title: Validity and Intrarater Reliability of 2-Dimensional Motion Analysis Using a Handheld Tablet Compared to Traditional 3-Dimensional Motion Analysis.
abstract: Lower extremity landing mechanics have been implicated as a contributing factor in knee pain and injury, yet cost effective and clinically accessible methods for evaluating movement mechanics are limited. The identification of valid, reliable, and readily accessible technology to assess lower extremity alignment could be an important tool for clinicians, coaches, and strength and conditioning specialists.
  
  
  
  The purpose of this study was to examine the validity and reliability of using a hand-held tablet and movement analysis application (app) for assessing lower extremity alignment during a drop vertical jump task.
  
  
  
  Concurrent Validation.
  
  
  
  Laboratory.
  
  
  
  Twenty-two healthy college aged subjects (11 female and 11 male, mean age = 21 ± 1.4 years; mean height: 1.73 ± .12 m, mean mass: 71 ± 13 kg) with no lower extremity pathology that prevented safe landing from a drop jump.
  
  
  
  Subjects performed six drop vertical jumps which were recorded simultaneously using a 3D motion capture system and a hand-held tablet.
  
  
  
  Angles on the tablet were calculated using a motion analysis app and from the 3D motion capture system using Visual 3D. Hip and knee angles were measured and compared between both systems.
  
  
  
  Significant correlations between the tablet and 3D measures for select frontal and sagittal plane ranges of motion (ROM) and angles at maximum knee flexion (MKF) ranged from r = 0.48 (P = .036) for frontal plane knee angle at MKF to r = .77 (P<.001) for knee flexion at MKF.
  
  
  
  Results of this study suggest that a hand-held tablet and app may be a reliable method for assessing select lower extremity joint alignments during drop vertical jumps, but this technology should not be used to measure absolute joint angles. However, sports medicine specialists could use a hand-held tablet to reliably record and evaluate lower extremity movement patterns on the field or in the clinic.
authors.affiliation: Ithaca College, Ithaca, New York.
authors.forename: Barbara C
authors.initials: BC
authors.lastname: Belyea
authors.forename: Ethan
authors.initials: E
authors.lastname: Lewis
authors.forename: Zachary
authors.initials: Z
authors.lastname: Gabor
authors.forename: Jill
authors.initials: J
authors.lastname: Jackson
authors.forename: Deborah L
authors.initials: DL
authors.lastname: King
mesh_terms: D001696:Biomechanical Phenomena; D034201:Computers, Handheld; D005260:Female; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D063731:Mobile Applications; D009068:Movement / Q000502:physiology*; D016059:Range of Motion, Articular; D015203:Reproducibility of Results; D013996:Time and Motion Studies; D055815:Young Adult
keywords: kinematics; lower extremity; landing; injury prevention