title: Gait phase varies over velocities.
abstract: We sought to characterize the percent (PT) of the phases of a gait cycle (GC) as velocity changes to establish norms for pathological gait characteristics with higher resolution technology. Ninety five healthy subjects (49 males and 46 females with age 34.9 ± 11.8 yrs, body weight 64.0 ± 11.7 kg and BMI 23.5 ± 3.6) were enrolled and walked comfortably on a 10-m walkway at self-selected slower, normal, and faster velocities. Walking was recorded with a high speed camera (250 frames per second) and the eight phases of a GC were determined by examination of individual frames for each subject. The correlation coefficients between the mean PT of the phases of the three velocities gaits and PT defined by previous publications were all greater than 0.99. The correlation coefficient between velocity and PT of gait phases is -0.83 for loading response (LR), -0.75 for mid stance (MSt), and -0.84 for pre-swing (PSw). While the PT of the phases of three velocities from this study are highly correlated with PT described by Dr. Jacquenlin Perry decades ago, actual PT of each phase varied amongst these individuals with the largest coefficient variation of 24.31% for IC with slower velocity. From slower to faster walk, the mean PT of MSt diminished from 35.30% to 25.33%. High resolution recording revealed ambiguity of some gait phase definitions, and these data may benefit GC characterization of normal and pathological gait in clinical practice. The study results indicate that one should consider individual variations and walking velocity when evaluating gaits of subjects using standard gait phase classification.
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, China; Department of Spinal Surgery, Tianjin Hospital, Tianjin, China.
authors.forename: Yancheng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Lu
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, China.
authors.forename: Songhua
authors.initials: S
authors.lastname: Yan
authors.affiliation: Minisun LLC, Fresno, CA, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Sun
authors.affiliation: Orthopedic Private Practice, Fresno, CA, USA.
authors.forename: D Kevin
authors.initials: DK
authors.lastname: Lester
authors.affiliation: School of Biomedical Engineering, Capital Medical University, Beijing, China. Electronic address: kzhang@ccmu.edu.cn.
authors.forename: Kuan
authors.initials: K
authors.lastname: Zhang
mesh_terms: D061725:Accelerometry / Q000379:methods*; D000328:Adult; D000367:Age Factors; D000368:Aged; D044466:Asian People; D001696:Biomechanical Phenomena; D015992:Body Mass Index; D001834:Body Water / Q000502:physiology; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D026741:Physical Therapy Modalities; D012737:Sex Factors; D016138:Walking / Q000502:physiology; D055815:Young Adult
keywords: Gait cycle; Gait phase; Gait velocity; Variation