The Value of Statistics to the Team and the Team Doctor
Injuries and players’ fitness are one of the most important areas in football—a sport where analysis of evidence-based statistics has only relatively recently been accepted as an important part of a team’s performance. The aim of the doctor, as the key authority on injuries within the team’s management structure, should be to use injury statistics to inform and support decisions, and to ensure, crucially, that team decisions are based on reliable scientific evidence wherever it is available. This is particularly important with regard to “return-to-play” decisions (decisions concerning a players’ fitness to return to football participation), where the doctor will regularly be questioned about injuries by the player, the coach, the club manager, the media, agents, and so on. The question “When can he/she play again?” is one that the team doctor should always be able to answer in an informed manner.
To ensure the validity of all instructions provided by this manual, reference is regularly made to the findings of the UEFA Elite Club Injury Study, formerly known as the UEFA Champions League Injury Study. This is a detailed longitudinal study of over 15 years’ duration documenting the types of injury incurred by teams participating in the UEFA Champions League, UEFA EURO final tournaments, and the final rounds of UEFA’s youth competitions, as well as the frequency of such injuries. The UEFA Elite Club Injury Study is the primary source of evidence-based data on injuries in football, and knowing its main findings can help doctors with numerous issues, such as the following:
How often specific injuries occur.
The mechanisms underlying those injuries.
When players can return to training and matches after specific injuries.
The risk of problems recurring.
Data from the UEFA Elite Club Injury Study is used in this manual to demonstrate numerous key points, such as the categorization, risk, and prevalence of injuries. The overall aim is to provide football doctors with a wide range of scientifically evaluated statistics and evidence-based examples to support their planning processes, daily activities, and decision-making. Such statistics offer vital insight into how injury affects both the individual player’s ability to take to the field and the team as a whole. This, in turn, allows doctors to both predict the likely prevalence of injuries and prepare their operations in advance with a view to managing likely injury situations effectively ( ▶ Fig. 1.1).
Fig. 1.1 The majority of injuries occur in contact situations.
1.3 What Is the Risk of Sustaining an Injury?
According to the FIFA and UEFA consensus on definitions and data collection procedures for studies of football injuries, a player is considered to be injured until medical staff allow full participation in training and the player is available for match selection. 7, 8 The risk of injury cannot be evaluated simply by calculating the number of injuries incurred or the percentage of players who are injured. Instead, it is measured using a variable known as “exposure.” Exposure is best defined as the frequency of participation in matches and training—essentially, a player’s exposure to the risk of injury.
Usually, injury risk is expressed as the number of injuries per 1,000 hours of exposure. The total number of injuries is not very meaningful, so injury risk needs, instead, to be separated into the risk of injury during matches and the risk of injury during training. This is because the injury risk during matches is usually much higher than the risk from training, so if such a distinction were not made, a difference in total injury risk could simply be due to the fact that players participated in more matches than training sessions.
▶ Table 1.1 compares the different levels of exposure for various groups of players, using data from the UEFA Elite Club Injury Study with similar studies on players in Sweden and Scandinavia. We can see that exposure to football increases as we approach the elite level owing to the increased frequency of training, increased attendance at training, and increases in the number of matches played.
UEFA Champions League
National top division
Amateurs (fourth division)
Amateurs (sixth division)
No. of training sessions per team
No. of matches per team
No. of training sessions per match
Training attendance (%)
No. of hours of training per player
No. of matches per player per season
Notes: UEFA Champions League = 2001–2002 to 2013–2014 seasons; National top division = top divisions in Sweden and Norway (2010 and 2011 seasons);
Semiprofessionals = second highest division in Sweden (1982 season);
Amateurs (fourth division in Sweden) = amateur level (2003 season);
Amateurs (sixth division in Sweden) = low amateur level (1982 season).
As is clearly demonstrated, the number of matches played is substantially higher for Champions League teams than it is for Scandinavian top division teams, with some Champions League teams having more than 70 fixtures in a season. However, the number of matches played by the individual players at Champions League clubs is much lower, at around 30 matches per season, as these teams usually have large squads and will rotate their players to keep them fit and avoid “overmatching.”
