B y most reports, soccer is among SUMMARY. and 2 School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Western Australia

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1 Injury Incidence, Body Site, and Severity in Soccer Players Aged 6 18 Years: Implications for Injury Prevention Michael Clemens Rumpf, MS 1 and John Cronin, PhD 2 1 Sports Performance Research Institute New Zealand, Auckland University of Technology, Auckland, New Zealand; and 2 School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Western Australia SUMMARY INJURY INCIDENCE DATA FOR YOUTH PARTICIPANTS IN SOCCER HAVE BEEN COLLATED AND SUM- MARIZED. SUCH INFORMATION SHOULD FORM A BASIS FOR INJURY PREVENTION PRACTICES. PLAYER CONTACT ACCOUNTS FOR MOST INJURIES (40 66%), WHEREAS THE LOWER EXTREMITIES ARE CONSID- ERED THE MOST VULNERABLE IN- JURY SITE IN THE BODY (70%). STRAINS (24%), SPRAINS (31%), AND CONTUSIONS (20%) ACCOUNT FOR 75% OF ALL INJURIES RE- PORTED THROUGHOUT THE IN- CLUDED LITERATURE. THESE SOFT TISSUE INJURIES RESULT IN MINOR (1 3 DAYS, 18%), MILD (3 7 DAYS, 36%), AND MODERATE (.1 WEEK, 30%) RECOVERY DURATIONS. SPE- CIFIC CONSIDERATIONS FOR IN- JURY PREVENTION PROGRAMS ARE PRESENTED. INTRODUCTION B y most reports, soccer is among the most played and/or the most popular sport in many countries. Many athletes in different age groups are participating in organized and unorganized soccer settings, and as such, injuries will occur across all levels of age and play. With injury, practice and competition time are lost. This is especially important in the developmental years of a player (6 18 years). To minimize lost playing time, injury surveillance data need to be collated and translated into injury prevention programs. By understanding the common types of injuries, age relevance, and injury mechanisms, the strength and conditioning coach may formulate a plan to prevent injury. Several different investigations have presented injury data on soccer aged 6 18 years, with the focus on one or a combination of the following points: gender comparison (18), age comparisons (14,18,26), and maturity groups; frequency and type of injuries, injury site, and severity (26); soccer experience (18) and skill level (14); position-specific injuries (18); injury history (18); games versus practice injury risks (26); injury occurrence at the time of the game (26); mechanisms of injury during game and practice (26); and seasonal injury occurrence (12). This article summarizes the major findings from these studies and provides information to guide training practices to prevent injuries in youth soccer. CONSIDERATIONS Several considerations need to be addressedtounderstandhowsurveillance reports were created and how data were evaluated and presented. DEFINITION OF INJURY AND SEVERITY The amount of registered injuries may vary depending on the definition of an injury. The common injury definition was related to injured absence in training or games for more than 48 hours, not including the day of the injury (19,20,26). The severity of injury was based on the duration of absence from training or competition and classed into 4 categories: minor (2 3 days), mild (4 7 days), moderate (1 4 weeks), and major (.4 weeks) (19,20,26). REPORT OF INJURIES AND TYPE OF ASSESSMENT There are multiple ways to assess and report injuries. Specific persons or institutions were used to diagnose and report injuries, that is, a physician (19,20,26), a certified trainer (3), or staff KEY WORDS: youth soccer; injury; prevention; incidence; body site; severity 20 VOLUME 34 NUMBER 1 FEBRUARY 2012 Copyright Ó National Strength and Conditioning Association

