title: Impact of lumbar spine posture on thoracic spine motion and muscle activation patterns.
abstract: Complex motion during standing is typical in daily living and requires movement of both the thoracic and lumbar spine; however, the effects of lumbar spine posture on thoracic spine motion patterns remain unclear. Thirteen males moved to six positions involving different lumbar (neutral and flexed) and thoracic (flexed and twisted) posture combinations. The thoracic spine was partitioned into three segments and the range of motion from each posture was calculated. Electromyographical data were collected from eight muscles bilaterally. Results showed that with a flexed lumbar spine, the lower-thoracic region had 14.83 ° and 15.6 1 ° more flexion than the upper- and mid-thoracic regions, respectively. A flexed lumbar spine significantly reduced the mid-thoracic axial twist angle by 5.21 ° compared to maximum twist in the mid-thoracic region. Functional differences emerged across muscles, as low back musculature was greatest in maintaining flexed lumbar postures, while thoracic erector spinae and abdominals showed bilateral differences with greater activations to the ipsilateral side. Combined postures have been previously identified as potential injury modulators and bilateral muscle patterns can have an effect on loading pathways. Overall, changes in thoracic motion were modified by lumbar spine posture, highlighting the importance of considering a multi-segmented approach when analyzing trunk motion.
authors.affiliation: School of Kinesiology & Health Science, Faculty of Health, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Nairn
authors.affiliation: School of Kinesiology & Health Science, Faculty of Health, York University, 4700 Keele Street, Toronto, ON M3J 1P3, Canada. Electronic address: jdrake@yorku.ca.
authors.forename: Janessa D M
authors.initials: JD
authors.lastname: Drake
mesh_terms: D000328:Adult; D001415:Back / Q000473:pathology; D001696:Biomechanical Phenomena; D004576:Electromyography; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture; D016059:Range of Motion, Articular / Q000502:physiology; D013131:Spine / Q000502:physiology*; D013904:Thoracic Vertebrae / Q000502:physiology*; D055815:Young Adult
keywords: Complex motion; Electromyography; Kinematic; Thoracic