| The purpose of this study was to investigate the mechanical aspect of balance behavior during nonlocomotor assessment. Secondary purposes were (a) to determine kinematic and temporal similarity and dissimilarity among three balance tasks, (b) to determine the predictive relationship of seven independent variables to the dependent variable time-on-balance, and (c) to determine the viability of a five level balance skill continuum paradigm. One temporal and seven kinematic variables were observed through the video analysis of 72 children between 108 and 143 months of age screened for average or above average orthoptic and refractive vision while performing three static balance tasks. The tasks were (a) single leg stand (SOL), (b) tandem stand on rail (TND), and (c) tip-toe balance stand (TTB). Subjects were filmed in the critical plane of movement, that exhibiting the greatest movement, using a Panasonic video camera at 30 fps and a shutter speed of 1/1000 s. Variables observed were (a) time-on-balance, (b) direction of loss of balance, (c) average position of the line of gravity relative to the base of support, (d) vertical displacement of the center of gravity, (e) trunk range of motion, (f) standard deviation of the line of gravity, (g) extreme recoverable line of gravity, and (h) extreme recoverable angle of stability. Film data were reduced using VuTech Freez Frame to capture video images and the TWU Film Analysis System developed by Noble, Zollman, and Yu (1988) modified by Zimmermann (1990). Descriptive statistics were computed and compared for each variable across tasks. Differences among tasks were examined using MANOVA with repeated measures. Mechanical task specificity, particular to time-on-balance, direction of loss of balance, standard deviation of the line of gravity, and the extreme recoverable line of gravity were reported. It was concluded balance tasks for nonlocomotor assessment are mechanically task specific and a continuum of balance ability was suggested. Although balance ability could be predicted using time-on-balance it can more adequately be determined using a combination of time-on-balance, direction of loss of balance, and the mechanical variables related to the line of gravity. (Abstract shortened with permission of author.). |
