Preventing injuries in female youth football--a cluster-randomized controlled trial

A set of exercises--the "11"--have been selected to prevent football injuries. The purpose of this cluster-randomized controlled trial was to investigate the effect of the "11" on injury risk in female youth football. Teams were randomized to an intervention (n=59 teams, 1091 players) or a control group (n=54 teams, 1001 players). The intervention group was taught the "11," exercises for core stability, lower extremity strength, neuromuscular control and agility, to be used as a 15-min warm-up program for football training over an 8-month season. A total of 396 players (20%) sustained 483 injuries. No difference was observed in the overall injury rate between the intervention (3.6 injuries/1000 h, confidence interval (CI) 3.2-4.1) and control group (3.7, CI 3.2-4.1; RR=1.0, CI 0.8-1.2; P=0.94) nor in the incidence for any type of injury. During the first 4 months of the season, the training program was used during 60% of the football training sessions, but only 14 out of 58 intervention teams completed more than 20 prevention training sessions. In conclusion, we observed no effect of the injury prevention program on the injury rate, most likely because the compliance with the program was low.

Performance aspects of an injury prevention program: a ten-week intervention in adolescent female football players

The injury rate in football is high, and effective injury prevention methods are needed. An exercise program, the "11," has been designed to prevent the most common injury types in football. However, the effect of such a program on performance is not known. The aim of this randomized-controlled trial was to investigate the effect of the "11" on performance after a 10-week training period. Thirty-four adolescent female football players were randomly assigned to either an intervention (n=18) or a control group (n=16). The "11" is a 15-min program consisting of ten exercises for core stability, lower extremity strength, balance and agility. Performance tests included isokinetic and isometric strength protocols for the quadriceps and hamstrings, isometric hip adduction and abduction strength, vertical jump tests, sprint running and soccer skill tests. There was no difference between the intervention and control groups in the change in performance from the pre- to post-test for any of the tests used. In conclusion, no effect was observed on a series of performance tests in a group of adolescent female football players using the "11" as a structured warm-up program.

Increased versican content is associated with tendinosis pathology in the patellar tendon of athletes with jumper's knee

Expansion of the extracellular matrix is a prominent but poorly characterized feature of tendinosis. The present study aimed to characterize the extent and distribution of the large aggregating proteoglycan versican in patients with patellar tendinosis. We obtained tendon from tendinopathy patients undergoing debridement of the patellar tendon and from controls undergoing intramedullary tibial nailing. Versican content was investigated by Western blotting and immunohistochemistry. Microvessel thickness and density were determined using computer-assisted image analysis. Markers for smooth muscle actin, endothelial cells (CD31) and proliferating cells (Ki67) were examined immunohistochemically. Western blot analysis and immunohistochemical staining revealed elevated versican content in the proximal patellar tendon of tendinosis patients (P=0.042). Versican content was enriched in regions of fibrocartilage metaplasia and fibroblast proliferation, as well as in the perivascular matrix of proliferating microvessels and within the media and intima of arterioles. Microvessel density was higher in tendinosis tissue compared with control tissue. Versican deposition is a prominent feature of patellar tendinosis. Because this molecule is not only a component of normal fibrocartilagenous matrices but also implicated in a variety of soft tissue pathologies, future studies should further detail both pathological and adaptive roles of versican in tendons.

Consensus statement on injury definitions and data collection procedures for studies of injuries in rugby union

Wide variations in the definitions and methodologies used for studies of injuries in rugby union have created inconsistencies in reported data and made interstudy comparisons of results difficult. The International Rugby Board established a Rugby Injury Consensus Group (RICG) to agree on appropriate definitions and methodologies to standardize the recording of injuries and reporting of studies in rugby union. The RICG reviewed the consensus definitions and methodologies previously published for football (soccer) at a meeting in Dublin to assess their suitability for and application to rugby union. Following this meeting, iterative draft statements were prepared and circulated to members of the RICG for comment; a follow-up meeting was arranged in Dublin at which time all definitions and procedures were finalized. At this stage, all authors confirmed their agreement with the consensus statement. The agreed-on document was presented to and approved by the International Rugby Board Council. Agreement was reached on definitions for injury, recurrent injury, nonfatal catastrophic injury, and training and match exposures together with criteria for classifying injuries in terms of severity, location, type, diagnosis, and causation. The definitions and methodology presented in this consensus statement for rugby union are similar to those proposed for football. Adoption of the proposals presented in this consensus statement should ensure that more consistent and comparable results will be obtained from studies of injuries within rugby union.

