Influence of definition and data collection on the incidence of injuries in football

Prevalence of Knee Osteoarthritis in 100 Athletically Active Veteran Soccer Players Compared With a Matched Group of 100 Military Personnel

BACKGROUND

Although knee injuries in professional soccer (football) have been extensively studied, the prevalence of knee osteoarthritis (OA) in veteran players is not well documented.

PURPOSE

To investigate the prevalence of knee OA in retired professional soccer players in comparison with a group of athletically active military personnel.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A group of 100 veteran Greek soccer players aged 35 to 55 years (mean [±SD] age, 46.90 ± 5.9 years) were examined for knee OA and were administered the Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire. A matched group of 100 athletically active military personnel served as a comparison group.

RESULTS

The sonographic prevalence of OA was significantly higher in the veteran soccer group (52%) than in the military group (33%) (n = 200; P = .010). This difference remained significant even after excluding participants with a history of knee surgery (44.1% vs 25.3%, respectively) (n = 151; P = .010). Femoral cartilage thickness was similar between the 2 groups (P = .473), while altered knee alignment had no effect on the prevalence of OA (P = .740). With the exception of perceived pain being more prevalent in the military group, there were no other statistically significant differences between the 2 groups in KOOS values.

CONCLUSION

Veteran soccer players had a higher sonographic prevalence of knee OA but better pain scores than a matched group of athletically active military personnel.

The scientific foundations and associated injury risks of early soccer specialisation

Early specialisation is characterised by formal participation in a single sport at the exclusion of others. Limited data are available to support this approach in the development of soccer players who attain elite status later in life. Of growing concern is the associated increased risk of injury and suggestions that single sport specialisation is a risk factor independent of age, growth, biological maturation and training volumes. In the United Kingdom, elite soccer organisations have recently adopted an early sport specialisation approach following the introduction of the Elite Player Performance Plan. A key tenet of this programme is increased opportunities for training through a marked rise in the specified on-pitch hours per week. The accumulation of high training hours may be less of a relevant marker for success, and the impact of such a significant increase in training volume for young athletes who are experiencing a range of growth and maturational processes is currently unknown. This critical commentary includes an evidence-based discussion of the effectiveness of early sport specialisation and the potential injury risks associated with such programmes placing a specific focus on elite male youth soccer players. Available data indicate that modifications to the existing Elite Player Performance Plan framework could enhance players' development and reduce injury risk. Proposed alterations include reduced volume of soccer-specific training at key stages of growth and maturation and guidelines for the provision of a greater variety of physical activities that are integrated within other programme components.

Methodological quality of the injury surveillance system used in international athletics championships

OBJECTIVES

Incidence and prevalence data obtained from injury surveillance studies could be biased by the response rate as well as by the completeness and quality of the reports. It therefore appears crucial to analyse the quality of the injury surveillance system itself and thereby validate the quality of the data. This study aimed to analyse the quality of and compliance with the injury surveillance system implemented during international athletics championships.

DESIGN

Prospective, epidemiological study.

METHODS

The national medical teams and the local organising committee physicians daily reported all injuries on a standardised injury report form during 14 international athletics championships from 2007 to 2015. The quality of the injury surveillance system was analysed following the guidelines laid down by the Centre for Disease Control and Prevention.

RESULTS

On average 41.7±17.4% (mean±standard deviation) of all registered countries participated in the injury surveillance project, accounting for a coverage of athletes of 79.5±10.2% of all registered athletes. Their medical staff returned 89.2±8.4% of the expected injury report forms (information is missing for one championship). The completeness of injury data provided by medical teams and local organising committee physicians averaged 95.8±6.5%. National medical teams reported 60.6±16.6% of all injuries, and local organising committee physicians 28.7±15.0% whereas 10.6±6.5% of injuries were reported by both.

CONCLUSIONS

The injury surveillance system used during international athletics championships provided good national medical team participation, coverage of athletes, response rate, and completeness of reports. These parameters should be systematically reported for injury surveillance studies to show the quality of the study.

Injury prediction in veteran football players using the Functional Movement Screen™

The Functional Movement Screen™ (FMS™) is aimed at assessing fundamental movements and is often used to identify players' injury risk. The purpose of this study was to determine whether the FMS™ can be used to predict injuries in veteran footballers (aged > 32 years). Eighteen veteran football teams (n = 238) were recruited and prospectively followed for 9 months. The players (44 ± 7 years; 178 ± 7 cm, 84 ± 11 kg) performed the FMS™ at the start of the study period. Players' exposure hours and injuries were recorded. The difference of FMS™ overall score between injured and uninjured players was not significant (11.7 ± 2.9 vs 12.2 ± 2.8 points; Mann-Whitney U-test P = 0.17). Players scoring <10 (score < 1 standard deviation [SD]) below the mean) had a significantly higher injury incidence (z-statistics P < 0.05) compared to an intermediate reference group (mean ± 1 SD; scores of 10-14). No lower injury incidence for players with scores of >14 (score > 1 SD above the mean) was found. Further analyses of potential risk factors suggest higher age, lower body mass and a longer football career to be risk factors for injuries. The findings of this study suggest that the suitability of the FMS™ for injury prediction in veteran footballers is limited.

Hip Range of Motion Is Lower in Professional Soccer Players With Hip and Groin Symptoms or Previous Injuries, Independent of Cam Deformities

BACKGROUND

Soccer (football) players often have hip and groin symptoms (HGS), and a previous groin injury is a risk factor for a relapse. Decreased hip range of motion (HROM) has been related to both hip and groin pain and the presence of a cam deformity. How these factors interact is unknown.

PURPOSE

The first aim was to study whether HGS are associated with HROM. The second aim was to study the association of the presence of a cam deformity with HROM. Additionally, the influence of a cam deformity on the relationship between HGS and HROM was examined.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Seasonal screening data of 2 professional soccer clubs were used. Variables for HGS were current hip or groin pain, the Copenhagen Hip and Groin Outcome Score (HAGOS), and previous hip- and groin-related time-loss injuries (HGTIs). HROM was determined for hip internal rotation (IR), external rotation, and total rotation (TR) in the supine position and for the bent knee fall out (BKFO) test. A cam deformity was defined by an alpha angle >60° on standardized anteroposterior pelvic and frog-leg lateral radiographs.

