INTRODUCTION: During the entire alpine Ski World-Cup-Season 2006/2007, the German coaches were equipped with a GPS-device to record the coordinates of the turning gates in all races in the disciplines Giant Slalom and Super G. The data of the turning gates in all three dimensions were used to calculate the distances between the gates, angles of the gates, and the radius of the turns. In some races, the video recordings of the two best racers were used to cover the times between the gates. Putting the data together, it is possible to calculate the velocity between gates, the radial acceleration in turns, and to estimate the ground reaction forces of particular racers. METHOD: Using the GPS device FRWD O400' the German coaches recorded the coordinates of the turning gates. These data were used to calculate the distances between the gates, the horizontal and longitudinal distance of the gates in the runner's plane, the vertical distance, the down tilt, the opening and curve angle between the gates, and the radius of the turn (Figure 1). An additional calculation was made for "double gates" where the turning gate was identified by the coach and the calculation was done with the turning gates before and after. A custom built program based on MS Excel enabled the coaches to present the actual race course to the athletes for preparation. Additionally the video recordings of one Giant Slalom with two runs and one Super G each for men and women were chosen to cover the times at the turning gates. The velocity was calculated by dividing the way at the circular arc with the average time used for the gate. The ground reaction force was estimated by vectorial addition of the centrifugal force and the approximated weight of the runner and equipment. DISCUSSION: Even though it is only an estimation based on physical principles, the results indicate the enormous loading in alpine ski racing. There is no difference seen between men and women, and the values are quite equal to those measured by different groups. The velocities indicate the strong influence of aero dynamical drag in SG and even in Giant Slaloms. CONCLUSION: Hopefully, studies like this can be a base for further discussions regarding the regulations of material and course settings to improve the safety of the ski racers. Respecting the muscular expenditure, preparation of strength, and endurance is of extreme importance for the athletes.
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