Players In Team Sports Research Articles

Nonverbal communication of young players in team sports

Background and study aim : Nonverbal communication is always present in sport teams’ competition, on the court and around the court. This paper purpose is to investigate the nonverbal skills in two elite basketball cadet teams. Material and Methods: Pursuing this goal, we applied the PONS test to a group of 38 young basketball players 15 -16-year-old: 20 girls and 18 boys. The teenagers were members of Romanian national cadet teams having at least 3 years up to 7 years of experience playing basketball. The test applied to this sample was The Profile of Nonverbal Sensitivity. The test results were statistically analysed aiming to evaluate the nonverbal decoding accuracy of each evaluated athlete and to identify the possible differences between the two teams: boys and girls. Results : There is a statistically significant difference between the two teams in boys’ favor, meaning that the girls have done lower average general scores. In decoding face cues both teams are almost equal, de difference relay on understanding the body movement and attitude. Conclusions: Due the scores obtained by the tested players we can conclude that their nonverbal skills are at high level. Training nonverbal communication potentially enhanced game planning and building into the team a healthy psychological and social environment.

Play-by-Play Network Analysis in Football.

This study identifies dominant and intermediary players in football by applying a play-by-play social network analysis (SNA) on 70 professional matches from the 1. and 2. German Bundesliga during the 2017/2018 season. SNA provides a quantification of the complex interaction patterns between players in team sports. So far, the individual contributions and roles of players in football have only been studied at match-level considering the overall passing of a team. In order to consider the real structure of football, a play-by-play network analysis is needed that reflects actual interplay. Moreover, a distinction between plays of certain characteristics is important to qualify different interaction phases. As it is often impossible to calculate well known network metrics such as betweenness on play-level, new adequate metrics are required. Therefore, flow betweenness is introduced as a new playmaker indicator on play-level and computed alongside flow centrality. The data on passing and the position of players was provided by the Deutsche Fußball Liga (DFL) and gathered through a semi-automatic multiple-camera tracking system. Central defenders are identified as dominant and intermediary players, however, mostly in unsuccessful plays. Offensive midfielders are most involved and defensive midfielders are the main intermediary players in successful plays. Forward are frequently involved in successful plays but show negligible playmaker status. Play-by-play network analysis facilitates a better understanding of the role of players in football interaction.

A comprehensive review of plus-minus ratings for evaluating individual players in team sports

Abstract The increasing availability of data from sports events has led to many new directions of research, and sports analytics can play a role in making better decisions both within a club and at the level of an individual player. The ability to objectively evaluate individual players in team sports is one aspect that may enable better decision making, but such evaluations are not straightforward to obtain. One class of ratings for individual players in team sports, known as plus-minus ratings, attempt to distribute credit for the performance of a team onto the players of that team. Such ratings have a long history, going back at least to the 1950s, but in recent years research on advanced versions of plus-minus ratings has increased noticeably. This paper presents a comprehensive review of contributions to plus-minus ratings in later years, pointing out some key developments and showing the richness of the mathematical models developed. One conclusion is that the literature on plus-minus ratings is quite fragmented, but that awareness of past contributions to the field should allow researchers to focus on some of the many open research questions related to the evaluation of individual players in team sports.

FPGA-Based Vision Processing System for Automatic Online Player Tracking in Indoor Sports