RESULTS

Sixty players (mean [±SD] age, 23.1 ± 4.2 years) were included. All were noninjured at the time of screening. Current hip or groin pain was not associated with HROM. Hips of players in the lowest HAGOS interquartile range (thus most affected by complaints; n = 12) showed less IR (23.9° ± 8.7° vs 28.9° ± 7.8°, respectively; P = .036) and TR (58.2° ± 13.5° vs 65.6° ± 11.8°, respectively; P = .047) than those in the highest interquartile range (n = 29). No such differences were found for BKFO (P = .417). Hips of players with a previous HGTI showed less IR (21.1° ± 6.8° vs 28.3° ± 8.9°, respectively; P < .001) and TR (56.0° ± 8.2° vs 64.5° ± 13.6°, respectively; P < .001) than those without a previous HGTI. This was independent of the presence of a cam deformity. BKFO did not differ between groups (P = .983). Hips with a cam deformity showed less but nonsignificant IR (25.5° ± 10.3° vs 29.0° ± 7.1°, respectively; P = .066) and TR (P = .062) and higher but nonsignificant BKFO values (17.1 cm ± 3.4 cm vs 14.2 cm ± 4.6 cm, respectively; P = .078) than those without a cam deformity.

CONCLUSION

Decreased HROM in professional soccer players is associated with more hip- and groin-related symptoms and with previous injuries, independent of the presence of a cam deformity.

Relation between performance in side bridge and injuries in amateur soccer

AbstractIntroduction Central instability is associated with insufficient endurance and strength of the stabilizer muscles, and it can lead to muscle imbalance and injuries.Objective Relate side bridge performance with the presence of injuries in amateur soccer athletes.Materials and methods A cross-sectional study with a sample of 188 male athletes, aged between 11 and 17 years. To identify the injuries, a questionnaire developed by researchers was applied and the players’ clinical records were reviewed. The time of the side bridge test was used to identify muscle imbalance. For statistical analysis, the following tests were used: chi-square test; Pearson’s chi-square test; Fisher’s exact test; Yates’s correction for continuity; two-way ANOVA; one-way ANOVA; and t-test. The significance level (α) of 5% was adopted.Results Injuries were reported by 59.6% of the athletes: sprain (31.3%); muscle strain (28.6%) and fracture; luxation and subluxation (19.6%) were the most frequently reported injuries. Athletes that reported any injury corresponded to 73.2% of the sample. The presence of injuries was not associated with muscle imbalance (p = 0.565), as it prevailed in athletes with both balance (64%) and imbalance (58%). Injury type and prevalence were not significant when compared with the presence of imbalance (p > 0.05).Final considerations No significant relation between muscle imbalance and injury was observed in the studied sample.

Does Gracilis Tendon Harvest During ACL Reconstruction with a Hamstring Autograft Affect Torque of Muscles Responsible for Shin Rotation?

Background

A growing body of evidence indicates that in patients after anterior cruciate ligament reconstruction (ACLR) with a combined semitendinosus and gracilis (STGR) graft there are large deficits in the internal rotation strength, which has led some authors to recommend harvest of only ST tendon whenever possible. The purpose of this study was to assess the isometric (IT) and peak torque (PT) of the muscles responsible for shin rotation in patients after ACLR with an ST or with an STGR graft.

Material/Methods

Twenty patients with an ST graft and 20 patients with a combined STGR graft underwent a 6-month postoperative rehabilitation program after ACLR. At the end of the rehabilitation program, the IT and PT of the muscles responsible for internal (IR) and external rotation (ER) of the shin were measured. The results were compared to the results of a control group. Additionally, to determine the reliability of the dynamometer for clinical research, a test-retest assessment was performed.

Results

There were no statistically significant differences between the 3 groups of participants. Nevertheless, in the STGR group there was a statistically significant difference between the IT of muscles internally rotating the shin in the involved knee and uninvolved knee at 25° of the internal shin rotation.

Conclusions

Comparison of IT and PT measurements performed after 24 weeks of postoperative rehabilitation generally showed no differences between patients after ACLR with the use of ST graft and patients who received a combination graft consisting of STGR. Nevertheless, there was an influence of GR harvest on internal shin rotation torque at a deep internal rotation angle.

Epidemiology of injury in male adolescent Gaelic games

OBJECTIVES

There is a lack of epidemiological research in adolescent Gaelic games, with previous research primarily focusing on elite adult males. This study aimed to prospectively capture the epidemiology of injury in male adolescent Gaelic games over one year.

DESIGN

Prospective cohort study.

METHODS

Two hundred and ninety two (15.7±0.8 years) male adolescent Gaelic footballers and hurlers took part in a one year prospective epidemiological study. Injuries were assessed weekly by a certified Athletic Rehabilitation Therapist and an injury was defined as any injury sustained during training or competition resulting in restricted performance or time lost from play. An injury report form was utilised to standardise injury information.

RESULTS

Match injuries were more frequent in Gaelic footballers (9.26 per 1000h) and hurlers (11.11 per 1000h) than training injuries (2.69 and 3.01 per 1000h, respectively). Over a quarter of injuries in adolescent Gaelic footballers (26.7%) and hurlers (26.5%) were overuse in nature. Recurrent injuries were also frequent, particularly in adolescent Gaelic footballers (47.3%). Lower limb injuries predominated (football 74.7%, hurling 58%), particularly in the knee (18.7%, 20.0%) and ankle (12.0%, 10.0%). Hamstring injuries were more frequent in footballers (13.3%), with lower back injuries more common in hurlers (22.0%). Minor injuries were common in hurling (61.7%), with moderate (20.8%) and severe (37.5%) injuries predominant in Gaelic football.

CONCLUSIONS

Injuries are frequent in adolescent Gaelic games and this study sets the scene for the establishment of injury prevention strategies for this at risk population.

A consensus definition of running-related injury in recreational runners: a modified Delphi approach

STUDY DESIGN

Delphi study.

OBJECTIVE

To reach a consensus definition of running-related injury in recreational runners through a modified Delphi approach.

BACKGROUND

Many studies have suggested the need for a standardized definition of running-related injury to provide uniformity to injury surveillance in running.

METHODS

We invited 112 researchers from running-related injury studies identified in a previous systematic review to classify words and terms frequently used in definitions of running-related injury in an online form during 3 rounds of study. In the last round, participants were asked to approve or disapprove the consensus definition. We considered an agreement level of at least 75% to be a consensus.

