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Comparison of segmental analysis and sacral marker methods for determining the center of mass during level and slope
Bora Jeong1, Chang-Yong Ko1, Yunhee Chang1
1Research Team, Rehabilitation Engineering Research Institute, Incheon, Republic of Korea.
Background:
A 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 Question:
The 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.
Methods:
Ten 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.
Results:
Comparative 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.
Significance:
Based on this latter finding, caution should be exercised when determining COM kinematics using the sacral marker method.
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