In recent years, there has been an increasing growth of using vision-based systems for tracking the players in team sports to evaluate and enhance their performance. Player tracking using vision systems is a very challenging task due to the nature of sports games, which includes severe and frequent interactions (e.g. occlusions) between the players. Additionally, these vision systems have high computational demands since they require processing of a huge amount of video data based on the utilization of multiple cameras with high resolution and high frame rate. As a result, most of the existing systems based on general-purpose computers are not able to perform online real-time player tracking, but track the players offline using pre-recorded video files, limiting, e.g., direct feedback on the player performance during the game. In this paper, we present a reconfigurable system to track the players in indoor sports automatically and without user interaction. The proposed system performs real-time processing of the incoming video streams from the cameras, achieving online player tracking. The teams are identified, and the players’ positions are detected based on the colors of their jerseys. FPGA technology is used to handle the compute-intensive vision processing tasks by implementing the video acquisition, video preprocessing, player segmentation, and team identification & player detection modules in hardware, realizing an online real-time system. While the pixel processing is performed in the FPGA, the less compute-intensive player tracking is performed on a general purpose computer. The maximum achieved frame rate for the FPGA implementation is 96.7 fps using a mature Xilinx Virtex-4 FPGA, and can be increased to 136.4 fps using a Xilinx Virtex-7 device. The Player tracking requires an average time of 2.5 ms per frame in the host-PC. As a result, the proposed reconfigurable system supports a maximum frame rate of 78.9 fps using two cameras with a resolution of 1392 × 1040 pixels each. Our results show that the achieved average precision and recall for player detection are up to 84.02% and 96.6%, respectively. Including player tracking, the achieved average precision and recall are up to 94.85% and 94.72%, respectively. Using the proposed FPGA implementation, a speedup by a factor of 15.2 is achieved compared to an OpenCV-based software implementation on a PC equipped with a 2.93 GHz Intel i7-870 CPU.

Modelling Movement Energetics Using Global Positioning System Devices in Contact Team Sports: Limitations and Solutions.

Quantifying the training and competition loads of players in contact team sports can be performed in a variety of ways, including kinematic, perceptual, heart rate or biochemical monitoring methods. Whilst these approaches provide data relevant for team sports practitioners and athletes, their application to a contact team sport setting can sometimes be challenging or illogical. Furthermore, these methods can generate large fragmented datasets, do not provide a single global measure of training load and cannot adequately quantify all key elements of performance in contact team sports. A previous attempt to address these limitations via the estimation of metabolic energy demand (global energy measurement) has been criticised for its inability to fully quantify the energetic costs of team sports, particularly during collisions. This is despite the seemingly unintentional misapplication of the model's principles to settings outside of its intended use. There are other hindrances to the application of such models, which are discussed herein, such as the data-handling procedures of Global Position System manufacturers and the unrealistic expectations of end users. Nevertheless, we propose an alternative energetic approach, based on Global Positioning System-derived data, to improve the assessment of mechanical load in contact team sports. We present a framework for the estimation of mechanical work performed during locomotor and contact events with the capacity to globally quantify the work done during training and matches.

Pacing behaviour of players in team sports: Influence of match status manipulation and task duration knowledge.

The study aimed to identify the influence of prior knowledge of exercise duration associated with initial information about momentary match status (losing or winning) on the pacing behaviour displayed during soccer game-based activities. Twenty semi-professional male players participated in four game scenarios divided in two sessions. In the first game scenario, players were not informed about the time duration or initial match status. In the second, players were only informed they would be required to play a small-sided game for 12 minutes. In the third, players were told they would play a small-sided game for 12 minutes and that one of the teams was winning 2 to 0. Finally, in the fourth game scenario, players were instructed they would play a small-sided game for 12 minutes and the score lines used at the start of the previous game scenario were reversed. The results showed a tendency for the unknown task duration to elicit greater physical responses in all studied variables, compared with knowing the task duration. Knowing the task duration and starting the game winning or losing did not affect the players’ activity profile between the two conditions. Thus, during small-sided soccer games, knowledge (or not) about the exercise duration alters the pacing behaviour of the players. Moreover, short and undisclosed-length exercise durations resulted in the adoption of more aggressive pacing strategies, characterised by higher initial exercise intensities. Furthermore, previous information on match status does not seem to interfere with pacing patterns if the players are aware of the exercise duration. Coaches may use knowledge of exercise duration to manipulate the small-sided games’ demands.