RESULTS

Thirty-eight participants agreed to participate in the study. The response rates were 94.7% (n = 36) for the first round, 83.3% (n = 30) for the second round, and 86.7% (n = 26) for the third round. A consensus definition of running-related injury was reached, with 80% of participants approving the following: "Running-related (training or competition) musculoskeletal pain in the lower limbs that causes a restriction on or stoppage of running (distance, speed, duration, or training) for at least 7 days or 3 consecutive scheduled training sessions, or that requires the runner to consult a physician or other health professional."

CONCLUSION

The proposed standardized definition of running-related injury could assist in standardizing the definitions used in sport science research and facilitate between-study comparisons. Future studies testing the validity of the proposed consensus definition, as well as its accurate translation to other languages, are also needed.

Descriptors used to define running-related musculoskeletal injury: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVES

To systematically review the descriptors used to define running-related musculoskeletal injury and to analyze the implications of different definitions on the results of studies.

BACKGROUND

Studies have developed their own definitions of running-related musculoskeletal injuries based on different criteria. This may affect the rates of injury, which can be overestimated or underestimated due to the lack of a standard definition.

METHODS

Searches were conducted in the Embase, PubMed, CINAHL, SPORTDiscus, LILACS, and SciELO databases, without limits on date of publication and language. Only articles that reported a definition of running-related injury were included. The definitions were classified according to 3 domains and subcategories: (1) presence of physical complaint (symptom, body system involved, region), (2) interruption of training or competition (primary sports involved, extent of injury, extent of limitation, interruption, period of injury), and (3) need for medical assistance. Spearman rank correlation was performed to evaluate the correlation between the completeness of definitions and the rates of injury reported in the studies.

RESULTS

A total of 48 articles were included. Most studies described more than half of the subcategories, but with no standardization between the terms used within each category, showing that there is no consensus for a definition. The injury rates ranged between 3% and 85%, and tended to increase with less specific definitions.

CONCLUSION

The descriptors commonly used by researchers to define a running-related injury vary between studies and may affect the rates of injuries. The lack of a standardized definition hinders comparison between studies and rates of injuries.

Injuries in professional male soccer players in the Netherlands: a prospective cohort study

CONTEXT

Injuries are a major adverse event in a soccer player's career. Reducing injury incidence requires a thorough knowledge of the epidemiology of soccer injuries.

OBJECTIVE

To investigate the incidence and characteristics of injuries in the Dutch premier soccer league.

DESIGN

Cohort study.

SETTING

The Dutch premier soccer league.

PATIENTS OR OTHER PARTICIPANTS

During the 2009-2010 soccer season, a total of 217 professional soccer players from 8 teams were prospectively followed.

MAIN OUTCOME MEASURE(S)

The medical staff recorded time-loss injuries, including information on injuries (ie, type, body part, duration) and exposure data for training sessions and matches.

RESULTS

A total of 286 injuries were recorded, affecting 62.7% of the players. The overall injury incidence was 6.2 injuries per 1000 player-hours, 2.8 in training sessions and 32.8 in matches. Most of the recorded injuries were acute (68.5%). Eight percent of the injuries were classified as recurrent. Injuries were most likely to be located in the lower extremities (82.9%). Injury time loss ranged from 1 to 752 days, with a median of 8 days. Knee injuries had the greatest consequences in terms of days of absence from soccer play (on average, 45 days). The most common diagnosis was muscle/tendon injury of the lower extremities (32.9%).

CONCLUSIONS

Injury risk in the Dutch premier soccer league is high, especially during matches. Preventive measures should focus on the most common diagnoses, namely, muscle/tendon injuries of the lower extremities.

Injuries in iran futsal national teams: a comparative study of incidence and characteristics

Background:

Futsal is a growing sport with lots of fans in many countries including Iran, but there are few papers in the literature which report injuries in top level futsal.

Objectives:

The aim of this study is to record and analyze the incidence and characteristics of injuries in Iran futsal national teams from March 2011 to September 2012.

Patients and Methods:

55 Iranian national futsal players participated in this prospective cohort study. Before entering the study, all players took part in Pre-Competition Medical Assessment (PCMA) in accordance with FIFA protocol. Team physicians recorded the injuries throughout the match and trainings in a special form which was designed for this purpose. Finally, data analysis was done with the SPSS software.

Results:

The total exposure time for all players was 24326 hours (21138 hours during training and 3188 hours during matches). During the study period, 32 of the 55 national players (58.2%) incurred 54 injuries (incidence rate = 2.22 injuries per 1000 players-hours). The incidence rate of injury in female players was significantly higher than male players (P = 0.001). The majority of injuries (85.2%) were located on the lower extremities. The ankle was the most frequent injury location (40.7%) and sprain was the most frequent type of injury.

Conclusions:

Injuries are common among futsal players and female players are more prone to injuries than male players. The ankle is the most frequent site and sprain is the most frequent type of injury among futsal players.

Competing with injuries: injuries prior to and during the 15th FINA World Championships 2013 (aquatics)

BACKGROUND

Injury and illness surveillance is the foundation for the development of prevention strategies.

OBJECTIVE

To examine injuries among the aquatic disciplines in the 4 weeks prior to and during the 2013 FINA World Championships.

METHODS

The study was comprised of two components: (1) a retrospective athlete survey recording injuries in the 4 weeks prior to the Championships and (2) a prospective recording of injuries and illnesses by the medical teams of the participating countries and the local host medical team.

RESULTS

One-third of the 1116 responding athletes reported an injury/physical complaint in the 4 weeks prior to the Championships. Significantly more women (36.7%) than men (28.6%) reported injuries. Divers reported the highest rate of injury/physical complaints (55.7%). At the start of the Championships, 70% of injured respondents (n=258) were still symptomatic; however, full participation was expected by 76%. During the Championships, 186 new injuries were reported (8.3/100 registered athletes) with the highest injury incidence rate in water polo (15.3/100 registered athletes). The most common injured body part was the shoulder (21%). A total of 199 illnesses were reported during the Championships (9.0/100 registered athletes) with the most common diagnosis of illness being gastrointestinal infection. Environmental exposure (allergy, otitis and jellyfish stings) was responsible for 27% of all illnesses in open water swimming.

CONCLUSIONS

Injuries pose a significant health risk for elite aquatic athletes. A prospective study would improve understanding of out-of-competition injuries. Future injury and illness surveillance at FINA World Championships is required to direct and measure the impact of prevention strategies.

