title: Course Setting as a Prevention Measure for Overuse Injuries of the Back in Alpine Ski Racing: A Kinematic and Kinetic Study of Giant Slalom and Slalom.
abstract: BACKGROUND
  A combination of frontal bending, lateral bending, and torsion in the loaded trunk has been suggested to be a mechanism leading to overuse injuries of the back in Alpine ski racing. However, there is limited knowledge about the effect of course setting on the aforementioned back-loading patterns.
  
  
  OBJECTIVE
  To investigate the effect of increased gate offset on the skier's overall trunk kinematics and the occurring ground-reaction forces and to compare these variables between the competition disciplines giant slalom (GS) and slalom (SL).
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Ten top-level athletes were divided into GS and SL groups. Both groups performed a total of 240 GS and 240 SL turns at 2 different course settings. The overall trunk movement components (frontal bending, lateral bending, and torsion angle) were measured using 2 inertial measurement units fixed on the sacrum and sternum. Total ground-reaction forces were measured by pressure insoles.
  
  
  RESULTS
  In SL, ground-reaction force peaks were significantly lower when the gate offset was increased, while in GS, no differences between course settings were observed. During the turn phase in which the highest spinal disc loading is expected to occur, the back-loading patterns in both GS and SL included a combination of frontal bending, lateral bending, and torsion in the loaded trunk. SL was characterized by shorter turns, lower frontal and lateral bending angles after gate passage, and a trend toward greater total ground-reaction force peaks compared with GS.
  
  
  CONCLUSIONS
  Course setting is a reasonable measure to reduce the skier's overall back loading in SL but not in GS. The distinct differences observed between GS and SL should be taken into account when defining discipline-specific prevention measures for back overuse injuries.
  
  
  CONCLUSIONS
  To reduce the magnitude of the overall back loading, in SL, minimal gate offsets should be avoided. Prevention measures in GS might particularly need to control and/or reduce the magnitude of frontal and lateral bending in the loaded trunk, whereas prevention measures in SL might especially need to mitigate the short and high total ground-reaction force peaks.
authors.affiliation: Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria.
authors.forename: Jörg
authors.initials: J
authors.lastname: Spörri
authors.affiliation: Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria.
authors.forename: Josef
authors.initials: J
authors.lastname: Kröll
authors.affiliation: Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Benedikt
authors.initials: B
authors.lastname: Fasel
authors.affiliation: Laboratory of Movement Analysis and Measurement, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
authors.forename: Kamiar
authors.initials: K
authors.lastname: Aminian
authors.affiliation: Department of Sport Science and Kinesiology, University of Salzburg, Hallein-Rif, Austria.
authors.forename: Erich
authors.initials: E
authors.lastname: Müller
keywords: athletes; back pain; injury prevention; overuse injuries; skiing; spine