Położenie klasowo-własnościowe graczy w profesjonalnych sportach drużynowych

Although social sciences do not ignore sports altogether, they do not attempt to analyse the class position of players in team sports. Yerefore, the aim of this paper is to conduct such analysis. Ye starting point is introduction of the idea of socio-economic class based on the theory of economic ownership understood as rent. As the term "economic rent" is used in neoclassical economy, I explain the di>erences between that approach and the one used in this paper. Building on theory and on empirical data on the earnings of players, I conclude that while the sports elite undoubtedly represent ownership and bourgeoisie class, the less !nancially attractive leagues or less earning players represent workers owning labour and sometimes that ownership is severely limited.

Measured and estimated energy cost of constant and shuttle running in soccer players.

Players in team sports like soccer often make acceleration and deceleration movements, which are more energetically demanding than running at constant speed. The first aim of the present study was to estimate this difference in associated energy cost. To this end, we compared the actual energy cost of shuttle running to that of running at constant speed. In addition, since measuring oxygen consumption is not feasible during soccer, the study's second aim was to determine the validity of an indirect approach to estimate energy cost provided by di Prampero et al. (2005) using time-motion data obtained from a tracking system as input. Fourteen male amateur soccer players performed aerobic constant and continuous shuttle running at six different speeds (range = 7.5-10.0 km·h⁻¹) on artificial turf. Measured energy cost was compared to the energy cost estimated with di Prampero's (2005) equation using data from a local position measurement (LPM) system as input. As expected, measured energy cost was significantly higher (∼30%-50%) for shuttle running than for constant running (P < 0.001), and this difference increased with speed. For constant running, estimated energy cost was significantly higher (6%-11%) than measured energy cost, whereas for shuttle running, estimated energy cost was significantly lower (-13% to -16%) than measured energy cost. Shuttle running raised the player's energy cost of running compared to constant running at the same average speed. Although actual energy cost of constant running was significantly overestimated by di Prampero's approach using LPM data as input, actual energy cost of shuttle running was significantly underestimated.

Disciplinary provisions for hate speech in football: comparative perspectives

Incidents of alleged racism between participants (primarily between opposing players) in team sports at the elite level have been subject to specific engagement by the relevant sports-based disciplinary procedures. In English football, two incidents in 2011 gained significant media coverage: the first involving the Liverpool player, Luis Suarez, who was penalized with an eight-match ban, the second involving the Chelsea player, John Terry, who received a four-match ban. Terry was also prosecuted and acquitted for a racially aggravated public order criminal offence. These two incidents demonstrate the increasing quasi-criminal nature of sports disciplinary procedures that can be seen as exhibiting characteristics of formal rationality, conflict-based adjudication processes and a punitive nature. This article provides a comparison with the Australian Rules football approach to incidents of this type, where a more overtly conciliatory approach has been adopted, with elements of mediation between the participants concerning allegations of inter-player racism.

Dynamic Tracking of a 2.4GHz Waist Mounted Beacon for Indoor Basketball Player Positioning

Wireless player tracking is being considered for use within indoor team sports for coaching assistance. Few research studies exist into wireless RF signal tracking of players in indoor team sports, in particular the game of basketball. Utilising the RF signal trilateration positioning technique with three anchor nodes per quarter court, players wearing RF beacons could be tracked and their positional data recorded in real time. This study builds on a previous study conducted under static conditions by Kirkup et al. (2013). Identifying the player with the ball is also important in recording and assessing team strategies. Accelerometer sensors located on the body have been widely used to monitor the movements of the body and can potentially be used to recognize when a player is bouncing the basketball (dribbling). This paper reports the findings of using the received signal strength positioning technique with one anchor node to estimate the position of a moving basketball player towards the node and the use of a wearable triaxial accelerometer sensor to identify the person bouncing the ball. Both slow and fast game pace conditions are tested. Player position accuracy can be achieved to within 0.5m for distances less than 9m. A study of the power law variation in signal strength over distance gives an exponent n of 2.23 under moderate paced conditions with a Pearson squared correlation coefficients of r2 = 0.42. This means that 42% of the variation can be explained by the approximation. Under moving conditions, changes in the transmit antenna orientation will result in an increase of random variation in position prediction which is included in this result. The acceleration signature from a wrist sensor of the hand-ball contact process while dribbling distinctively shows ball dribbling possession. A single moving player scenario is discussed and measured results with and without the basketball demonstrate the accuracy and feasibility of the positioning and ball possession techniques. The techniques will provide valuable information for further study into multiple player and multiple beacon wireless indoor positioning.