2 from a medical clinic (9). Another option was the utilization of retrospective questionnaires (13,14). INJURY OCCURRENCE IN DIFFERENT AGE GROUPS Tables 1 4 present injury incidence per 1,000 hours and the affected body site of soccer, including age associations. The inclusion of studies for data reporting consisted of a 3- to 4-year age range, gender-specific play, and competitive play undertaken by male in outdoor soccer. The analysis of literature did not include any reference to maturation level, injury history, playing position for the, or monthly injury data specifics. It should be noted that data were not presented for the 6- to 8-year-old soccer because of the paucity of quality literature in this area. MAJOR FINDINGS CAUSES OF INJURIES Causes of injury can be related to intrinsic (person-related) or extrinsic (environment-related) factors (6). Examples of each designation are given below: Intrinsic (person-related) factors are as follows: Joint instability, muscle strength, tightness, and asymmetry Body mechanics Psychological (30) Injury history (18). Extrinsic (environment-related) factors are as follows: Level of play and position on the field (5,24,25,30) Amount and standard of training and competition (2) Warm-up and stretching (1,2) Pitch (indoor/outdoor) (10) Quality of pitch (33) Rules of play Equipment. Contact injuries accounted for 40 66% of injuries (5,11,13,15,16), whereas reinjury and poor pitch conditions seemed to be responsible for many injuries as well (2,7). Table 1 Injury incidence and body site for 9- to 12-year-olds Injury location Type of injury Injury rate Duration Level Total/ training/ game Number of Author Age (y) Total Only in #/1,000 h Lower extremities (64%), head (15%), upper extremities (13%), trunk (8%) Elias (9),12 3,370 1 y Cup Soccer Tournament Schiff (27) mo Premier teams Total 1.1 Lower extremity (78%), upper extremity (13%), trunk (9%), head (9%) Schiff (27) mo Premier teams Total 1.4 Lower extremity (78%), upper extremity (13%), trunk (9%), head (9%) Game 7.9 Only with regard to received treatment International tournament boys 5-d tournament Schmidt-Olsen et al. (28) Total 3.4 Knee (29%), ankle (21%), back (13%), lower leg (9%), groin (7%), arm (7%), shoulder (2%), hip and glute region (4%), muscle fiber (3%), eye region (2%), head and face (2%), foot (1%) mo Elite and recreational level in 3 soccer clubs Schmidt-Olsen et al. (29) Strength and Conditioning Journal 21

3 22 VOLUME 34 NUMBER 1 FEBRUARY 2012 Author Age (y) Number of Table 2 Injury incidence and body site for 13- to 15-year-olds Duration Level Total/ training/ game Elias (9),14 3,370 1 y Cup Soccer Tournament Emery et al. (11) Kakavelakis et al. (15) et al. (19) et al. (19) et al. (19) et al. (20), potential 6 wk 1 y Canadian football [soccer] club Injury rate Type of injury Injury location Total Only in #/1,000 h Lower extremities (61%), upper extremities (15%), head (11%), trunk (11%) Total boys 7.88 Only grouped over all Total girls 7.92 age groups 12 to season Not stated Total Training Sprain (33%), strain (23%), contusion (21%), fracture (8%), tendonitis (7%), joint Game 5.6 subluxation (3%), concussion (1%), severe knee injury (1%), miscellaneous (3%) seasons Elite male youth football [soccer] seasons Elite male youth football [soccer] seasons Elite male youth football [soccer], seasons Elite male youth football [soccer] Only grouped over all age groups Total 5.7 Training 4.5 Game 13.2 Total 5.8 Training 4.8 Game 12.3 Total 4.6 Training 4.3 Game 6.5 Total 4.9 Contusion (26%), sprain (18%), Training 4.1 strain (13%), fracture (6%), dislocation (1%), others (37%) Game 9.5 Knee (36%), ankle (29%), upper limb (12%), upper leg (9%), lower leg (6%), torso (5%), head/neck (3%) Upper leg (21%), ankle (18%), knee (18%), foot (10%), back (7%), hand (7%), lower leg (6%), pelvis (6%), arm (3%), hip (2%), shoulder (2%), head (1%), abdomen (1%) Injury Incidence, Body Site, and Severity in Soccer Players Aged 6 18 Years

