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Characterization of course and terrain and their effect on skier speed in World Cup alpine ski racing.

Gilgien M, Crivelli P, Spörri J, Kröll J, Müller E - PLoS ONE (2015)

Bottom Line: In giant slalom the horizontal gate distance increased with terrain inclination, while super-G and downhill did not show such a connection.Skier speed decreased with increasing steepness of terrain in all disciplines except for downhill.In steep terrain, speed was found to be controllable by increased horizontal gate distances in giant slalom and by shorter gate distances in giant slalom and super-G.

View Article: PubMed Central - PubMed

Affiliation: Norwegian School of Sport Sciences, Department of Physical Performance, Oslo, Norway.

ABSTRACT
World Cup (WC) alpine ski racing consists of four main competition disciplines (slalom, giant slalom, super-G and downhill), each with specific course and terrain characteristics. The International Ski Federation (FIS) has regulated course length, altitude drop from start to finish and course setting in order to specify the characteristics of the respective competition disciplines and to control performance and injury-related aspects. However to date, no detailed data on course setting and its adaptation to terrain is available. It is also unknown how course and terrain characteristics influence skier speed. Therefore, the aim of the study was to characterize course setting, terrain geomorphology and their relationship to speed in male WC giant slalom, super-G and downhill. The study revealed that terrain was flatter in downhill compared to the other disciplines. In all disciplines, variability in horizontal gate distance (gate offset) was larger than in gate distance (linear distance from gate to gate). In giant slalom the horizontal gate distance increased with terrain inclination, while super-G and downhill did not show such a connection. In giant slalom and super-G, there was a slight trend towards shorter gate distances as the steepness of the terrain increased. Gates were usually set close to terrain transitions in all three disciplines. Downhill had a larger proportion of extreme terrain inclination changes along the skier trajectory per unit time skiing than the other disciplines. Skier speed decreased with increasing steepness of terrain in all disciplines except for downhill. In steep terrain, speed was found to be controllable by increased horizontal gate distances in giant slalom and by shorter gate distances in giant slalom and super-G. Across the disciplines skier speed was largely explained by course setting and terrain inclination in a multiple linear model.

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Terrain inclination change in relation to time expressed as degrees per second inclination change for skier trajectory projected on the DTM.The disciplines are represented in black (GS), gray (SG) and white (DH).
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pone.0118119.g012: Terrain inclination change in relation to time expressed as degrees per second inclination change for skier trajectory projected on the DTM.The disciplines are represented in black (GS), gray (SG) and white (DH).

Mentions: The median of terrain inclination change along PS per meter skied and relative to time were not different from zero and are shown in histograms in Figs. 11 and 12. For the terrain inclination change along PS per meter skied it was found that GS was significantly overrepresented compared to SG for values larger than 1.3°/m and values smaller than −1.2°/m, while GS and DH and SG and DH were not significantly different in their distribution of data in those ranges. For the terrain inclination change along PS per second skied it was found that DH was significantly overrepresented compared to SG and GS for values larger than 19°/s and values smaller than −21°/s, while the distributions for GS and SG and were not significantly different from each other.


Characterization of course and terrain and their effect on skier speed in World Cup alpine ski racing.

Gilgien M, Crivelli P, Spörri J, Kröll J, Müller E - PLoS ONE (2015)

Terrain inclination change in relation to time expressed as degrees per second inclination change for skier trajectory projected on the DTM.The disciplines are represented in black (GS), gray (SG) and white (DH).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4356573&req=5

pone.0118119.g012: Terrain inclination change in relation to time expressed as degrees per second inclination change for skier trajectory projected on the DTM.The disciplines are represented in black (GS), gray (SG) and white (DH).
Mentions: The median of terrain inclination change along PS per meter skied and relative to time were not different from zero and are shown in histograms in Figs. 11 and 12. For the terrain inclination change along PS per meter skied it was found that GS was significantly overrepresented compared to SG for values larger than 1.3°/m and values smaller than −1.2°/m, while GS and DH and SG and DH were not significantly different in their distribution of data in those ranges. For the terrain inclination change along PS per second skied it was found that DH was significantly overrepresented compared to SG and GS for values larger than 19°/s and values smaller than −21°/s, while the distributions for GS and SG and were not significantly different from each other.

Bottom Line: In giant slalom the horizontal gate distance increased with terrain inclination, while super-G and downhill did not show such a connection.Skier speed decreased with increasing steepness of terrain in all disciplines except for downhill.In steep terrain, speed was found to be controllable by increased horizontal gate distances in giant slalom and by shorter gate distances in giant slalom and super-G.

View Article: PubMed Central - PubMed

Affiliation: Norwegian School of Sport Sciences, Department of Physical Performance, Oslo, Norway.

ABSTRACT
World Cup (WC) alpine ski racing consists of four main competition disciplines (slalom, giant slalom, super-G and downhill), each with specific course and terrain characteristics. The International Ski Federation (FIS) has regulated course length, altitude drop from start to finish and course setting in order to specify the characteristics of the respective competition disciplines and to control performance and injury-related aspects. However to date, no detailed data on course setting and its adaptation to terrain is available. It is also unknown how course and terrain characteristics influence skier speed. Therefore, the aim of the study was to characterize course setting, terrain geomorphology and their relationship to speed in male WC giant slalom, super-G and downhill. The study revealed that terrain was flatter in downhill compared to the other disciplines. In all disciplines, variability in horizontal gate distance (gate offset) was larger than in gate distance (linear distance from gate to gate). In giant slalom the horizontal gate distance increased with terrain inclination, while super-G and downhill did not show such a connection. In giant slalom and super-G, there was a slight trend towards shorter gate distances as the steepness of the terrain increased. Gates were usually set close to terrain transitions in all three disciplines. Downhill had a larger proportion of extreme terrain inclination changes along the skier trajectory per unit time skiing than the other disciplines. Skier speed decreased with increasing steepness of terrain in all disciplines except for downhill. In steep terrain, speed was found to be controllable by increased horizontal gate distances in giant slalom and by shorter gate distances in giant slalom and super-G. Across the disciplines skier speed was largely explained by course setting and terrain inclination in a multiple linear model.

Show MeSH