title: Anticipation of direction and time of perturbation modulates the onset latency of trunk muscle responses during sitting perturbations.
abstract: Trunk muscles are responsible for maintaining trunk stability during sitting. However, the effects of anticipation of perturbation on trunk muscle responses are not well understood. The objectives of this study were to identify the responses of trunk muscles to sudden support surface translations and quantify the effects of anticipation of direction and time of perturbation on the trunk neuromuscular responses. Twelve able-bodied individuals participated in the study. Participants were seated on a kneeling chair and support surface translations were applied in the forward and backward directions with and without direction and time of perturbation cues. The trunk started moving on average approximately 40ms after the perturbation. During unanticipated perturbations, average latencies of the trunk muscle contractions were in the range between 103.4 and 117.4ms. When participants anticipated the perturbations, trunk muscle latencies were reduced by 16.8±10.0ms and the time it took the trunk to reach maximum velocity was also reduced, suggesting a biomechanical advantage caused by faster muscle responses. These results suggested that trunk muscles have medium latency responses and use reflexive mechanisms. Moreover, anticipation of perturbation decreased trunk muscles latencies, suggesting that the central nervous system modulated readiness of the trunk based on anticipatory information.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada; Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada.
authors.forename: Matija
authors.initials: M
authors.lastname: Milosevic
authors.affiliation: Department of Life Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Shinya
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada; Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada. Electronic address: k.masani@utoronto.ca.
authors.forename: Kei
authors.initials: K
authors.lastname: Masani
authors.affiliation: Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada; Division of Engineering Science, University of Toronto, 35 St. George Street, Toronto, Ontario M5S 1A4, Canada.
authors.forename: Kramay
authors.initials: K
authors.lastname: Patel
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada; Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada; Department of Electrical and Computer Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario M5B 2K3, Canada.
authors.forename: Kristiina M V
authors.initials: KM
authors.lastname: McConville
authors.affiliation: Department of Life Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan.
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Nakazawa
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario M5S 3G9, Canada; Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario M4G 3V9, Canada.
authors.forename: Milos R
authors.initials: MR
authors.lastname: Popovic
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D059031:Anticipation, Psychological / Q000502:physiology*; D004576:Electromyography / Q000379:methods; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology; D011187:Posture / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D013028:Space Perception / Q000502:physiology*; D013998:Time Perception / Q000502:physiology*; D060726:Torso / Q000502:physiology*; D055815:Young Adult
keywords: Anticipation; Perturbation; Sitting; Support surface translation; Trunk muscles