Chronic ankle instability in sporting populations

BACKGROUND

Chronic ankle instability (CAI) is a term used to identify certain insufficiencies of the ankle joint complex following an acute ankle injury. Acute ankle injuries are often associated with sporting mishaps; however, this review was the first to identify the aspects of CAI (perceived instability, mechanical instability and recurrent sprain), and persisting symptoms following an ankle sprain, that have been reported within sporting cohorts.

OBJECTIVE

To determine the presence of common aspects of CAI within individual sports.

METHODS

A systematic search of the MEDLINE, Web of Science, CINAHL, SPORTDiscus and AMED databases up until 1 October, 2013 produced 88 studies appropriate for review. A calculated weighted percentage of the outcome data allowed the comparison of figures across a range of sports.

RESULTS

Soccer, basketball and volleyball were the most represented sports and recurrent ankle injury/sprain was the most reported aspect of CAI. Soccer had the highest percentage of participants with recurrent sprain (61%) and mechanical instability (38%), whilst track and field had the highest percentage of participants with perceived instability (41%). Gymnasts had the highest percentage of ankles with persisting symptoms following an initial ankle sprain.

CONCLUSION

This review was the first to assess aspects of CAI within sporting cohorts and has identified limitations to the research reporting these data. The problem of CAI across a range of sports remains unclear and thus advocates the need for further controlled research in the area to ascertain the true extent of CAI within sporting populations.

Football injuries in children and adolescent players: are there clues for prevention?

Football (soccer) is the world's most popular sport with most players being younger than 18 years. Playing football can induce beneficial health effects, but there is also a high risk of injury. Therefore, it is necessary to implement measures for preventing injuries. The present review analyzes and summarizes published scientific information on the incidence and characteristics of football injuries in children and adolescent players to arrive at sound conclusions and valid considerations for the development of injury-prevention programs. A literature search was conducted up to November 2012. Fifty-three relevant scientific publications were detected. Thirty-two studies fulfilled the inclusion criteria for pooled analysis. Additional information from the remaining 21 studies was considered where appropriate to obtain a broader perspective on the injury problem in children and youth football. Training injury incidence was nearly constant for players aged 13-19 years, ranging from 1 to 5 injuries per 1,000 h training. Match injury incidence tended to increase with age through all age groups, with an average incidence of about 15 to 20 injuries per 1,000 match hours in players older than 15 years. Between 60 and 90 % of all football injuries were classified as traumatic and about 10-40 % were overuse injuries. Most injuries (60-90 %) were located at the lower extremities with the ankle, knee, and thigh being mostly affected. The frequency of upper-extremity and head/face injuries was higher in those studies that analyzed match injuries only. The most common injury types were strains, sprains, and contusions (10 up to 40 % each). There is some evidence that the risk of traumatic injuries and, in particular, of sustaining a fracture, contusion, or concussion was higher during match play than in practice sessions. Fractures were more frequent in children younger than 15 years than in older players. About half of all time-loss injuries led to an absence from sport of less than 1 week, one third resulted in an absence between 1 and 4 weeks, and 10 to 15 % of all injuries were severe. Separate data for players under the age of 11 years are almost absent. Maturation status seems to have an influence on injury characteristics, although evidence is not conclusive at this time. Three main areas seem to be of particular relevance for future prevention research in young football players: (1) the substantial number of severe contact injuries during matches, (2) the high number of fractures in younger players, and (3) the influence of maturation status and growth spurts.

The effectiveness of preventive programs in decreasing the risk of soccer injuries in Belgium: national trends over a decade

BACKGROUND

Although characterized by a relatively high injury rate, soccer is the world's most popular sport. In Belgium, the national Royal Belgian Football Association involves about 420,000 licensed players, whose injury reports are collected in a nationwide registry. Over a period of 10 years, the association has introduced the Fédération Internationale de Football Association preventive programs and has initiated a stringent postponement policy of competition in case of nonoptimal weather conditions.

HYPOTHESIS

The authors questioned whether these preventive programs effectively decreased the incidence of soccer-related injuries.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

The authors compared the incidence, location, timing, and severity of all registered soccer injuries in Belgium during 2 complete seasons separated by a decade (1999-2000 vs 2009-2010).

RESULTS

A total of 56,364 injuries were reported, with an average of 6.8 injuries per 100 players per season. There was a 21.1% reduction in injury rate in the second season (rate ratio = 0.789; 95% confidence interval, 0.776-0.802), predominantly caused by a significant reduction in injuries during the winter period. In both seasons, an injury peak was noted during the first 3 months of the season. Recreational players had a higher risk for injury than national-level players (7.2 vs 4.4 injuries per 100 players per season; rate ratio = 1.64; 95% confidence interval, 1.59-1.69). The relative proportion of severe injuries was higher for female players and male youth players in general.

CONCLUSION

The introduction of injury preventive programs has led to a significant reduction of soccer-related injuries, especially during the winter period. However, there is still room for improvement, and preventive programs can become more effective when specific parameters are targeted, such as adequate conditioning of players in the preseason.

Descriptive epidemiology of injuries in a Brazilian premier league soccer team

Soccer, which has a large number of participants, has a high injury incidence that causes both financial and time burdens. Therefore, knowledge about the epidemiology of soccer injuries could allow sports-medicine professionals, such as physicians and physiotherapists, to direct their work in specific preventive programs. Thus, our aim was to conduct an epidemiological survey of injuries sustained by professional soccer players from the same team who participated in the Brazilian championship premier league in 2009. To this end, we evaluated retrospectively player medical records from the team, which included name, date of birth, position, date of injury, mechanism of injury, and type of injury. In the period of study, 95 injuries were recorded: 42 (44.2%) were recorded during matches, and 53 (55.8%) during the training period. Injuries occurred more frequently in midfielders and strikers. All injuries happened in the lower limb, most of the injuries were muscular, and most occurred as the result of collisions with other athletes. In summary, this study demonstrates that there is a need for greater safety awareness in the training environment.

Incidence, mechanisms, and severity of match-related collegiate women's soccer injuries on FieldTurf and natural grass surfaces: a 5-year prospective study

BACKGROUND

Numerous injuries have been attributed to playing on artificial turf. Over the past 2 decades, however, newer generations of synthetic turf have been developed to duplicate the playing characteristics of natural grass. Although synthetic turf has been determined to be safer than natural grass in some studies, few long-term studies have been conducted comparing match-related collegiate soccer injuries between the 2 playing surfaces.

HYPOTHESIS

Collegiate female soccer athletes do not experience any difference in the incidence, mechanisms, and severity of match-related injuries on FieldTurf and on natural grass.

