Determinants of possession of the ball in soccer

Abstract

In research on the importance of the possession of the ball in soccer, little attention has been paid to its determinants. Using data from 170 matches of the 2003 – 2004 Spanish Soccer League, we explain why differences in the possession of the ball among teams are so great. In particular, four variables are examined: evolving match status (i.e. whether the team is winning, losing or drawing), venue (i.e. playing at home or away), and the identities of the team and the opponent in each match. Results of linear regression analysis show that these four variables are statistically significant and together explain most of the variance in possession. In short, home teams have more possession than away teams, teams have more possession when they are losing matches than when winning or drawing, and the identity of the opponent matters – the worse the opponent, the greater the possession of the ball. Combinations of these variables could be used to develop a model that predicts possession in soccer.     

Determinants of the half-turn with the ball in sub-elite youth soccer players

We explored the biomechanics of the 180° change-of-direction with the ball (half-turn) in soccer. We aimed at identifying movement strategies which enhance the players’ half-turning performance, by characterising technique kinematics and understanding the structure of biomechanical and anthropometrics variables. Ten Under-13 sub-elite male players were recorded with an optoelectronic motion analyser while performing a 5-m straight dribbling followed by a half-turn with the sole. Joints kinematics differences between faster and slower trials were found in support-side hip rotation, driving-side hip adduction, trunk flexion and rotation, and arms abduction. To unveil the data-set structure, a principal component (PC) analysis and a stepwise linear discriminant analysis were performed using 30 biomechanical parameters and four anthropometric variables for each trial. Seven retained PCs explained 79% of the overall variability, featuring combinations of original variables that help in understanding the factors facilitating fast half-turns: keeping short steps, minimising lateral and forward body movements, and centre-of-mass lowering, even with ample lower limbs ranges of motion (RoM); abducting the upper limbs while limiting trunk flexion and pelvic inclination RoM. Balance and task-constrained exercises may be proposed to improve this technique. Moreover, a quantitative knowledge of the movement structure could give coaches objective insights to better instruct young players.     

Fundamental aerodynamics of the soccer ball

When the boundary layer of a sports ball undergoes the transition from laminar to turbulent flow, a drag crisis occurs whereby the drag coefficient (C _d) rapidly decreases. However, the aerodynamic properties and boundary-layer dynamics of a soccer ball are not yet well understood. In this study we showed that the critical Reynolds number (Re _crit) of soccer balls ranged from 2.2 × 10⁵ to 3.0 × 10⁵. Wind-tunnel testing, along with visualisation of the dynamics of the boundary layer and the trailing vortex of a ball in flight, demonstrated that both non-spinning and spinning (curved) balls had lowC _d values in the super-critical region. In addition, theRe _crit values of the soccer balls were lower than those of smooth spheres, ranging from ∼ 3.5 × 10⁵ to 4.0 × 10⁵, due to the effects of their panels. This indicated that the aerodynamic properties of a soccer ball were intermediate between those of a smooth ball and a golf ball. In a flow visualisation experiment, the separation point retreated and theC _d decreased in a super-critical regime compared with those in a sub-critical regime, suggesting a phenomenon similar to that observed in other sports balls. With some non-spinning and spinning soccer balls, the wake varied over time. In general, the high-frequency component of an eddy dissipated, while the low-frequency component increased as the downstream vortex increased. The causes of the large-scale fluctuations in the vortex observed in the present study were unclear; however, it is possible that a ‘knuckle-ball effect’ of the non-rotating ball played a role in this phenomenon.     

得分进攻活动获得球阶段的分析

采用文献资料，调查访谈和数理统计等方法对得分进攻活动获得球阶段进行了分析，发现其存在的特点和规律，并对男子足球运动和女子足球运动间的异同点进行了较为详细的探讨。     

The influence of situational variables on ball possession in the English Premier League

