Dynamical Stability and Predictability of Football Players: The Study of One Match

The game of football demands new computational approaches to measure individual and collective performance. Understanding the phenomena involved in the game may foster the identification of strengths and weaknesses, not only of each player, but also of the whole team. The development of assertive quantitative methodologies constitutes a key element in sports training. In football, the predictability and stability inherent in the motion of a given player may be seen as one of the most important concepts to fully characterise the variability of the whole team. This paper characterises the predictability and stability levels of players during an official football match. A Fractional Calculus (FC) approach to define a player’s trajectory. By applying FC, one can benefit from newly considered modeling perspectives, such as the fractional coefficient, to estimate a player’s predictability and stability. This paper also formulates the concept of attraction domain, related to the tactical region of each player, inspired by stability theory principles. To compare the variability inherent in the player’s process variables (e.g., distance covered) and to assess his predictability and stability, entropy measures are considered. Experimental results suggest that the most predictable player is the goalkeeper while, conversely, the most unpredictable players are the midfielders. We also conclude that, despite his predictability, the goalkeeper is the most unstable player, while lateral defenders are the most stable during the match.

Annual Review of the European Football Players' Labour Market / Etude annuelle du marché du travail européen des footballeurs

The key reference on the labour market and the logics of squad formation in the big-5 European leagues. One hundred richly coloured pages, illustrated by graphics, maps, rankings, statistical models and analysis in French and English which inform managers about potential strategies to put their clubs on the road to success help managers of federations and players' unions to understand current trends and to take decisions ... suggest to journalists new lines of investigation likely to interest the general public allow researchers and students to benefit from reliable and comparable sources, developed with the greatest possible rigour ... give fans the possibility to understand in detail the dynamics at work in their favourite sport and club.

High-intensity intermittent training in hypoxia: a double-blinded, placebo-controlled field study in youth football players.

High-intensity intermittent training in hypoxia: A double-blinded, placebo-controlled field study in youth football players. J Strength Cond Res 29(1): 226-237, 2015-This study examined the effects of 5 weeks (∼60 minutes per training, 2 d·wk) of run-based high-intensity repeated-sprint ability (RSA) and explosive strength/agility/sprint training in either normobaric hypoxia repeated sprints in hypoxia (RSH; inspired oxygen fraction [FIO2] = 14.3%) or repeated sprints in normoxia (RSN; FIO2 = 21.0%) on physical performance in 16 highly trained, under-18 male footballers. For both RSH (n = 8) and RSN (n = 8) groups, lower-limb explosive power, sprinting (10-40 m) times, maximal aerobic speed, repeated-sprint (10 × 30 m, 30-s rest) and repeated-agility (RA) (6 × 20 m, 30-s rest) abilities were evaluated in normoxia before and after supervised training. Lower-limb explosive power (+6.5 ± 1.9% vs. +5.0 ± 7.6% for RSH and RSN, respectively; both p < 0.001) and performance during maximal sprinting increased (from -6.6 ± 2.2% vs. -4.3 ± 2.6% at 10 m to -1.7 ± 1.7% vs. -1.3 ± 2.3% at 40 m for RSH and RSN, respectively; p values ranging from <0.05 to <0.01) to a similar extent in RSH and RSN. Both groups improved best (-3.0 ± 1.7% vs. -2.3 ± 1.8%; both p ≤ 0.05) and mean (-3.2 ± 1.7%, p < 0.01 vs. -1.9 ± 2.6%, p ≤ 0.05 for RSH and RSN, respectively) repeated-sprint times, whereas sprint decrement did not change. Significant interactions effects (p ≤ 0.05) between condition and time were found for RA ability-related parameters with very likely greater gains (p ≤ 0.05) for RSH than RSN (initial sprint: 4.4 ± 1.9% vs. 2.0 ± 1.7% and cumulated times: 4.3 ± 0.6% vs. 2.4 ± 1.7%). Maximal aerobic speed remained unchanged throughout the protocol. In youth highly trained football players, the addition of 10 repeated-sprint training sessions performed in hypoxia vs. normoxia to their regular football practice over a 5-week in-season period was more efficient at enhancing RA ability (including direction changes), whereas it had no additional effect on improvements in lower-limb explosive power, maximal sprinting, and RSA performance.

Annual Review of the European Football Players' Labour Market / Etude annuelle du marché du travail européen des footballeurs

The key reference on the labour market and the logics of squad formation in the five main European leagues. One hundred richly coloured pages, illustrated by graphics, maps, rankings, statistical models and analysis in French and English which... - inform managers about potential strategies to put their clubs on the road to success - help managers of federations and players' unions to understand current trends and to take decisions - suggest to journalists new lines of investigation likely to interest the general public - allow researchers and students to benefit from reliable and comparable sources, developed with the greatest possible rigour - give fans the possibility to understand in detail the dynamics at work in their favourite sport and club Demographic Study of Footballers in Europe The Demographic Study of European Footballers is an annual publication destined for anyone who wishes to acquire a scientific understanding of the European football players' labour market. It presents the dynamics at work in 36 first division leagues in UEFA member countries. This edition covers our biggest ever survey comprising more than 520 clubs and 13,000 footballers. Statistical indicators relative to nine thematics (morphology, age, experience training, origin, etc.) allow the comparison of player profiles and squad compositions at league and club level. Through easily-understable regression analyses, the Study brings to light the principle differences between clubs and leagues according to economic and sporting level of championships. The final part presents the list of the most promising players under 23 years of age by league and position

Neuro-mechanical and metabolic adjustments to the repeated anaerobic sprint test in professional football players.

