INTRODUCTION: While relative fore/aft motion between the skier and skis along the ski's longitudinal axis is a commonly acknowledged element of alpine skiing technique, there are differing opinions as to how much movement occurs and how important it is for performance. Although there exist numerous qualitative descriptions, few quantitative analyses of fore/aft dynamics have been published. The aim of this study was to quantify the fore/aft dynamics of a group of highly-skilled athletes in slalom and to relate these measures to performance. METHODS: The performances of 6 members of the Norwegian men's Europa Cup team were analyzed during a slalom race Simulation. Skier 3-D positions were determined from 4 panning Video cameras and calibration control points distributed near the course (Nachbauer et al., 1996). A local coordinate System (LCS) originating at the outside ankle joint center was defined at each point in time (Schiefermüller et al., 2005). The LCS axes were defined as being parallel and perpendicular to the longitudinal axis of the outside ski and normal to the plane of the snow surface (x, y, and z axes, respectively). Motion of the whole body center of mass (COM) in the local x-dimension was time-normalized to the turn cycle. Fore/aft range of motion (XROM), and average position in the local x-dimension (XAVG), during a turn cycle were used to characterize the athlete's fore/aft movements. Partial correlation coefficients between XAVG, XROM and performance time were calculated while controlling for entrance velocity. RESULTS & DISCUSSION: Figure 1 shows the ensemble average COM position in the local x-dimension for the 6 athletes. The mean ± SD XROM and XAVG during a turn cycle were 28.4 ± 3.6 cm and 3.9 ± 2.7 cm, respectively. Partial correlation coefficients for XROM and XAVG with performance time were r = 0.76 and r = 0.98 (p = 0.003), respectively, indicating the importance of fore/aft motion for performance. In this study, the motion of faster skiers was centered further aft and closer to the ski center than that of slower skiers. A cyclic pattern in fore/aft dynamics is apparent in Figure 1 and this pattern was more consistent for faster athletes. CONCLUSION: This study has quantitatively described the fore/aft dynamics of a group of highly skilled skiers in slalom. These results indicate that fore/aft dynamics are important for performance. Further research is required to develop a fuller understanding of this relationship.
© Copyright 2007 4th International Congress on Science and Skiing. Julkaistu Tekijä University of Salzburg. Kaikki oikeudet pidätetään. / Kääntänyt https://www.DeepL.com/Translator