# Goal Shot Analysis in Elite Water Polo--World Cup Final 2018 in Berlin
## 1 Introduction  
The sports game of water polo is the oldest Olympic ball sport (first played in St. Louis in 1904). Shooting is one of the most important performance prerequisites in water polo [1, 2, 3, 4]. Successful throws on the goal are of primary interest to coaches and players, and thus also in the focus of game analysis in training science. Deficits in the individual throw performance, when trying to score a goal, mainly result from poor talent selection overseeing throwing competence, and bad technical education of youth players regarding to throwing techniques and goal shooting skills. Besides poor education, also the lack of scientific knowledge about throwing techniques and shooting skills in water polo competition plays an important role. On the individual level, the biomechanics of the sports-specific skills \"drive\" shot and \"faint\" shot (with a waving movement of the throwing arm) were investigated predominantly under isolated training conditions [5, 6]. This research revealed that the personal differences in throw performance between the players do not primarily result from ball speed. This leads to the assumption that in competition environment and task constraints (Figure 1) of the skill execution are much more important for the goal throw performance compared to organismic strength alone. The water polo polo education guidelines describe the most important shot techniques overhead shot, backhand shot, push shot (incl. \"self-doubler\"), bounce shot, lob etc. under morphological [10; 11; 12] or function-analytical aspects [13] at least with regard to the elementary teaching-learning situations of technician acquisition and technique application [14] in the junior age. However, it is not sufficiently clarified with which frequency and effectiveness these shot techniques are used especially under competition game conditions. From a biomechanical perspective the individual goal shot result primarily depends on the following parameters of high quality shooting: (i) Shot velocity respectively the ball speed during a goal shot is the most important performance prerequisite in male elite water polo [1; 2; 15]. Thus, shot velocity has increased over the last 20 years from 20 ms\({}^{-1}\)[16] to 25 ms\({}^{-1}\)[17], mostly due to better ball quality, but also because of more intense strength training in elite teams [18]. (ii) Ball speed is significantly different between different shot techniques, such as (a) drive shot, (b) goal shot after feinting (fake shot), and (c) goal shot directly from the catch of the ball [19]. (iii) Shot velocity in match-play (at least of women) is influenced by the players' load. [PERSON] [20] found (for women) significantly higher shot velocities in a controlled rest condition (11.6 ms\({}^{-1}\)) compared to throwing velocity after a series of repeated swim sprints (11.2 ms\({}^{-1}\)). Shot velocity is also strongly influenced by the age of the (male) players [17], vertical jump height during a water polo boost out of the water [17], the strength of shoulder rotators [18], as well as by body height [21]. Nevertheless, throwing velocity is an independent factor of water polo performance [21]. However, there is still a deficit of specific measurements in competitive games. Diagnoses seem to be particularly necessary for the overhead shot that is dominantly used in competitive play (as a direct \"drive\" shot, as a mounted \"bounce\" shot, or as a \"fake\" shot after a feinting waving movement of the throwing arm), because relevant measured values are primarily only available for shot movements under isolated training conditions or in laboratory situations [5; 6; 22]. Thus, important performance-related parameters in the competitive game, such as throwing distance and throwing speed, as well as flight and reaction time, remain unclear.