title: Shoulder pain and cycle to cycle kinematic spatial variability during recovery phase in manual wheelchair users: a pilot investigation.
abstract: Wheelchair propulsion plays a significant role in the development of shoulder pain in manual wheelchair users (MWU). However wheelchair propulsion metrics related to shoulder pain are not clearly understood. This investigation examined intra-individual kinematic spatial variability during semi-circular wheelchair propulsion as a function of shoulder pain in MWU. Data from 10 experienced adult MWU with spinal cord injury (5 with shoulder pain; 5 without shoulder pain) were analyzed in this study. Participants propelled their own wheelchairs on a dynamometer at 3 distinct speeds (self-selected, 0.7 m/s, 1.1 m/s) for 3 minutes at each speed. Motion capture data of the upper limbs were recorded. Intra-individual kinematic spatial variability of the steady state wrist motion during the recovery phase was determined using principal component analysis (PCA). The kinematic spatial variability was calculated at every 10% intervals (i.e at 11 interval points, from 0% to 100%) along the wrist recovery path.
  
  
  RESULTS
  Overall, spatial variability was found to be highest at the start and end of the recovery phase and lowest during the middle of the recovery path. Individuals with shoulder pain displayed significantly higher kinematic spatial variability than individuals without shoulder pain at the start (at 10% interval) of the recovery phase (p<.004).
  
  
  CONCLUSIONS
  Analysis of intra-individual kinematic spatial variability during the recovery phase of manual wheelchair propulsion distinguished between those with and without shoulder pain. Variability analysis of wheelchair propulsion may offer a new approach to monitor the development and rehabilitation of shoulder pain.
authors.affiliation: Department of Industrial and Enterprise Systems Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
authors.forename: Chandrasekaran
authors.initials: C
authors.lastname: Jayaraman
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
authors.forename: Yaejin
authors.initials: Y
authors.lastname: Moon
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Rice
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
authors.forename: Elizabeth T
authors.initials: ET
authors.lastname: Hsiao Wecksler
authors.affiliation: Department of Industrial and Enterprise Systems Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
authors.forename: Carolyn L
authors.initials: CL
authors.lastname: Beck
authors.affiliation: Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America.
authors.forename: Jacob J
authors.initials: JJ
authors.lastname: Sosnoff
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003710:Demography; D005260:Female; D006801:Humans; D008297:Male; D010865:Pilot Projects; D016059:Range of Motion, Articular; D020069:Shoulder Pain / Q000503:physiopathology*; D014910:Wheelchairs; D014953:Wrist / Q000503:physiopathology