Injuries in male professional football: A prospective comparison between individual and team‐based exposure registration

Methodological considerations of football injury epidemiology have only scarcely been described. The aim of this study was to evaluate the inter‐rater agreement in injury capture rate and injury categorization for data registered in two different prospective injury surveillance audits studying the same two Norwegian male professional football clubs for two consecutive seasons, 2008–2009. One audit used team‐based exposure (TBE) recording and the other individual‐based exposure (IBE). The number of injuries recorded and corresponding injury rates (injuries/1000 h exposure) were compared between audits. Cohen's kappa and prevalence‐adjusted bias‐adjusted kappa (PABAK) coefficients were calculated for injury variables. Of 323 injuries included, the IBE audit captured 318 (overall capture rate 98.5%, training 98.9%, match 97.8%) and the TBE audit 303 injuries (overall capture rate 93.8%, training 91.4%, match 97.1%). Agreement analysis showed kappa and PABAK coefficients regarded as almost perfect (> 0.81) for 8 of 9 injury variables, and substantial (? 0.75) for the variable injury severity. In conclusion, the capture rate for training injuries was slightly higher with IBE recording, and inter‐agreement in injury categorization was very high.     

Investigation of knee control as a lower extremity injury risk factor: A prospective study in youth football

This prospective study in youth football examined the relationship between frontal plane knee projection angle (FPKPA ) during the single‐leg squat and sustaining an acute lower extremity injury or acute non‐contact lower extremity injury. Secondly, side‐to‐side asymmetry in FPKPA and sex as injury risk factors were explored. In addition, we investigated the influence of age, sex, and leg dominance on the FPKPA . A total of 558 youth football players (U11 to U14) participated in the single‐leg squat test and prospective injury registration. FPKPA was not found as a risk factor for injuries at this age. There was no difference in the mean FPKPA between sexes. However, FPKPA was associated with age; oldest subjects displayed the smallest FPKPA . Among boys, the frontal plane knee control improved by age. Among girls, the relationship between age and FPKPA was not as clear, but the oldest girls displayed the smallest mean FPKPA in the study (12.2° ± 8.3°). The FPKPA was greater on the dominant kicking leg compared to the non‐dominant support leg (P  <  .001 for boys, P  =  .001 for girls). However, side‐to‐side asymmetry in FPKPA was not associated with future injuries. In conclusion, frontal plane knee control in the single‐leg squat was not associated with lower extremity injuries among young football players. As the single‐leg squat to 90° knee flexion was too demanding for many subjects, easier single‐leg squat test procedure or a different movement control test, such as a double‐legged squat, could be more suitable for the young football players.     

Exposure and injury risk in Swedish elite football: a comparison between seasons 1982 and 2001

The long-term development of injury risk in Swedish male elite football was studied. Two prospective cohort studies from seasons 1982 and 2001 were compared with respect to exposure to football, injury incidence and injury severity. The mean number of training sessions during the season had increased by 68% between 1982 and 2001 (142 vs. 238, P<0.001), whereas teams played more matches in 1982 (49 vs. 41, P=0.02). The total exposure to football had increased by 27%. Three out of four players incurred an injury in both seasons. In 2001, players suffered more training injuries due to an increased training exposure. Accounting for risk exposure, there was no difference in injury incidence or severity between the two seasons. The incidence was 8.3 injuries/1000 h of total exposure (4.6 in training and 20.6 in matches) in 1982, compared to 7.8/1000 h-1 (5.2 in training and 25.9 in matches) in 2001. Major injuries accounted for 9% of all injuries, corresponding to an incidence of 0.8/1000 h of football, in both seasons. A trend from semi-professionalism to full professionalism in Swedish elite football was seen during the last two decades. The injury risk did not change over the same period.     