PURPOSE: This study aimed to determine the neuro-mechanical and metabolic adjustments in the lower limbs induced by the running anaerobic sprint test (the so-called RAST). METHODS: Eight professional football players performed 6 × 35 m sprints interspersed with 10 s of active recovery on artificial turf with their football shoes. Sprinting mechanics (plantar pressure insoles), root mean square activity of the vastus lateralis (VL), rectus femoris (RF), and biceps femoris (BF) muscles (surface electromyography, EMG) and VL muscle oxygenation (near-infrared spectroscopy) were monitored continuously. RESULTS: Sprint time, contact time and total stride duration increased from the first to the last repetition (+17.4, +20.0 and +16.6 %; all P < 0.05), while flight time and stride length remained constant. Stride frequency (-13.9 %; P < 0.001) and vertical stiffness decreased (-27.2 %; P < 0.001) across trials. Root mean square EMG activities of RF and BF (-18.7 and -18.1 %; P < 0.01 and 0.001, respectively), but not VL (-1.2 %; P > 0.05), decreased over sprint repetitions and were correlated with the increase in running time (r = -0.82 and -0.90; both P < 0.05). Together with a better maintenance of RF and BF muscles activation levels over sprint repetitions, players with a better repeated-sprint performance (lower cumulated times) also displayed faster muscle de- (during sprints) and re-oxygenation (during recovery) rates (r = -0.74 and -0.84; P < 0.05 and 0.01, respectively). CONCLUSION: The repeated anaerobic sprint test leads to substantial alterations in stride mechanics and leg-spring behaviour. Our results also strengthen the link between repeated-sprint ability and the change in neuromuscular activation as well as in muscle de- and re-oxygenation rates.

Adaptation and validation in Spanish of the Group Environment Questionnaire (GEQ) with professional football players

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Coping strategies among brazilian professional and amateur football players

To identify coping strategies used among professional and amateur Brazilian football players. The Ways of Coping Scale (WOCS) was completed by 134 male football players (71 professionals: mean age = 22.77 ± 3.98 years; 63 amateurs: mean age = 17.18 ± 0.84 years) from three teams that participated in the Campeonatos Estaduais da Primeira Divisão (the state championships for the first division of football). There was no significant difference between the two groups in the type of coping strategy they used (e.g., problem-focused, emotion-focused, fantasy thoughts, religious practices and social support). Problem-focused coping was the most frequently used strategy by all of the players and social support was the least frequently used strategy. Both professional and amateur players failed to focus on the development of adequate coping strategies. Further studies are needed to better understand the impact that Brazilian athletes experience has on their choice of coping strategies during pre-competitive and competitive phases of their sport. © JPES.

The impact of the achievement motive on athletic performance in adolescent football players

Researchers largely agree that there is a positive relationship between achievement motivation and athletic performance, which is why the achievement motive is viewed as a potential criterion for talent. However, the underlying mechanism behind this relationship remains unclear. In talent and performance models, main effect, mediator and moderator models have been suggested. A longitudinal study was carried out among 140 13-year-old football talents, using structural equation modelling to determine which model best explains how hope for success (HS) and fear of failure (FF), which are the aspects of the achievement motive, motor skills and abilities that affect performance. Over a period of half a year, HS can to some extent explain athletic performance, but this relationship is not mediated by the volume of training, sport-specific skills or abilities, nor is the achievement motive a moderating variable. Contrary to expectations, FF does not explain any part of performance. Aside from HS, however, motor abilities and in particular skills also predict a significant part of performance. The study confirms the widespread assumption that the development of athletic performance in football depends on multiple factors, and in particular that HS is worth watching in the medium term as a predictor of talent.

National youth team football players between the conflicting priorities of sports success and vocational training

In view of the risks involved in relying on a professional career in football as a way of making a future living, most players on Swiss National Youth Football Teams pursue some form of vocational training at the same time. This paper investigates the question under what conditions a successful football career is possible when faced with such a dual burden. In order to examine the development process as holistically as possible, a person-oriented approach was chosen. 159 former Swiss National Youth Team players were retrospectively interviewed about their careers, and the data were analysed using the LICUR method (Bergman, Magnusson, & El-Khouri, 2003). This involves identifying certain patterns in the relevant variables of sports career, vocational career and family support, and then comparing these with the performance at the age of peak performance. Through this, it was possible to identify promising patterns of development. It turns out that the critical transition, at the age of about 15–16 years, is characterised overall by stability. The most successful patterns display above-average family support accompanied by above-average professional talent promotion in the clubs. In this constellation, the football players who are later successful pursue vocational training courses leading to low levels of educational qualification.

