Lower trunk motion and speed-dependence during walking.

Area of Science:

• Biomechanics
• Human movement analysis
• Gait dynamics

Background:

• Limited understanding of gait speed's influence on upper body motion control.
• Gait speed's effect on lower trunk motion during walking is not well-defined.
• Postural responses during walking at varying speeds require further investigation.

Purpose of the Study:

• To investigate how gait speed affects lower trunk motion in healthy individuals during overground walking.
• To evaluate the utility of Principal Component Analysis (PCA) in analyzing postural responses across different walking speeds.

Main Methods:

• Thirteen healthy subjects walked at self-selected slow, preferred, and fast speeds.
• Lower trunk accelerations (AP, VT, ML) were measured using a triaxial accelerometer.
• Stride-to-stride acceleration amplitude, regularity, repeatability, and coupling were analyzed; PCA was applied to trunk acceleration data.

Main Results:

• Root Mean Square (RMS) acceleration amplitude increased with gait speed in all directions.
• Lower gait speeds (slow vs. preferred) showed reduced regularity and repeatability in mediolateral (ML) and vertical (VT) trunk accelerations.
• No significant differences in regularity and repeatability were observed between preferred and fast speeds, attributed to increased frontal plane coupling.

Conclusions:

• Walking slower than preferred primarily alters lower trunk accelerations in the frontal plane.
• Despite increased acceleration amplitudes at faster speeds, trunk motion characteristics are preserved compared to preferred speed.
• Principal Component Analysis (PCA) has limited discriminatory power for speed-dependent walking pattern differences compared to regularity, repeatability, and coupling measures.