4 Table 2 (Continued) Strength and Conditioning Journal 23 Author Age (y) Number of et al. (20) et al. (20) Peterson et al. (24) Schmidt-Olsen et al. (29) Duration Level Total/ training/ game, seasons Elite male youth football [soccer], seasons Elite male youth football [soccer],14 to,16 Injury rate Type of injury Total 4.6 Contusion (37%), strain (17%), Training 3.7 sprain (16%), fracture (5%), dislocation (1%), others (24%) Game 10.4 Total 5.2 Contusion (30%), strain (17%), Training 3.8 sprain (16%), fracture (7%), dislocation (1%), others (30%) Game y High level Total Sprain (54%), strain (33%), Training 7.2 contusion (4%), fracture (3%), dislocation (3%), others (3%) Game 35.0 Injury location Upper leg (30%), ankle (16%), knee (14%), back (10%), foot (7%), hand (5%), lower leg (5%), pelvis (4%), arm (3%), hip (3%), shoulder (2%), head (2%) Upper leg (23%), ankle (20%), knee (14%), back (12%), foot (8%), hand (6%), lower leg (5%), pelvis (5%), arm (2%), hip (2%), shoulder (2%), head (1%), abdomen (1%) Complaints for without injury history: ankle (21%), head (16%), lumbar spine (14%), knee (14%), thigh (10%) 23 1 y Low level Total Lumbar spine (35%), Training 14.1 knee (30%), thigh (26%), ankle (22%), head (22%) Game to mo Elite and recreational level in 3 soccer clubs Total 3.8 Knee (25%), ankle (19%), back (19%), lower leg (15%), arm (9%), groin (3%), shoulder (3%), eye region (3%), hip and glute region (3%)

5 24 VOLUME 34 NUMBER 1 FEBRUARY 2012 Author Age (y) Number of Table 3 Injury incidence and body site for 16- to 19-year-olds Duration Level Total/ training/ game Elias (9),16 3,370 1 y Cup Soccer Tournament Elias (9),19 3,370 1 y Cup Soccer Tournament Emery et al. (11) Emery et al. (11) Merron et al. (22) Nielsen and Yde (23) Peterson et al. (24) Schmidt- Olsen et al. (28) Schmidt- Olsen et al. (29), potential, potential 6 wk 1 y Canadian football [soccer] club 6 wk 1 y Canadian football [soccer] club 16 to y English Premier League Football [Soccer] Club 16 to season Danish Soccer Club Injury rate Type of injury Injury location Total Only in #/1,000 h Lower extremities (65%), head (13%), upper extremities (12%), trunk (9%) Total Only in #/1,000 h Lower extremities (70%), head (13%), upper extremities (10%), trunk (7%) Total boys 5.86 Only grouped Total girls 5.74 over all age groups Total boys 3.22 Only grouped Total girls 2.53 over all age groups Only grouped over all age groups Only grouped over all age groups Total 8.07 Knee (19%), ankle (19%), foot (8%), Training 6.1 lower leg (7%), thigh (7%), spine (7%), pelvis (7%), groin (6%), abdomen (6%), Game 25 hamstrings (5%), arm (5%), head (3%), hip (3%) Total 3.6 Ankle (37%), knee (22%), others (18%), Training 14.4 groin/thigh (15%), foot (8%) Game,16 to, y High level Total Only for all age Training 7.9 groups Game 38.4 Complaints for without injury history: head (20%), lumbar spine (19%), ankle (17%), thigh (16%), knee (16%) 22 1 y Low level Total Lumbar spine (41%), ankle (36%), head Training 17.4 (23%), thigh (18%), knee (14%) 17 to 19 1,292 boys 5-d tournament International tournament 16 to mo Elite and recreational level in 3 soccer clubs Game 63.8 Game 20.6 Only with regard to received treatment Total 4.0 Ankle (28%), knee (23%), back (11%), lower leg (11%), groin (9%), arm (8%), shoulder (3%), hip and glute region (2%), eye region (1%), head and face (1%) Injury Incidence, Body Site, and Severity in Soccer Players Aged 6 18 Years

6 Table 4 Injury incidence in relation to total, training, and game values with regard to age groups 1,000 hours 6 SD) INJURY INCIDENCE IN TRAINING VERSUS GAMES In comparison with training situations, games involve greater speed and generally more stress on the body. As a result, there are more injuries, and more severeinjuriesareexpectedtohappenin games compared with training sessions. INJURY INCIDENCE IN DIFFERENT LEVELS OF PLAY Questions arise whether higher soccer skills/standards and level of play influence injury incidence. High-skilled versus low-skilled were identified via coach ratings (30) or by their team placement in a league system. Therefore, teams of high-skilled were placed in higher leagues than those involving low-skilled (5,24,25). Because of different skill