Abstract

The aims of this study were twofold: (1) to examine the influence of situational variables on ball possession in elite soccer and (2) to quantify the variables that discriminate between high or low percentage ball possession teams (HPBPT and LPBPT) across different playing positions. Match performance data were collected from English Premier League matches using a multiple-camera system. Data were examined using linear regression, a 2 × 5 factorial analysis of variance and discriminant analysis. Playing against weak opposition was associated with an increase (P < 0.01) in time spent in possession while playing away decreased (P < 0.01) the time spent in possession by ~3%. Possession was increased (P < 0.01) when losing than winning or drawing. Finally, the better the ranking of a team, the higher (P < 0.01) the time spent in possession. The playing position effect was significant for all variables (P < 0.05); however, there were only interactions with team ball possession in some cases. The discriminant analysis identified functions for all five playing positions (P < 0.01). The variables that discriminated performance between HPBPT and LPBPT were different for various playing positions, although the number of successful passes was the most common discriminating variable. The results demonstrate that HPBPT and LPBPT developed different possession strategies during matches and that selected variables such as successful passes were identified to explain these data trends across various playing positions. Combinations of variables could be used to develop a probabilistic model for predicting time spent in possession by teams.     

Determinants of stable volunteering in Swiss soccer clubs

This study analysed the underlying determinants of soccer club volunteers’ tendency to continue or terminate their voluntary engagement. Stable voluntary engagement was analysed in terms of volunteers’ subjective expectations regarding club-related working conditions, expressed by level of job satisfaction and orientation of collective solidarity to their soccer club. These relationships were tested empirically using an online questionnaire with 345 volunteers in a selection of 20 Swiss soccer clubs. The results indicate that the volunteers’ job satisfaction and orientation toward collective solidarity correlated positively with their volunteering commitment. The discussion presents recommendations to help both Swiss soccer clubs as well as the Swiss Soccer Association to retain their volunteers more effectively.     

Modelling the flight of a soccer ball in a direct free kick

This study involved a theoretical and an experimental investigation of the direct free kick in soccer. Our aim was to develop a mathematical model of the ball's flight incorporating aerodynamic lift and drag forces to explore this important 'set-play'. Trajectories derived from the model have been compared with those obtained from detailed video analysis of experimental kicks. Representative values for the drag and lift coefficients have been obtained, together with the implied orientation of the ball's spin axis in flight. The drag coefficient varied from 0.25 to 0.30 and the lift coefficient from 0.23 to 0.29. These values, used with a simple model of a defensive wall, have enabled free kicks to be simulated under realistic conditions, typical of match-play. The results reveal how carefully attackers must engineer the dynamics of a successful kick. For a central free kick some 18.3 m (20 yards) from goal with a conventional wall, and initial speed of 25 m·s^?1, the ball's initial elevation must be constrained between 16.5° and 17.5° and the ball kicked with almost perfect sidespin.     

Modelling the flight of a soccer ball in a direct free kick

This study involved a theoretical and an experimental investigation of the direct free kick in soccer. Our aim was to develop a mathematical model of the ball's flight incorporating aerodynamic lift and drag forces to explore this important 'set-play'. Trajectories derived from the model have been compared with those obtained from detailed video analysis of experimental kicks. Representative values for the drag and lift coefficients have been obtained, together with the implied orientation of the ball's spin axis in flight. The drag coefficient varied from 0.25 to 0.30 and the lift coefficient from 0.23 to 0.29. These values, used with a simple model of a defensive wall, have enabled free kicks to be simulated under realistic conditions, typical of match-play. The results reveal how carefully attackers must engineer the dynamics of a successful kick. For a central free kick some 18.3 m (20 yards) from goal with a conventional wall, and initial speed of 25 m x s(-1), the ball's initial elevation must be constrained between 16.5 degrees and 17.5 degrees and the ball kicked with almost perfect sidespin.     

A mathematical analysis of the motion of an in-flight soccer ball

In this paper, an analytical and numerical study of the three-dimensional equations describing the motion through the air of a spinning ball is presented. The initial analysis involves constant drag coefficients, but is later extended to involve drag varying with the spin ratio. Excellent agreement is demonstrated between numerical, analytical and experimental results. The analytical solution shows explicitly how the ball’s motion depends on parameters such as ball roughness, velocity and atmospheric conditions. The importance of applying three-dimensional models, rather than two-dimensional approximations, is demonstrated.     

