Author(s): DAISUKE, Y., Institution: TENRI UNIVERSITY, Country: JAPAN, Abstract-ID: 2041

INTRODUCTION:
The discus throw is a complex event that requires a high-speed rotation and the exertion of great force. For achieving higher performance, it is important to increase the discus velocity at release. The velocity of the discus can be decomposed into the velocity components produced by each motion of the body. By identifying these velocities, we can grasp the characteristics of each thrower. Therefore, the purpose of this study was to investigate the relationship between discus velocity at release and each velocity component in order to clarify which motion is emphasized to achieve higher performance. Furthermore, we classify discus acceleration techniques into patterns based on the common characteristics of these components.
METHODS:
The subjects were 47 male discus throwers (records: 32.26–68.94 m). 3D motion analysis was performed on the subjects' throwing motion. Modifying the method of Tauchi et al. (2006), the lower limb-trunk-upper limb model was used to decompose horizontal discus velocity into six components generated by 1) lower limb motion (L-limb), 2) trunk tilt (T-til), 3) shoulder length change(Sh-len) shoulder rotation(Sh-ro), 5) arm length change (Arm-len), and 6) arm rotation (Arm-ro). Correlation analysis was performed to examine the relationship between these component velocities and the horizontal discus velocity at release. Furthermore, cluster analysis was conducted using the contribution ratio, attempting to categorize disc acceleration patterns.
RESULTS:
The horizontal discus velocity at release (Average: 17.09 ± 1.91 m/s) showed significant positive correlations with the velocities generated by Sh-len, Sh-ro, and A-len, respectively (r = 0.331, p<0.05; r = 0.356, p < 0.05; r = 0.476, p < 0.01). In the K-means clustering analysis, each contribution was assigned to three clusters. To examine the characteristics of each cluster, a one-way ANOVA was conducted as an exploratory analysis for each contribution ratio. As a result, significant differences between clusters were observed for Sh-ro (F = 30.35, p<0.001), A-len (F = 33.81, p<0.001), and A-ro (F = 25.06, p<0.001).
CONCLUSION:
The results indicated that higher-performing throwers achieved greater discus velocity through Sh-len, Sh-ro, and A-len. In particular, the contribution of Sh-ro was notably large (54.6±11.2%), confirming that it is a crucial motion that determines performance. Cluster analysis results revealed acceleration technique types: 1) Arm Swing Utilization Type, where A-ro contributes approximately 30%; 2) Shoulder Rotation Emphasis Type, where Sh-ro contributes up to 70% while upper limb rotation shows a negative contribution; and 3) Arm Extension Type, where A-len contributes a high 46%. These results suggest that shoulder rotation is the most critical key motion, and it is important to develop acceleration technique strategies tailored to each thrower's characteristics, including physical attributes and fitness levels.