title: Age-related differences in dynamic balance control during stair descent and effect of varying step geometry.
abstract: The incidence of stairway falls and related injuries remains persistently high; however, the risk of stair injuries could be reduced through improved stairway design. The current study investigated dynamic balance control during stair descent and the effects of varying the step geometry. Data were collected from 20 healthy young and 20 older adults as they descended three staircases (riser heights of 7, 7.5 and 8 inches (178, 190 and 203 mm, respectively)). At each riser height, the tread run length was varied between 8 and 14 inches (203 mm and 356 mm) in one-inch (25 mm) increments. Kinematic data provided measures of segmental and whole-body dynamic control. Results demonstrated that older adults had greater lateral tilt of the upper body than young adults, but actually had larger margins of stability than the young in the antero-posterior direction as a result of their slower cadence. Nonetheless, for both age groups, the longer run lengths were found to provide the largest margins of stability. In addition, increase in run length and decrease in riser height tended to reduce forward upper body tilt. These results help to explain the underlying biomechanical factors associated with increased risk of falls and the relationship with step geometry. Considering the importance of stair ambulation in maintaining independence and activity in the community, this study highlights the definite need for safer stair design standards to minimize the risk of falls and increase stair safety across the lifespan.
authors.affiliation: iDAPT, Toronto Rehabilitation Institute, University Health Network, 550 University Ave, Toronto, Ontario M5G 2A2 Canada(1). Electronic address: alison.novak@uhn.ca.
authors.forename: A C
authors.initials: AC
authors.lastname: Novak
authors.affiliation: iDAPT, Toronto Rehabilitation Institute, University Health Network, 550 University Ave, Toronto, Ontario M5G 2A2 Canada(1); Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada.
authors.forename: V
authors.initials: V
authors.lastname: Komisar
authors.affiliation: iDAPT, Toronto Rehabilitation Institute, University Health Network, 550 University Ave, Toronto, Ontario M5G 2A2 Canada(1); Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada; Department of Surgery, University of Toronto, 149 College Street, Toronto, Ontario M5T 1P5, Canada; Institute of Medical Science, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
authors.forename: B E
authors.initials: BE
authors.lastname: Maki
authors.affiliation: iDAPT, Toronto Rehabilitation Institute, University Health Network, 550 University Ave, Toronto, Ontario M5G 2A2 Canada(1); Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada; Department of Surgery, University of Toronto, 149 College Street, Toronto, Ontario M5T 1P5, Canada; Institute of Medical Science, University of Toronto, 1 King's College Circle, Toronto, Ontario M5S 1A8, Canada.
authors.forename: G R
authors.initials: GR
authors.lastname: Fernie
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control; D000328:Adult; D000367:Age Factors; D000368:Aged; D001696:Biomechanical Phenomena / Q000502:physiology; D004779:Environment Design / Q000592:standards; D005260:Female; D005684:Gait / Q000502:physiology; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology; D055815:Young Adult
keywords: Ageing; Dynamic balance; Kinematics; Stair ambulation