Thor Einar Andersen

Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries

Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football (soccer) injuries, making interstudy comparisons difficult. Therefore an Injury Consensus Group was established under the auspices of Fédération Internationale de Football Association Medical Assessment and Research Centre. A nominal group consensus model approach was used. A working document on definitions, methodology, and implementation was discussed by the group. Iterative draft statements were prepared and circulated to members of the group for comment before the final consensus statement was produced. Definitions of injury, recurrent injury, severity, and training and match exposures in football together with criteria for classifying injuries in terms of location, type, diagnosis, and causation are proposed. Proforma for recording players’ baseline information, injuries, and training and match exposures are presented. Recommendations are made on how the incidence of match and training injuries should be reported and a checklist of issues and information that should be included in published reports of studies of football injuries is presented.

Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial

Objective To examine the effect of a comprehensive warm-up programme designed to reduce the risk of injuries in female youth football. Design Cluster randomised controlled trial with clubs as the unit of randomisation. Setting 125 football clubs from the south, east, and middle of Norway (65 clusters in the intervention group; 60 in the control group) followed for one league season (eight months). Participants 1892 female players aged 13-17 (1055 players in the intervention group; 837 players in the control group). Intervention A comprehensive warm-up programme to improve strength, awareness, and neuromuscular control during static and dynamic movements. Main outcome measure Injuries to the lower extremity (foot, ankle, lower leg, knee, thigh, groin, and hip). Results During one season, 264 players had relevant injuries: 121 players in the intervention group and 143 in the control group (rate ratio 0.71, 95% confidence interval 0.49 to 1.03). In the intervention group there was a significantly lower risk of injuries overall (0.68, 0.48 to 0.98), overuse injuries (0.47, 0.26 to 0.85), and severe injuries (0.55, 0.36 to 0.83). Conclusion Though the primary outcome of reduction in lower extremity injury did not reach significance, the risk of severe injuries, overuse injuries, and injuries overall was reduced. This indicates that a structured warm-up programme can prevent injuries in young female football players. Trial registration ISRCTN10306290.

Prevention of hamstring strains in elite soccer: an intervention study.

The purpose was to test the effect of eccentric strength training and flexibility training on the incidence of hamstring strains in soccer. Hamstring strains and player exposure were registered prospectively during four consecutive soccer seasons (1999–2002) for 17–30 elite soccer teams from Iceland and Norway. The first two seasons were used as baseline, while intervention programs consisting of warm‐up stretching, flexibility and/or eccentric strength training were introduced during the 2001 and 2002 seasons. During the intervention seasons, 48% of the teams selected to use the intervention programs. There was no difference in the incidence of hamstring strains between teams that used the flexibility training program and those who did not [relative risk (RR)=1.53, P=0.22], nor was there a difference compared with the baseline data (RR=0.89, P=0.75). The incidence of hamstring strains was lower in teams who used the eccentric training program compared with teams that did not use the program (RR=0.43, P=0.01), as well as compared with baseline data for the same intervention teams (RR=0.42, P=0.009). Eccentric strength training with Nordic hamstring lowers combined with warm‐up stretching appears to reduce the risk of hamstring strains, while no effect was detected from flexibility training alone. These results should be verified in randomized clinical trials.

Consensus statement on injury definitions and data collection procedures in studies of football (soccer) injuries.

Variations in definitions and methodologies have created differences in the results and conclusions obtained from studies of football injuries; this has made inter‐study comparisons difficult.

Research approaches to describe the mechanisms of injuries in sport: limitations and possibilities

A number of different methodological approaches have been used to describe the inciting event for sports injuries. These include interviews of injured athletes, analysis of video recordings of actual injuries, clinical studies (clinical findings of joint damage are studied to understand the injury mechanism, mainly through plain radiography, magnetic resonance imaging, arthroscopy, and computed tomography scans), in vivo studies (ligament strain or forces are measured to understand ligament loading patterns), cadaver studies, mathematical modelling and simulation of injury situations, and measurement/estimation from “close to injury” situations. In rare cases, injuries have even occurred during biomechanical experiments. This review describes each research approach and assesses its strengths and weaknesses in contributing to the understanding and prevention of sports injuries.

Video Analysis of the Mechanisms for Ankle Injuries in Football

Background Although ankle sprains are frequent in football, little is known about their mechanisms. Purpose To describe the injury mechanisms for ankle injuries in male elite football. Study Design Prospective cohort study. Methods Videotapes and injury information were collected for 313 of 409 matches from Norwegian and Icelandic elite football during the 1999 to 2000 seasons. Video recordings of incidents that resulted in ankle injuries were analyzed and cross-referenced with injury reports from the team medical staff. Results A total 46 acute ankle injuries were reported to have occurred, that is, 4.5 injuries per 1000 match hours. Of these, 26 (57%) were identified on the videotapes. Two mechanisms thought to be specific to football were found: 1) player-to-player contact with impact by an opponent on the medial aspect of the leg just before or at foot strike, resulting in a laterally directed force causing the player to land with the ankle in a vulnerable, inverted position; and 2) forced plantar flexion where the injured player hit the opponents foot when attempting to shoot or clear the ball. Conclusions Systematic video analysis provides detailed information on the mechanisms for ankle injuries in football—for lateral ligament sprains and for the condition dubbed “OpenCurlyDoubleQuote;footballers ankle.”