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.

Injury pattern in youth team handball: a comparison of two prospective registration methods

The purpose of this study was to examine the injury incidence and pattern of injuries in youth female and male team handball players using two different prospective registration methods; match reports (90 teams, 1080 players) and coach reports (34 teams, 428 players). A total of 118 injuries were recorded by the coach report, of which 93 (79%) were acute injuries (incidence training: 0.9+/-0.16 injuries/1000 player hours; matches: 9.9+/-1.26; rate ratio vs training: 10.8 [95% confidence interval (CI) 7.0-16.6]; P<0.0001) and 25 (21%) were overuse injuries. Knee (26%) and ankle (24%) injuries accounted for half of the acute injuries (training: 0.5+/-0.12 injuries/1000/h; matches: 4.4+/-0.84; rate ratio vs training: 8.0 (95% CI 4.5-14.5); P<0.0001). No gender difference was found in the injury rate (rate ratio female vs male: 1.3 (95% CI 0.8-2.1); P=0.40). Most of the injuries occurred in the attacking phase by back or wing players doing a plant-and-cut, landing or turning movement, and more than half in contact situations with the opponent. Similar results were observed for acute match injuries in the match report. These results indicate that the rate of injuries in youth team handball is as high as at the senior level, and prevention should focus on knee and ankle injuries. The coach report seems to be the best method to register injuries in youth team handball to provide a full spectrum of injuries according to their type, incidence and severity.

[Intraoperative neuro-monitoring of the recurrent laryngeal nerve. Experience of 1000 consecutive patients]

Intraoperative neuro-monitoring was introduced in thyroid surgery several years ago resulting in a facilitated identification of the recurrent laryngeal nerve and less recurrent laryngeal nerve injuries. Between 1999 and 2005 data of all patients undergoing thyroid resection were recorded and analyzed yearly. The intraoperative identification of recurrent laryngeal nerve succeeded in 99.2% (1768 nerves at risk). The percentage of complete resecting surgical procedures raised from 17% to 84%. Minimal vocal cord dysfunction, associated with hematoma and edema in most cases, was diagnosed laryngoscopically in 2.9%. The permanent palsy rate of 0.8% in the first year decreased down to 0.32%. Routinely introduction of intraoperative neuro-monitoring in thyroid surgery is associated with a demonstrable decreased palsy rate. Anyway, the rate of minimal vocal cord movement disorders and transient recurrent laryngeal nerve palsies is not changed.

Biomechanical analysis of anterior cruciate ligament injury mechanisms: three-dimensional motion reconstruction from video sequences

BACKGROUND

Methods for analyzing the mechanisms of injuries in sports from video sequences of injury situations are so far limited to a simple visual inspection, which has shown poor accuracy.

PURPOSE

To investigate whether a new model-based image-matching technique could successfully be applied to estimate kinematic characteristics of three typical anterior cruciate ligament (ACL) injury situations.

METHODS

A four-camera basketballvideo, a three-camera European team handball video and a single-camera downhill skiing video were imported into the program Poser 4, where a skeleton model and a model of the surroundings were matched to the background image frame by frame. When the match was considered satisfactory, joint angles as well as velocity and acceleration of the center of mass were calculated using Matlab.

RESULTS

In the basketball and handball matchings, the skeleton and surrounding models were successfully matched to the background through all frames in all camera angles. Detailed time courses for joint kinematics and ground reaction force were obtained, while less information could be acquired from the single-view skiing accident.

CONCLUSION

The model-based image matching technique can be used to extract kinematic characteristics from videotapes of actual ACL injuries, and may provide valuable information on the mechanisms for ACL injuries in sports.

Strategies for the prevention of volleyball related injuries

Although the overall injury rate in volleyball and beach volleyball is relatively low compared with other team sports, injuries do occur in a discipline specific pattern. Epidemiological research has revealed that volleyball athletes are, in general, at greatest risk of acute ankle injuries and overuse conditions of the knee and shoulder. This structured review discusses both the known and suspected risk factors and potential strategies for preventing the most common volleyball related injuries: ankle sprains, patellar tendinopathy, and shoulder overuse.