levels and involvement in the game, injury incidence varied. Low-level experienced a greater amount of injuries in general (30) and a greater amount of severe injuries (24) compared with high-skilled. The risk probability for severe injuries was twice as high for low-skilled compared with highskilled (5). However, Chomiak et al. (5) also stated that there were no general differences between low- and high-skilled groups in frequency of injury. In general, high-skilled were cited as those with lower injury risks (24). Possible explanations were a greater exposure to training (24) and therefore a higher training to game ratio, whereas low-skilled attended more competitions, where injuries occurred more often (25). INJURY INCIDENCE IN DIFFERENT LEVELS OF EXPERIENCE Less experienced soccer were reported to have a higher incidence of Age 9 12 y Age y Age y Total Training Game injury compared with experienced (30). It is proposed that experienced were able to avoid injury because of their familiarity with injury-causing situations. INJURY INCIDENCE IN CONNECTION WITH THE AMOUNT AND STANDARD OF TRAINING A higher amount of training sessions and a longer preseason period were related to fewer injuries during the competitive season (2). Additionally, the quality of the training was another factor influencing injury occurrences in soccer. Proper warm-up and stretching programs were related to absence of muscle strain injuries (1). Evidence for the effectiveness of proper warm-up and flexibility procedures was observed in adult soccer (8). Shooting on goal before warm-up was the main reason for quadriceps strains. The absence of special flexibility programming for hamstrings increased strain injury risks (8). INJURY OCCURRENCE ACCORDING TO PLAYING POSITION Defenders and midfielders were injured more often than strikers and goalkeepers. Generally, the incidence of injury increased with age for all positions, except for goalkeepers. Goalkeepers younger than 14, 15, and 16 years experienced similar levels of injury compared with field. DIFFERENCES IN INJURY OCCURRENCE, BODY SITE, AND SEVERITY ASSOCIATED WITH DIFFERENT MATURITY STATUSES Maturity status was not related to the risk of injury in youth soccer (19). Early and normal maturers experienced a nonsignificant higher injury incidence compared with late maturers. Normal maturation of subjects referred to a skeletal maturity within 1 year of chronological age; early maturation referred to a skeletal maturity older than 1 year of chronological age, and late maturation referred to a skeletal age more than 1 year younger than chronological age. However, the severity of injury was greater in late maturers compared with early maturers. The one and only significant difference between in different maturational groups was related to knee injury as the most injured site in normal and late maturers compared with the thigh in early maturers. Early maturers experienced greater incidence of groin injuries, strains, and sprains, whereas normal maturers experienced more back problems compared with other maturational groups. DIFFERENCES IN INJURY OCCURRENCE OVER THE CALENDAR YEAR Injuries vary throughout the season. Training injuries peaked in/after preseason in January, and competitive injuries peaked after a midseason break (26). However, et al. (19) determined that September had the highest rate of injuries, but Chomiak et al. (5) did not find any differences in injury occurrence over different months of the year. DIFFERENCES IN INJURY OCCURRENCE WITH RESPECT TO INJURY HISTORY Youth with a previous injury or youth athletes with multiple injuries were at greater risk of injury incidence. Players with a single previous injury had a 2-fold greater risk of injury. Two or more previous injuries altered the risk of injury to 3 times the risk in without previous injuries (18). Besides individual injury histories, insufficient rehabilitation was a critical factor in reinjuries. DIFFERENCES IN INJURY OCCURRENCE IN MALES VERSUS FEMALES Girls show a 2-fold greater injury risk in comparison with boys (28,33). Females Strength and Conditioning Journal 25

