| dc.description.abstract | Competitive success in the sport of ski jumping is made possible through the
optimal performance of junkers during flight. While the flight phase has been the subject
of several scientific investigations, there remain many questions concerning the
optimization of this most important phase.
The purpose of this study was to identify and quantify specific kinematic variables
of both the mid-flight and the preparation for landing phases of ski jumping flight.
Secondly, the study sought to examine the statistical contribution of variables in both
phases to the distance jumped. Finally, an attempt was made to develop a model which
would provide a general view of the structure of the relationships among analyzed
variables.
The subjects for this investigation were 50 highly skilled nordic combined
competitors participating in the 1996 World Cup K-88 event. Fourty trials from the first
round of competition were selected for inclusion in the data analysis.
The data for the 40 analyzed subjects was collected using two cameras mounted
on Peak Performance Pan and Tilt Heads. The jumpers were taped as they passed through
the field of view, from 55 to 85 meters on the jump hill. The Pan and IHt hardware
enabled the data to be collected over a wide field of view which resulted in the analysis of
both the mid-flight and preparation for landing phases. Values for the distance jumped
and the inrun velocity were collected from the official results printed by the FIS
competition committee.
The Peak Performance 3D Video Analysis System was used to extract the
horizontal and vertical coordinates for a 19 point segmental model The center of truss
was calculated for the model, which included the masses of skis, helmets and boots. Data was smoothed and processed to compute linear displacements and velocities and angular
displacements in the three planes of motion. Statistical treatment of the raw kinematic
data was performed using the appropriate computer programs from SPSS.
Correlation analyses were conducted on the variables of the mid-flight and
preparation for landing phases to determine the strength of any relationships between the
selected variables and distance jumped. Both frill and stepwise regression analyses were
conducted on the two analyzed phases of fright to assess the predictability of the
dependent variable, distance jumped. Also, a varimax rotated factor analysis was
developed for each of the mid-flight and preparation for landing phases to examine the
complex intercorrelations between independent variables.
The results of the study revealed the kinematic variables that are associated with
increasing the distance jumped. A general model of the relationships between independent
variables and their contribution to the distance jumped gave insight into the traits that may
be optimized in order to improve ski jump performance. The results of the mid-flight
phase suggested that, in order to increase distance jumped, athletes should attain a
compact, forward flight position with a small angle of attack, optimize previous
movements in order to achieve a high flight curve, and maximize the inrun velocity. The
preparation for landing results indicate that the best jumpers had an open flight position
and a greater negative vertical velocity. Flight positions in both analyzed phases were
observed to have a large effect on aerodynamic factors and the distance jumped. | |
