title: Influence of input device, work surface angle, and task on spine kinematics.
abstract: BACKGROUND
  With the increase of tablet usage in both office and industrial workplaces, it is critical to investigate the influence of tablet usage on spine posture and movement.
  
  
  OBJECTIVE
  To quantify spine kinematics while participants interacted with a tablet or desktop computer.
  
  
  METHODS
  Fourteen participants volunteered for this study. Marker clusters were fixed onto body regions to analyze cervical and lumbar spine posture and sampled at 32 Hz (Optotrak Certus, NDI, Waterloo, Canada). Participants sat for one hour in total. Cervical and lumbar median angles and range of motion (10th to 90th % ile angles) were extracted from amplitude probability distribution functions performed on the angle data.
  
  
  RESULTS
  Using a sloped desk surface at 15°, compared to a flat desk, influenced cervical flexion (p = 0.0228). Completing the form fill task resulted in the highest degree of cervical flexion (p = 0.0008) compared to the other tasks completed with cervical angles between 6.1°-8.5° higher than emailing and reading respectively. An interaction between device and task (p = 0.0061) was found for relative lumbar median spine angles.
  
  
  CONCLUSIONS
  Increased lumbar flexion was recorded when using a computer versus a tablet to complete various tasks. Task influenced both cervical and lumbar spine posture with the highest cervical flexion occurring while completing a simulated data entry task. A work surface slope of 15° decreased cervical spine flexion compared to a horizontal work surface slope.
authors.forename: Maureen F
authors.initials: MF
authors.lastname: Riddell
authors.forename: Kaitlin M
authors.initials: KM
authors.lastname: Gallagher
authors.forename: Colin D
authors.initials: CD
authors.lastname: McKinnon
authors.forename: Jack P
authors.initials: JP
authors.lastname: Callaghan
mesh_terms: D000293:Adolescent; D000328:Adult; D001696:Biomechanical Phenomena; D002170:Canada; D034201:Computers, Handheld / Q000592:standards* / Q000706:statistics & numerical data; D006804:Ergonomics / Q000379:methods / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D011187:Posture; D013131:Spine / Q000503:physiopathology; D013647:Task Performance and Analysis
keywords: Sloping desk; posture; sit-stand chairs; tablets; task