# Development and Reliability of a Street Skateboarding Notational Analysis Framework and Application
## 1 Introduction  
Street skateboarding debuted at the Tokyo 2020 Olympic games and is approved for Los Angeles 2028 after its inclusion in the Paris 2024 games [1]. Inclusion into the Olympic programme has accelerated the professionalisation of skateboarding, driving more skaters to train to compete on the world stage [2]. To effectively support athletes navigating the evolving landscape, we need a comprehensive understanding of performance to identify and enhance the capacities that underpin success [3]. A first step to support street skaters in competition is the objective definition and measurement of aspects of performance, before understanding how success is determined.  
In competitive street skating, athletes must interact with obstacles in the environment, performing technical tricks through complex board and body movement [4]. In current competition formats, skaters perform isolated tricks on obstacles (best-trick (BT)) and/or a sequence of tricks linked together around the skatepark (RUN) [5]. Success in Olympic competitions is determined by judges who utilise a set of criteria such as trick and obstacle difficulty, variety, and execution, to award an overall impression score for each attempt inorder to rank performances in that competition round [6]. Whilst some criteria--like execution quality and style--appear subjective, they may have objective underpinnings (e.g., height, speed, or distance travelled) [6] that could be systematically evaluated. However, the subjective application of these criteria, coupled with impression scoring overall, complicates tying specific judging decisions to measurable, targetable, or trainable performance attributes. Accordingly, coaches and athletes lack understanding of performance metrics upon which to train to perform--a fact which is made even more difficult by diverse and evolving competition formats, and the inherent technical complexity and creative variability of tricks performed [7].  
Performance analysis (PA) is a systematic process of examining sports performance [8] to provide insights into tactics and strategies [9]. The goal of PA is to capture factors related to how and why outcomes (e.g., winning) occur [10]. PA could be a useful strategy to identify differences between successful and less successful performances [11]. Yet, despite its adoption in many Olympic sports [12], no researchers have yet explored the application of PA approaches in skateboarding. As the tactical demands of competitive skateboarding remain ambiguous [5], a PA system tailored to the unique context of street skateboarding is warranted.  
One PA method by which objective performance data can be captured [13] is notational anlaysis (NA). NA systems are often employed in traditional sports [14] to retrospectively extract spatio-temporal variables to systematically quantify athlete activity from video footage [15]. This method is particularly beneficial when freestyle athlete movement across a large 'field of play' is integral to performance, such as in the board sports surfing [16; 17] and snowboarding [18]. Despite relevance, NA has yet to be fully adopted in skateboarding [5]. However, the growing availability of high-quality broadcast footage (e.g., X-Games and Olympics) and recent validation of video-derived temporal trick metrics [19; 20; 21], supports the use of an NA approach to use broadcast footage to quantify spatio-temporal performance aspects of trick selection, obstacle selection, and execution judging criteria.  
Therefore, the aim of this research was to design an NA system and protocol to capture potential outcome-impacting aspects of competitive street skateboarding performance. Additionally, we aimed to test reliability of the system for measuring style-focused spatio-temporal metrics from broadcast footage, leveraging performances during the semi-finals of the 2020 Tokyo Olympics street skateboarding debut.