Injuries in Swedish elite football--a prospective study on injury definitions, risk for injury and injury pattern during 2001

The purpose of this study was to study the risk for injury and injury pattern in Swedish male elite football and to compare two different injury definitions. A prospective cohort study was conducted during 2001 on all 14 teams (310 players) in the Swedish top division. Injuries and individual exposure were recorded. Injury was defined as time-lost injury (715 injuries) and for comparison as tissue injury (765 injuries). No significant difference in the risk for injury between tissue injuries and time-lost injuries was found during matches (27.2 vs. 25.9 injuries per 1000 match hours, P=0.66) or training sessions (5.7 vs. 5.2 injuries per 1000 training hours, P=0.65). The risk for injury during training was significantly higher during the pre-season compared with the competitive season (P=0.01). Thigh strain was the single most common injury (14%). Knee sprain was the most common major injury (absence >4 weeks). Overuse injuries and re-injuries were frequent and constituted 37% and 22% of all injuries. Re-injuries caused significantly longer absence than their corresponding initial injuries (P=0.02). The risk for re-injury (P=0.02) and overuse injury (P<0.01) was significantly higher during the pre-season compared with the competitive season.     

A comparison of injuries in elite male and female football players: A five‐season prospective study

The aim was to compare the epidemiology of injuries between elite male and female football players from the same club. Injuries and individual exposure time in a male team and a female team, both playing in the Spanish first division, were prospectively recorded by the club's medical staff for five seasons (2010‐2015) following the FIFA consensus statement. Total, training, and match exposure hours per player‐season were 20% higher for men compared to women (P< .01). Total, training, and match injury incidence were 30%‐40% higher in men (P≤ .04) mainly due to a 4.82 (95% confidence interval [CI ] 2.30‐10.08) times higher incidence of contusions, as there were no differences in the incidence of muscle and joint/ligament injuries (P≥ .44). The total number of absence days was 21% larger in women owing to a 5.36 (95% CI 1.11‐25.79) times higher incidence of severe knee and ankle ligament injuries. Hamstring strains and pubalgia cases were 1.93 (95% CI 1.16‐3.20) and 11.10 (95% CI 1.48‐83.44) times more frequent in men, respectively; whereas quadriceps strains, anterior cruciate ligament ruptures, and ankle syndesmosis injuries were 2.25 (95% CI 1.22‐4.17), 4.59 (95% CI 0.93‐22.76), and 5.36 (95% CI 1.11‐25.79) times more common in women, respectively. In conclusion, prevention strategies should be tailored to the needs of male and female football players, with men more predisposed to hamstring strains and hip/groin injuries, and women to quadriceps strains and severe knee and ankle ligament injuries.     

High ankle injury rate in adolescent basketball: A 3‐year prospective follow‐up study

This prospective study investigated the incidence and pattern of acute time‐loss injuries in young female and male basketball players. Eight basketball teams (n=201; mean age 14.85±1.5) participated in the follow‐up study (2011‐2014). The coaches recorded player participation in practices and games on a team diary. A study physician contacted the teams once a week to check new injuries and interviewed the injured players. In total, 158 injuries occurred. The overall rate of injury (per 1000 hours) was 2.64 (95% CI 2.23‐3.05). Injury rate was 34.47 (95% CI 26.59‐42.34) in basketball games and 1.51 (95% CI 1.19‐1.82) in team practices. Incidence rate ratio (IRR) between game and practice was 22.87 (95% CI 16.71‐31.29). Seventy‐eight percent of the injuries affected the lower limbs. The ankle (48%) and knee (15%) were the most commonly injured body sites. The majority of injuries involved joint or ligaments (67%). Twenty‐three percent of the injuries were severe causing more than 28 days absence from sports. Number of recurrent injuries was high (28% of all injuries), and most of them were ankle sprains (35 of 44, 79%). No significant differences were found in injury rates between females and males during games (IRR 0.88, 0.55, to 1.40) and practices (IRR 1.06, 0.69, to 1.62). In conclusion, ankle and knee ligament injuries were the most common injuries in this study. Moreover, the rate of recurrent ankle sprains was alarming.     

