title: Constraints on perception of information from obstacles during foot clearance in people with chronic stroke.
abstract: The aim of this study was to examine effects of different types of task constraints on coupling of perception and action in people with chronic stroke when crossing obstacles during a walking task. Ten participants with hemiplegic chronic stroke volunteered to walk over a static obstacle under two distinct task constraints: simple and dual tasks. Under simple task constraints, without specific instructions, participants walked at their preferred speed and crossed over an obstacle. Under dual task constraints, the same individuals were required to subtract numbers whilst walking. Under both distinct task constraints, we examined emergent values of foot distance when clearing a static obstacle in both affected and unaffected legs, measured by a 3D motion tracking system. Principal component analysis was used to quantify task performance, and discriminant analysis was used to compare gait performance between task constraints. Results suggested that patients, regardless of affected body side, demonstrated differences in perception of distance information from the obstacle, which constrained gait differences in initial swing, mid-swing, and crossing phases. Furthermore, dual task constraints, rather than hemiplegic body side, were a significant discriminator in patients' perceptions of distance and height information to the obstacle. These findings suggested how performance of additional cognitive tasks might constrain perception of information from an obstacle in people with chronic stroke during different phases of obstacle crossing, and thus may impair their adaptive ability to successfully manoeuvre around objects.
authors.affiliation: Faculty of Health and Wellbeing, Academy of Sport and Physical Activity, Sheffield Hallam University, Sheffield, S10 2BP, UK. m.shafizadeh@shu.ac.uk.
authors.forename: Mohsen
authors.initials: M
authors.lastname: Shafizadeh
authors.affiliation: Faculty of Health and Wellbeing, Centre for Sport Engineering Research, Sheffield Hallam University, Sheffield, S10 2BP, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Wheat
authors.affiliation: Faculty of Health and Wellbeing, Centre for Sport Engineering Research, Sheffield Hallam University, Sheffield, S10 2BP, UK.
authors.forename: Keith
authors.initials: K
authors.lastname: Davids
authors.affiliation: Department of Physiotherapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Noureddin Nakhostin
authors.initials: NN
authors.lastname: Ansari
authors.affiliation: Department of Geriatrics and Stroke Medicine, Sheffield Teaching Hospitals, Royal Hallamshire Hospital, Glossop Road, Sheffield, S10 2JF, UK.
authors.forename: Ali
authors.initials: A
authors.lastname: Ali
authors.affiliation: University of Social Welfare and Rehabilitation Sciences, Kodakyar Ave, Daneshjo Blvd, Evin, Tehran, 1985713834, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Garmabi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D002908:Chronic Disease; D004215:Distance Perception / Q000502:physiology*; D005260:Female; D005528:Foot / Q000503:physiopathology*; D020233:Gait Disorders, Neurologic / Q000209:etiology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010468:Perceptual Disorders / Q000209:etiology / Q000503:physiopathology*; D011597:Psychomotor Performance / Q000502:physiology*; D020521:Stroke / Q000150:complications / Q000503:physiopathology*; D016138:Walking / Q000502:physiology*
keywords: Cognitive task constraints; Gait; Obstacle crossing; Perception; Stroke