Tuned to walk: cue type, beat perception, and gait dynamics during rhythmic stimulation in aging

Rhythmic auditory cueing (RAC) improves spatiotemporal gait parameters in older adults, often using isochronous rhythmic cues (i.e., with constant inter-beat-intervals). However, healthy gait contains fractal-like variability, (i.e., with persistent long-range correlations; LRC) which is disturbed when walking to isochronous cues. Embedding auditory cues with a fractal structure increases LRC in gait among young and older adults, though middle-aged adults are under researched. Walking requires greater cognitive resources with increased age, though how different cue-types interact with attentional load during RAC is under researched. This may depend on beat perception, as those with better beat perception benefit more from RAC. The aim of this study was to investigate the optimal parameters for RAC across the adult lifespan. We predicted that 1) walking to fractal cues would increase LRC in gait across the adult lifespan; 2) increasing attentional load would decrease LRC in gait, particularly for older adults. Moderating effects of beat perception on the impact of cue-type on LRC were also explored. Young, middle-aged, and older adults (n = 62) walked around an elliptical track in silence and in three cued walking conditions of increasing attentional load. Tones were presented in isochronous and fractal rhythms. Fractal cues increased LRC in gait, with qualitatively greater increase among middle-aged adults. Attentional load had no effect on LRC in gait. Isochronous cues resulted in decreased LRC in gait, particularly for those with better beat perception. The optimal parameters of RAC therefore depend on age, beat perception, and the target gait parameter.