7 26 VOLUME 34 NUMBER 1 FEBRUARY 2012 Author Backous et al. (3) Chomiak et al. (5) Emery et al. (11) Hoff and Martin (13) Age (y) Number of Duration Level Injury rate 6 to boys 4.5 d State camp Total boys = 7.3; total girls = to 16,14 to, potential 1 y Players from different skill levels (local teams to first league teams) in the Czech Republic 344 potential 6 wk 1 y Canadian football [soccer] club 8 to seasons Soccer league Table 5 Body site, type of injury, and severity Type of injury Injury location Severity of injury Strain/quadriceps (11%), strain/leg (10%), sprain/ ankle (7%), contusion/knee (7%), contusion/leg (7%), contusion/ankle (7%), blisters/foot (5%), contusion/ head (5%), contusion/foot (4%), strain/groin (4%), strain/ knee (4%), contusion/nose (3%), strain/back (2%), strain/ fingers (2%), sprain/wrist (2%), strain/foot (2%), strain/ankle (1%), others (16%) Sprain (35%), fracture (22%), strain (12%), rupture (12%), contusion (6%), dislocation (5%), others (19%) Total boys ( ); total girls ( ) Not reported Ankle sprain (39%), groin strain (13%), calf strain (13%), concussion (13%), thigh strain (7%), back strain (6%), knee sprain (4%) Sprain (35%), strain (24%), contusion (17%), fractures (2%), others (22%) Reported in combination with type of injury Only for ages y Ankle (25%), lower leg (16%), knee (13%), head/ face (10%), groin (10%), upper leg (6%), foot (6%), back (6%), ribs (3%) Lower extremities (66%), head/face (22%), trunk (8%), upper extremities (6%) Different categories Injury Incidence, Body Site, and Severity in Soccer Players Aged 6 18 Years

8 Table 5 (Continued) Author Age (y) Number of Duration Level Injury rate Type of injury Injury location Severity of injury Kakavelakis et al. (15) 12 to season Soccer clubs Total (4.0); training (3.3); game (5.6) Sprain (33%), strain (23%), contusion (21%), fracture (8%), tendonitis (7%), joint subluxation (3%), concussion (1%), severe knee injury (1%), miscellaneous (3%) Knee (36%), ankle (29%), upper limb (12%), upper leg (9%), lower leg (6%), torso (5%), head/neck (3%) Minor (not reported), mild (30%), moderate (38%), major (32%) et al. (20),14 to, season Elite male youth football [soccer] Total (39.2); training (11.2); game (4.8) Contusion (31%), sprain (17%), strain (16%), fracture (6%), dislocation (1%), others (29%) Upper leg (25%), ankle (18%), knee (15%), back (9%), foot (8%), hand (6%), lower leg (5%), pelvis (5%), arm (3%), hip (2%), shoulder (2%), head (1%), abdomen (1%) Minor (31%) Mild (29%) Moderate (30%) Major (10%) Strength and Conditioning Journal 27 et al. (19) McCarroll et al. (21) Merron et al. (22), seasons Elite male youth football [soccer] 8 to 18 4,018 1 season Youth Soccer Association 16 to y Premiership English Football [Soccer] Club Total (5.6); training (4.7); game (11.8) Only in % per age group Total (8.07); match (25); training (6.1) Minor (26%), mild (33%), moderate (31%), major (10%) Sprain (27%), contusion (25%), fracture (13), strain (19%), concussion (3%), others (23%) Impossible to determine Ankle (19%), knee (19%), foot (8%), lower leg (7%), quadriceps (7%), pelvis (7%), spine (7%), groin (6%), abdomen (6%), hamstrings (5%), arm (5%), hip (1%), chest (1%), head (1%) Mild (36%), moderate (37%), major (27%) (continued)

