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
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).
INJURY INCIDENCE IN TRAINING VERSUS GAMES
In comparison with training situations, games involve greater speed and generally more stress on the players' body. As a result, there are more injuries, and more severe injuries are expected to happen in 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 players versus low-skilled players were identified via coach ratings (30) or by their team placement in a league system. Therefore, teams of high-skilled players were placed in higher leagues than those involving low-skilled players (5,24,25). Because of different skill levels and involvement in the game, players' injury incidence varied. Low-level players experienced a greater amount of injuries in general (30) and a greater amount of severe injuries (24) compared with high-skilled players. The risk probability for severe injuries was twice as high for low-skilled players compared with high-skilled players (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 players 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 players attended more competitions, where injuries occurred more often (25).
INJURY INCIDENCE IN DIFFERENT LEVELS OF EXPERIENCE
Less experienced soccer players were reported to have a higher incidence of injury compared with experienced players (30). It is proposed that experienced players 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 players.
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 players (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 players 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, Le Gall 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 players 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 players 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 Women were responsible for 44% of all reported injuries (33) and represented 27% of the studied population. A higher injury rate in female soccer players 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 non-significant higher risk for girls compared to boys (32).
DIFFERENCES IN INJURY OCCURRENCE IN INDOOR VERSUS OUTDOOR SOCCER
Youth soccer players (<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, players' 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 a player's injury is critical in prevention of reinjury. Strength and conditioning coaches, athletic trainers, and/or physiotherapists need to ensure that the players 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 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 players (31) and improved physical abilities of young male soccer players (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 players who are more likely to get injured, that is, players 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 players, (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 players.
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 sport-specific 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 physical ability) and characteristics (maturation, flexibility, and asymmetries) is needed for youth soccer players.
1. Agre JC and Baxter TL. Musculoskeletal profile of male collegiate soccer players. Arch Phys Med Rehabil
68: 147–150, 1987.
2. Arnason A, Gudmundsson A, Dahl HA, and Johannsson E. Soccer injuries in Iceland. Scand J Med Sci Sports
6: 40–45, 1996.
3. 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: 839–842, 1988.
4. Baxter-Jones A. The young athlete. In: Paediatric Exercise Physiology
. Armstrong N, ed. Philadelphia, PA: Churchill Livingstone Elsevier, 2007. pp. 299–324.
5. Chomiak J, Junge A, Peterson L, and Dvorak J. Severe injuries in football [soccer] players. Influencing factors. Am J Sports Med
28: 58–68, 2000.
6. Dvorak J and Junge A. Football [soccer] injuries and physical symptoms. A review of the literature. Am J Sports Med
28: 3–9, 2000.
7. Ekstrand J and Gillquist J. The avoidability of soccer injuries. Int J Sports Med
2: 124–128, 1983.
8. 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 J Sports Med
11: 63–67, 1983.
9. Elias SR.10-year trend in USA Cup soccer injuries: 1988-1997. Med Sci Sports Exerc
33: 359–367, 2001.
10. Emery CA and Meeuwisse WH. Risk factors for injury
in indoor compared with outdoor adolescent soccer. Am J Sports Med
34: 1636–1642, 2006.
11. Emery CA, Meeuwisse WH, and Hartmann SE. Evaluation of risk factors for injury
in adolescent soccer: Implementation and validation of an injury
surveillance system. Am J Sports Med
33: 1882–1891, 2005.
12. Hawkins RD and Fuller CW. A prospective epidemiological study of injuries in four English professional football [soccer] clubs. Br J Sports Med
33: 196–203, 1999.
13. Hoff GL and Martin TA. Outdoor and indoor soccer: Injuries among youth players. Am J Sports Med
14: 231–233, 1986.
14. Junge A, Dvorak J, Chomiak J, Peterson L, and Graf-Baumann T. Medical history and physical findings in football [soccer] players of different ages and skill levels. Am J Sports Med
28: 16–21, 2000.
15. Kakavelakis KN, Vlazakis S, Vlahakis I, and Charissis G. Soccer injuries in childhood. Scand J Med Sci Sports
13: 175–178, 2003.
16. Kibler WB. Injuries in adolescent and preadolescent soccer players. Med Sci Sports Exerc
25: 1330–1332, 1993.
17. Kilding A, Tunstall H, and Kuzmic D. Suitability of FIFA's “The 11” training programme for young football [soccer] players—Impact on physical performance. J Sci Med Sport
7: 320–326, 2008.
18. Kucera KL, Marshall SW, Kirkendall DT, Marchak PM, and Garrett WE Jr. Injury
history as a risk factor for incident injury
in youth soccer
. Br J Sports Med
39: 462–466, 2005.
19. Le Gall F, Carling C, and Reilly T. Biological maturity and injury
in elite youth football [soccer]. Scand J Med Sci Sports
17: 564–572, 2007.
20. Le Gall F, Carling C, Reilly T, Vandewalle H, Church J, and Rochcongar P. Incidence
of injuries in elite French youth soccer
players: A 10-season study. Am J Sports Med
34: 928–938, 2006.
21. McCarroll JR, Meaney CJ, and Sieber JM. Profile of youth soccer
injuries Physician Sportsmed
12: 113–117, 1984.
22. Merron R, Selfe J, Swire R, and Rolf CG. Injuries among professional soccer players of different age groups: A prospective four-year study in an English Premier League Football [Soccer] Club. Int Sport Med J
7: 266–276, 2006.
23. Nielsen AB and Yde J. Epidemiology and traumatology of injuries in soccer. Am J Sports Med
17: 803–808, 1989.
24. Peterson L, Junge A, Chomiak J, Graf-Baumann T, and Dvorak J. Incidence
of football [soccer] injuries and complaints in different age groups and skill-level groups. Am J Sports Med
28: 51–57, 2000.
25. Poulsen TD, Freund KG, Madsen F, and Sandvej K. Injuries in high-skilled and low-skilled soccer: A prospective study. Br J Sports Med
25: 151–153, 1991.
26. Price RJ, Hawkins RD, Hulse MA, and Hodson A. The Football [Soccer] Association medical research programme: An audit of injuries in academy youth football. Br J Sports Med
38: 466–471, 2004.
27. Schiff MA. Soccer injuries in female youth players. J Adolesc Health
40: 369–371, 2007.
28. Schmidt-Olsen S, Bünemann LK, Lade V, and Brassoe JO. Soccer injuries of youth. Br J Sports Med
19: 161–164, 1985.
29. Schmidt-Olsen S, Jørgensen U, Kaalund S, and Sørensen J. Injuries among young soccer players. Am J Sports Med
19: 273–275, 1991.
30. Schwebel DC, Banaszek MM, and McDaniel M. Brief report: Behavioral risk factors for youth soccer injury
. J Pediatr Psychol
32: 411–416, 2007.
31. Soligard T, Myklebust G, Steffen K, Holme I, Silvers H, Bizzini M, Junge A, Dvorak J, Bahr R, and Andersen TE. Comprehensive warm-up programme to prevent injuries in young female footballers: Cluster randomised controlled trial. BMJ
337: 2469, 2008.
32. Spinks AB and McClure RJ. Quantifying the risk of sports injury
: a systematic review of activity-specific rates for children under 16 years of age. Br J Sports Med
41: 548–557, 2007.
33. Sullivan JA, Gross RH, Grana WA, and Garcia-Moral CA. Evaluation of injuries in youth soccer
. Am J Sports Med
8: 325–327, 1980.
Keywords:© 2012 National Strength and Conditioning Association
youth soccer; injury; prevention; incidence; body site; severity