How does the modern football goalkeeper train? - An exploration of expert goalkeeper coaches' skill training approaches

Developing a New Expected Goals Metric to Quantify Performance in a Virtual Reality Soccer Goalkeeping App Called CleanSheet

As virtual reality (VR) sports training apps start to become more mainstream, it is important that human performance is measured from VR gameplay interaction data in a more meaningful way. CleanSheet is a VR training app that is played by over 100,000 users around the world. Many of those players are aspiring goalkeepers who want to use the app as a new way to train and improve their general goalkeeping performance. Whilst the leaderboards display how many shots players saved, these data do not take into account the difficulty of the shot faced. This study presents a regression model developed from a combination of existing expected goals (xG) models, goalkeeper performance metrics, and psychological research to produce a new shot difficulty metric called CSxG. Utilizing user save rate data as the target variable, a model was developed that incorporated three input variables relating to ball flight and in-goal positioning. Our analysis showed that the required rate of closure (RROC), adapted from Tau theory, was the most significant predictor of the proportion of goals conceded. A validation process evaluated the new xG model for CleanSheet by comparing its difficulty predictions against user performance data across players of varying skill levels. CSxG effectively predicted shot difficulty at the extremes but showed less accuracy for mid-range scores (0.4 to 0.8). Additional variables influencing shot difficulty, such as build-up play and goalpost size, were identified for future model enhancements. This research contributes to the advancement of predictive modeling in sports performance analysis, highlighting the potential for improved goalkeeper training and strategy development using VR technology.

Searching for the perfect goalkeeping personality. Myth or reality?

Background

Psychological factors such as personality characteristics are influential factors of the goalkeeping performance in football (soccer). Not only for individualized treatment in practice, also from a scientific point of view, profiling goalkeepers is a relevant part of understanding athletes. The aim of this study was to investigate personality traits of goalkeepers of different expertise, age, and sex.

Methods

Using the Five Factor Model of personality we assessed personality traits of 132 male and female football goalkeepers ranging from youth to senior and low to elite level. A series of analysis investigated differences between the groups focusing on expertise, age, and sex.

Results

Significant differences in the personality trait agreeableness between groups of different expertise and sex could be detected. Although a significant difference in neuroticism levels of males and females could be shown.

Conclusion

This study was a first step of profiling football goalkeepers of different expertise, age, and sex. The study calls for more replication in this specific field of football and goalkeeping in general to understand the influence of personality characteristics on sport performance.

Early identification of the opposition shot taker characterises elite goalkeepers' ability to read the game

Researchers investigating expertise in soccer goalkeepers have overwhelmingly focused on anticipating penalty kicks and identifying kinematic cues that are used to anticipate action outcomes. In this study, we took a novel approach to exploring 'game reading' skills in soccer goalkeepers. Specifically, we investigated whether and by what point during an attacking sequence in open play, elite goalkeepers can identify the opposition shot taker, a skill that is likely to facilitate organisation of the defensive line and interception of forward creative attacking passes. We used a moving window temporal occlusion paradigm to present elite, sub-elite, and amateur goalkeepers with 11-vs-11 attacking sequences that were divided into progressive segments. After viewing each segment, participants identified the player they thought would shoot at goal at the end of the attacking sequence. Elite goalkeepers identified the opposition shot taker earlier and more accurately than sub-elite and amateur participants. Findings suggest that elite goalkeeping is underpinned not only by anticipation of action outcomes but also game-reading skill that enables identification of the player most likely to carry out those actions.

On-Field Biomechanical Assessment of High and Low Dive in Competitive 16-Year-Old Goalkeepers through Wearable Sensors and Principal Component Analysis

Diving saves are the main duty of football goalkeepers. Few biomechanical investigations of dive techniques have been conducted, none in a sport-specific environment. The present study investigated the characteristics of goalkeepers’ dive in preferred (PS) and non-preferred (nPS) side through an innovative wearables-plus-principal-component analysis (PCA) approach. Nineteen competitive academy goalkeepers (16.5 ± 3.0 years) performed a series of high and low dives on their PS and nPS. Dives were performed in a regular football goal on the pitch. Full-body kinematics were collected through 17 wearable inertial sensors (MTw Awinda, Xsens). PCA was conducted to reduce data dimensionality (input matrix 310,878 datapoints). PCA scores were extracted for each kinematic variable and compared between PS and nPS if their explained variability was >5%. In high dive, participants exhibited greater hip internal rotation and less trunk lateral tilt (p < 0.047, ES > 0.39) in PS than nPS. In low dives, players exhibited greater ipsilateral hip abduction dominance and lower trunk rotation (p < 0.037, ES > 0.40) in PS than nPS. When diving on their nPS, goalkeepers adopted sub-optimal patterns with less trunk coordination and limited explosiveness. An ecological testing through wearables and PCA might help coaches to inspect relevant diving characteristics and improve training effectiveness.

Acceleration and deceleration demands during training sessions in football: a systematic review

PURPOSE

The aim of this review is to summarize the current scientific knowledge about acceleration and deceleration demands during football training.

