• Bojan Jost
  • Milan Coh
Keywords: kinematics, skijumping, flight, factor analysis, center of gravity


INTRODUCTION: The purpose of this study was to find the latent structure of the sample of ten manifest kinematic variables of ski jumping and on the sample of fifty of the best ski jumpers, participants at the first series at World Cup in Innsbruck in 1996. METHODS: A two-dimensional kinematic ARIEL PERFORMANCE analysis was made of the flight phase of the jump, defined at the 75 m point beyond the ski-jump table. RESULTS: We obtained in the flight phase three latent factors that can be generalized, encompassing 81.7% of the manifest variables' variance. The first factor was very dominant with a 46.8% share; the second explained 25.0% and the third 9.9% of the manifest kinematic variables' variance. After an oblique OBLIMIN rotation the structure of the first factor was highly defined with the length of the jump (-0.89) on one side and on the other by variables which show the angle between the body line and the horizontal (-0.78), angle between the body line and the skis (-0.88), angle between the upper part of the body and the horisontal (-0.85) and the angle between the trajectory of the body center of gravity and the horisontal (0.85). The second factor was dominated by projections of variables of velocity. The highest was from the resultant of the velocity of the center of gravity (0.95), then the horisontal velocity (0.93), vertical velocity (-0.74) and approach velocity (0.68). The third factor was mostly defined by variables giving the angle between the thigs and trunk (0.90), skis and the horisontal (0.90) and the trunk and arms (-0.80). CONCLUSIONS: Only the first factor showed a statistically significant correlation with the lenght of the jump, at the same time also possesing the most complex structure of the manifest kinematic variables.
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