Motivational patterns as an instrument for predicting success in promising young football players

Psychological characteristics are crucial to identifying talents, which is why these are being incorporated in today’s multidimensional talent models. In addition to multidimensionality, talent studies are increasingly drawing on holistic theories of development, leading to the use of person-oriented approaches. The present study adopts such an approach by looking at the influence that motivational characteristics have on the development of performance, in a person-oriented way. For this purpose, it looks at how the constructs achievement motive, achievement goal orientation and self-determination interact with one another, what patterns they form and how these patterns are linked to subsequent sports success. 97 top young football players were questioned twice. Another year later, it was enquired which of these players had been selected for the U15 national team. At both measuring points, four patterns were identified, which displayed a high degree of structural and individual stability. As expected, the highly intrinsically achievement-oriented players were significantly more likely to move up into the U15 national team. The results point to the importance of favourable patterns of motivational variables in the form of specific types, for medium-term performance development among promising football talents, and thus provide valuable clues for the selection and promotion of those.

Holistic patterns as an instrument to predict promising young football players

Multidimensional talent models represent the current state of the art. However, it remains unclear how these different dimensions interact. Based on current theories of human development, person-oriented approaches seem to be particularly appropriate for talent research. The present study adopts this approach by looking at how a holistic system consisting of the dimensions motivation, motor behaviour and the stage of development goes along with athletic performance. For this purpose, it has to be examined which patterns were formed by the constructs net hope, motor abilities, technical skills and the so far achieved percentage of the predicted adult height and how these patterns are related to subsequent sporting success. 119 young elite football players were questioned and tested three times at intervals of one year, beginning at the age of 12. At the age of 15, the performance level the players had reached was examined. At all three measuring points, four patterns were identified which displayed partial structural and high individual stability. As expected, the players showing values above average in all factors were significantly more likely to advance to the highest performance level. Physically strong, precocious developed players though having some technical weaknesses, have good chances to reach the middle performance level. The results point to the importance of holistic approaches for the prediction of performance among promising football talents in the medium-term and thus provide valuable clues for their selection and promotion.

Patterns of motor abilities and technical skills as predictors of success for young elite football players

Sport-motor tests play an important role in football talent selections. However, single tests represent only parts of the complex game performance. The best game performance therefore does not necessarily need to go hand in hand with the best results in all tests of a test battery. Considering the complexity of the game performance appropriately, a holistic perspective together with a person-oriented approach are applied. Thereby, systems consisting of several variables are identified and analysed in a longitudinal study. Following this idea, six sport-motor tests were aggregated into a subsystem. 106 young male elite football players were tested three times (2011, 2012, 2013; Mage, t2011=12.26, SD=0.29). One year later (2014) their performance level was enquired. Data were analysed using the LICUR method, a cluster analytical method. Four patterns were identified, which remained stable at all measuring points. The players frequently show intraindividual and structurally similar patterns over time. At the third measuring point, a pattern occurred out of which the players are significantly more likely to advance to the highest performance level one year later. This pattern appears consistently above average, but does not always show best test performances. The significantly frequent development along structurally stable patterns suggests a predictive validity of the subsystem sport-motor tests between the ages of 12 to 15. Above average, but not necessarily outstanding performances both in the motor abilities as well as in the football specific tests appears to be particularly promising. This finding emphasizes the need of a holistic perspective in the talent selection.

Patterns of motor abilities and technical skills as predictors of success for young elite football players

Sport-motor tests play an important role in football talent selections. However, single tests represent only parts of the complex game performance. The best game performance therefore does not necessarily need to go hand in hand with the best results in all tests of a test battery. Considering the complexity of the game performance appropriately, a holistic perspective together with a person-oriented approach are applied. Thereby, systems consisting of several variables are identified and analysed in a longitudinal study. Following this idea, six sport-motor tests were aggregated into a subsystem. 106 young male elite football players were tested three times (2011, 2012, 2013; Mage, t2011=12.26, SD=0.29). One year later (2014) their performance level was enquired. Data were analysed using the LICUR method, a cluster analytical method. Four patterns were identified, which remained stable at all measuring points. The players frequently show intraindividual and structurally similar patterns over time. At the third measuring point, a pattern occurred out of which the players are significantly more likely to advance to the highest performance level one year later. This pattern appears consistently above average, but does not always show best test performances. The significantly frequent development along structurally stable patterns suggests a predictive validity of the subsystem sport-motor tests between the ages of 12 to 15. Above average, but not necessarily outstanding performances both in the motor abilities as well as in the football specific tests appears to be particularly promising. This finding emphasizes the need of a holistic perspective in the talent selection.