9 28 VOLUME 34 NUMBER 1 FEBRUARY 2012 Author Peterson et al. (24) Price et al. (26) Schmidt-Olsen et al. (28) Sullivan et al. (33) Age (y),14 to,16 Number of Duration Level Table 5 (Continued) Injury rate 70 1 y High level Training (7.2); game (35.0) 23 1 y Low level Training (14.1); game (59.4) 9 to football academies, 4, to 19 1,292 boys 5-d 232 girls tournament 2 seasons English Football [Soccer] Academies International tournament,19 1,272 1 season Soccer Federation for Western Oklahoma Type of injury Injury location Severity of injury Sprain (54%), strain (33%), contusion (4%), fracture (3%), dislocation (3%), others (3%) Strain (31%), sprain (20%), contusion (8%), fracture (4%), dislocation (1%), others (30%) Total boys (20.6); total girls (47.2) Boys (0.51); girls (1.1) Total: contusion (33%), blisters (17%), sprain/ankle (13%), strain/muscle (10%), skin abrasions and cuts (7%), overuse (5%), sprain/ knee (4%), sprain/upper extremity (4%), fractures/ upper extremities (3%), concussions (1%), fractures/clavicular (1%), fractures/lower extremities (1%), others (1%) Contusion (38%), sprain (35%), strain (9%), fracture (6%), dislocation (3%), others (9%) Complaints for without injury history: ankle (21%), head (16%), lumbar spine (14%), knee (14%), thigh (10%) Lumbar spine (35%), knee (30%), thigh (26%), ankle (22%), head (22%) Thigh (19%), ankle (19%), knee (18%), lower leg (10%), groin (9%), foot (8%), lumbar spine (4%), hip (3%), toe (1%), skull (1%), shoulder (1%), abdomen (1%), finger (1%), others (4%) Total: foot and toes (28%), ankle (16%), thigh (15%), lower limb (10%), knee (10%), hand and fingers (6%), head and face (5%), arm (2%), trunk (2%), groin and hip (2%), shoulder (2%), back (2%) Youth 16 18: highskill : mild (55%), moderate (35%), major (10%); low skill : mild (61%), moderate (21%), major (17%) Youth 14 16: highskill : mild (57%), moderate (30%), major (13%); low-skill : mild (43%), moderate (30%), major (25%) Minor (10%), mild (23%), moderate (44%), major (22%) Only in relation to treatment Injury Incidence, Body Site, and Severity in Soccer Players Aged 6 18 Years

10 Women were responsible for 44% of all reported injuries (33) and represented 27% of the studied population. A higher injury rate in female soccer compared with the male counterparts of the same age was explained by the lack of experience and inferior technical skills (4). However, a more recent study reported only a nonsignificant higher risk for girls compared to boys (32). DIFFERENCES IN INJURY OCCURRENCE IN INDOOR VERSUS OUTDOOR SOCCER Youth soccer (,16 years of age) had a 2-fold greater chance of sustaining a training injury. Indoor soccer has a 4.5-fold greater injury risk than outdoor soccer (13). Not only the injury occurrence but also the severity of the injuries were different in indoor versus outdoor soccer. Severity differed as 6.5% of outdoor injuries and 24.3% of indoor injuries required medical assistance (13). The lower extremities were the most common site for an injury in both environments. BODY SITE, TYPE OF INJURY, AND SEVERITY Table 5 and Figures 1 3 summarize data pertaining to the affected body site, type of injury, and severity of injury in youth soccer athletes aged 7 19 years. In assimilating this information, no attention was paid to age bands, maturation level, injury history, positions, game injury versus training injury, or time frame in the calendar year. The lower extremities are the most affected body site for injuries (70%) (Figure 1). However, 56% of all injuries are healed within 1 week (Figure 2). The most common injuries were ankle sprains (31%), strains (23%), and contusions (20%) (Figure 3). SUMMARY AND PRACTICAL APPLICATIONS In terms of injury prevention, it would seem that enforcing rules of fair play in soccer is important because more than 60% of all injuries are from contact situations. Complete rehabilitation of Figure 1. Type of injury in youth soccer. a player s injury is critical in prevention of reinjury. Strength and conditioning coaches, athletic trainers, and/or physiotherapists need to ensure that the complete progressive functional exercise programs and a comprehensive battery of tests before returning to play. Players physical preparations in the form of training and appropriate injury prevention programs might affect the Figure 2. Severity of injuries in youth soccer. incidence of injury. High training/game time and longer preseasons have been shown to lower injury occurrence (8) and proper warm-up and stretching procedures (1). Therefore, warm-up and injury prevention can be combined into a single protocol. The FIFA 11+ as a soccer-specific warm-up and injury prevention program has already been established and shown to reduce injury in young female soccer (31) and Strength and Conditioning Journal 29