METHODS

A systematic search of three electronic databases (PubMed, SPORTDiscus, Web of Science) was performed to identify peer-reviewed relevant English-language articles, following PRISMA guidelines.

RESULTS

All acceleration and deceleration data were analyzed and organized into four categories: i) training drills variables (i.e. manipulated drills variables such as number of players in small-sided games), ii) training exercises (i.e. different drills such small games or circuit training), iii) players' positions (i.e. demands for each playing position) and iv) training schedule (i.e. training sessions presented as microcycles, season sections or full season). Full-text articles of 42 studies were included in the final analysis. Players' level included: amateur, youth, semi-professional, professional and elite players. All playing positions were considered, including goalkeepers. Six different global position systems brands were used, with the majority measuring data at 10 Hz. Different thresholds and intensities were used in several papers. Lower acceleration and deceleration intensities occurred more often than higher intensities in all four categories.

CONCLUSION

Different exercises elicit different demands and small-sided games presented higher acceleration and deceleration demands than circuit training and other running based drills. Furthermore, manipulating drills variables, as reducing or increasing number of players in small-sided games increase or decrease demands, respectively. Additionally, wide playing positions, such as fullbacks, are generally exposed to higher acceleration and deceleration demands. From a planning point of view, acceleration and deceleration demands decrease as match day approaches.

Inter- and intra-microcycle external load analysis in female professional soccer players: A playing position approach

This study analyzes the inter- and intra-differences in external load across the microcycle in professional female soccer players. External load during four consecutive microcycles (i.e., M1, M2, M3, and M4) and training sessions (i.e., MD-4, MD-3, MD-2, and MD-1) and a match day (i.e., MD) were registered in seventeen female professional soccer players (age: 26.3 ± 4.6 years; height: 166.3 ± 6.1 cm; body mass: 59.8 ± 6.8 kg; and body mass index: 21.6 ± 1.7 kg·m^-2) who belonged to the same team in Spanish first division. A 10-Hz GPS that integrated a 100-Hz triaxial accelerometer was used to register external load. The results showed lower decelerations in M2 compared to M1 and M3 (p < 0.05), lower high-intensity distance (>16.0 km·h^-1) in M3 vs. M2, and greater relative sprint distance (>21.0 km·min^-1) in M4 vs. M1 and M3 (p < 0.05). MD-3 registered the highest load for all variables (p < 0.05). Forwards (FWs) performed (p < 0.05) significantly more sprints (meters and number > 21.0 km·h^-1) than central midfielders (CMs) and central defenders (CDs) in MD-2 and MD. Both, fitness and conditioning staff should pay special attention to the external loads for each playing position in training sessions to optimize the training process.

Sports Energy Consumption Evaluation Based on Improved Adaptive Weighted Data Fusion Energy-Saving Algorithm

The purpose of this study is to use a portable cardiopulmonary function tester to measure the effect of sports smart bracelets and smartphone application software in monitoring the energy consumption of different types of physical activities, and to select several popular sports software in daily life for research. The tester is an accurate reference value. It compares the energy consumption monitoring effect and error percentage of several software in periodic exercise and discusses the relationship between the measured value and reference value of several software, so as to provide a scientific basis for exercise for the majority of athletes. The selection of software provides a reference and chooses a more suitable movement method according to its own actual situation to achieve the most objective and effective periodic movement. In this study, the CMA (constant modulus algorithm) is introduced into the decision feedback equalizer, and the CMA-DFE (decision feedback equalization) algorithm is formed. Since the CMA algorithm adopts a fixed step size, there is no way to solve the contradiction between the convergence speed and the steady-state residual error, so a constant modulus algorithm with a variable step size is proposed. The algorithm increases the step size in its initial stage to increase the convergence speed and reduces the step size after the algorithm converges to reduce the steady-state residual error. This study replaces the traditional CMA algorithm with the constant modulus algorithm with a variable step size. In this section, two basic algorithms for calculating the adaptive weighting factor are first proposed. Due to its limitations, a modified adaptive weighting factor is proposed. During normal running, the Huawei Band relatively accurately monitors the number of steps and energy consumption, and the motion software of the motion software relatively accurately monitors the distance. The monitoring of distance and energy consumption is relatively accurate in the Codoon sports software; in jogging, the Huawei Band is relatively accurate in monitoring the number of steps; the LeDong sports software is relatively accurate in monitoring distance; and the Codoon sports software in the energy consumption is relatively accurate.

The Development of Bilateral Skill Symmetry: Insights From Gaelic Football Players and Coaches

Developing players who are adept at using both sides of the body (i.e., bilateral skill) is a challenge for coaches in many sports. With players being required to execute a range of skills with hand and foot on both sides of the body, Gaelic football provides an ideal natural laboratory for the study of laterality. Previous quantitative research has produced equivocal findings regarding the importance of bilateral skill performance in sport. In light of this equivocality, this paper utilized a qualitative approach to distill the beliefs and experiences of 14 players and five coaches who had performed at the highest level in Gaelic football. Three higher order categories were produced from the transcripts: the importance of being bilaterally skilled, the potential to develop bilateral skill, and methods to develop bilateral skills. Overall, this study highlights lessons for the design of future quantitative studies of bilateral skill in sport and should stimulate reflection on current practice regarding both short- and long-term bilateral skill development on the part of researchers, applied sport scientists, and coaches.

