title: Heel strike detection using split force-plate treadmill.
abstract: A common source of error when detecting heel-strike moments utilizing split force-plate treadmills is unwillingly stepping on contra-lateral force-plate. In this study, we quantified this error when heel-strike was detected based on such erroneous data and compared three methods to investigate how well the heel-strikes and stride-intervals were detected with erroneous data. Eleven subjects walked on a split force-plate treadmill for more than 20min. We used 20N and 50% body-weight thresholds to detect the heel-strike moments (HS20N and HS50%, respectively). Besides, we used linear approximation to estimate the unaffected force profile from affected force-plate data, and subsequently to detect the heel-strike moments (HSest). We used heel-strike moments detected by a foot-switch as a reference to compare accuracy of HS20N, HS50% and HSest. HS20N and HSest detected heel-strike moments accurately for unaffected force-plate data (median(max) errors for all subjects: 9(23) and 9(37) ms) but HS50% showed significantly larger errors (52(74) ms). Unlike HS50% and HSest, HS20N was considerably affected by the affected force-plate data (23(68) ms). The error in stride-interval measurement was relatively small using any methods for unaffected force-plate data (3(7), 6(8), and 6(12) ms), while stride-interval errors were large for some subjects when using HS20N for affected data (6(175) ms). We concluded that unwillingly stepping on contra-lateral force-plate occurred a few percent and up to 37.7% of all strides (median: 12.9%). Our proposed method (HSest) robustly showed small errors for heel-strike detection and stride-interval calculation consistently among subjects, while HS50% and HS20N showed large errors depending on subjects.
authors: Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada; Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada. Electronic address: hossein.rouhani@utoronto.ca.
authors: Hossein
authors: H
authors: Rouhani
authors: Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan.
authors: Masaki O
authors: MO
authors: Abe
authors: Department of Life Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors: Kimitaka
authors: K
authors: Nakazawa
authors: Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada; Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada.
authors: Milos R
authors: MR
authors: Popovic
authors: Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada; Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada.
authors: Kei
authors: K
authors: Masani
mesh_terms: D000328:Adult; D005080:Exercise Test / Q000295:instrumentation*; D005684:Gait / Q000502:physiology*; D064368:Healthy Volunteers; D006365:Heel / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D016138:Walking / Q000502:physiology*
keywords: Foot switch; Gait phase; Stride interval