title: Quick foot placement adjustments during gait: direction matters.
abstract: To prevent falls, adjustment of foot placement is a frequently used strategy to regulate and restore gait stability. While foot trajectory adjustments have been studied during discrete stepping, online corrections during walking are more common in daily life. Here, we studied quick foot placement adjustments during gait, using an instrumented treadmill equipped with a projector, which allowed us to project virtual stepping stones. This allowed us to shift some of the approaching stepping stones in a chosen direction at a given moment, such that participants were forced to adapt their step in that specific direction and had varying time available to do so. Thirteen healthy participants performed six experimental trials all consisting of 580 stepping stones, and 96 of those stones were shifted anterior, posterior or lateral at one out of four distances from the participant. Overall, long-step gait adjustments were performed more successfully than short-step and side-step gait adjustments. We showed that the ability to execute movement adjustments depends on the direction of the trajectory adjustment. Our findings suggest that choosing different leg movement adjustments for obstacle avoidance comes with different risks and that strategy choice does not depend exclusively on environmental constraints. The used obstacle avoidance strategy choice might be a trade-off between the environmental factors (i.e., the cost of a specific adjustment) and individuals' ability to execute a specific adjustment with success (i.e., the associated execution risk).
authors.affiliation: Department of Kinesiology, Movement Control and Neuroplasticity Research Group, KU Leuven, Tervuursevest 101 bus 1501, 3001, Louvain, Belgium. wouter.hoogkamer@faber.kuleuven.be.
authors.forename: Wouter
authors.initials: W
authors.lastname: Hoogkamer
authors.affiliation: Department of Kinesiology, Movement Control and Neuroplasticity Research Group, KU Leuven, Tervuursevest 101 bus 1501, 3001, Louvain, Belgium.
authors.forename: Zrinka
authors.initials: Z
authors.lastname: Potocanac
authors.affiliation: Department of Kinesiology, Movement Control and Neuroplasticity Research Group, KU Leuven, Tervuursevest 101 bus 1501, 3001, Louvain, Belgium.|Biomechatronics Lab, Mechatronics Department, Escola Politécnica da Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Jacques
authors.initials: J
authors.lastname: Duysens
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005528:Foot / Q000502:physiology; D005684:Gait / Q000502:physiology*; D006801:Humans; D011597:Psychomotor Performance / Q000502:physiology*; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: Falls; Locomotion; Obstacle avoidance; Online corrections; Stepping accuracy; Walking