The injury epidemiology in soccer

This article aims to provide a summarized analysis and a guideless of injury epidemiology in soccer.

Soccer is an interaction sport characterized by the alternance of high-intensity actions, thus implying a high injury incidence (1,3). In recent years there has been an increased physical demands in competition, being more aggressive and requiring better physical preparation of players to withstand the match demands (4,5). In addition, considering the high number of matches in high-level soccer during the season, playing two matches per week over a long period of season (a total of 60-70 matches), it is logically understood the augmented injury risk of players in soccer practice (1,3). In this way, although several authors showed that a recovery time of 72 to 96 hours between two matches is sufficient to maintain the level of physical performance, it is not enough time to maintain a low injury rate (6). On the other hand, the player age, training load (TL), level of competition and training standard are some of the main injury risk factors (3). 

The systematic review and meta-analysis performed by Pfirrmann et al. (3) with high-level junior and senior soccer players, it has been shown a total injury incidence of 2.0 to 19.4 injuries per 1000 hours of practice in junior players; and  2.5 to 9.4 injuries per 1000 hours of practice in professional senior soccer players, with the higher injury incidence found in competition. In the same way, Ekstrand et al. (1) accounted a total of 50 injuries per season by team, that’s 2 injuries by player. 57% of these injuries are in match whereas a 43% are in training sessions.

Main conclusions

Retrieved from the bibliography reviewed relative to the epidemiological analysis in soccer are:

• There are more injuries in match than in training sessions. 
• The most common injuries are the muscle strain, ligament sprain and contusion.
• Muscular injuries account for 30% of all injuries.
• The most common body location is the thigh in both junior and senior soccer players. The following most common were the knee, the ankle and the hip/groin. In addition, this injury pattern is not affected by the player age.
• Thigh strains represent the 17% of injury incidence and 7 of 10 injuries are in hamstrings.
  • Hamstrings strain: 12% 
  • Quadriceps strain: 5% 
• Other injuries:
  • Adductor pain/strain: 9%
  • Ankle sprain: 7%
  • Medial collateral knee ligament (MCL): 5%
• The high risk of hamstring strain reflects the high intensity of professional soccer.
• Overuse injuries account for 27 to 33% of the injury incidence. These injuries are caused by a repetitive stress without sufficient time to undergo the natural regenerative process. 
• 2/3 of injuries are trauma injuries: 81% in match and 59% in training. 
• Severe injuries, which accompany longer recovery process and RTP, occurred more often during matches.
• Most common severe injuries: 
  • Hamstring strain (12%)
  • MCL knee sprain (9%)
  • Quadriceps strain (7%)
  • Adductor pain/strain (6%)
• 21% of all injuries are due to foul play: ankle sprain (15%), knee sprain (9%) and thigh contusion (10%).
• Head injury: 2%.
• Fractures represent only a small percentage of all injuries.
• In young soccer players, the most severe injuries occurred in the range age between 14 to 16 years. 
• Reinjury (R-in):
  • The injury risk factors (RF) are 4 to 7 times higher for soccer players previously injured.
  • Ekstrand et al. accounted the R-in incidence for 12% of injury incidence in professional soccer players. However, there are differences in the research (9-30%) which author attributes for a better medical support in elite clubs. 
  • R-in causes longer absences than new injuries.
  • Junior players had lower reinjury rate.
  • R-in are more common during training than match.
  • These injuries are overuse injuries.
• There are differences in the injury incidence according to the season period.
  • Preseason (few matches, high training volume)
    • Overuse injuries (e.g., groin pain)
    • Quadriceps strain. 
  • Competitive period (many matches, high intensity)
    • Traumatic injuries, hamstring strain (previously commented)
  • Injury incidence increases towards the end of each half of play (fatigue).
  • The injury incidence during matches is influenced by the playing position: midfield players and defenders were the most at-risk groups*.

*However, although a there are authors showing differences between playing positions, a recent systematic review did not find enough evidence to provide general considerations of injury incidence by position (7). Only goalkeepers show lower injury incidence.  

Table 1 shows a visual guideless of injury epidemiology in soccer.

	Elite Youth Soccer Players	Professional Adults Soccer Players
Total Injury Incidence	From 2.0 to 19.4 injuries per 1000 h(+ severe on match and 14-16y than older adolescents)	From 2.5 to 9.4 injuries per 1000 h(the majority were moderate severity and ≤ 1 week)
Incidence on Match	From 9.5 to 48.7 injuries per 1000 h	From 8.7 to 65.9 injuries per 1000 h
Incidence on Training	From 3.7 to 11.1 injuries per 1000 h	From 1.4 to 5.8 injuries per 1000 h
Match-Training relationship	Match >x5 than Training	Higher during matches53% on match, 47% training
Most common injury types	Strains, sprains and contusions2/3 Traumatic – 1/3 overuse (*Prevention plans)	Strains, sprains and contusions
Most frequently injured body part	Thigh – Hamstrings	Thigh – Hamstrings (strains)
Most frequently injury	–	Hamstrings strain*Quadriceps injury = Longer absence
Others injuries	Ankle, knee, groin, lower limb*Fractures: small % but major injury	Groin, knee, ankle*Fractures: small % but major injury
Reinjury	Sprains (42.9%) and strains (22.9%)	15.3% of all injuries
	+40% recovery time than initial injury	2/3 or 63% were overuse injuries
	Most common during training	16% of Hamstring injuries
	Overuse injuries	Needs + recovery time

References

1. Ekstrand J, Hägglund M, Waldén M. Injury incidence and injury patterns in professional football: The UEFA injury study. Br J Sports Med. 2011;45(7):553–8. 
2. Guerrero-Calderón B. The effect of short-term and long-term coronavirus quarantine on physical performance and injury incidence in high-level soccer. Soccer Soc. 2020 Jun 7;00(00):1–11.
3. Pfirrmann D, Herbst M, Ingelfinger P, Simon P, Tug S. Analysis of injury incidences in male professional adult and elite youth soccer players: A systematic review. J Athl Train. 2016;51(5):410–24. 
4. Bradley PS, Archer DT, Hogg B, Schuth G, Bush M, Carling C, et al. Tier-specific evolution of match performance characteristics in the English Premier League: it’s getting tougher at the top. J Sports Sci [Internet]. 2016 May 18 [cited 2017 Jan 29];34(10):980–7.
5. Carling C. Interpreting physical performance in professional soccer match-play: Should we be more pragmatic in our approach? Sport Med. 2013;43(8):655–63. 
6. Dupont G, Nedelec M, McCall A, McCormack D, Berthoin S, Wisløff U. Effect of 2 soccer matches in a week on physical performance and injury rate. Am J Sports Med. 2010;38(9):1752–8. 
7. Della Villa F, Mandelbaum BR, Lemak LJ. The Effect of Playing Position on Injury Risk in Male Soccer Players: Systematic Review of the Literature and Risk Considerations for Each Playing Position. Am J Orthop (Belle Mead NJ). 2018;47(10).

Berni Guerrero-Calderón

S&C Coach | Rehab Therapist | Sport Scientist 

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This article has been made based on the references showed, other studies reviewed but not showed and according to the experience and knowledge of the author. In this way, it may include subjective ideas and opinions not contrasted in the research.