Comparison of segmental analysis and sacral marker methods for determining the center of mass during level and slope walking

Abstract

BackgroundA human’s center of mass (COM) is a widely used parameter in both clinical and practical applications. The segmental analysis method for determining the COM is considered the gold standard but is difficult to apply in a real environment. Research questionThe purpose of this study was to confirm the efficacy of an alternative COM determination method—the sacral marker method—by comparing segmental analysis and sacral marker method results in three dimensions during level or slope walking. MethodsTen healthy young subjects (age = 24.0 ± 4.5 yr, height = 174.5 ± 5.9 cm, and weight = 66.9 ± 9.4 kg) participated in the study. Each participant was monitored using a Helen Hayes full-body marker set and asked to walk on level and sloped (7°) terrain. The markers’ trajectories were subsequently recorded. Each participant’s COM was determined using segmental analysis and sacral marker methods via calculation and direct measurement, respectively. ResultsComparative results indicated no significant differences (p > 0.05) between the segmental analysis and sacral marker method results for the COM displacement, velocity, or acceleration in the fore-aft and vertical directions. Conversely, significant differences (p < 0.05) between the two methods were observed for the COM displacement and acceleration in the medial-lateral direction, suggesting kinematic differences. SignificanceBased on this latter finding, caution should be exercised when determining COM kinematics using the sacral marker method.