# Goal Shot Analysis in Elite Water Polo--World Cup Final 2018 in Berlin
## 1 Introduction
Since international performance differences in maximum throwing velocity under laboratory conditions are comparatively small, recent international research has focused on the primarily tactical situational dependence, e.g., the specific environmental conditions (so-called \"constraints\" or limitations) of successful finishing actions in sports games [23; 24; 25]. This development has gone largely unnoticed in water polo. On the basis of the dynamical systems approach [7; 8; 9], the goal shot has to be interpreted as the result of a coherent interpersonal coordination of the attackers in relation to the interpersonal coordination of the defenders, and thus must be investigated also on the complex team level. Therefore, recent research on goal shot behavior in different sports games has focused on the situational constraints that are imposed on the shooter when scoring or missing a goal [23; 24; 25]. Important variables describing the macroscopic formations of the players as agents in a complex adaptive system were e.g., the distances and angles between the assisting and shooting player or between the attacker, defender and goalkeeper, or also the team centroids (\"center of gravity\") of the teams in offense and defense [26]. As goal shots are the outcome of dynamic and self-organized multi-agent patterns learned by the players during tactical training and match-play, game analysis is focused on the most functional states of the complex performer-environment system. Despite the huge variety of influential constraints acting on the players during match-play,  
Figure 1: The constraints-led approach of technical education in sport (based on [7; 8; 9]). the number of such perfectly timed interpersonal actions patterns is limited, because less functional states of team or sub-group organization will vanish during the performance development of the team [27]. In our study we focused on the individual technical movement parameters of the single players, as well as on the group tactical behavior of the team shortly before the throws were finally executed. On the individual level there is abundant research on the shot velocity [6], and the various throw positions [28] of world class water polo athletes in competition games, but the quality of the technical execution and its impact on the throw efficacy of the players was not yet described. Furthermore, on the team level--to our knowledge--no research exists on the relevance of collective variables such as e.g., the defensive position of the opposite goal keeper or the position, angle and speed of the assist pass to the shooter in the own offense. Therefore, the goal of this paper is to analyze the three constraints of the playing behavior of teammates and opponents (semi-collective goal throw characteristics: shot angle, passing distance and speed as well as the goalkeeper position during the goal throw) and to relate them to the situational throw success. A further analysis will clarify the connection between the overall collective offensive and defensive behavior and the goal-scoring success rate using the concepts of \"local dominance\" [27] in the sense of \"space control\" [29]. For this purpose, the partial areas of the field controlled by each individual player in the offense and defense will be calculated and compared using Voronoi-cells. In summary, our analysis of goal throw in elite water polo focuses on both scenarios of the situational movement solution under the specific competition constraints (Figure 1): (i) typical patterns of intra-player movement coordination resulting in high accuracy and speed of the ball during a goal throw on individual level of a specific player, and (ii) coherent patterns of collective inter-player coordination resulting on team (or sub-group) level in the successful scoring of a goal.