Complementary cooperation, minimal winning coalitions, and power indices

We introduce a new simple game, which is referred to as the complementary weighted multiple majority game (C-WMMG for short). C-WMMG models a basic cooperation rule, the complementary cooperation rule, and can be taken as a sister model of the famous weighted majority game (WMG for short). In C-WMMG, each player is characterized by a nonnegative vector with a fixed dimension, and players in the same coalition cooperate by producing a characteristic vector for this coalition (each dimension of this vector equals the maximum of the corresponding dimensions of its members). The value of a coalition is 1 if and only if the sum of its characteristic vector is larger than that of its complementary coalition, in which case the coalition is called winning. Otherwise, the coalitional value is 0. In this paper, we concentrate on the two dimensional C-WMMG. An interesting property of this case is that there are at most n+1 minimal winning coalitions (MWCs for short), and they can be enumerated in time O(nlogn), where n is the number of players. This property guarantees that the two dimensional C-WMMG is more handleable than WMG. In particular, we prove that the main power indices, i.e. the Shapley–Shubik index, the Penrose–Banzhaf index, the Holler–Packel index, and the Deegan–Packel index, are all polynomially computable. To make a comparison with WMG, we know that it may have exponentially many MWCs, and none of the four power indices is polynomially computable (unless P=NP). Still for the two dimensional case, we show that local monotonicity holds for all of the four power indices. In WMG, this property is possessed by the Shapley–Shubik index and the Penrose–Banzhaf index, but not by the Holler–Packel index or the Deegan–Packel index. Since our model fits very well the cooperation and competition in team sports, we hope that it can be potentially applied in measuring the values of players in team sports, say help people give more objective ranking of NBA players and select MVPs, and consequently bring new insights into contest theory and the more general field of sports economics. It may also provide some interesting enlightenments into the design of non-additive voting mechanisms. Last but not least, the threshold version of C-WMMG is a generalization of WMG, and natural variants of it are closely related with the famous airport game and the stable marriage/roommates problem.

A Prospective Study of the Relationship between Lower Body Stiffness and Hamstring Injury in Professional Australian Rules Footballers

Background Hamstring strains remain one of the most prevalent injuries in Australian Rules football. The authors prospectively examined the relationship between musculotendinous stiffness of the hamstring and leg stiffness with hamstring injury in professional Australian Rules footballers during the 2006 season. Hypothesis Higher hamstring stiffness and leg stiffness are related to noncontact, soft tissue hamstring injury risk in professional Australian Rules footballers. Study Design Case-control study; Level of evidence, 3. Methods Unilateral hamstring stiffness and leg stiffness were assessed in 136 professional footballers in the month before the commencement of the competitive season. This information was then investigated relative to players who suffered noncontact, soft tissue hamstring injuries during either matches or training throughout the season to identify whether preseason stiffness was related to injury occurrence. Results Fourteen tested players recorded acute, noncontact hamstring injuries, resulting in 3.3 ± 2.8 weeks of missed match play per injury. At preseason testing, the players who ended up sustaining a hamstring injury during the season recorded significantly higher mean hamstring stiffness (11%, P = .04) and leg stiffness (5%, P = .03). When considering the injured players, the leg stiffness of the involved limb was significantly higher than the noninjured players (P = .02), whereas hamstring stiffness was significantly higher on the noninvolved limb (P = .01). Further, those players who suffered a hamstring injury were significantly older than the noninjured players (P = .01). Conclusion It appears that a high bilateral hamstring stiffness and leg stiffness may be a determinant in the risk of sustaining a hamstring injury. Further, relatively lower hamstring stiffness in the involved limb of injured players appears to be associated with increased injury and may be related to a lack of strength. The information from stiffness assessment may allow medical staff to determine the hamstring risk status for individual players in team sports.