Involving research‐invested clinicians in data collection affects injury incidence in youth football

It is well established that differences in injury definition and recording methodology restrict comparisons between injury surveillance programmes. There is, however, little documentation of the variation that can exist between data recorders. The aim of this study was, therefore, to explore the effect on reported injuries when team recorders or supervisors are involved in research. Injury data collected prospectively over five seasons for the U16, U17, and U18 age groups in a youth football (soccer) academy were used to compare different recording settings based on the research involvement of the clinicians. A research‐invested team physiotherapist reported an 8.8 times greater incidence (P < 0.001) of non‐time‐loss injuries and a 2.5 times greater incidence (P < 0.001) of minimal injuries (1‐3 days lost) compared to a setting where neither the team physiotherapists nor the supervisor relied on the collected data for research purposes. When team physiotherapists were not invested in research themselves but were supervised by a researcher, the incidence of non‐time‐loss injuries and minimal injuries was 2.5 times (P < 0.001) and 2.0 times greater (P < 0.01) than in the non‐invested setting, respectively. However, there were no differences between recording settings for overall incidence of time‐loss injuries. The results from this study demonstrate that involving clinicians that are relying on the collected data for research purposes can significantly affect the reported rates of non‐time‐loss and minimal injuries. Time‐loss injuries overall were not affected by research investment, and should therefore be preferred for comparisons between teams and seasons.     

Risk of injury in elite football played on artificial turf versus natural grass: a prospective two-cohort study

Objective

To compare injury risk in elite football played on artificial turf compared with natural grass.

Design

Prospective two‐cohort study.

Setting

Male European elite football leagues.

Participants

290 players from 10 elite European clubs that had installed third‐generation artificial turf surfaces in 2003–4, and 202 players from the Swedish Premier League acting as a control group.

Main outcome measure

Injury incidence.

Results

The incidence of injury during training and match play did not differ between surfaces for the teams in the artificial turf cohort: 2.42 v 2.94 injuries/1000 training hours and 19.60 v 21.48 injuries/1000 match hours for artificial turf and grass respectively. The risk of ankle sprain was increased in matches on artificial turf compared with grass (4.83 v 2.66 injuries/1000 match hours; rate ratio 1.81, 95% confidence interval 1.00 to 3.28). No difference in injury severity was seen between surfaces. Compared with the control cohort who played home games on natural grass, teams in the artificial turf cohort had a lower injury incidence during match play (15.26 v 23.08 injuries/1000 match hours; rate ratio 0.66, 95% confidence interval 0.48 to 0.91).

Conclusions

No evidence of a greater risk of injury was found when football was played on artificial turf compared with natural grass. The higher incidence of ankle sprain on artificial turf warrants further attention, although this result should be interpreted with caution as the number of ankle sprains was low.     

The impact of playing in matches while injured on injury surveillance findings in professional football

This study aimed to analyze the frequency, nature, and consequences of footballers playing matches while injured, and to examine the impact on injury surveillance findings. High levels of inter‐rater reliability and content validity were established for a tool designed to document players who were already injured at the start of a match. The tool was implemented in three English football teams (a Championship, League 1, and League 2 team) for one season, using a “time loss” definition of injury. One hundred forty‐three matches were surveyed, revealing 102 match appearances by players who were already injured. Almost half of all games featured at least one injured player, with episodes of playing with injury occurring more frequently and lasting longer in League 2 players compared with higher level players. No association was observed between the number of injured players starting matches and match outcome [χ²(4, N = 143) = 3.27, P = 0.514]. Fifteen percent of all injury episodes captured were only through prospective documentation of playing while injured. The findings show that both traumatic and overuse injuries are managed by footballers through competitive matches, and have important implications for aiding understanding of the epidemiology of injury in professional football.     

Epidemiology and traumatology of injuries in elite soccer: a prospective study in Finland

A prospective study of male soccer injuries among 12 teams playing at the highest competition level was carried out in Finland in 1993. Overall, two out of three players were injured during the whole season. The injury incidence per 1000 playing hours among injured players and all players during games was higher than during practice, 14.2 vs. 11.3 and 2.3 vs. 1.8, respectively. The lower extremity was involved in 76% of the injuries. Thigh injuries were most frequent (22%), whereas overuse injuries were scarce (6%). Eighteen per cent of the injured players needed surgery and in most cases (58%) the reason for surgery was a knee injury. Sixteen per cent of all injured players were absent from soccer for more than 1 month after the injury. The mean absence time was 17 days for all and 84 days for operatively treated players.     

