By Nirmala Perera (@Nim_Perera) with contributions from Martin Hägglund (@MHgglund) and Markus Waldén (@MarkusWalden)

What are the most common/’costly’ football injuries?

Hamstring Injuries

Hamstring injuries are the most common injuries in football. The findings are consistent across studies. In fact, hamstring injury rates seem to be increasing in elite football.¹ The long head of biceps femoris is most at risk, sustaining more than 80% of the hamstring injuries/strains. Approximately every eighth injury leading to time-loss in football is associated with hamstrings. Hamstring injury affects more than one fifth of elite players over a season. Additionally, hamstring injuries are one of the most ‘costly’ injuries in football in terms of time-loss. The median time-loss from a hamstring injury is about two weeks, but due to their high incidence they comprise approximately 14% of the total days lost from the sport.

ACL Injuries

Anterior cruciate ligament (ACL) injuries are not as common as hamstring injuries in football. It is, however, well-known that female players are up to three times more likely to incur an ACL injury compared with male players.²  The underlying reason for this remains unclear. Men’s professional football clubs are faced with an ACL injury every other season, whereas female elite clubs can expect an injury every season. A recent 15-year follow-up study of men’s professional footballers reported that ACL injury rates have unfortunately not declined since 2000s in spite of substantial research on prevention of these injuries.³

Although not being among the most frequent injury types, ACL injuries are a significant time-loss injury. Few players with a total ACL tear go back to the pitch before six months. The average time-loss in Waldén and colleague’s aforementioned study was almost seven months to the release to full team training and another month to match play.³

What are the most important risk factors and injury mechanisms?

Previous injury is the number one risk factor for most football injuries.^4,5 Low (eccentric) muscle strength and higher age are other factors associated with hamstring injury occurrence. Acute posterior thigh pain during high speed running is the most common hamstring injury situation in football.

The most common ACL injury mechanism in male elite players is pressing, where a player makes a side-step cut during a defensive playing situation. In addition, landing awkwardly on one leg after a heading duel is another established non-contact injury mechanism.⁶ Studies on women’s football are scarce and, therefore, it is not fully clear if the same injury mechanisms are at play.⁷

Short-term and accumulated fatigue seem to play a crucial role in hamstring injuries.⁸ For instance, accumulated fatigue over a congested playing period has been associated with increased hamstring injury rates. In addition, more hamstring injuries tend to occur towards the end of matches. In contrast, most ACL injuries occur early in the game, typically just after kick-off or after substitution, and it is, therefore, more likely that these injuries might be the result of accumulated fatigue over time rather than game-related energy depletion.

What are the most effective injury prevention strategies?

Injury prevention is most effective when it starts in youth football. These programs can improve motor control, therefore potentially reduce injury risk. Neuromuscular training programs such as FIFA 11+ and FIFA11+ for kids (http://f-marc.com/11plus/home/) and Knäkontroll (https://itunes.apple.com/se/app/knakontroll/id573826071?l=en&mt=8) are efficacious in reducing lower limb and knee injury rates, respectively.^9,10

For instance, the overall ACL injury rate was reduced by two-thirds in adolescent female football players who used the Knäkontroll program during one season.¹⁰ An important note is that adherence to training is a key factor for successful prevention, where players who were in the top adherence tertile in the Knäkontroll RCT had a 88% lower rate of ACL injury compared with players in the bottom tertile.¹¹

The most effective hamstring injury prevention measure to date is the Nordic hamstring exercise (NHE). Football players who adhere to eccentric training programs are they shown to reduce hamstring injury rates by 50%.¹² Still, a recent survey study from European professional football suggest that adoption and implementation of the NHE was poor among the teams.¹³

How can we boost adherence to injury prevention programs?

As discussed above, neuromuscular injury prevention programs and hamstring exercises are beneficial when players adhere to the programs and when they perform the exercises as prescribed. Coaches’ involvement, having high self-efficacy and being in control of the intervention are key factors to increase adherence. Better team success is evident when clubs ‘buy-in’ to invest in injury prevention.¹⁴ Similarly, buy-in from coaches boost the self-efficacy.

Organisational factors such as time constraints, worry that the exercises are not sports specific, not adapted to environment are barriers for adherence. Therefore it is important to have a clear plan of implementation, understand the context and provide support to coaches and empower players.

