Elite football teams that do not have a winter break lose on average 303 player-days more per season to injuries than those teams that do: a comparison among 35 professional European teams

The impact of a mid-season FIFA World Cup™ on injury occurrence and patterns in French professional soccer clubs

This study retrospectively compared the effect of holding the 2022 FIFA World Cup™ (WC) mid-season (season 2022/23) on injury rates and patterns in French Ligue 1 soccer clubs. Epidemiological data in 17 clubs were prospectively recorded by their physicians. Time-loss injuries (injuries leading to a player being unable to fully participate in play over the following 72-hour period) were compared with those reported during a regular season (2021-22). In the WC season, an increase of approximately 23% (training + match-play) was observed for both the total number of injuries and knee, ankle and muscle injuries combined. Incidences for match-play injury overall and for the knee, ankle and muscle regions combined and the hamstrings and calf regions specifically also rose significantly (range: p < 0.05-p < 0.01). These results suggest that injury occurrence and patterns in French L1 soccer clubs were substantially affected during the 2022/23 season when a mid-season WC was held.

Epidemiology of Injuries in Elite Male Futsal Players

OBJECTIVE

This study aimed to describe and characterize injuries sustained by elite male futsal players in Portugal.

DESIGN

Prospective cohort study.

SETTING

Top-tier Portuguese league in the 2019 to 2020 season.

PARTICIPANTS

One hundred sixty-seven players from 9 elite/international-level (tier 4) futsal teams.

INDEPENDENT VARIABLES

The location, type, body side, body part, mechanism of injury, severity, occurrence, days lost, training, and match exposure were collected.

MAIN OUTCOME MEASURES

Injury incidence, prevalence, and burden.

RESULTS

The study was conducted during an 8-month season. A total of 133 injuries were recorded, and 92 (67.6%) players sustained injuries. The overall time-loss injury incidence was 4.5 injuries per 1000 hours of exposure. Injury incidence during matches was higher than during training sessions (25.9 vs 3.0 per 1000 hours of exposure, respectively). Average time loss was 9 days, and moderate injuries were the most frequent (44%), followed by mild injuries (24%). Injury burden was 73.8 days lost per 1000 hours of total player exposure. Sprains/ligament (29%) and muscle rupture/tear/strains (32%) were the most common injuries. The groin (19%), thigh (17%), knee (19%), and ankle (15%) were the most affected body areas. Noncontact injuries were the most reported mechanism (65%), and 24% were overuse injuries.

CONCLUSIONS

This study showed that elite/international-level (tier 4) male futsal players are more prone to noncontact injuries, primarily affecting the lower limbs. The incidence during match play increased by 9-fold compared with training sessions.

Impact of the COVID-19 Pandemic on Injury Incidence in Japanese Male Professional Soccer Players

Background

The outbreak of the 2019 novel coronavirus disease (COVID-19) led to an enforced quarantine period and limited training and match activities for athletes.

Purpose

To report the influence of the COVID-19 pandemic on the occurrence of injury in Japanese male professional soccer players.

Study Design

Descriptive epidemiology study.

Methods

In total, 21 clubs in the 2019 season and 28 clubs in the 2020 season from the Japan Professional Football League were prospectively followed, and 16 clubs in 2019 and 24 clubs in 2020 were analyzed in this study. Individual training, match exposure, and time-loss injuries were recorded using an electronic data capture system. The influence of COVID-19-related suspension during the 2020 season was retrospectively investigated via comparisons with the 2019 season.

Results

Total activity time included 114,001 hours in training and 16,339 hours in matches in 2019 and 170,798 hours in training and 25,411 hours in matches in 2020. The mean training interruption period caused by COVID-19 in 2020 was 39.9 days (range, 3-65 days), and the mean game-interruption period was 70.1 days (range, 58-79 days). The total number of injuries was 1495 in 2019 and 1701 in 2020. The overall injury incidence per 1000 hours of exposure was 5.7 in 2019 and 5.8 in 2020. The overall injury burden per 1000 hours of exposure was 155.5 days in 2019 and 130.2 days in 2020. The muscle injury incidence was highest in May 2020, immediately after the suspension period.

