title: Gait stability, variability and complexity on inclined surfaces.
abstract: This study evaluated the gait stability, variability, and complexity of healthy young adults on inclined surfaces. A total of 49 individuals walked on a treadmill at their preferred speed for 4min at inclinations of 6%, 8%, and 10% in upward (UP) and downward (DOWN) conditions, and in horizontal (0%) condition. Gait variability was assessed using average standard deviation trunk acceleration between strides (VAR), gait stability was assessed using margin of stability (MoS) and maximum Lyapunov exponent (λs), and gait complexity was assessed using sample entropy (SEn). Trunk variability (VAR) increased in the medial-lateral (ML), anterior-posterior, and vertical directions for all inclined conditions. The SEn values indicated that movement complexity decreased almost linearly from DOWN to UP conditions, reflecting changes in gait pattern with longer and slower steps as inclination increased. The DOWN conditions were associated with the highest variability and lowest stability in the MoS ML, but not in λs. Stability was lower in UP conditions, which exhibited the largest λs values. The overall results support the hypothesis that inclined surfaces decrease gait stability and alter gait variability, particularly in UP conditions.
authors.affiliation: Bioengineering and Biomechanics Laboratory, Federal University of Goiás, Goiânia, Brazil; Faculty of Electrical Engineering, Postgraduate Program in Electrical and Biomedical Engineering, Centre for Innovation and Technology Assessment in Health, Federal University of Uberlândia, Brazil. Electronic address: marcus@ufg.br.
authors.forename: Marcus Fraga
authors.initials: MF
authors.lastname: Vieira
authors.affiliation: Bioengineering and Biomechanics Laboratory, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Fábio Barbosa
authors.initials: FB
authors.lastname: Rodrigues
authors.affiliation: Bioengineering and Biomechanics Laboratory, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Gustavo Souto
authors.initials: GS
authors.lastname: de Sá E Souza
authors.affiliation: Bioengineering and Biomechanics Laboratory, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Rina Márcia
authors.initials: RM
authors.lastname: Magnani
authors.affiliation: Bioengineering and Biomechanics Laboratory, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Georgia Cristina
authors.initials: GC
authors.lastname: Lehnen
authors.affiliation: Bioengineering and Biomechanics Laboratory, Federal University of Goiás, Goiânia, Brazil.
authors.forename: Natalia Guimarães
authors.initials: NG
authors.lastname: Campos
authors.affiliation: Faculty of Electrical Engineering, Postgraduate Program in Electrical and Biomedical Engineering, Centre for Innovation and Technology Assessment in Health, Federal University of Uberlândia, Brazil.
authors.forename: Adriano O
authors.initials: AO
authors.lastname: Andrade
mesh_terms: D000054:Acceleration; D000328:Adult; D001696:Biomechanical Phenomena; D019277:Entropy; D005080:Exercise Test; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D060726:Torso / Q000502:physiology; D055815:Young Adult
keywords: Gait variability; Inclined walking; Margin of stability; Maximum Lyapunov exponent; Nonlinear analysis