STUDY DESIGN

Cohort study: Level of evidence, 2.

METHODS

Female soccer athletes from 13 universities were evaluated over 5 competitive seasons for injury incidence, injury category, time of injury, injury time loss, player position, injury mechanism and situation, primary type of injury, injury grade and anatomic location, field location at the time of injury, injury severity, head and lower extremity trauma, cleat design, turf age, and environmental factors. In sum, 797 collegiate games were evaluated for match-related soccer injuries sustained on FieldTurf or natural grass during 5 seasons.

RESULTS

Overall, 355 team games (44.5%) were played on FieldTurf versus 442 team games (55.5%) on natural grass. A total of 693 injuries were documented, with 272 (39.2%) occurring during play on FieldTurf and 421 (60.8%) on natural grass. Multivariate analysis per 10 team games indicated a significant playing surface effect: F₂,₆₉₀ = 6.435, P = .002, n-β = .904. A significantly lower total injury incidence rate (IIR) of 7.7 (95% confidence interval [CI], 7.2-8.1) versus 9.5 (95% CI, 9.3-9.7) (P = .0001) and lower rate of substantial injuries, 0.7 (95% CI, 0.5-1.0) versus 1.5 (95% CI, 1.2-1.9) (P = .001), were documented on FieldTurf versus natural grass, respectively. Analyses also indicated significantly less trauma on FieldTurf when comparing injury time loss, player position, injury grade, injuries under various field conditions and temperatures, cleat design, and turf age.

CONCLUSION

Although similarities existed between FieldTurf and natural grass during competitive match play, FieldTurf is a practical alternative when comparing injuries in collegiate women's soccer. It must be reiterated that the findings of this study may be generalizable to only collegiate competition and this specific artificial surface.

The incidence and nature of injuries sustained on grass and 3rd generation artificial turf: a pilot study in elite Saudi National Team footballers

PURPOSE OF THE STUDY

To compare the incidence, severity and nature of injuries sustained by Saudi National Team footballers during match-play and training on natural grass and 3rd generation (3G) artificial turf.

METHOD

Injury data was collected on all Saudi National Team players competing at the Gulf Cup (Yemen December 2010: 3G) and the Asian Cup (Qatar January 2011; grass). A total of 49 players were studied (mean ± SD; Age 27 ± 4 yr; body mass 71.4 ± 6.7 kg; height 176.8 ± 6.3 cm; professional playing experience 9 ± 3 yr) of which 31 competed at the Gulf Cup, 32 at the Asian Cup (14 at both). A prospective cohort design was used to investigate the incidence, nature and severity of injuries sustained with data collected using a standardised injury questionnaire. All data were collected by the team physiotherapist with the definition of injury set at any injury that required player and clinician contact. Injury and exposure data were collected and reported for games, training and all football activity.

RESULTS

A total of 82 injuries [incidence - 56.1 per 1000 h total game and training exposure] were recorded at the Asian Cup (grass) and 72 injuries [incidence - 37.9 per 1000 h total game and training exposure] were recorded at the Gulf Cup (3G). Incidence data for training, game and all football exposure injury rates were higher when playing on grass. The vast majority of injuries on both surfaces were very minor that, whilst requiring medical attention, did not result in loss of match/training exposure. Injuries that resulted in 1-3 days absence from training or game play had similar incidence rates (Grass: 7.4 vs. 3G: 7.4 injuries per 1000 h exposure). More severe injuries were less frequent but with a higher incidence when playing on grass. Lower limb injuries were the most common in both tournaments with a higher incidence on grass (Grass: 14.2 vs. 3G: 7.9 injuries per 1000 h exposure). Muscle injuries were the most frequent of all injuries with similar incidence rates on both surfaces (Grass: 5.4 vs. 3G: 4.7 injuries per 1000 h exposure). Injuries that involved player contact were also more common on grass (Grass: 11.5 vs. 3G: 3.2 injuries per 1000 h exposure).

CONCLUSION

Whether reporting all injuries or just those that prevented players from taking part in training or match play, injury incidence rates were generally higher when Saudi National Team footballers played on grass than on 3G artificial surface. Although this is a small study, the unique quasi-repeated measures study design with elite Saudi National Team footballers, adds to the current belief that 3G artificial turf does not increase injury risk in football.

The health profile of professional soccer players: future opportunities for injury prevention

Injuries are a major adverse event during a soccer player's career; they require medical and surgical treatment and rehabilitation and thus may interrupt the player's activity, often with severe physical and psychological sequel. Specialists have tried to identify the risk factors for injuries, in an attempt to discover predictors that could be prevented and or eliminated before the injury occurs, but the results are scarce. This article reviews the epidemiology of the frequency and occurrence of injuries in Italian soccer players, reports a list of preventable risk factors that are associated with injuries, and identifies preventable risk factors. We have identified personal factors (age, previous traumatic events, physical and biological characteristics of the player, life style habits such as smoking, alcohol, and diet, changes in physical-athletic aspects of the players, such as increased muscle strength, and use of medications) as possible risk factors for injuries. However, environmental factors such as changes in training techniques, field composition, and shoes structure may also have a major influence. This summary indicates that appropriate preventive measures can be undertaken to prevent injuries in professional soccer players. Professionals who are in close contacts with the players should be informed of the predictors of injuries and should be trained to intervene and plan appropriate preventive measures.

Psychosensorial assessment of skin damage caused by a sliding on artificial turf: the development and validation of a skin damage area and severity index

OBJECTIVES

Injury prevention is an important reason for the development of performance standards in football. Currently, there is no objective method available to classify sliding induced skin injuries, which includes the perceived sliding friendliness of football pitches. The purpose of this study was to develop a non-invasive method for quantification of the observed sliding induced skin damage and evaluate whether there is a correlation between the subjective perceived skin irritation and sliding friendliness.

STUDY DESIGN

Randomized controlled trial.

METHODS

Previously obtained clinical images of sliding induced skin lesions where rated by a dermatologist on the degree of abrasion, erythema and type of exudation. To test the practical feasibility of a proposed Skin Damage and Severity Index (SDASI) to characterize sliding induced skin lesions, a randomized user trial with nine amateur football players was performed. The sliding friendliness of three different grades of infill materials was tested.