Mechanisms of head injuries in elite football

Objectives: The aim of this study was to describe, using video analysis, the mechanisms of head injuries and of incidents with a high risk of head injury in elite football. Methods: Videotapes and injury information were collected prospectively for 313 of the 409 matches played in the Norwegian (2000 season) and Icelandic (1999 and 2000 season) professional leagues. Video recordings of incidents where a player appeared to be hit in the head and the match was consequently interrupted by the referee were analysed and cross referenced with reports of acute time loss injuries from the team medical staff. Results: The video analysis revealed 192 incidents (18.8 per 1000 player hours). Of the 297 acute injuries reported, 17 (6%) were head injuries, which corresponds to an incidence of 1.7 per 1000 player hours (concussion incidence 0.5 per 1000 player hours). The most common playing action was a heading duel with 112 cases (58%). The body part that hit the injured player’s head was the elbow/arm/hand in 79 cases (41%), the head in 62 cases (32%), and the foot in 25 cases (13%). In 67 of the elbow/arm/hand impacts, the upper arm of the player causing the incident was at or above shoulder level, and the arm use was considered to be active in 61 incidents (77%) and intentional in 16 incidents (20%). Conclusions: This study suggests that video analysis provides detailed information about the mechanisms for head injuries in football. The most frequent injury mechanism was elbow to head contact, followed by head to head contact in heading duels. In the majority of the elbow to head incidents, the elbow was used actively at or above shoulder level, and stricter rule enforcement or even changes in the laws of the game concerning elbow use should perhaps be considered, in order to reduce the risk of head injury.

Risk of injury on artificial turf and natural grass in young female football players

Background: Artificial turf is becoming increasingly popular, although the risk of injury on newer generations of turf is unknown. Aim: To investigate the risk of injury on artificial turf compared with natural grass among young female football players. Study design: Prospective cohort study. Methods: 2020 players from 109 teams (mean (SD) 15.4 (0.8) years) participated in the study during the 2005 football season. Time-loss injuries and exposure data on different types of turf were recorded over an eight-month period. Results: 421 (21%) players sustained 526 injuries, leading to an injury incidence of 3.7/1000 playing hours (95% CI 3.4 to 4.0). The incidence of acute injuries on artificial turf and grass did not differ significantly with respect to match injuries (rate ratio (RR) 1.0, 95% CI 0.8 to 1.3; p = 0.72) or training injuries (RR 1.0, 95% CI 0.6 to 1.5, p = 0.93). In matches, the incidence of serious injuries was significantly higher on artificial turf (RR 2.0, 95% CI 1.3 to 3.2; p = 0.03). Ankle sprain was the most common type of injury (34% of all acute injuries), and there was a trend towards more ankle sprains on artificial turf than on grass (RR 1.5, 95% CI 1.0 to 2.2; p = 0.06). Conclusion: In the present study among young female football players, the overall risk of acute injuries was similar between artificial turf and natural grass.

Video analysis of injuries and incidents in Norwegian professional football

Objectives: This study describes the characteristics of injuries and high risk situations in the Norwegian professional football league during one competitive season using Football Incident Analysis (FIA), a video based method. Methods: Videotapes and injury information were collected prospectively for 174 of 182 (96%) regular league matches during the 2000 season. Incidents where the match was interrupted due to an assumed injury were analysed using FIA to examine the characteristics of the playing situation causing the incident. Club medical staff prospectively recorded all acute injuries on a specific injury questionnaire. Each incident identified on the videotapes was cross referenced with the injury report. Results: During the 174 matches, 425 incidents were recorded and 121 acute injuries were reported. Of these 121 injuries, 52 (43%) were identified on video including all head injuries, 58% of knee injuries, 56% of ankle injuries, and 29% of thigh injuries. Strikers were more susceptible to injury than other players and although most of the incidents and injuries resulted from duels, no single classic injury situation typical for football injuries or incidents could be recognised. However, in most cases the exposed player seemed to be unaware of the opponent challenging him for ball possession. Conclusions: This study shows that in spite of a thorough video analysis less than half of the injuries are identified on video. It is difficult to identify typical patterns in the playing events leading to incidents and injuries, but players seemed to be unaware of the opponent challenging them for ball possession.

Football incident analysis: a new video based method to describe injury mechanisms in professional football

Objectives: To develop and test a new video based method for match analysis that combines football specific and medical information to achieve a better understanding of the injury mechanisms and events leading up to high risk situations. Methods: Football incident analysis (FIA) is a video based method describing incidents that may result in an injury using 19 variables and categories modified from match analysis. Videos from 35 of 76 (46%) official Norwegian under 21 matches played from 1994 to 1998 were analysed. Two football experts classified each incident on the basis of predetermined criteria, and their results were compared using interobserver and intraobserver reliability tests. Results: κ correlation coefficients for interobserver and intraobserver agreement were very good for 63% and 95% and good for 37% and 5% of the variables respectively. Fifty two incidents were recorded (1.6 incidents per team per match or 94 per 1000 player hours), and 16 (31%) led to injuries (0.5 injuries per match or 29 injuries per 1000 player hours). FIA results showed that 28 incidents occurred while attacking in midfield zone 2 or the attacking zone, and 24 took place while defending in the defensive zone or midfield zone 1. Midfielders were exposed in 67% of the incidents, mainly in breakdown attacks or during long attacks by the opposing team. Of the 28 incidents during offence, only one was classified as having great potential to score a goal. Most incidents (70%) were the result of tackling duels both in the offensive and defensive playing phases. Of the 21 offensive incidents resulting from tackling duels, in 19 cases the exposed player was unaware of the tackling (passive duellist). Conclusions: This study shows that football incident analysis is a potentially valuable tool for understanding the events leading up to injuries in football.