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.

Injuries among elite snowboarders (FIS Snowboard World Cup)

BACKGROUND

Although snowboarding is already established as an Olympic sport, it is still a developing sport, with new disciplines, more demanding snow installations, and spectacular tricks. A recent study on subjects at Norwegian national elite level showed that injury risk is high and that injuries among competitive snowboarders differ from those seen in recreational snowboarders, with fewer wrist injuries and more knee and back injuries.

OBJECTIVE

To describe the incidence and type of injuries among female and male snowboarders at international elite level.

METHOD

At the last race of the Fédération Internationale de Ski Snowboard World Cup, acute injuries resulting in missed participation and overuse injuries influencing performance, were recorded during a retrospective interview (91% response rate). The registration period was from April 2002 (end of season) until March 2003. Exposure was recorded as the number of runs in all disciplines, and the incidence was calculated as number of injuries per 1000 runs.

RESULTS

The 258 athletes interviewed reported 3193 competition days (n = 46 879 runs) in all disciplines. In total, 135 acute injuries were recorded; 62 (46%) during competition in the official disciplines. Of the 135 acute injuries, the most common injury locations were knee (n = 24; 18%), shoulder (n = 18; 13%), back (n = 17; 13%), and wrist (n = 11; 8%). The overall incidence during competition was 1.3 (95% confidence interval 1.0 to 1.7) injuries per 1000 runs; 2.3 (0.9 to 3.8) for big air (n = 10), 1.9 (1.1 to 2.8) for halfpipe (n = 21), 2.1 (1.2 to 3.0) for snowboard cross (n = 20), 0.6 (0.2 to 1.0) for parallel giant slalom (n = 8), and 0.3 (0.0 to 0.7) for parallel slalom (n = 3). The severity of injuries was graded based on time loss (27% lost >21 days) and score on the Abbreviated Injury Scale (AIS) (38% AIS 1, 61% AIS 2 and 1% AIS 3). There were 122 overuse injuries, 38 (31%) of these to the knee.

CONCLUSION

The injury risk for big air, snowboard cross, and halfpipe disciplines is high, while that for the snowboard slalom disciplines is lower. The injury pattern is different from recreational athletes, with a greater share of knee injuries and fewer wrist injuries. Compared with national level, the injury risk appears to be lower at World Cup level.

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. An Injury Consensus Group was established under the auspices of FIFA Medical Assessment and Research Centre. Using a nominal group consensus model approach, a working document that identified the key issues related to definitions, methodology and implementation was discussed by members of the group during a 2-day meeting. Following this meeting, 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. The definitions and methodology proposed in the consensus statement will ensure that consistent and comparable results will be obtained from studies of football injuries.

Effects of heading exposure and previous concussions on neuropsychological performance among Norwegian elite footballers

BACKGROUND

Cross-sectional studies have indicated that neurocognitive performance may be impaired among football players. Heading the ball has been suggested as the cause, but recent reviews state that the reported deficits are more likely to be the result of head injuries.

OBJECTIVE

To examine the association between previous concussions and heading exposure with performance on computer based neuropsychological tests among professional Norwegian football players.

METHODS

Players in the Norwegian professional football league (Tippeligaen) performed two consecutive baseline neuropsychological tests (Cogsport) before the 2004 season (90.3% participation, n = 271) and completed a questionnaire assessing previous concussions, match heading exposure (self-reported number of heading actions per match), player career, etc. Heading actions for 18 players observed in two to four matches were counted and correlated with their self-reported values.

RESULTS

Neither match nor lifetime heading exposure was associated with neuropsychological test performance. Nineteen players scored below the 95% confidence interval for one or more subtasks, but they did not differ from the rest regarding the number of previous concussions or lifetime or match heading exposure. The number of previous concussions was positively associated with lifetime heading exposure (exponent (B) = 1.97(1.03-3.75), p = 0.039), but there was no relation between previous concussions and test performance. Self-reported number of headings correlated well with the observed values (Spearman's rho = 0.77, p < 0.001).

CONCLUSION

Computerised neuropsychological testing revealed no evidence of neuropsychological impairment due to heading exposure or previous concussions in a cohort of Norwegian professional football players.

