title: Entrainment to a real time fractal visual stimulus modulates fractal gait dynamics.
abstract: Fractal patterns characterize healthy biological systems and are considered to reflect the ability of the system to adapt to varying environmental conditions. Previous research has shown that fractal patterns in gait are altered following natural aging or disease, and this has potential negative consequences for gait adaptability that can lead to increased risk of injury. However, the flexibility of a healthy neurological system to exhibit different fractal patterns in gait has yet to be explored, and this is a necessary step toward understanding human locomotor control. Fifteen participants walked for 15min on a treadmill, either in the absence of a visual stimulus or while they attempted to couple the timing of their gait with a visual metronome that exhibited a persistent fractal pattern (contained long-range correlations) or a random pattern (contained no long-range correlations). The stride-to-stride intervals of the participants were recorded via analog foot pressure switches and submitted to detrended fluctuation analysis (DFA) to determine if the fractal patterns during the visual metronome conditions differed from the baseline (no metronome) condition. DFA α in the baseline condition was 0.77±0.09. The fractal patterns in the stride-to-stride intervals were significantly altered when walking to the fractal metronome (DFA α=0.87±0.06) and to the random metronome (DFA α=0.61±0.10) (both p<.05 when compared to the baseline condition), indicating that a global change in gait dynamics was observed. A variety of strategies were identified at the local level with a cross-correlation analysis, indicating that local behavior did not account for the consistent global changes. Collectively, the results show that a gait dynamics can be shifted in a prescribed manner using a visual stimulus and the shift appears to be a global phenomenon.
authors.affiliation: Department of Kinesiology, University of North Carolina at Greensboro, Greensboro, NC, USA. Electronic address: ckrhea@uncg.edu.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Rhea
authors.affiliation: Division of Sports Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH, USA; Center for Cognition, Action, and Perception, Department of Psychology, University of Cincinnati, Cincinnati, OH, USA.
authors.forename: Adam W
authors.initials: AW
authors.lastname: Kiefer
authors.affiliation: Gait and Motion Analysis Laboratory, Providence VA Medical Center, Providence, RI, USA.
authors.forename: Susan E
authors.initials: SE
authors.lastname: D'Andrea
authors.affiliation: Department of Cognitive, Linguistic & Psychological Sciences, Brown University, Providence, RI, USA.
authors.forename: William H
authors.initials: WH
authors.lastname: Warren
authors.affiliation: Gait and Motion Analysis Laboratory, Providence VA Medical Center, Providence, RI, USA.
authors.forename: Roy K
authors.initials: RK
authors.lastname: Aaron
mesh_terms: D000328:Adult; D000375:Aging; D001696:Biomechanical Phenomena; D005080:Exercise Test; D005260:Female; D017709:Fractals; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D013997:Time Factors; D014796:Visual Perception; D016138:Walking; D055815:Young Adult
keywords: 2330; Fractals; Gait; Global entrainment; Persistence