Kinematics of running on 'off-road' terrain.

It has been established that running on natural 'off-road' terrain elicits a higher energy demand than running on road. Running on such terrain may also result in changes to the characteristics of the normal running stride. The aim of this study was to investigate biomechanical alterations to stride characteristics during off-road running. Nine female participants were recorded on video while running over three terrain types: surfaced footpath, short grass and long grass. The videos were digitized in order to quantify temporal, displacement and velocity variables. Cycle time was not significantly different between conditions (p = 0.315). Step length decreased (p < 0.01) and both vertical displacement of the hip and knee lift increased significantly (p < 0.01) with increasing difficulty of terrain. Despite assisted pacing, there was a significant decrease in velocity (p < 0.01) with each progressively rougher terrain condition. The peak extension angular velocity of the knee was not affected significantly (p < 0.098) by the terrain despite the fact that there was a significant difference in the peak flexion angular velocity (p < 0.01). It was concluded that participants altered their stride displacement and velocity patterns significantly in response to changes in running surface.