title: Influence of gait speed on the control of mediolateral dynamic stability during gait initiation.
abstract: This study investigated the influence of gait speed on the control of mediolateral dynamic stability during gait initiation. Thirteen healthy young adults initiated gait at three self-selected speeds: Slow, Normal and Fast. The results indicated that the duration of anticipatory postural adjustments (APA) decreased from Slow to Fast, i.e. the time allocated to propel the centre of mass (COM) towards the stance-leg side was shortened. Likely as an attempt at compensation, the peak of the anticipatory centre of pressure (COP) shift increased. However, COP compensation was not fully efficient since the results indicated that the mediolateral COM shift towards the stance-leg side at swing foot-off decreased with gait speed. Consequently, the COM shift towards the swing-leg side at swing heel-contact increased from Slow to Fast, indicating that the mediolateral COM fall during step execution increased as gait speed rose. However, this increased COM fall was compensated by greater step width so that the margin of stability (the distance between the base-of-support boundary and the mediolateral component of the "extrapolated centre of mass") at heel-contact remained unchanged across the speed conditions. Furthermore, a positive correlation between the mediolateral extrapolated COM position at heel-contact and step width was found, indicating that the greater the mediolateral COM fall, the greater the step width. Globally, these results suggest that mediolateral APA and step width are modulated with gait speed so as to maintain equivalent mediolateral dynamical stability at the time of swing heel-contact.
authors.affiliation: Laboratoire DIMPS-CURAPS, UFR des Sciences de l'Homme et de l'Environnement, Université de la Réunion, 117 rue du Général Ailleret, 97430 Le Tampon, Ile de la Réunion. Electronic address: teddy.caderby@univ-reunion.fr.
authors.forename: Teddy
authors.initials: T
authors.lastname: Caderby
authors.affiliation: Laboratoire CIAMS, Team RIME, UFR STAPS, Université Paris-Sud, 91440 Orsay Cedex, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Yiou
authors.affiliation: Laboratoire DIMPS-CURAPS, UFR des Sciences de l'Homme et de l'Environnement, Université de la Réunion, 117 rue du Général Ailleret, 97430 Le Tampon, Ile de la Réunion.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Peyrot
authors.affiliation: Laboratoire de Simulation et Modélisation du Mouvement, Département de Kinésiologie, Université de Montréal, Laval, QC, Canada.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Begon
authors.affiliation: Laboratoire DIMPS-CURAPS, UFR des Sciences de l'Homme et de l'Environnement, Université de la Réunion, 117 rue du Général Ailleret, 97430 Le Tampon, Ile de la Réunion.
authors.forename: Georges
authors.initials: G
authors.lastname: Dalleau
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005260:Female; D005528:Foot / Q000502:physiology; D005684:Gait / Q000502:physiology*; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D004856:Postural Balance; D011312:Pressure; D055815:Young Adult
keywords: Anticipatory postural adjustments; Foot placement; Gait initiation; Gait speed; Margin of stability