title: Validation of an inertial measurement unit for the measurement of jump count and height.
abstract: OBJECTIVE
  To validate the use of an inertial measurement unit (IMU) for the collection of total jump count and assess the validity of an IMU for the measurement of jump height against 3-D motion analysis.
  
  
  METHODS
  Cross sectional validation study.
  
  
  METHODS
  3D motion-capture laboratory and field based settings.
  
  
  METHODS
  Thirteen elite adolescent volleyball players.
  
  
  METHODS
  Participants performed structured drills, played a 4 set volleyball match and performed twelve counter movement jumps.
  
  
  METHODS
  Jump counts from structured drills and match play were validated against visual count from recorded video. Jump height during the counter movement jumps was validated against concurrent 3-D motion-capture data.
  
  
  RESULTS
  The IMU device captured more total jumps (1032) than visual inspection (977) during match play. During structured practice, device jump count sensitivity was strong (96.8%) while specificity was perfect (100%). The IMU underestimated jump height compared to 3D motion-capture with mean differences for maximal and submaximal jumps of 2.5 cm (95%CI: 1.3 to 3.8) and 4.1 cm (3.1-5.1), respectively.
  
  
  CONCLUSIONS
  The IMU offers a valid measuring tool for jump count. Although the IMU underestimates maximal and submaximal jump height, our findings demonstrate its practical utility for field-based measurement of jump load.
authors.affiliation: Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada. Electronic address: kerry.macdonald@ubc.ca.
authors.forename: Kerry
authors.initials: K
authors.lastname: MacDonald
authors.affiliation: Oslo Sports Trauma Research Center, Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway; Aspetar Injury & Illness Prevention Program, Aspetar, Qatar; Orthopaedic and Sports Medicine Hospital, Doha, Qatar.
authors.forename: Roald
authors.initials: R
authors.lastname: Bahr
authors.affiliation: Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Canada.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Baltich
authors.affiliation: Department of Physical Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada; Glen Sather Sports Medicine Clinic, University of Alberta, Edmonton, Canada.
authors.forename: Jackie L
authors.initials: JL
authors.lastname: Whittaker
authors.affiliation: Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada.
authors.forename: Willem H
authors.initials: WH
authors.lastname: Meeuwisse
mesh_terms: D000293:Adolescent; D054874:Athletic Performance / Q000592:standards*; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D008297:Male; D009068:Movement; D014741:Video Recording; D054798:Volleyball
keywords: Injury prevention; Jump load; Training load; Wearable technology