FSI Football Science Update

1. Factors affecting return to play and graft re-rupture after primary ACL reconstruction in professional footballers.

Balendra G, Jones M, Borque KA, Willinger L, Pinheiro VH, Williams A

Fortius Clinic, London, UK

Knee Surg Sports Traumatol Arthrosc. 2021 Oct 12. doi: 10.1007/s00167-021-06765-8

This retrospective review of 232 ACL surgical reconstructions ACL-R undertaken in professional footballers between 2005 and 2018 found that 96.1% returned to professional football, 90.1% returning to the same or higher Tegner level. The mean time to RTP from surgery was 10.5 ± 3.6 months. The re-rupture rate was 8.2% at 2 years. Patella tendon autograft in an anteromedial bundle femoral tunnel position with addition of lateral extra-articular tenodesis has the lowest re-rupture rate (2.0%).


2. Influence of 2D:4D ratio on fitness parameters and accumulated training load in elite youth soccer players

Nobari H, Alves AR, Clemente FM, Pérez-Gómez J

University of Mohaghegh Ardabili, Ardabil, Iran

BMC Sports Sci Med Rehabil. 2021 Oct 11;13(1):125. doi: 10.1186/s13102-021-00354-5

This study analyzed the relationship between the hands’ Digit ratio (2D:4D), characterized by the length of the second finger or digit (2D) divided by the length of the fourth digit (4D), with fitness parameters in 24 U17 elite soccer players, finding that the 2D:4D ratio (left and right) showed a large and inverse association with the isometric muscular strength of hamstrings and quadriceps, and significantly predicted changes in muscular strength and VO2max in these players, concluding that 2D:4D ratio revealed as a mighty predictor of physical fitness changes in soccer players, and thus can be useful for the identification of talent.


3. External Loads of Elite Soccer Referees: A Systematic Review with meta-analysis

Birk Preissler AA, Reichert T, Schons P, Costa RR, Delevatti RS, Denadai BS, Kruel LFM

Federal University of Rio Grande Do Sul, Porto Alegre, Brazil

Res Sports Med. 2021 Oct 11:1-15. doi: 10.1080/15438627.2021.1988948

This systematic review of 32 studies, incorporating 578 referees evaluated in 3170 games through video analysis or a global positioning system, observed that the total average distance covered by the referees was 10,461.74 m, with running speeds predominantly below 13 km.h-1 for approximately 4500 m, and high-intensity running of 18 to 24 km.h-1 for approximately 800 m.


4. The Neuromuscular Effects of the Copenhagen Adductor Exercise: A Systematic Review

Schaber M, Guiser Z, Brauer L, Jackson R, Banyasz J, Miletti R, Hassen-Miller A

Walsh University, Ohio, USA

Int J Sports Phys Ther. 2021 Oct 1;16(5):1210-1221. doi: 10.26603/001c.27975

This systematic review of 5 articles found that the Copenhagen Adductor Exercise (CAE) significantly increased eccentric hip adductor strength, eccentric hip abductor strength, EHAD:EHAB ratio, and electromyography (EMG) activity of the adductor muscles. This increase in strength may reduce adductor muscle injuries, although more research needs to be done in this area to identify a clear relationship between the CAE and groin injury prevention.

5. Systematic Review and Meta-Analysis of the Y-Balance Test Lower Quarter: Reliability, Discriminant Validity, and Predictive Validity.

Plisky P, Schwartkopf-Phifer K, Huebner B, Garner MB, Bullock G

University of Evansville, Indiana, USA

Int J Sports Phys Ther. 2021 Oct 1;16(5):1190-1209. doi: 10.26603/001c.27634

This systematic review of 13 studies about the Y-Balance Test Lower Quarter (YBT-LQ) dynamic neuromuscular control test reported good reliability of the test, and a relationship between reach asymmetry with injury risk. However, when general cut points (i.e., not population specific) are used, the YBT-LQ may not be predictive of injury, so population-specific parameters (e.g., age, sex, sport/activity) should be considered when interpreting YBT-LQ performance.



Sheridan HC, Parker LJF, Hammond KM

Tottenham Hotspur Football Club, London, UK. Football Science Institute

Eur J Sport Sci. 2021 Oct 8:1-17. doi: 10.1080/17461391.2021.1988149

This paper reviews and resumes the current role of nutritional supplements in professional female football. Female players should aim to improve the frequency of protein intake throughout the day, whilst tailoring doses to individual body mass. Vitamin D should be administered based on individual blood test results. Iron is likely to be important, in particular during the menses. Omega-3 and collagen may be of greater benefit to female than male athletes during recovery from soft tissue injury, whilst probiotics and creatine are beneficial throughout the season for reducing risk of illness and optimising recovery, respectively. Other supplements for football include beta-alanine, nitrate and caffeine.


7. High Risk of New Knee Injuries in Female Soccer Players After Primary Anterior Cruciate Ligament Reconstruction at 5- to 10-Year Follow-up

Fältström A, Kvist J, Hägglund M

Rehabilitation Centre, Ryhov County Hospital, Jönköping, Sweden

Am J Sports Med. 2021 Oct 8:3635465211044458. doi: 10.1177/03635465211044458

This study analyzed data were for 317 female soccer players 1.6 ± 0.7 years after ACL reconstruction and for 119 matched controls. Two-thirds of female soccer players with ACL reconstruction who returned to soccer sustained a new knee injury within 5 to 10 years; 42% had a new ACL injury. Their risk of a new knee injury and knee surgery was 2 to 5 times greater than that for players who did not return and for knee-healthy controls.


8.Downtrends in Offside Offenses Among ‘The Big Five’ European Football Leagues

Zhao Y

School of Physical Education and Health, Wenzhou University, China.

Front Psychol. 2021 Sep 20;12:719270. doi: 10.3389/fpsyg.2021.719270

This study examined a 10-season period in the top five European soccer leagues, with a total of 18259 Match observations. The total offside offenses committed during a match experienced a clear decline during the 10 seasons, mostly after the implementation of VAR. Moderate increases were evident for all passing differential variables, the English Premier League having the greatest value in the touch differential, pass differential, successful pass differential, and key pass differential among all leagues.


9. Return-to-Play Times and Player Performance After Medial Collateral Ligament Injury in Elite-Level European Soccer Players

Lavoie-Gagne OZ et al

Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois, USA

Orthop J Sports Med. 2021 Sep 28;9(9):23259671211033904. doi: 10.1177/23259671211033904

This descriptive epidemiology study identified athletes who had sustained a knee MCL injury between 2000 and 2016 across the 5 major European soccer leagues. A total of 59 athletes sustained 61 MCL injuries, with the majority of injuries treated nonoperatively, and missing a median of 33 days (range, 3-259 days). Overall, 71% of athletes returned successfully at the same level, with only 3% reinjury rate. Player performance and long-term retention were not compromised.