Article ID: 26-00062
This study investigated the low-dimensional spatiotemporal structure of overground walking using displacement-based principal component analysis (PCA). Four healthy young male subjects participated in the walking measurement experiment. Three-dimensional marker trajectories were collected during overground walking at three different walking rates, and marker displacements were analyzed to reduce the influence of translational components. Cumulative variance of the first two principal components (PC1 and PC2) consistently accounted for more than 85% of the total variance across all walking rates. Temporal analysis showed that PC1 exhibited a regular sinusoidal waveform corresponding to the fundamental gait frequency, whereas PC2 showed a periodic structure at approximately twice that frequency. In contrast, higher-order components displayed complex composite waveforms. Principal component loadings indicated that PC1 primarily represented alternating anterior–posterior displacements of the left and right lower limbs, while PC2 reflected coordinated in-phase displacements associated with the double-support phase. The variance explained by PC1 slightly increased with walking rate, likely due to increased step length. Sinusoidal models of PC1 and PC2 were used to successfully reconstruct walking movements with high temporal fidelity. The temporal and spatial characteristics of these components were preserved across all walking rates. Within this preliminary dataset of four healthy young males, overground walking was characterized by low-dimensional periodic coordination patterns that were relatively consistent across individuals. These findings highlight the effectiveness of displacement-based PCA for revealing fundamental walking movement organization.