RESULTS

The Skin Damage and Severity Index correlates both with the perceived skin irritation (r=-0.53, P=0.02) and sliding friendliness (r=-0.58, P=0.01). Statistical analysis of the individual clinical scores showed that perception of skin irritation and sliding friendliness correlate very well with the degree of erythema and abrasion. However, these scores are independent of the size of the lesion and type of exudation. There was no statistical significant difference found between the three evaluated types of infill and their sliding performance.

CONCLUSIONS

This study demonstrated that the Skin Damage and Severity Index, which is a tool for quantification of a sliding induced skin lesion, correlates very well with the perceived skin irritation and the sliding friendliness.

A retrospective survey on injuries in Croatian football/soccer referees

Background

Injury among soccer referees is rarely studied, especially with regard to differences in the quality level of the refereeing. Additionally, we have found no study that has reported injury occurrence during official physical fitness testing for soccer referees. The aim of this study was to investigate the frequency, type and consequences of match-related and fitness-testing related injuries among soccer referees of different competitive levels.

Methods

We studied 342 soccer referees (all males; mean age 32.9 ± 5.02 years). The study was retrospective, and a self-administered questionnaire was used. In the first phase of the study, the questionnaire was tested for its reliability and applicability. The questionnaire included morphological/anthropometric data, refereeing variables, and musculoskeletal disorders together with the consequences.

Results

The sample comprised 157 main referees (MR; mean age 31.4 ± 4.9 years) and 185 assistant referees (AR; mean age 34.1 ± 5.1 years) divided into: international level (Union of European Football Associations-UEFA) referees (N = 18; 6 MRs; 12 ARs) ; 1^st (N = 78; 31 MRs; 47 ARs), 2^nd (N = 91; 45 MRs; 46 ARs); or 3^rd national level referees (N = 155; 75 MRs; 80 ARs). In total, 29% (95%CI: 0.23–0.37) of the MRs and 30% (95%CI: 0.22–0.36) of the ARs had experienced an injury during the previous year, while 13% (95%CI: 0.05–0.14) of the MRs, and 19% (95%CI: 0.14–0.25) of the ARs suffered from an injury that occurred during fitness testing. There was an obvious increase in injury severity as the refereeing advanced at the national level, but the UEFA referees were the least injured of all referees. The results showed a relatively high prevalence of injuries to the upper leg (i.e., quadriceps and hamstrings) during physical fitness testing for all but the UEFA referees. During game refereeing, the ankles and lower legs were the most commonly injured regions. The MRs primarily injured their ankles. The ARs experienced lower leg and lower back disorders. However, the overall injury rate was equal for both groups, with 5.29 (95%CI: 2.23–8.30) and 4.58 (95%CI: 2.63–6.54) injuries per 1000 hours of refereeing for MRs and ARs, respectively.

Conclusion

In addition to the reported risk of injury during soccer games, physical fitness testing should be classified as a risk for injury among soccer referees. Special attention should be given to (I) lower leg injuries during games and (II) upper leg injuries during physical fitness tests. A higher physical fitness level and a qualitative approach to training are recognized as protective factors against injury. Subsequent studies should investigate the specific predictors of injuries among referees.

Epidemiological Study on Professional Football Injuries During the 2011 Copa America, Argentina

OBJECTIVE

Develop an epidemiological study of injuries occurred among male professional football players during the Copa America 2011, held in Argentina.

METHODS

We conducted a retrospective study of injuries sustained during the 43rd edition of the Copa America football in Argentina, in 2011. The lesions were evaluated by the medical department of the selections and reported to the CONMEBOL. The data were compiled and reported in accordance with rules established by the FIFA Medical Assessment and Research Centre (F-MARC) in 2005.

RESULTS

There was a higher prevalence of lesions in the lower limbs. Thighs and knees were the most affected segments. The most frequent diagnoses were muscle injuries. The injuries were mostly minor degrees of severity and there was little difference in the prevalence of lesions according to the stages of the match, with slight predominance in the final 15 minutes. The incidence of lesions per 1,000 game hours was similar to the average found in the literature.

CONCLUSIONS

The results obtained allowed us to outline a profile of the prevalence, distribution per body segment, minute in which occurred and severity of injuries in professional football players of participating teams in the Copa America 2011 in Argentina. The extreme rigor of referees may be partly attributed to the highly competitive nature of international tournaments. However, this results cannot be considered definitive because of the need to be compared to other epidemiological studies with same design using similar concepts and criteria.

What are the main running-related musculoskeletal injuries? A Systematic Review

Background

Musculoskeletal injuries occur frequently in runners and despite many studies about running injuries conducted over the past decades it is not clear in the literature what are the main running-related musculoskeletal injuries (RRMIs).

Objective

The aim of this study is to systematically review studies on the incidence and prevalence of the main specific RRMIs.

Methods

An electronic database search was conducted using EMBASE (1947 to October 2011), MEDLINE (1966 to October 2011), SPORTDiscus™ (1975 to October 2011), the Latin American and Caribbean Center on Health Sciences Information (LILACS) [1982 to October 2011] and the Scientific Electronic Library Online (SciELO) [1998 to October 2011] with no limits of date or language of publication. Articles that described the incidence or prevalence rates of RRMIs were considered eligible. Studies that reported only the type of injury, anatomical region or incomplete data that precluded interpretation of the incidence or prevalence rates of RRMIs were excluded. We extracted data regarding bibliometric characteristics, study design, description of the population of runners, RRMI definition, how the data of RRMIs were collected and the name of each RRMI with their rates of incidence or prevalence. Separate analysis for ultra-marathoners was performed. Among 2924 potentially eligible titles, eight studies (pooled n = 3500 runners) were considered eligible for the review. In general, the articles had moderate risk of bias and only one fulfilled less than half of the quality criteria established.

Results

A total of 28 RRMIs were found and the main general RRMIs were medial tibial stress syndrome (incidence ranging from 13.6% to 20.0%; prevalence of 9.5%), Achilles tendinopathy (incidence ranging from 9.1% to 10.9%; prevalence ranging from 6.2% to 9.5%) and plantar fasciitis (incidence ranging from 4.5% to 10.0%; prevalence ranging from 5.2% to 17.5%). The main ultra-marathon RRMIs were Achilles tendinopathy (prevalence ranging from 2.0% to 18.5%) and patellofemoral syndrome (prevalence ranging from 7.4% to 15.6%).

Conclusion

This systematic review provides evidence that medial tibia stress syndrome, Achilles tendinopathy and plantar fasciitis were the main general RRMIs, while Achilles tendinopathy and patellofemoral syndrome were the most common RRMIs for runners who participated in ultra-marathon races.

