title: Elite and amateur orienteers' running biomechanics on three surfaces at three speeds.
abstract: OBJECTIVE
  Orienteering athletes must adapt to running on various surfaces, with biomechanics likely contributing to performance. Here, our aims were to identify the effect of athletic status and of surface on the running biomechanics of orienteers.
  
  
  METHODS
  Seven elite and seven amateur male orienteers ran 20 m on road, path, and forest surfaces at maximal, 3.8 m·s, and 85% of maximal speeds. A three-dimensional motion capturing system monitored temporal gait and lower extremity kinematic parameters. Data were analyzed using mixed effects models that considered surface (road-path-forest), group (elite-amateur), and surface-group interaction effects.
  
  
  RESULTS
  Forest running at maximal speed was slower and involved longer step and cycle times, greater knee extension at foot strike, smaller peak hip flexion and dorsiflexion during stance, and increased ranges of vertical pelvis motion compared with those observed on the road. Elites specifically exhibited greater hip extension at foot strike, larger dorsiflexion at toe-off, and lower pelvis at foot strike and toe-off, whereas amateurs displayed longer stance, greater plantarflexion at foot strike, and greater knee with lesser ankle motion. At the slowest speed, subjects exhibited greater knee flexion at foot strike, greater dorsiflexion at toe-off, shorter strides, smaller peak dorsiflexion during stance, and greater hip, knee, and vertical pelvis motions on forest than on road surfaces. Elites specifically demonstrated shorter stance, step, and cycle times whereas amateurs did not.
  
  
  CONCLUSIONS
  Orienteering athletes adjusted their running biomechanics when off-road, with distinct adaptations observed in elite versus amateur competitors. The vertical pelvis motion was consistently greater when running off-road, coherent with reported increases in energy expenditure. However, our athletes did not exhibit more crouched lower limb postures when sprinting in the forest, indicating alternative responses to off-road running to that previously proposed by "Groucho" running.
authors.affiliation: 1Swedish Winter Sports Research Centre, Department of Health Sciences, Mid Sweden University, Östersund, SWEDEN; and 2Research Unit EA4660 Department, Culture Sport Health Society and Exercise Performance Health Innovation Platform, Franche-Comté University, Besançon, FRANCE.
authors.forename: Kim
authors.initials: K
authors.lastname: Hébert-Losier
authors.forename: Laurent
authors.initials: L
authors.lastname: Mourot
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
mesh_terms: D000328:Adult; D000842:Ankle / Q000502:physiology; D001696:Biomechanical Phenomena; D004777:Environment; D005528:Foot / Q000502:physiology; D005684:Gait / Q000502:physiology; D006615:Hip / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009051:Mountaineering / Q000502:physiology*; D010388:Pelvis / Q000502:physiology; D011187:Posture; D016059:Range of Motion, Articular; D012420:Running / Q000502:physiology*; D013996:Time and Motion Studies; D055815:Young Adult