Age- and speed-related differences in harmonic ratios during walking

Area of Science:

• Biomechanics
• Gait Analysis
• Gerontology

Background:

• Harmonic ratios (HRs) quantify trunk motion smoothness during gait.
• Previous research suggested HRs are optimized at preferred walking speeds.
• Recent findings challenge this optimization hypothesis.

Purpose of the Study:

• To investigate age-related differences in HRs across various self-selected walking speeds.
• To compare trunk motion smoothness in young, older, and old-old adults.

Main Methods:

• Measured anteroposterior (AP), vertical (VT), and mediolateral (ML) HRs in 13 young, 13 older, and 13 old-old adults.
• Participants walked at very slow, slow, preferred, fast, and very fast speeds.
• Assessed stride time variability in relation to HRs.

Main Results:

• Young and older adults had similar HRs across speeds; old-old adults showed lower AP- and VT-HRs.
• All groups exhibited reduced HRs at speeds slower than preferred.
• No significant HR differences between preferred and faster speeds, except for VT-HR in older groups at very fast speeds.
• Stride time variability inversely correlated with HRs, indicating smoother motion with less variability.

Conclusions:

• Trunk motion smoothness (HRs) does not appear to be optimized at preferred walking pace for any age group.
• Older adults, particularly the oldest, may experience reduced trunk motion smoothness.
• Stride time variability is a key factor influencing gait smoothness across the lifespan.