Electronic Supplementary Material

Supplementary material is available for this article at 10.1007/BF03262301 and is accessible for authorized users.

Terminology and classification of muscle injuries in sport: the Munich consensus statement

Objective

To provide a clear terminology and classification of muscle injuries in order to facilitate effective communication among medical practitioners and development of systematic treatment strategies.

Methods

Thirty native English-speaking scientists and team doctors of national and first division professional sports teams were asked to complete a questionnaire on muscle injuries to evaluate the currently used terminology of athletic muscle injury. In addition, a consensus meeting of international sports medicine experts was established to develop practical and scientific definitions of muscle injuries as well as a new and comprehensive classification system.

Results

The response rate of the survey was 63%. The responses confirmed the marked variability in the use of the terminology relating to muscle injury, with the most obvious inconsistencies for the term strain. In the consensus meeting, practical and systematic terms were defined and established. In addition, a new comprehensive classification system was developed, which differentiates between four types: functional muscle disorders (type 1: overexertion-related and type 2: neuromuscular muscle disorders) describing disorders without macroscopic evidence of fibre tear and structural muscle injuries (type 3: partial tears and type 4: (sub)total tears/tendinous avulsions) with macroscopic evidence of fibre tear, that is, structural damage. Subclassifications are presented for each type.

Conclusions

A consistent English terminology as well as a comprehensive classification system for athletic muscle injuries which is proven in the daily practice are presented. This will help to improve clarity of communication for diagnostic and therapeutic purposes and can serve as the basis for future comparative studies to address the continued lack of systematic information on muscle injuries in the literature.

What are the new things

Consensus definitions of the terminology which is used in the field of muscle injuries as well as a new comprehensive classification system which clearly defines types of athletic muscle injuries.

Level of evidence

Expert opinion, Level V.

Incidence of injury in Gaelic football: a 4-year prospective study

BACKGROUND

Gaelic football is a national sport of Ireland. While predominantly played in Ireland, it is recognized in North America, the United Kingdom, Europe, and Australasia. Its high-velocity, multidirectional, and high physical contact elements expose players to a risk of injury. To date, prospective injury data for Gaelic football has been of short duration.

PURPOSE

To describe the incidence and nature of sport-related injuries in elite male Gaelic football players over 4 consecutive seasons.

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Over the period 2007 to 2010, a total of 851 Gaelic football players were tracked. Players were members of county-level teams who volunteered to be included in the study. Team injury, training, and match play data were submitted by the team physiotherapist on a weekly basis through a dedicated web portal to the National Gaelic Athletic Association (GAA) injury database. Injury was defined using a time loss criterion, in accordance with consensus statements in sports applicable to Gaelic games.

RESULTS

A total of 1014 Gaelic football injuries were recorded. Incidence of injury was 4.05 per 1000 hours of football training. Match-play injury rates were 61.86 per 1000 hours. Muscle was the most frequently injured tissue (42.6%) and fractures accounted for 4.4% of Gaelic football injuries. Lower extremity injuries predominated (76.0%). Hamstring injuries were the single most common injury overall, representing almost one quarter (24%) of all injuries and over half of muscle injuries. Anterior cruciate ligament (ACL) injuries accounted for 13% of knee injuries. The majority of injuries were defined as new injuries (74.7%), with recurrent injuries constituting 23% of all injuries. The majority (59%) of match play injuries occurred in the second half of the match. Eighty six percent of injuries caused over one week's absence from play.

CONCLUSION

These findings illustrate injury patterns in Gaelic football using a prospective methodology, over 4 consecutive seasons. Comparison with published literature suggests that Gaelic football match play injury risk is greater than soccer but less than rugby union.

Injury profile of a professional soccer team in the premier league of iran

Purpose

Despite numerous studies which have been done regarding soccer injuries worldwide, there is lack of available data considering the epidemiology of injuries in the Iranian soccer premier league, although it is the most popular sport in the country. The main goal of this research was to determine the incidence of physical injuries in the studied population, considering other characteristics such as site, type and mechanism as well.

Methods

Twenty one adult male professional soccer players (age 24±3), members of a team (Tehran-Pas) participating in Iranian premier league, were followed during a 4-month period. The injury characteristics and exposure times were recorded by the team physician during all the matches and training sessions.

Results

The total exposure time was 2610 playing hours (2352 h of training versus 258 h of competition). Eighty six percent of the injuries were acute. Incidence of acute injuries was 16.5 (95% CI: 12-22) per 1000 hours of playing (11.5 per 1000 hrs of training and 62 per 1000 hrs of competition). The most common types of injuries were strains followed by contusions, each of which constituted 30% of acute injuries. More than 80% of injuries occurred in lower limbs, especially in thigh and groin regions. Nearly 60% of acute injuries occurred in dominant side of the body, and collision was the reason of about half of the acute injuries. Severity of more than 70% of the injuries was minor. On average each injury had led the player being off the field for about 10 days.

Conclusion

The incidence of injury in this research is in range of numbers obtained in important international tournaments but the rate of injuries during training sessions is higher than comparable studies.

Injury profile of competitive alpine skiers: a five-year cohort study

PURPOSE

The aim of this study was to make a survey of injuries in young elite alpine skiers.

METHODS

During 5 years, all students at the Swedish Ski High schools were prospectively followed regarding injuries, time of exposure, injury location, type of injury, injury severity and gender. Four hundred and thirty-one skiers, 215 males and 216 females completed the entire study.

RESULTS

Of 431 skiers, 193 (91 males, 102 females) sustained 312 injuries during the 5-year study period. The injury incidence for males was 1.62 injuries/1,000 ski hours or 2.97 injuries/100 months at a Ski High school, and the corresponding values for females were 1.77 and 3.25, respectively. Forty-one percent of the injuries involved the knee, 69% were ligament injuries, and 49% were classified as severe injuries. Of 190 injured skiers, 120 injured their left leg (P = 0.0097). This was their first time injury. The risk of sustaining a re-injury or a new injury increased the sooner the first time injury occurred (P = 0.001).

CONCLUSION

There was a high risk for alpine ski students to sustain an injury during their education at the Swedish Ski High schools. Most injuries, especially ligament injuries, occurred in the knee joint in both males and females. Both genders were more likely to sustain injuries to the left than to the right leg. Nearly 50% of the injuries were classified as severe.

LEVEL OF EVIDENCE

II.

