title: Reduced instantaneous center of rotation movement in patients with low back pain.
abstract: The instantaneous center of rotation (ICR) can be used to investigate movement coordination and control in patients with low back pain (LBP). Tracking of the ICR in LBP patients has not been systematically investigated. This study aimed to (1) determine the within-session measurement error of ICR parameters, and (2) characterize the change in ICR among three groups of participants (no history of LBP = HC; history of LBP = HLBP; and current LBP = LBP).
  
  
  
  Ninety-three participants (HC = 31; HLBP = 33; and LBP = 29) were recruited. Participants performed two sets of three repetitions of an active forward bend, while their lumbar and pelvic movements were recorded with an electromagnetic tracking system. Total ICR displacement and the radius of the bounding sphere containing the ICR were derived during the forward bending and the return to upright phases. Intra-class correlation coefficients (ICC3,3) and minimal detectable difference (MDD) were used to determine measurement error and interpret findings of the group analysis. One-way ANOVAs and post hoc Bonferroni comparisons were used to determine differences among groups.
  
  
  
  ICC3,3demonstrated excellent within-session test-retest reliability of the ICR parameters (ICC3,3= 0.86-0.97). The MDD values were 0.20-3.40 mm. Comparisons between the HC and LBP groups and between the HLBP and LBP groups showed significant differences (p < 0.05) for all ICR parameters, with medium effect sizes (0.51-0.66), except for total displacement during forward bending between the HC and LBP groups.
  
  
  
  Less ICR displacement and variability in patients with LBP may indicate coping strategies to stiffen the lumbar spine. This could result from patients with LBP adopting a strategy of increased muscle activation to provide spinal stability during functional tasks.
authors.affiliation: Motor Control and Neural Plasticity Laboratory, Faculty of Physical Therapy, Mahidol University, Salaya, Nakhon Pathom, Thailand. peemongkon.wat@mahidol.ac.th.
authors.forename: Peemongkon
authors.identifier: 0000-0001-8691-0125
authors.initials: P
authors.lastname: Wattananon
authors.affiliation: Motor Control and Neural Plasticity Laboratory, Faculty of Physical Therapy, Mahidol University, Salaya, Nakhon Pathom, Thailand.
authors.forename: Nattaporn
authors.initials: N
authors.lastname: Intawachirarat
authors.affiliation: Rehabilitation Sciences Spine Research Lab, Drexel University, Philadelphia, PA, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Cannella
authors.affiliation: Rehabilitation Sciences Spine Research Lab, Drexel University, Philadelphia, PA, USA.|Good Shepherd Penn Partners, Penn Therapy and Fitness, Philadelphia, PA, USA.
authors.forename: Won
authors.initials: W
authors.lastname: Sung
authors.affiliation: Rehabilitation Sciences Spine Research Lab, Drexel University, Philadelphia, PA, USA.|Physical Therapy and Rehabilitation Sciences Department, Drexel University, Philadelphia, PA, USA.
authors.forename: Sheri P
authors.initials: SP
authors.lastname: Silfies
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology; D016059:Range of Motion, Articular / Q000502:physiology*; D015203:Reproducibility of Results; D055815:Young Adult
keywords: Aberrant movement; Center of rotation; Kinematics; Non-specific low back pain