The effect of surface geometry on soccer ball trajectories

Two different measurement techniques are used to examine the effect of surface geometry on soccer ball trajectories. Five professional players are observed using high-speed video when taking curling free kicks with four different soccer balls. The input conditions are measured and the average launch velocity and spin are found to be approximately 24 m/s and 106 rad/s. It is found that the players can apply more spin (~50%) on average to one ball, which has a slightly rougher surface than the other balls. The trajectories for the same four balls fired at various velocities and spin rates across a sports hall using a bespoke firing device are captured using high-speed video cameras, and their drag and lift coefficients estimated. Balls with more panels are found to experience a higher lift coefficient. The drag coefficient results show a large amount of scatter, and it is difficult to distinguish between the balls. Using the results in a trajectory prediction programme it is found that increasing the number of panels from 14 to 32 can significantly alter the final position of a 20 m-curling free kick by up to 1 m.     

Novel mathematical model to estimate ball impact force in soccer

To assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of ‘footballer’s ankle’. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view.     

Physical characteristics that predict involvement with the ball in recreational youth soccer

This study examined the relative contribution of age, stage of puberty, anthropometric characteristics, health-related fitness, soccer-specific tests and match-related technical performance to variance in involvements with the ball during recreational 5-a-side small-sided (32 × 15 m) soccer matches. Using a cross-sectional design, 80 healthy male students (14.6 ± 0.5 years of age; range 13.6–15.4) who played soccer recreationally were randomly divided into 10 teams and played against each other. Measurements included height, body mass, pubertal status, health-related fitness (12-min walk/run test, standing long jump, 15-m sprint and sit-ups in 30 s), soccer-specific tests (kicking for speed, passing for accuracy and agility run with and without a ball), match-related technical performance (kicks, passes and dribbles) and involvements with the ball during matches. Forward multiple regression analysis revealed that cardiorespiratory fitness (12-min walk/run test) accounted for 36% of the variance in involvements with the ball. When agility with the ball (zigzag running) and power (standing long jump) were included among the predictors, the total explained variance increased to 62%. In conclusion, recreational adolescent players, regardless of their soccer-specific skills, may increase participation in soccer matches most through physical activities that promote improvement in cardiorespiratory fitness, muscle power and agility.     

Finite element modelling and experimental study of oblique soccer ball bounce

In this study, we develop a finite element model to examine the oblique soccer ball bounce. A careful simulation of the interaction between the ball membrane and air pressure in the ball makes the model more realistic than analytical models, and helps us to conduct an accurate study on the effect of different parameters on a bouncing ball. This finite element model includes a surface-based fluid cavity to model the mechanical response between the ball carcass and the internal air of the ball. An experimental set-up was devised to study the bounce of the ball in game-relevant impact conditions. Ball speed, angle, and spin were measured before and after the bounce, as well as ball deformation and the forces during the impact. The finite element model has been validated with three different sets of data, and the results demonstrate that the finite element model reported here is a valuable tool for the study of ball bounce. After validation of the model, the effect of the friction coefficient on soccer ball bounce was studied numerically. Simulation results show that increasing the friction coefficient may result in reversal of the horizontal impact force.     

Wind tunnel measurement and flow visualisation of soccer ball knuckle effect

Wind tunnel experiments were conducted, in particular focusing on slow unsteady variations of aerodynamic forces as a potential cause of the knuckle effect of a new soccer ball (Teamgeist) under non-spinning condition. The experiments included simultaneous measurements of the drag, the side force and the surface pressure on a ball surface, and the tuft visualisation to investigate the flow field behind a ball. Of particular interest was the erratic nature of the knuckle effect resulting from the unsteady movement of vortical wake structure in the supercritical Reynolds number regime. A simple 2-D numerical simulation of the ball flight trajectory was performed by taking into account the unsteady side force data measured in the present experiments.     