Prevalência de lesões em atletas do futsal feminino brasileiro: um estudo retrospectivo

INTRODUÇÃO: O futsal vem se destacando no cenário internacional como uma das modalidades em maior ascensão. Na literatura, são escassos os estudos que relatam as lesões no gênero feminino nesta modalidade. OBJETIVO: O objetivo deste estudo foi identificar a prevalência de lesões em atletas do futsal feminino brasileiro. MÉTODOS: A amostra correspondeu às atletas que participaram da Liga Nacional de Futsal 2011, totalizando 135 atletas. Investigou-se a prevalência de lesões apresentadas durante toda a temporada de 2010. RESULTADOS: Das 135 atletas, 73 (54,1%) apresentaram algum tipo de lesão, sendo identificados 104 traumas. As lesões nos membros inferiores corresponderam a 86,5% do total, com 28,9% (n = 30) no tornozelo, 24% (n = 25) na coxa e o joelho correspondeu a 23,1% (n = 24). Quanto à forma, 51,9% (n = 54) ocorreram sem contato e 46,1% (n = 48) por contato direto. Durante o treinamento técnico/tático ou treinamento físico ocorreram 59,6% das lesões (n = 62) e 40,4% (n = 42), durante os jogos. Das lesões, 58,6% ocorreram pela primeira vez e 40,4% são recidivas. Não foi encontrada associação entre acompanhamento fisioterapêutico em treinos e competições, com o número e a gravidade das lesões. Também não há relação com o membro dominante e o hemicorpo do trauma. CONCLUSÕES: As atletas do futsal feminino brasileiro apresentam grande prevalência de lesões, principalmente no tornozelo, coxa e joelho, sendo que a maioria delas ocorre nos treinamentos. Lesões que acontecem sem contato com outro adversário prevaleceram em relação aos traumas com contato, fato que se opõe aos demais achados da literatura. O número de primeiras lesões foi maior em relação às recidivas e, quanto à gravidade, prevaleceram as lesões moderadas. Para minimizar o número de lesões, são necessárias estratégias específicas de prevenção, enfatizando os segmentos do tornozelo, joelho e coxa.

Injury risk factors in young soccer players detected by a multivariate survival model

Soccer is a popular game practiced all around the world by teenagers. However, despite being a relatively safe sport, muscle-strain injuries during competitive matches are common compared to other team-sports. Few studies, to date, have investigated risk factors for soccer injuries using a multivariate survival model (e.g., Cox regression). The aim of this study was to use a multivariate survival model to investigate factors associated with an increased risk of thigh muscle strains, in young soccer players. A multivariate Cox regression was used to evaluate survival probability predictors for thigh muscle strains. 84 young male soccer players (16.4 ± 1.6 years) were followed for a season. Baseline tests were performed for body size, body composition, endurance, flexibility, and jump height from both a static position (SJ), and with a countermovement (CMJ); the percentage difference between the two types of jumps was also calculated (ΔJH). Cox regression result (hazard ratio; C.I. 95%) showed that: previous injuries (2.80; 1.19-6.54), ΔJH (0.79; 0.71-0.87), and stature (1.17; 1.06-1.25) were significantly correlated to thigh-strain survival probability. This study confirms that previous injuries are an important risk factor. However, we also report that a negative ΔJH and an elevated stature increased the probability of thigh strain. This could be explained by poor player coordination, influencing jumping ability, which may be even more evident in tall young players.

Remodelling of human hamstring autografts after anterior cruciate ligament reconstruction

PURPOSE

Histological analysis of the remodelling process of human hamstring tendon (HT) grafts after standardized anterior cruciate ligament reconstruction (ACLR) with an accelerated rehabilitation protocol.

METHODS

Sixty-seven patients underwent retrieval of mid-substance biopsies after clinically successful hamstring autograft ACLR. Samples were allocated to one of three groups depending on the time point of retrieval: group 1 (6-12 months; n = 15), group 2 (13-24 months; n = 16) and group 3 (>24 months; n = 11). Biopsies from native HT (n = 17) and ACL (n = 8) served as controls. Cellular density, vascular density and myofibroblast density and collagen fibril alignment were analysed by haematoxylin-eosin, Masson-Goldner-Trichrom and immunohistochemical staining protocols.

RESULTS

Compared with native HT (330.4/mm²), total cell number was increased in groups 1-3 (Group 1 = 482.0/mm² (P = 0.036); group 2 = 850.9/mm² (P = 0.005); and group 3 = 595.6/mm² (P = 0.043). There were no significant differences between the groups for vessel density. Myofibroblast density was higher in group 2 (199.6/mm²) compared with native HT (1.9/mm², P = 0.014). Collagen orientation was irregular up to 12 months. Thereafter, collagen orientation became more regular, adapting to, but not fully restoring, the appearance of the intact ACL. For the first 12 months, cells were predominantly ovoid. Ensuing cell morphology changed to spindle shaped in group 2 and predominantly narrow long cells over 24 months.

CONCLUSION

Human hamstring grafts showed typical stages of graft remodelling, which was not complete up to 2 years after ACLR. The remodelling process in humans was prolonged compared with the results obtained in several animal studies.

LEVEL OF EVIDENCE

Case-control study, Level III.

Examining the effect of the injury definition on risk factor analysis in circus artists

A secondary data analysis of a prospective cohort study was conducted to explore how different definitions of injury affect the results of risk factor analyses. Modern circus artists (n=1281) were followed for 828,547 performances over a period of 49 months (2004-2008). A univariate risk factor analysis (age, sex, nationality, artist role) estimating incidence rate ratios (IRR) with 95% confidence intervals (95% CI) was conducted using three injury definitions: (1) medical attention injuries, (2) time-loss injuries resulting in ≥1 missed performances (TL-1) and (3) time-loss injuries resulting in >15 missed performances (TL-15). Results of the risk factor analysis were dependent on the injury definition. Sex (females to male; IRR=1.13, 95% CI; 1.02-1.25) and age over 30 (<20 years to >30 years; IRR=1.37, 95% CI; 1.07-1.79) were risk factors for medical attention injuries only. Risk of injury for Europeans compared with North Americans was higher for TL-1 and TL-15 injuries compared with medical attention injuries. Finally, non-sudden load artists (low-impact acts) were less likely than sudden load artists (high-impact acts) to have TL-1 injuries, but the risk of medical attention injuries was similar. The choice of injury definition can have effects on the magnitude and direction of risk factor analyses.