Given that many of the Champions League teams’ matches are played abroad, involving longer journey times, the number of possible training sessions is lower, so the training-to-match ratio is lower for Champions League teams than it is for national leagues (at least in Scandinavia). Attendance rates at training average around 80% at professional and semiprofessional levels (bearing in mind that training is a mandatory part of the player’s work), while they are, perhaps understandably, substantially lower at amateur level.
1.4 What Does This Reveal about Injury Risk at Different Levels of the Game?
Statistics indicate that injury rates during training are similar at professional and amateur level, with around three to five injuries per 1,000 training hours. Only at EURO final tournaments is the risk lower, probably because more training sessions are devoted to recovery (with a lower injury risk) on account of the intensive match schedule.
As suggested above ( ▶ Fig. 1.2), the risk of suffering an injury during a match increases with the level of football. At Champions League, EURO, and national team level, there is an average of 25 to 30 injuries per 1,000 match hours, whereas the injury rate for amateurs averages less than half that amount ( ▶ Fig. 1.3).
Fig. 1.2 Injury rates at different levels of men’s football (values expressed as means).
Notes: UEFA Champions League = 2001–2002 to 2013–2014 seasons; National top division = top divisions in Sweden and Norway (2010 and 2011 seasons); Semiprofessionals = second highest division in Sweden (1982 season); Amateurs, fourth division in Sweden = amateur level (2003 season); Amateurs, sixth division in Sweden = low amateur level (1982 season).
Fig. 1.3 Injury risk increases with age.
The injury risk during matches can be dependent on various factors, such as a player’s age and the competition schedule. Both variables are shown in ▶ Fig. 1.4, which shows how injury risk increases with age, from men’s Under-17 final tournaments through to EURO final tournaments. This finding probably reflects the increasing speed and intensity of play at elite level and players’ increased weight as they get older (with the mean weight of senior players at EURO tournaments standing at 80 kg, compared with 79, 76, and 73 kg for Under-21, Under-19, and Under-17 players, respectively). The majority of injuries occur in contact situations, where the forces created depend on the weight and speed of the players involved.
Fig. 1.4 Injury rates for various club and national team competitions (values expressed as means).
Notes: EUROs = EURO 2004, EURO 2008, and EURO 2012; UEFA Champions League = 2001–2002 to 2013–2014 seasons; Under-21s = final rounds of UEFA European Under-21 Championship between 2006 and 2011; Under-19s = final rounds of UEFA European Under-19 Championship between 2005 and 2010; Under-17s = final rounds of UEFA European Under-17 Championship between 2006 and 2011.
Match play injury The risk of injury during matches at UEFA’s men’s youth final tournaments (i.e., those at Under-21, Under-19, and Under-17 levels) is similar to that faced by elite club teams participating in the UEFA Champions League between 2001–2002 and 2013–2014. However, the risk appears to increase for matches at senior EURO final tournaments.
Total injury risk The total injury risk is higher for players participating in EURO final tournaments than for players participating in the Champions League. However, the injury rate during training is lower during tournaments—probably again reflecting the high percentage of low-risk recovery training sessions during tournaments.
1.5 Has the Risk of Injury Increased or Decreased in Recent Years?
The ligament injury rate in European male professional football has decreased by about 30% between 2001–2002 and 2011–2012. 3, 9, 10 One possible explanation for this could be the implementation of intensive treatment and rehabilitation strategies by teams, to complement more established preventive methods, such as proprioceptive training and bracing/taping ( ▶ Fig. 1.5). 3
Fig. 1.5 External risk factors should be considered in injury prevention.
Total injury rates for training and matches have remained high over the last decade, as have rates for both muscle injury and severe injury ( ▶ Fig. 1.6).
Fig. 1.6 Injury rates per season for UEFA Champions League teams.
Preventive actions targeting player-related risk factors may be insufficient for professional players, with the possible exception of ligament injuries. External risk factors, such as training load, playing style, and continuity of club medical and technical staff, should be considered in injury prevention, and should be investigated further. 3
1.6 How Are Injuries Distributed over the Football Season?
▶ Fig. 1.7 shows the distribution of traumatic and overuse injuries over the season for clubs participating in the UEFA Champions League. Traumatic injuries (i.e., injuries with a sudden onset and a known cause) are more common during the competitive season, while overuse injuries (i.e., injuries with a slow onset and no known traumatic cause) are most common during the preseason preparation period in July.
Fig. 1.7 Distribution of traumatic and overuse injuries over an autumn–spring season.