Evaluation of contrast baths and ice baths for recovery in U/20 rugby union

Introduction: Players in team sports must recover from competition and training in a relatively short period of time in order to perform at optimal levels in either training or games. To enhance recovery Cryotherapy is widely used. To date there is limited scientific data to support the use of Cryotherapy for recovery. Methods: Players (n = 25) from a U/20 competition volunteered to participate in a random control trial using contrast baths, ice baths and no recovery. Between group and with-in group analysis with repeated measures were used to identify significant differences in three field tests. Multistage shuttle test, 300 m test and a phosphate decrement test were performed several times across four weeks during training. Results: Repeated measures analysis identified a significant difference between base tests, retests and last tests multistage shuttle test (p < 0.001) and the phosphate decrement test (p < 0.05). However no treatment interaction was identified. No significant difference was identified in 300 m test and retests; a lack of data was available from retests. Discussion: Results from this study may indicate that during pre-season training, the physical work undertaken may be more important than the recovery protocol for improvements in fitness parameters tested in this study. However, consideration should take into account the number of days between sessions. With no games at this stage of the season, participants had up to 4 days off, allowing for ample recovery. The relative small sample size in groups and level of missing data is another factor impacting on results. Future research should be directed towards larger sample sizes and during periods of cyclic activity which include games and training to evaluate benefits of cryotherapy in recovery from team sport.

Hydration Practices Of Elite Male Team Athletes During Training Sessions

PURPOSE: To study the hydration practices of two groups of elite male team athletes during a typical training session. METHODS: We collected urine specific gravity (USG) measurements from early morning samples and fluid balance characteristics during a standard morning training session for two Australian national mens teams: basketball (n = 17) and cricket (n = 12). Basketball testing was undertaken indoors during winter (12 degrees C, 59% r.h) while cricket testing was done outdoors during summer (29 degrees C and 50% r.h.). RESULTS: USG was 1.025 ± 0.005 for basketball players and 1.017 ± 0.008 (mean ± SD), with 15 basketball players and 5 cricket players showing a result > 1.020 signifying possible dehydration. Mean sweat losses of the sixteen basketball players observed over a full practice were 2058 ± 601 mL or 895 ± 261 mL/h. Voluntary fluid intakes were 1086 ± 597 mL over the session, equivalent to 472 ± 260 mL/h or 52 ± 21% of sweat losses. Mean sweat losses of 11 cricket players were 3004 ± 1014 mL or 1202 ± 406 mL/h. Voluntary fluid intakes were 2172 ± 482 mL over the session, which was equivalent to 869 ± 193 mL/h or 76 ± 21% of sweat losses. Body mass losses over the session were 1.0 ± 0.7% of body mass. CONCLUSION: Some players in team sports are unable to meet their acute and daily hydration needs during intensified training both in cool and hot weather, and could benefit from individualized education to improve their drinking practices.

Hidden patterns of play interaction in soccer using SOF-CODER

Traditional methods for quantifying sport performances are limited in their capacity to describe the complex interactions of events that occur within a performance over time. The following article outlines a new approach to the study of actions between players in team sports--mainly, soccer. Since the observational design is nomothetic, point, and multidimensional, an observational and data-collecting instrument has been developed. The instrument is mixed and combines a field format with a category system for game events, as well as an ad hoc instrument that considers the game actions of one or both teams, each recorded according to the same criteria. The article also outlines a new approach to the analysis of time-based event records--in this case, sports performance--known as T-pattern detection. The relevant elements of the T-pattern detection process are explained, and exemplar data from analyses of soccer matches are presented to highlight the potential of this form of data analysis. The results suggest that it is possible to identify new kinds of profiles for both individuals and teams on the basis of observational criteria and a further analysis of temporal behavioral patterns detected within the performances.