11 Injury Incidence, Body Site, and Severity in Soccer Players Aged 6 18 Years physical ability) and characteristics (maturation, flexibility, and asymmetries) is needed for youth soccer. Michael Clemens Rumpf is a PhD candidate at the Auckland University of Technology. John Cronin is the director of the Sport Performance Research Institute New Zealand and professor of Strength and Conditioning, Exercise Science Stream. Figure 3. Injured body site of youth soccer. improved physical abilities of young male soccer (17). Further soccer-specific preparation programs should also take different forms of muscle contractions, including speed and joint position related to game actions. In addition to injury prevention programs, specific screening programs would help identify who are more likely to get injured, that is, with injury history, muscle tightness, asymmetries, and joint instability. The injury prevention program for youth soccer needs to account for the following research outcomes: (a) injury incidence increased with age and especially after the age of 14 regardless of maturity and experience, (b) the lower extremities, mainly the ankle and knee joints and accompanied muscles and ligaments of the thigh and calf, were the most injured body site (;80%), (c) severe injuries were more likely to be experienced by low-skilled, (d) indoor soccer had a greater risk of injury compared with outdoor soccer, (e) poor pitch conditions were a significant external factor affecting injury occurrence, and (f) higher incidences of injury occurred in female. Finally, only few studies investigated the injury occurrence and its relation to maturity status. As stated previously, injury occurrence was not significantly different in various maturation levels (19). Injuries increase steadily with age but definitely after the age of 14, which coincides with peak height velocity (PHV) or pubescence in boys. Therefore, an optimal time to introduce sportspecific preparation and injury prevention protocols would occur before the onset of PHV. Further research should take maturation, injury occurrence, injury history, reinjuries, and especially etiology of injury into consideration. To gain better insight into the prevention of soccer injuries, more information pertaining to subject parameters (position played, accumulated training hours, and REFERENCES 1. Agre JC and Baxter TL. Musculoskeletal profile of male collegiate soccer. Arch Phys Med Rehabil 68: , Arnason A, Gudmundsson A, Dahl HA, and Johannsson E. Soccer injuries in Iceland. Scand J Med Sci Sports 6: 40 45, Backous DD, Friedl KE, Smith NJ, Parr TJ, and Carpine WD Jr. Soccer injuries and their relation to physical maturity. Am J Dis Child 142: , Baxter-Jones A. The young athlete. In: Paediatric Exercise Physiology. Armstrong N, ed. Philadelphia, PA: Churchill Livingstone Elsevier, pp Chomiak J, Junge A, Peterson L, and Dvorak J. Severe injuries in football [soccer]. Influencing factors. Am J Sports Med 28: 58 68, Dvorak J and Junge A. Football [soccer] injuries and physical symptoms. A review of the literature. Am J Sports Med 28: 3 9, Ekstrand J and Gillquist J. The avoidability of soccer injuries. Int J Sports Med 2: , Ekstrand J, Gillquist J, Möller M, Öberg B, and Liljedahl S-O. Incidence of soccer injuries and their relation to training and team success. Am JSportsMed11: 63 67, Elias SR.10-year trend in USA Cup soccer injuries: Med Sci Sports Exerc 33: , Emery CA and Meeuwisse WH. Risk factors for injury in indoor compared with 30 VOLUME 34 NUMBER 1 FEBRUARY 2012

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