Football: why despite scientific studies the results are unpredictable

Whereas football has the largest number of players in the world, 265 million players (4.6 million in France) according to FIFA, it is also the most scientifically studied sport. In Medline, one of the most important biomedical bibliographic databases, indexing articles since 1946, football with more than 14,000 indexed references exceeds by more than 60% the second most studied sport (tennis).

As noted by Donald Kirkendall, a member of the Center for Evaluation and Medical Research of FIFA and of the American Football Sports Medicine Committee, this very quantitative body of studies expresses trends, predictive subjects for research over time. Indeed, specific issues emerge in the comparison of football with other team sports.

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The problems of injuries and their prevention, the optimization of training for better physical performance, the level of play during matches, prove to be recurrent. The solicitations of the cardiovascular system in the alternation of game actions where players with hybrid behaviors walk, run, sprint and recover passively or actively, are of particular interest to the authors in order to optimize them.

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Finally, the exponential growth in the number of studies using new technologies (GPS, heart rate monitors and other sensors) and in particular artificial intelligence remains a sign of major progress.

Integrating the individual into the collective

In this aspect of quantitative measures, since 2005 there has been in Neuchâtel, Switzerland, Football Observatory , a research group specializing in the statistical analysis of football, integrated into the International Center for Sports Studies (CIES). From 2010, the Observatory has developed a footballer analysis model where his performance is integrated into his collective game context. That is to say that the player’s efficiency is perceived in his environment of evolution, depending mainly on collective physical and spatio-temporal turbulence (among other things because the spectators, the weather, the place of the match… also influence this performance).

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Surrounded by partners but also by adversaries, the player’s efficiency shifts to specific playing areas on the field. This conditions the nature of his movements and reciprocally influences his techniques. On the other hand, the perception of the passage of time fluctuates according to the score of the match and the positive or negative differential of the team.

There is a reciprocity between the desired dynamic characteristics of the game and those of the players, who must have a suitable morphology to exercise at the highest level their basic physical qualities such as: endurance, resistance, strength, speed, coordination and flexibility.

In this changing game context, researchers characterize technical player profiles based on a role-based approach. A model of footballer performance through eight domains themselves subdivided into variables emerges:

  • air defense (air duels won – defense),
  • ground defense (ground duels won – defense),
  • recovery (recovery of lost balls/interceptions),
  • distribution (passes),
  • percussion (successful crosses/dribbles),
  • endangerment (passing for chances/goal passing),
  • finishing (shots),
  • air attack (air duels won – attack).

These indicators make it possible to establish the specific technical profile of the players while facilitating their comparisons throughout a season. It is possible to test this profiling on the CIES Football Observatory website powered by data from the company specializing in sports data InStat with world-renowned players who have won the Golden Ball, among others: Karim Benzema (2022), Lionel Messi (2021…), Luka Modric (2018) , Cristiano Ronaldo (2017…).[]

Drawing up a profile on the effectiveness of a football player remains difficult, especially since it depends on the potential of his team, the strategies and tactics envisaged by the coach, but also on the luck factor, sometimes “to find oneself at the right time and in the right place”, of the exceptional technical gesture conditioned by a momentary euphoric state. Some commentators speak of opportunism or exploits, others more modestly of favorable circumstances, no doubt of complex justifications and explanations.

Models, by nature, imperfect

Indeed, in any performative athlete profile, physiological and morphological factors are intertwined, as stated above, but also psychological and biomechanical factors that complete the models. However, like any proposed analysis model, this one has specific explanatory virtues while simplifying a reality that is always difficult to master. In these analytical decompositions of performance made up of many variables that also interact with each other, the transcriptions remain delicate as for any explanation of living, fluid and moving systems.

Finally, there are few studies that analyze performance in team sports over time according to the evolution of the structure or tactics of the game. Football integrates complex and non-linear dynamic systems, the variations of which cannot be represented based on simple proportional relationships between cause and effect. Compared to dynamic systems sensitive to multiple conditions, however, football teams emerge with consistent patterns of play that lead to the goal.

The broadcast images of the finals of world Cup between 1966 and 2010 were analyzed in particular to track changes in duration, patterns of play, type and duration of stoppages in play, ball speed, player density and success rates. This shows that during this period the variables have changed significantly over time. These changes are not random, but rather illustrate patterns of play that are likely to confer advantages to players.

Ball speed increased by 15% over the 44-year period

On the one hand, the duration of play decreased while the duration of stoppage increased; both affecting work/recovery ratios. Indeed, the results show that the total number of stoppages in play remained unchanged over time. However, there have been consistent increases in the average duration of almost all outage events. According to the authors, for the period 1966-2010, this would correspond to a 10.6% drop in playing time.

Ball speed has increased by 15% over the 44-year period. The structure of the game has evolved towards a higher density of players. Finally, the increase in the speed of circulation of the ball and the density of the players can be at the origin of the structures of play and their evolution. The increased intensity of play is accompanied by longer breaks in play which allow for greater player recovery. This leads to a more intense game accompanied by defensive strategies that increase over time.

Since 1966, the FIFA Technical Study Group has published a report since extracting a lot of data that confirms developments. The 2018 report notes that despite the will of the great tacticians to control the game without taking excessive risks, the competition reminds us that all strategy and tactics can be reduced to nothing by the vagaries of the game, the “caprices of the round ball”, the luck factor.

The technology integrates the world of football to, in the near future, generate with a group of potential players, the optimal composition of a team to confront the adversary of the moment. Algorithmic logic becomes necessary because the decision maker comes up against an increasing amount of information to process. The coach always responsible for the strategic, tactical and technical choices of the team decides for the best according to the opinion of the multiple members of the staff. Statistical engineers specializing in modeling will gradually integrate the staff to optimize decision-making through big data.

From a rigorous and stable defense, teams will need to have the ability to dynamically vary their ways of adapting

To increase the probability of success in future competitions, teams should train to develop their potential as well as generate plans for rapid collective self-organization to master the fluctuations of spatio-temporal dynamic systems during matches. . More specifically, from a rigorous and stable defense, the teams must have the ability to dynamically vary their ways of adapting, but above all of countering the strategies and tactics of the opponent, while producing originality in their game. From the cohesion of the team emerges performance potential greater than the sum of the potential of each player.

Long-term trends suggest that professionals improve in these areas through the processes of self-selection, conditioning, and positive feedback on successful strategies.

On the basis of solid strategic and tactical fundamentals, the teams will have to show inventiveness, creativity and ingenuity. It is through a set of skills developed around a sustained intensity, during execution speeds, in ball transmissions in order to generate active, precise but also turbulent and destabilizing possession, that s will make the differences. The reversibility of player statuses (defenders, midfielders, forwards) and roles (coverers, stabilizers, creators) in the game will be fundamental to achieving total football facilitating goal opportunities. These characteristics should make it possible to generate rupture zones, tipping actions among opposing teams. Since mastered techniques, optimized physical form for an easier perception of the game, teams with these characteristics should get closer to the podium.

This article is republished from The Conversation under Creative Commons license. Read theoriginal article.

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Football: why despite scientific studies the results are unpredictable

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