title: Reliability of assessing trunk motor control using position and force tracking and stabilization tasks.
abstract: System-based methods have been applied to assess trunk motor control in people with and without back pain, although the reliability of these methods has yet to be established. Therefore, the goal of this study was to quantify within- and between-day reliability using systems-based methods involving position and force tracking and stabilization tasks. Ten healthy subjects performed six tasks, involving tracking and stabilizing of trunk angular position in the sagittal plane, and trunk flexion and extension force. Tracking tasks involved following a one-dimensional, time-varying input signal displayed on a screen by changing trunk position (position tracking) or trunk force (force tracking). Stabilization tasks involved maintaining a constant trunk position (position stabilization) or constant trunk force (force stabilization) while a sagittal plane disturbance input was applied to the pelvis using a robotic platform. Time and frequency domain assessments of error (root mean square and H2 norm, respectively) were computed for each task on two separate days. Intra-class correlation coefficients (ICC) for error and coefficients of multiple correlations (CMC) for frequency response curves were used to quantify reliability of each task. Reliability for all tasks was excellent (between-day ICC≥0.8 and CMC>0.75, within-day CMC>0.85). Therefore, position and force control tasks used to assess trunk motor control can be deemed reliable.
authors.affiliation: MSU Center for Orthopedic Research, Michigan State University, USA; Department of Osteopathic Surgical Specialties, Michigan State University, USA. Electronic address: reevesn@msu.edu.
authors.forename: N Peter
authors.initials: NP
authors.lastname: Reeves
authors.affiliation: MSU Center for Orthopedic Research, Michigan State University, USA; Department of Osteopathic Surgical Specialties, Michigan State University, USA.
authors.forename: John M
authors.initials: JM
authors.lastname: Popovich
authors.affiliation: MSU Center for Orthopedic Research, Michigan State University, USA; Department of Mechanical Engineering, Michigan State University, USA.
authors.forename: M Cody
authors.initials: MC
authors.lastname: Priess
authors.affiliation: MSU Center for Orthopedic Research, Michigan State University, USA; Department of Osteopathic Surgical Specialties, Michigan State University, USA.
authors.forename: Jacek
authors.initials: J
authors.lastname: Cholewicki
authors.affiliation: MSU Center for Orthopedic Research, Michigan State University, USA; Department of Mechanical Engineering, Michigan State University, USA; Department of Electrical and Computer Engineering, Michigan State University, USA.
authors.forename: Jongeun
authors.initials: J
authors.lastname: Choi
authors.affiliation: MSU Center for Orthopedic Research, Michigan State University, USA; Department of Mechanical Engineering, Michigan State University, USA.
authors.forename: Clark J
authors.initials: CJ
authors.lastname: Radcliffe
mesh_terms: D000293:Adolescent; D000328:Adult; D001416:Back Pain / Q000503:physiopathology; D001696:Biomechanical Phenomena; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D008875:Middle Aged; D009048:Motor Skills; D011187:Posture; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D012371:Robotics; D013314:Stress, Mechanical; D013597:Systems Analysis; D060726:Torso; D055815:Young Adult
keywords: Disturbance rejection; H(2) norm; Systems approach; Trunk force control; Trunk position control