走高跳における助走の定量化

On jumping events of track and field, the run-up approach is one of the most important phases for determining a jumper’s performance. Among the jumping events, the high jump event has a unique approach that has no constraints regarding the take-off position and is combined with the straight and curved approach. Thus, the optimal way to regulate the run-up approach for high jumping is unclear. The aim of this research is to examine the variables which can quantitatively evaluate the high jump approach. The candidate variables were the footfall position, step length, and step direction. The variables regarding the footfall positions were defined based on the absolute coordinate referenced by the position of bar, and the relative coordinates referenced by the distribution of the trials. The variables for the step lengths were defined as the straight distance and curved distance between two footfall positions. The variables for the step directions were the absolute angle as the direction of steps against the bar and the relative angle as the direction of following step against a previous one. A total of 34 trials at six different heights of one high jump athlete were analyzed. The two-dimensional data for eight footfall positions in the run-up approach were extracted from the movie clips recorded by video camera by using the two-dimensional direct linear transformation method. The values of the mean and standard deviation among the trials on each height for each variable were calculated by using the data of the footfall position. A few possibilities were discovered for the proposed variables to evaluate the quantification of the high jump approach. First, the ratio between the standard deviations of the footfall positions of the two axis directions on the absolute coordinate might reveal the method for the regulation on the two-dimensional take-off position. Second, both the variables for the straight and curve step length might verify the regulation for the approach immediately before the take-off which has been suggested in a previous study about the long jump. Third, the value of the absolute angle might help evaluate the change of the approach angle against the bar right before the take-off, and the value of relative angle might help evaluate the beginning of the curved approach. The analysis of these variables has revealed that the trajectory of the run-up approach of the high jump has redundancy and that would include an ill-posed problem.