Reproducibility of computer based neuropsychological testing among Norwegian elite football players

BACKGROUND

Head injuries account for 4-22% of all football injuries. The rate of brain injuries is difficult to assess, due to the problem of defining and grading concussion. Thus computerised testing programs for cognitive function have been developed.

OBJECTIVE

To assess the reliability of a computerised neuropsychological test battery (CogSport) among Norwegian professional football players.

METHODS

Norwegian professional football league players (90.3% participation) performed two consecutive baseline Cogsport tests before the 2004 season. CogSport consists of seven different subtasks: simple reaction time (SRT), choice reaction time (ChRT), congruent reaction time (CgRT), monitoring (MON), one-back (OBK), matching (Match) and learning (Learn).

RESULTS

There was a small but significant improvement from repeated testing for the reaction time measurements of all seven subtasks (SRT: 0.7%, ChRT: 0.4%, CgRT: 1.2%, MON: 1.3%, OBK: 2.7%, Match: 2.0%, Learn: 1.1%). The coefficient of variation (CV) ranged from 1.0% to 2.7%; corresponding intraclass correlation coefficients ranged from 0.45 (0.34 to 0.55) to 0.79 (0.74 to 0.84). The standard deviation data showed higher CVs, ranging from 3.7% (Learn) to 14.2% (SRT). Thus, the variance decreased with increasing complexity of the task. The accuracy data displayed uniformly high CV (10.4-12.2) and corresponding low intraclass correlation coefficient (0.14 (0.01 to 0.26) to 0.31 (0.19 to 0.42)).

CONCLUSION

The reproducibility for the mean reaction time measures was excellent, but less good for measures of accuracy and consistency. Consecutive testing revealed a slight learning effect from test 1 to test 2, and double baseline testing is recommended to minimise this effect.

Understanding injury mechanisms: a key component of preventing injuries in sport

Anterior cruciate ligament (ACL) injuries are a growing cause of concern, as these injuries can have serious consequences for the athlete with a greatly increased risk of early osteoarthrosis. Using specific training programmes, it may be possible to reduce the incidence of knee and ankle injuries. However, it is not known which programme components are the key to preventing knee and ankle injuries or how the exercises work to reduce injury risk. Our ability to design specific prevention programmes, whether through training or other preventive measures, is currently limited by an incomplete understanding of the causes of injuries. A multifactorial approach should be used to account for all the factors involved-that is, the internal and external risk factors as well as the inciting event (the injury mechanism). Although such models have been presented previously, we emphasise the need to use a comprehensive model, which accounts for the events leading to the injury situation (playing situation, player and opponent behaviour), as well as to include a description of whole body and joint biomechanics at the time of injury.

Methods for epidemiological study of injuries to professional football players: developing the UEFA model

A problem with epidemiological studies of football injuries is the inconsistent manner in which injury is defined and data are collected. Projects have been initiated to study the incidence and causes of injury in football, but there is no uniformly accepted reporting system. In this report, some common pitfalls encountered in the recording of injury are addressed, and practical guidelines for epidemiological studies are provided. An injury reporting system developed for the UEFA Football Safety Project for studies on professional footballers is used as a starting point for a general discussion on injury registration and compared with other existing reporting systems. The recording definition of injury may vary between studies depending on its purpose. A time loss injury definition is practical for all playing levels, and, as a minimum, results on time loss injuries should therefore always be reported separately to allow direct comparisons between studies. There is a need to agree on a uniform sports injury classification system with corresponding diagnostic criteria, as well as standardised return to play criteria after injury.

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 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.

Intensity limits for propagation of 0.527 microm laser beams through large-scale-length plasmas for inertial confinement fusion

We have established the intensity limits for propagation of a frequency-doubled (2omega, 527 nm) high intensity interaction beam through an underdense large-scale-length plasma. We observe good beam transmission at laser intensities at or below 2x10(14) W/cm(2) and a strong reduction at intensities up to 10(15) W/cm(2) due to the onset of parametric scattering instabilities. We show that temporal beam smoothing by spectral dispersion allows a factor of 2 higher intensities while keeping the beam spray constant, which establishes frequency-doubled light as an option for ignition and burn in inertial confinement fusion experiments.

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.