Figure 1. The set-up of the camera on the sections video-taped, with the four red poles creating a regular rectangle, the fifth pole set exactly in the middle of the side of this rectangle closest to the camera, and two orange lines on the snow between the poles perpendicular to the ski track. In addition, the definitions of the entire cycle (left pole plant to consecutive left pole plant) and poling and swing phases are indicated. The red arrow illustrates the calibration line for determination of the scaling factors (real-life size to video size) for calculations of distance for one of the tracks.