balance scale or EquiTest. The performance on the Balance Scale was generally more highly related to and more predictive of gait performance than the composite balance score obtained from the EquiTest. This is somewhat surprising given that performance on the Balance Scale was generally high, while performance of the same individuals on the EquiTest revealed relatively poor balance control. The Berg Balance Scale, however, involves a number of common everyday activities (e.g., standing and reaching, sitting and standing, stepping up and down from a step) that likely tap some of the same abilities (e.g., leg strength) involved in going up and down stairs and walking over obstacles, thus making it a relatively good measure of functional performance. The EquiTest, however, may be more useful for uncovering specific sensory deficits that may be implicated in falls and fear of falling, because it is a more sensitive measure of overall balance abilities.