#IOCprev2017

Looking for more cutting-edge information on this topic? The IOC World Conference on Prevention of Injury and Illness in Sport in Monaco (#IOCprev2017) will showcase the latest research innovations in football injury prevention. Notably, Martin and Markus will share their latest research during several symposiums.

References

1. Ekstrand J, Waldén M, Hägglund M. Hamstring injuries have increased by 4% annually in men’s professional football, since 2001: a 13-year longitudinal analysis of the UEFA Elite Club injury study. Br J Sports Med 2016;50:731-7.
2. Waldén M, Hägglund M, Werner J, Ekstrand J. The epidemiology of anterior cruciate ligament injury in football (soccer): a review of the literature from a gender-related perspective. Knee Surg Sports Traumatol 2011;19:3-10.
3. Waldén M, Hägglund M, Magnusson H, Ekstrand J. Anterior cruciate ligament injuries in men’s professional football: a 15-year prospective study on time-trends and return to play rates reveals only 65% of players still play at the top level 3 years after ACL rupture. Br J Sports Med 2016;50:744-50.
4. Hägglund M, Waldén M, Ekstrand J. Previous injury as a risk factor for injury in elite football – a prospective study over two consecutive seasons. Br J Sports Med 2006;40:767-72.
5. Hägglund M, Waldén M, Ekstrand J. Risk factors for lower extremity muscle injury in professional soccer: the UEFA injury study. Am J Sports Med 2013;41:327-35.
6. Waldén M, Krosshaug T, Bjørneboe J, Andersen TE, Faul O, Hägglund M. Three distinct mechanisms predominate in non-contact anterior cruciate ligament injuries in male professional football: a systematic video analysis of 39 cases. Br J Sports Med 2015;49:1452-60.
7. Brophy RH, Stepan JG, Silvers HJ, Mandelbaum BR. Defending Puts the Anterior Cruciate Ligament at Risk During Soccer A Gender-Based Analysis. Sports Health 2015;7:244-9.
8. Bengtsson H, Ekstrand J, Hägglund M. Muscle injury rates in professional football increase with match congestion – an 11-year follow up of the UEFA Champions League injury study. Br J Sports Med 2013;47:743-7.
9. Soligard T, Myklebust G, Steffen K, Holme I, Silvers H, Bizzini M, Junge A, Dvorak J, Bahr R, Andersen TE. Comprehensive warm-up programme to prevent injuries in young female footballers: cluster randomised controlled trial. BMJ 2008;337:a2469. doi: 10.1136/bmj.a2469.
10. Waldén M, Atroshi I, Magnusson H, Wagner P, Hägglund M. Prevention of acute knee injuries in adolescent female football players: cluster randomised controlled trial. BMJ 2012;344:e3042 doi: 10.1136/bmj.e3042.
11. Hägglund M, Atroshi I, Wagner P, Waldén M. Superior compliance with a neuromuscular training programme is associated with fewer ACL injuries and fewer acute knee injuries in female adolescent football players: secondary analysis of an RCT. Br J Sports Med 2013;47:974-9.
12. Goode AP, Reiman MP, Harris L, DeLisa L, Kauffman A, Beltramo D, Poole C, Ledbetter L, Taylor AB. Eccentric training for prevention of hamstring injuries may depend on intervention compliance: a systematic review and meta-analysis. Br J Sports Med 2015;49:349-56.
13. Bahr R, Thorborg K, Ekstrand J. Evidence-based hamstring injury prevention is not adopted by the majority of Champions League or Norwegian Premier League football teams: the Nordic Hamstring survey. Br J Sports Med 2015;49:1466-71.
14. Hägglund M, Waldén M, Magnusson H, Kristenson K, Bengtsson H, Ekstrand J. Injuries affect team performance negatively in professional football: an 11-year follow-up of the UEFA Champions League injury study. Br J Sports Med 2013;47:738-42.

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Nirmala Perera (@Nim_Perera) is a health practitioner, an epidemiologist and a PhD scholar at the Australian Centre for Research into Injury in Sport and its Prevention (@ACRISPFedUni). She is the @IOCprev2017 #SoMe campaign coordinator.

Markus Walden (@MarkusWalden) is an orthopaedic surgeon, researcher at the Football Research Group (@frgsweden), team physician for IFK Kristianstad (@IFKKristianstad), and @IOCprev2017 scientific committee member.

Martin Hägglund (@MHgglund) is a physiotherapist and associate professor at Linköping University (@liu_university) and researcher at the Football Research Group (@frgsweden).