Intrinsic risk factors for acute knee injuries among male football players: a prospective cohort study

This prospective cohort study was conducted to identify the risk factors for acute knee injuries among male football players. A total of 508 players representing 31 amateur teams were tested during the 2004 preseason for potential risk factors for knee injury through a questionnaire on previous injury, Knee Osteoarthritis Outcome Score (KOOS) and a clinical examination. Generalized estimating equations were used in univariate analyses to identify candidate risk factors, and factors with a P-value <0.10 were then examined in a multivariate model. During the football season, 61 acute knee injuries, affecting 57 legs (53 players), were registered. Univariate analyses revealed the KOOS subscores "Pain" and "Function in daily living" (OR for a 10-point difference in score: 1.26, 95% CI 1.03-1.55 and 1.35, 95% CI 0.98-1.85, respectively), any findings at clinical examination (OR: 2.62, 95% CI 1.03-6.68), flexion contraction in range of motion testing (OR: 0.96, 95% CI 0.93-1.00) and varus stress tests in full extension (OR: 8.50, 95% CI 1.85-39.0) and 30° flexion (OR: 5.69, 95% CI 1.73-18.8) as candidate factors. However, in a multivariate analysis, none of these factors were associated with an increased injury risk.     

Previous injury as a risk factor for injury in elite football: a prospective study over two consecutive seasons

Background

Previous injury is often proposed to be a risk factor for football injury, but most studies rely on players reporting their own medical history and are thus potentially subject to recall bias. Little is known about the natural variation in injury pattern between seasons.

Objectives

To study whether prospectively recorded injuries during one season are associated with injuries sustained during the following season, and to compare injury risk and injury pattern between consecutive seasons.

Methods

The medical staffs of 12 elite Swedish male football teams prospectively recorded individual exposure and time loss injuries over two full consecutive seasons (2001 and 2002). A multivariate model was used to determine the relation between previous injury, anthropometric data, and the risk of injury.

Results

The training and match injury incidences were similar between seasons (5.1 v 5.3 injuries/1000 training hours and 25.9 v 22.7/1000 match hours), but analysis of injury severity and injury patterns showed variations between seasons. Players who were injured in the 2001 season were at greater risk of any injury in the following season compared with non‐injured players (hazard ratio 2.7; 95% confidence interval 1.7 to 4.3, p<0.0001). Players with a previous hamstring injury, groin injury, and knee joint trauma were two to three times more likely to suffer an identical injury in the following season, whereas no such relation was found for ankle sprain. Age was not associated with an increased injury risk.

Conclusions

This study confirmed previous results showing that previous injury is an important risk factor for football injury. Overall injury incidences were similar between consecutive seasons, indicating that an injury surveillance study covering one full season can provide a reasonable overview of the injury problem among elite football players in a specific environment. However, a prolonged study period is recommended for analyses of specific injury patterns.     

The prevalence and severity of health problems in youth elite sports: A 6‐month prospective cohort study of 320 athletes