Conclusion

The overall injury incidence did not differ between 2019 and 2020. However, muscle injury incidence notably increased in the 2 months after the COVID-19 pandemic suspension period.

Do Fans Impact Sports Outcomes? A COVID-19 Natural Experiment∗

This paper studies the effect of fan attendance on home field advantage in top European soccer leagues. We exploit exogenous variation in the level of fan attendance driven by COVID-19 mitigation policies and find that the home field advantage, as measured by home minus away (expected) goals, is reduced by more than 50% across the English Premier League, German Bundesliga, Italian Serie A, and Spanish La Liga. This leads to a decrease in probability for a home win, indicating that these goals are pivotal with respect to match outcomes.

A Systematic Review of the Relationship between Workload and Injury Risk of Professional Male Soccer Players

The number of studies on the relationship between training and competition load and injury has increased exponentially in recent years, and it is also widely studied by researchers in the field of professional soccer. In order to provide practical guidance for workload management and injury prevention in professional athletes, this study provides a review of the literature on the effect of load on injury risk, injury prediction, and interpretation mechanisms. The results of the research show that: (1) It appears that short-term fixture congestion may increase the match injury incidence, while long-term fixture congestion may have no effect on both the overall injury incidence and the match injury incidence. (2) It is impossible to determine conclusively whether any global positioning system (GPS)-derived metrics (total distance, high-speed running distance, and acceleration) are associated with an increased risk of injury. (3) The acute:chronic workload ratio (ACWR) of the session rating of perceived exertion (s-RPE) may be significantly associated with the risk of non-contact injuries, but an ACWR threshold with a minimum risk of injury could not be obtained. (4) Based on the workload and fatigue recovery factors, artificial intelligence technology may possess good predictive power regarding injury risk.

FIFA World Cup Qatar 2022: Solutions to the Physical Fitness Challenge

In 2022, the FIFA World Cup has been scheduled to take place in Qatar in November and December, months which coincide with the in-season period of the European soccer season. This will be challenging for the staff of the participating national teams and the domestic clubs to which participating players are attached. The aim of this letter to the editor is to propose solutions on how to manage the associated challenges. Regular training and competition over the course of a season in European professional soccer is generally characterized by a pre-competition preparation period of five to six weeks, followed by two competition phases, interspersed with a winter break (Eliakim et al., 2018). Certain leagues such as the English Premier League do not typically have a winter break meaning that games are played almost continuously across the season. During World Cup years, there is usually an average of four to five weeks between the end of national domestic championships and the start of the World Cup tournament (Table 1, Figure 1) which traditionally takes place during the off-season period. However, in 2022, the FIFA World Cup has been scheduled to take place in November and December, months which coincide with the in-season period of the European soccer season (Figure 1). With the World Cup being staged during this part of the season, many national team players (notably those in the major European Leagues) will have just one week of preparation between the last match of their domestic leagues and the start of the World Cup tournament (November 20th, 2022). More precisely, the major European soccer leagues will interrupt match schedules between November 9th and 13th with differences in the number of games completed at this time of the season ranging from 14 to 17 across the various leagues (Table 2). The physical and mental demands placed on modern professional players have steadily risen over recent years due to an increase in the number of matches played during congested periods across the season (Anderson et al., 2016). Since the number of matches is not evenly distributed across the typical 40-week season, players can often compete in as many as three matches in a seven-day period. Aside from the physical and mental demands that are imposed during a match, players might experience insufficient recovery between these games; in part due to extensive travelling which can disrupt the sleep/wake cycle (Lastella et al., 2019). Indeed, poor quality of sleep and the stress induced by a match can negatively affect physical fitness and may even increase the risk of sustaining injuries and/or infections (Clemente et al., 2021) in the period leading up to the World Cup. National teams are composed of players from different leagues who have varying levels of exposure to match-play (e.g., starters, non-starters) in terms of the average weekly volume of soccer matches at their clubs (“Rapports - Observatoire du football CIES”). Moreover, both starters and non-starters are exposed to different external match and training loads (Anderson et al., 2016). External loads have previously been defined as the overall volume of activity that a player performs during both training sessions and matches (Ravé et al., 2020). There is evidence that this metric correlates with a player’s physical fitness status (Clemente et al., 2019) and their injury risk (Malone et al., 2017). Accordingly, it will be challenging for national teams to manage the fitness of players such that they are physically ready to play at the World Cup tournament. This is especially applicable to individuals who play in the major European leagues and we note a significant contrast between European match schedules and those on other continents. For example, in Major League Soccer (MLS) in North America, match schedules will be interrupted from November 5th, 15 days before the World Cup tournament begins. Similarly, in the Japanese J-League in Asia, Saudi Pro League and Qatar Star League, matches will be interrupted one month before the World Cup tournament begins, leaving more time for players on these continents to prepare. It is also important to note that the French, Spanish and English domestic championships will resume their match schedules on December 27th which is just ten days after the end of the World Cup (Figure 1). Clubs will clearly want their players to return uninjured and with sufficient fitness levels to resume domestic competition but these goals could be compromised by the aforementioned scheduling of the World Cup tournament.

