INTRA-INDIVIDUAL DIFFERENCES OF MOVEMENT PATTERNS IN JAVELIN THROWS

Abstract

INTRODUCTION: The aim of this study was the identification of changes of individual movement patterns in javelin throw, using process oriented analysis methods as suggested by Bauer & Schöllhorn (1997). METHODS: Nine throws (57,96m - 68,80m) by a female javelin thrower were filmed in 3D during competition (16mm film, two Locam high speed cameras, 200f/s). Based on a 3-D model of the javelin thrower’s body (Menzel 1990), the three dimensionally defined angles between the segments and the angular velocities of the relative rotations were calculated. A process-oriented description of the movement pattern is characterized by the time-continuous intensities of these variables. The movement pattern of each throw was analyzed by the factor analysis P-technique and the resulting factor matrices were subsequently compared using an algorithm developed by Gebhardt (1967). In this way a matrix of similarity coefficients was created that was then structured by a hierarchical cluster analysis. RESULTS: The hierarchical cluster analysis seperated the movement patterns into two main clusters. For one cluster (3 throws), the release velocity was greater than and for the other (6 throws) less than 25 m/s. The factor loading matrices of the two clusters (main movement patterns) have a two factor structure, whereby the time course of the knee angle of the bracing leg has the highest factor loads for factor one in both clusters. An additional factor analysis (S-technique), however, reveales different course characteristics of the knee angle for the two clusters. The variables with the highest factor loads for the second factor are the course characteristics of the angles describing the trunk movement (throws with release velocity > 25 m/s) and the course characteristics of the angles describing the throwing arm movement (throws with release velocity < 25 m/s). CONCLUSIONS: For top level female javelin throwers, different intra-individual movement patterns can be identified and correlated with performance levels. The most important differences between these movement patterns are the course characteristics of the knee angle (bracing leg) and the angles which define the trunk movement. Technical training should be organized according to individual movement patterns. Further studies analyzing compensatory mechanisms should be made. REFERENCES: Bauer, H. U., Schöllhorn, W. (1997). Self-organizing Maps for the Analysis of Complex Movement Patterns. Neural Processing Letters 5, 193-199. Gebhardt, F. (1967). Über die Ähnlichkeit von Faktormatrizen. Psychol.Beiträge 10, 591-599. Menzel, H.-J. (1990). Biomechanical Analyses of the Javelin Throw of Top Class Athletes. In G. P. Brüggemann, J. K. Rühl (Eds.), Techniques in Athletics - Conference Proceedings 2, (pp. 662-668). Köln: Sport und Buch Strauß.