Little is known regarding the overall health of youth elite athletes. Our aim was to describe the prevalence and severity of health problems in a cohort of youth elite athletes representing a variety of endurance, team, and technical sports. Elite sport athletes (N = 260, 16.2 years) from different Sport Academy High Schools in Norway, and a group of their teammates (N = 60, 16.4 years) attending regular high schools, were included in the study. The Oslo Sports Trauma Research Centre (OSTRC ) questionnaire on health problems was used to self‐report injuries and illnesses for 26 weeks. At any given time, an average of 43% [95% CI : 37%‐49%] of the elite sport athletes had some form of health problem and 25% [20%‐31%] had substantial health problems. The prevalence of health problems was similar between the elite team sport athletes and their teammates, except for substantial injuries (22% [16%‐30%] vs 10% [5%‐20%]). Endurance sport athletes reported more illnesses (23% [15%‐35%]) than technical and team sport athletes (10% [5%‐20%] and 8% [4%‐14%]). In contrast, technical and team sport athletes reported more injuries (36% [95% CI : 25‐48] and 37% [95% CI 29‐45]) compared to endurance sport athletes (15% [8%‐25%]). The total impact of health problems was roughly split in thirds between overuse injuries (37%), acute injuries (34%), and illnesses (30%). This is the first prospective study to present self‐reported injury and illness data in a large heterogeneous group of youth elite athletes, documenting a substantial impact of both injuries and illnesses on the health of this population.     

Injury incidence and distribution in elite football--a prospective study of the Danish and the Swedish top divisions

The Danish and Swedish male top football divisions were studied prospectively from January to June 2001. Exposure to football and injury incidence, severity and distribution were compared between the countries. Swedish players had greater exposure to training (171 vs. 123 h per season, P<0.001), whereas exposure to matches did not differ between the countries. There was a higher risk for injury during training in Denmark than in Sweden (11.8 vs. 6.0 per 1000 h, P<0.01), whereas for match play there was no difference (28.2 vs. 26.2 per 1000 h). The risk for incurring a major injury (absence from football more than 4 weeks) was greater in Denmark (1.8 vs. 0.7 per 1000 h, P = 0.002). The distribution of injuries according to type and location was similar in both countries. Of all injuries in Denmark and Sweden, overuse injury accounted for 39% and 38% (NS), and re-injury for 30% and 24% (P = 0.032), respectively. The greater training exposure and the long pre-season period in Sweden may explain some of the reported differences.     

Rescheduling Part 2 of the 11+ reduces injury burden and increases compliance in semi‐professional football

Although the 11+ program has been shown to reduce injuries in sub‐elite football, program compliance is typically poor, suggesting that strategies to optimize delivery are necessary. This study investigated the effect of rescheduling Part 2 of the three‐part 11+ program on program effectiveness. Twenty‐five semi‐professional football clubs were randomly allocated to either a Standard‐11+ (n = 398 players) or P2_post group (n = 408 players). Both groups performed the 11+ program at least twice a week throughout the 2017 football season. The Standard‐11+ group performed the entire 11+ program before training activities commenced, whereas the P2_post group performed Parts 1 and 3 of the 11+ program before and Part 2 after training. Injuries, exposure, and individual player 11+ dose were monitored throughout the season. No significant between group difference in injury incidence rate (P2_post vs Standard‐11+ = 11.8 vs 12.3 injuries/1000 h) was observed. Severe time loss injuries > 28 days (33 vs 58 injuries; P < .002) and total days lost to injury (4303 vs 5815 days; P < .001) were lower in the P2_post group. A higher 11+ program dose was observed in the P2_post (29.1 doses; 95% CI 27.9‐30.1) versus Standard‐11+ group (18.9 doses; 95% CI 17.6?20.2; P < .001). In semi‐professional football, rescheduling Part 2 of the 11+ program to the end of training maintained the effectiveness of the original 11+ program to reduce injury incidence. Importantly, rescheduling Part 2 improved player compliance and reduced the number of severe injuries and total injury burden, thereby enhancing effectiveness of the 11+ program.     

A 1‐year prospective analysis of injuries in amateur and elite fistball

The purpose of this study was to examine the incidence and mechanisms of acute injuries in the sport of fistball. No scientific studies on injury characteristics have yet been conducted in this traditional sport game. The study was conducted prospectively over the course of 12 months. During a total of 40.308 h of sport‐specific exposure, 240 players reported 492 injuries, representing an overall injury rate of 12.2 injuries/1000 h of exposure. Most injuries were classified as bagatelle injuries (67.8%). The majority of the injuries were located in the knee (23.5%) followed by the elbow (11.9%) and the hip (11.5%). Ankle injuries resulted in the longest impairment from sports participation. The most common types of injury were abrasions (38.2%), contusions (21.1%), distortions (7.5%) and muscle strains (6.9%). Wrong or insufficient equipment (15.0%) was the most commonly mentioned causes of injury. The data indicate that the injury risk in fistball is rather high; however, the sport should not be considered a high‐risk sport because most of the injuries are slight and do not prevent the players from training or competition. Injury prevention strategies should include the development of fistball‐specific protective equipment with focus on the knee and elbow joint.     