Contextual considerations using the 'control-chaos continuum' for return to sport in elite football - Part 1: Load planning

The 'control-chaos continnum' is an adaptable framework developed to guide the on-pitch rehabilitation process in elite football. One of the key objectives of the continuum is to progressively return players to their preinjury chronic running load, while incorporating the qualitative aspects of movement and cognitive stresses integral to competitive match-play. Whilst injury and player-specific considerations are key to an individualised rehabilitation approach, a host of contextual factors also play an important role in return to sport (RTS) planning. In this article, we highlight some key intrinsic and extrinsic contextual factors for the practitioner to consider in the RTS planning process to help mitigate reinjury risk upon a return to team training. While a return to chronic running load is generally a critical component of the framework, we highlight circumstances in elite football where it is a less relevant factor in RTS decision-making.

Estudo prospectivo das lesões musculares em três temporadas consecutivas do Campeonato Brasileiro de Futebol

Objective  To perform a prospective evaluation of muscle injuries that occurred during the matches of series A and B of the Brazilian Men's Football Championship from 2016 to 2018.

Prospective  A prospective-cohort study with data collection regarding muscle injuries that occurred during the official matches of the first and second divisions of the Brazilian Men's Soccer Championship in the 2016, 2017 and 2018 seasons.

Results  The total number of muscle injuries was of 577 throughout the 3 seasons, with a gradual and annual reduction in the incidence of injuries (219 injuries in 2016, 195 in 2017, and 163 in 2018), with a statistically significant difference between the 2016 and 2018 seasons. Muscle injuries represented approximately 35% of the total lesions. The incidence of muscle injuries was of 7.66 per 1,000 hours of play. During the 3 seasons (2016 to 2018), the most common injury was of the hamstring muscle (41.1%, 40.5%, and 33.7% respectively). Wingers were the most affected players, and the most common injury severity scale was moderate (8 to 28 days). The moment of the match with the highest incidence of injuries was in the period between 61 and 75 minutes, with an index of 19.9%, with no statistical difference in relation to the other periods of the match.

Conclusion  There was an incidence of muscle injuries of 7.7 /1,000 h, and they occurred predominantly in home games, in defenders (wingers and centre-backs), with an average age of 28 years, mainly involving the hamstring muscles, with a moderate mean time of absence (8 to 28 days).