Specialist Coaching Integrated into a Department of Methodology in Team Sports Organisations

With increasing resources in sports organisations being allocated to the development and preparation of individual athletes and sub-groups with specialist performance roles, the work of coaches, specialist (role) coaches and support staff needs to be functionally and coherently integrated. This integration of sport science support and coaching can be administered by staff in a Department of Methodology (DoM). Particularly, in this paper, we propose how specialist coaching can be situated in a DoM, presenting a model advocating effective functioning in high-performance team sports organisations. Using principles of ecological dynamics, we provide a rationale for a functional methodology for the design of practice tasks in a DoM that views learners as wayfinders, self-regulating their way through competitive performance environments. This rationale for athlete self-regulation in practice could improve athlete performance by enhancing problem solving, engagement with constraints of learning designs and supporting better attunement to contextual information abundant in a competitive environment. Finally, by introducing this unified and multidisciplinary DoM, specialist coaches, team coaches and sport science support staff, within the organisational structure, can collaboratively debate and co-design individualised athlete training programmes to enrich skill adaptability and performance functionality. To underline these contentions, three high-performance sport case studies from Australian Football: goalkeeping in Association Football and Rugby League are presented.

What actually happens during a practice session? A coach's perspective on developing and delivering practice

Despite the considerable role coaches play in the development and performance of athletes, the manner in which (i.e. how and why) they develop and implement their practice sessions is mostly unknown. The disconnect between practice and match environments within the sport of cricket makes it challenging for coaches to provide practice environments that encourage player development, are engaging, and allow for transferability. This study looked to gain insight, from the perspective of the coach, into the type of practice environments and activities that cricket coaches use and why. In-depth, semi-structured interviews were conducted with ten cricket coaches followed by thematic analysis to interpret the data. Cricket coaches used a mixture of Training and Playing Form activities, with net-based activities the most common. Regardless of the type of practice, the use of various specialised equipment was also prevalent. Developing game awareness and technical skill were the main practice objectives noted by coaches. Various external and internal factors were also suggested to impact on the development and implementation of practice environments. Findings provide novel insights into how and why coaches operationalise their practice (design) in ways which are perhaps incongruent with recommendations in current literature.

When and How to Provide Feedback and Instructions to Athletes?-How Sport Psychology and Pedagogy Insights Can Improve Coaching Interventions to Enhance Self-Regulation in Training

In specialist sports coaching, the type and manner of augmented information that the coach chooses to use in communicating and training with individual athletes can have a significant impact on skill development and performance. Informed by insights from psychology, pedagogy, and sport science, this position paper presents a practitioner-based approach in response to the overarching question: When, why, and how could coaches provide information to athletes during coaching interventions? In an ecological dynamics rationale, practice is seen as a search for functional performance solutions, and augmented feedback is outlined as instructional constraints to guide athletes' self-regulation of action in practice. Using the exemplar of team sports, we present a Skill Training Communication Model for practical application in the context of the role of a specialist coach, using a constraints-led approach (CLA). Further based on principles of a non-linear pedagogy and using the recently introduced Periodization of Skill Training (PoST) framework, the proposed model aims to support practitioners' understanding of the pedagogical constraints of feedback and instruction during practice. In detail, the PoST framework's three skill development and training stages work to (1) directly impact constraint manipulations in practice designs and (2) indirectly affect coaches' choices of external (coach-induced) information. In turn, these guide practitioners on how and when to apply different verbal instruction methodologies and aim to support the design of effective skill learning environments. Finally, several practical guidelines in regard to sports coaches' feedback and instruction processes are proposed.

Skill Training Periodization in "Specialist" Sports Coaching-An Introduction of the "PoST" Framework for Skill Development

Across sports and movement science, training periodization has been recognized as key for athlete development and performance. While periodization with regard to physiology has a proven history, the structuring and periodization of motor learning and skill development is seemingly less researched and practiced. Despite the existence of numerous theoretical accounts underpinning skill acquisition training and more recently emerging periodization models, a cohesive framework to practically support coaches in the context of “specialist coaching” appears to be needed. The use of “specialist coaches” for individualized, one-on-one or small group trainings displays a growing trend in team ball sports. Despite limiting the replication of game-representative environments (i.e., by constraining the number of involved athletes in training), “specialist coaches” in performance sport constantly aim to achieve marginal gains and refinements in athlete development. In order to support these “specialist coaches” and fill a research gap on skill training periodization, the current paper seeks to review and transfer contemporary skill acquisition training theory (driven by the constraints-led approach) into a practically-applicable “Periodization of Skill Training” framework (“PoST” framework). This framework provides valuable conceptual and practical support for “specialist coaches” in performance sport; which will in turn, enhance, and refine adaptive movement variability for sport skills and manipulate skill training environments (i.e., over the course of macro- and micro-cycles, and for the planning of single training sessions). Practical examples from soccer goalkeeping (i.e., a “specialist coaching” context, often constrained to a small number of players in the training environment) will underline the proposed framework.