Measuring step kinematic variability on an instrumented treadmill: how many steps are enough?

Variability of step kinematics has been associated with falls by older adults. However, between-study differences with regard to the number of steps used to compute variability have varied by an order of magnitude. If the number of steps used to compute variability is too low there is the potential...

Full description

Saved in:
Bibliographic Details
Published in:Journal of biomechanics 2003-08, Vol.36 (8), p.1215-1218
Main Authors: Owings, Tammy M., Grabiner, Mark D.
Format: Article
Language:English
Subjects:
Adult
Assessment
Biomechanical Phenomena
Exercise Test - instrumentation
Exercise Test - methods
Female
Fitness equipment
Foot - physiology
Gait - physiology
Humans
Locomotion
Locomotion - physiology
Male
Models, Biological
Models, Statistical
Older people
Sample Size
Step length
Step time
Step width
Stress, Mechanical
Studies
Variables
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Variability of step kinematics has been associated with falls by older adults. However, between-study differences with regard to the number of steps used to compute variability have varied by an order of magnitude. If the number of steps used to compute variability is too low there is the potential for a statistically spurious outcome. On the other hand, for subjects with mobility impairments a protocol requiring too many steps to estimate variability imposes an unnecessary burden on the subjects. We have determined the minimum number of steps needed to estimate the variability of spatial and temporal step kinematics. More than 700 steps were collected during level walking on an instrumented treadmill. Accurate estimation of step kinematic variability required at least 400 steps. The increased error in estimating the mean and standard deviations of the step kinematic variables with too few steps can impose an experimental cost with regard to statistical design considerations. The extent to which translation of these results can be made to the variability of spatial and temporal step kinematics collected during over-ground walking awaits further research.
ISSN:0021-9290
1873-2380
DOI:10.1016/S0021-9290(03)00108-8