Purpose: Orienteering athletes must adapt to running on various surfaces, with biomechanics likely contributing to performance. Here, our aims were to identify the impact of athletic status and of surface on the running biomechanics of orienteers.
Methods: Seven elite and seven amateur male orienteers ran 20m on road, path, and forest surfaces at maximal, 3.8m/s, and 85% of maximal speeds. A three-dimensional motion capturing system monitored temporal gait and lower-extremity kinematic parameters. Data were analysed 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 flight and cycle times, greater knee extension at foot-strike, smaller peak hip flexion and dorsi-flexion during stance, and increased ranges of vertical pelvis motion compared to road running. Elites specifically exhibited greater hip extension at foot-strike, larger dorsi-flexion at toe-off, and lower pelvis at foot-strike and toe-off, whereas amateurs displayed longer stance, greater plantar-flexion at foot-strike, and greater knee with lesser ankle motion. At the slowest speed, subjects exhibited greater knee flexion at foot-strike, greater dorsi-flexion at toe-off, shorter strides, smaller peak dorsi-flexion during stance, and greater hip, knee, and vertical pelvis motions on forest than road surfaces. Elites specifically demonstrated shorter stance, flight, and cycle times; whereas amateurs did not.
Conclusion: 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 than previously proposed by "Groucho" running.
(C) 2014 American College of Sports Medicine