A dynamic model of the head acceleration associated with heading a soccer ball

This study develops a dynamic model of head acceleration, which incorporates physiologically related neck muscle contributions, to further the understanding of the mechanical behaviour of the head-neck system during soccer heading. An inverted pendulum is combined with a linear visco-elastic element to model the head-neck system following a half-sine input force. Model parameter values were varied to obtain agreement with previously published experimental data (Naunheimet al., 2003), and were subsequently compared to literature values. The model predicted the same mechanical angular kinematics as observed experimentally both during and post impact. The greatest acceleration was in the anterior direction at the instant the ball left the head, attributed to the elastic stiffness of the neck musculature. The head-neck stiffness and damping coefficients determined from the model (350 N m rad^-1 and 4 N m s rad^-1, respectively) were similar to those reported elsewhere when subjects were asked to resist maximally. The model may be subsequently used to investigate differences in technique and ability with respect to the salient model parameters to further our biomechanical understanding of soccer heading.     

Three-dimensional kinematic correlates of ball velocity during maximal instep soccer kicking in males

Abstract

Achieving a high ball velocity is important during soccer shooting, as it gives the goalkeeper less time to react, thus improving a player's chance of scoring. This study aimed to identify important technical aspects of kicking linked to the generation of ball velocity using regression analyses. Maximal instep kicks were obtained from 22 academy-level soccer players using a 10-camera motion capture system sampling at 500 Hz. Three-dimensional kinematics of the lower extremity segments were obtained. Regression analysis was used to identify the kinematic parameters associated with the development of ball velocity. A single biomechanical parameter; knee extension velocity of the kicking limb at ball contact Adjusted R² = 0.39, p ≤ 0.01 was obtained as a significant predictor of ball-velocity. This study suggests that sagittal plane knee extension velocity is the strongest contributor to ball velocity and potentially overall kicking performance. It is conceivable therefore that players may benefit from exposure to coaching and strength techniques geared towards the improvement of knee extension angular velocity as highlighted in this study.     

Mechanical factors associated with the development of high ball velocity during an instep soccer kick

The purpose of this study was to determine whether joint velocities and segmental angular velocities are significantly correlated with ball velocity during an instep soccer kick. We developed a deterministic model that related ball velocity to kicking leg and pelvis motion from the initiation of downswing until impact. Three-dimensional videography was used to collect data from 16 experienced male soccer players (age = 24.8 ± 5.5 years; height = 1.80 ± 0.07 m; mass = 76.73 ± 8.31 kg) while kicking a stationary soccer ball into a goal 12 m away with their right foot with maximal effort. We found that impact velocities of the foot center of mass (CM), the impact velocity of the foot CM relative to the knee, peak velocity of the knee relative to the hip, and the peak angular thigh velocity were significantly correlated with ball velocity. These data suggest that linear and angular velocities at and prior to impact are critical to developing high ball velocity. Since events prior to impact are critical for kick success, coordination and summation of speeds throughout the kicking motion are important factors. Segmental coordination that occurs during a maximal effort kick is critical for completing a successful kick.     

足球运动踢球腿摆动阶段的不同时相运动特征

运用生物力学手段对5名高水平足球运动员摆动腿进行研究发现:根据摆动腿环节摆动顺序与环节摆动速度相结合的方法可将其划分为用力蹬伸、主动后摆、大腿前摆、小腿前摆,脚触球5个阶段.其中,用力蹬伸阶段是不可忽视的重要阶段之一,主动后摆阶段摆动腿应在不影响前摆速度的前提下尽力后摆;大腿前摆阶段摆动腿应在大腿摆到一定幅度时进行积极制动,摆动幅度不宜过大;小腿前摆阶段摆动腿除了膝关节的积极制动外还应主动施力.     

我国足球产业化进程中足球精神的缺失

20世纪90年代以来,我国足球产业化逐步展开,并得到了比较稳定的发展。但是在足球产业化的同时,暴露出足球精神严重缺失的问题,包括运动员体育精神的沦丧,裁判等工作人员公平公正精神的模糊与球迷缺乏健康向上、理智成熟的素养。我国足球精神的缺失主要由于功利主义思想泛滥和精神文明建设的松懈。     

现代足球的民族精神与中国足球的文化缺失

对现代足球与民族精神的关系以及我国足球发展中存在的问题进行了分析研究。结果认为,民族精神是支持现代足球发展的重要社会文化条件,传承与弘扬民族精神是现代足球的基本价值取向;当前我国足球的发展存在着深刻的文化缺失问题,关于优秀的传统文化精神以及改革时代的民族精神的缺失则是我国足球文化建设中的突出问题。