Text messaging as a new method for injury registration in sports: A methodological study in elite female football

Methodological differences in epidemiologic studies have led to significant discrepancies in injury incidences reported. The aim of this study was to evaluate text messaging as a new method for injury registration in elite female football players and to compare this method with routine medical staff registration. Twelve teams comprising 228 players prospectively recorded injuries and exposure through one competitive football season. Players reported individually by answering three text messages once a week. A designated member of the medical staff conducted concurrent registrations of injuries and exposure. Injuries and exposure were compared between medical staff registrations from nine teams and their 159 affiliated players. During the football season, a total of 232 time‐loss injuries were recorded. Of these, 62% were captured through individual registration only, 10% by the medical staff only, and 28% were reported through both methods. The incidence of training injuries was 3.7 per 1000 player hours when calculated from individual registration vs 2.2 from medical staff registration [rate ratio (RR): 1.7, 1.2–2.4]. For match injuries, the corresponding incidences were 18.6 vs 5.4 (RR: 3.4, 2.4–4.9), respectively. There was moderate agreement for severity classifications in injury cases reported by both methods (kappa correlation coefficient: 0.48, confidence interval: 0.30–0.66).     

Type of sport is related to injury profile: A study on cross country skiers,swimmers, long‐distance runners and soccer players. A retrospective 12‐month study

This 12‐month retrospective questionnaire compared the occurrence of sports injuries in 149 cross country skiers, 154 swimmers, 143 long‐distance runners and 128 soccer players aged 15–35 years. Soccer had significantly more injuries (5.1 injuries/1000 exposure hour) than other sports (2.1–2.8, P<0.001). More runners than soccer players reported overuse injuries (59% vs 42%, P=0.005), locating typically in the foot in runners, soccer players and skiers. Swimmers reported overuse injuries in the shoulder more commonly than skiers (40% vs 1%, P<0.001), who also intensively load shoulders. Acute injuries in skiers (80%) and in swimmers (58%), and overuse injuries in skiers (61%), occurred during exercise other than own event. In soccer and running the absence time from sport because of injuries was significantly longer than in skiing and swimming. No severe permanent disabilities occurred due to injury but seven women quit sports because of injury. In conclusion, type of loading is strictly associated with the anatomical location of an overuse injury as shown by the difference in shoulder injury incidence between swimmers and cross country skiers. In some sports, a significant proportion of acute injuries occur in other than the main event.     

A prospective video-based analysis of injury situations in elite male football: football incident analysis

BACKGROUND: The mechanisms for football injuries are largely unknown. AIM: To describe the characteristics of injury situations in elite male football using a video-based method called football incident analysis. STUDY DESIGN: Prospective cohort study. METHODS: During the 1999 season, videotapes from 52 matches in the Icelandic elite football league were reviewed. Incidents (N = 95) were recorded when the match was interrupted by the referee because of a suspected injury. Team physical therapists recorded injuries prospectively (N = 28 time-loss injuries). RESULTS: Duels caused 84 of the incidents, mostly tackling duels (n = 54). The exposed player's attention appeared to be focused away from the opponent in 93% of the cases. The 3 main mechanisms observed were (1) breakdown attacks, tackling from the side or the front, attention focused on the ball (24%); (2) defensive tackling duels, attention focused on the ball or low ball control (20%); and (3) heading duels, attention focused on the ball in the air (13%). CONCLUSION: Most incidents and injuries occurred during breakdown attacks and when a player was involved in tackling duels. Player attention appeared to be focused mainly on the ball, not on the opponent challenging him to gain ball possession.