Strength development and non-contact lower limb injury in academy footballers across age groups

Non-contact lower limb injuries are common in academy football. Yet, the impact these injuries have on strength development in academy footballers remains unclear. This study aimed to investigate the impact of non-contact lower limb injury on hip, groin, and knee flexor strength development in male academy youth footballers. Furthermore, this study: reports normative strength data of emerging field-based tests that can be easily deployed in football academies; explores the effect of age on injury occurrence; and highlights the number of days lost from injury in male youth footballers. Assessments of hip adductor, abductor, and eccentric knee flexor strength were obtained from 195 academy football players during pre-season and at the end of season. In-season injuries were recorded by medical staff. Those footballers who sustained non-contact lower limb injury were compared with those who did not sustain a non-contact lower limb injury. No between-group differences were observed for any strength assessments when controlled for pre-season measures. Stronger footballers at pre-season experienced strength loses, while those weaker players gained strength across the season. Hip strength development was impaired in older age group footballers. Sustaining a non-contact lower limb injury had minimal impact on strength development. In the absence of in-season lower limb strength monitoring, development in academy youth footballers may not progress as expected, and in particular, stronger and older youth athletes may benefit from individualized strength training.

Injury burden differs considerably between single teams from German professional male football (soccer): surveillance of three consecutive seasons

PURPOSE

The purpose of this study was to analyse unique injury data of the national statutory accident insurance for the two highest divisions in German male football (Bundesliga and 2. Bundesliga) over three consecutive seasons regarding inter-season, inter-division and inter-team differences.

METHODS

This was a prospective observational open cohort study over the seasons 2014/2015, 2015/2016 and 2016/2017. Every acute injury that was registered by clubs or physicians with the German statutory accident insurance for professional athletes (VBG) as part of occupational accident reporting and that led to time loss and/or to medical attention, was included.

RESULTS

The complete sample consisted of 1449 players. The study covered 2663.5 player seasons with an observed match exposure of 69,058 h and a projected training exposure of 529,136 h. In total, 7493 injuries were included. The overall incidence rate was 12.5 (± 0.28) injuries per 1000 exposure hours, which translated into match and training rates of 47.0 (± 1.62) and 8.02 (± 0.24) injuries per 1000 h, respectively.

CONCLUSION

Findings of 2.7 injuries per player and season underline the need of effective preventive approaches. Higher injury incidences in seasons after international tournaments suggest an increasing risk of injury with increasing number of matches. However, large differences between the single teams from the same division indicate that a reduction in the injury burden is generally possible. Continuing the presented injury surveillance might be helpful to identify injury trends in the future and to evaluate the effectiveness of preventive approaches under real-life conditions.

LEVEL OF EVIDENCE

Level  II.

A Longitudinal Investigation of Muscle Injuries in an Elite Spanish Male Academy Soccer Club: A Hamstring Injuries Approach

The aims of this study were to analyze the muscle injury incidence in an elite Spanish soccer academy during three consecutive seasons attending to different chronological age groups (i.e., U14, U16, U19 and senior) and to examine the hamstring injury incidence in this elite soccer academy. Elite male youth soccer players (227) participated in this study. A total of 207 time-loss injuries (i.e., injuries that involve at least one absence day) were observed during this study period. The overall incidence rate of muscle injury was 1.74 muscle injuries/1000 h. In addition, higher muscle injury incidence was observed during match play in comparison to training sessions (6.78 vs. 3.20 muscle injuries/1000 h, p < 0.05). The oldest age group presented the highest injury rate (2.73 muscle injuries/1000 h, p < 0.05), with the burden (i.e., number of absence days per 1000 h of exposure) peak values recorded in the U16 age group (26.45 absence days/1000 h). In addition, muscle tears accounted for the greatest percentage of muscle injuries (43.5%), and the most frequent anatomical site of injury was the hamstring (30.4%). Muscle tear was the most common type of hamstring injury (49.2%), with the biceps femoris the most commonly injured muscle of the hamstring complex (39.7%). Fullbacks (FB), wide midfielders (WM) and forwards (F) suffered a greater number of hamstring injuries. Hamstring injury incidence showed a seasonal variation, as indicated by peaks in August and October. Specifically, the highest injury incidence was observed in the final part of each period during match play. These results reinforce the necessity to implement individual preventive strategies according to each specific injury profile across the youth soccer development phase.