Aging alters both biomechanical and neural factors related to walking, leading to reductions in preferred gait speed with age. Biomechanical variability in human walking has been an area of great interest for aging research. Neural variability has not been well studied in this context. Electroencephalography (EEG) can measure brain activity during walking, allowing us to quantify interstride variability of electrocortical activity. We recruited younger and older adults to walk (0.25-1.0 m/s) while we measured EEG interstride variability in theta, alpha, and beta power. We hypothesized that theta, alpha, and beta variability would decrease at faster walking speeds like most gait kinematic variables. We also hypothesized that older adults would have more interstride variability compared to younger due to reduced gait automaticity. We observed sensorimotor and posterior parietal cortices for their roles in motor action and sensory processing. Interstride variability in theta power lessened with faster walking speeds in posterior parietal cortex, and Interstride variability in alpha and beta power lessened in both sensorimotor and posterior parietal cortex. Further, we found that older adults had less interstride variability than younger adults, primarily in alpha and beta. We also observed interstride phasic alignment of electrocortical activity across the gait cycle. We found broadband increases in interstride phase alignment across the gait cycle, and that older higher functioning adults had greater phase alignment in gamma (30-50 Hz) than younger adults in parietal cortex. These findings suggest that the automaticity of gait is greater at faster walking speeds, and that older adults' reduced automaticity of gait may be unrelated to electrical brain activity.
Salminen et al. (Mon,) studied this question.