FSI Football Science Update

1. How Relative Age Effects Associate with Football Players’ Market Values: Indicators of Losing Talent and Wasting Money

Romann M, Javet M, Cobley S, Born DP

Swiss Federal Institute of Sport Magglingen, Switzerland

Sports (Basel). 2021 Jul 9;9(7):99. doi: 10.3390/sports9070099

This study analyzes the relationship between the annual age-group categorization or relative age effects (RAEs), and the market values of youth players by studying the data of 11,738 youth male football players obtained from the “transfermarkt.de” database, which delivers a good proxy for real market values. Assuming an equal distribution of football talent exists across annual cohorts, results indicate a potential biased selection, with undervaluing of Q4 (4th quarter of the year) players in younger age groups, and overvaluing of Q1 players both in performance and monetary terms. This effect should be taken into account for talent detection and development.


2. Outcomes of Surgically Treated Fifth Metatarsal Fractures in Major League Soccer Athletes.

Stone JA, Miranda AD, Gerhardt MB, Mandelbaum BR, Giza E

Orthopedic Institute of Wisconsin, USA

Am J Sports Med. 2021 Aug 6:3635465211030279. doi: 10.1177/03635465211030279

This study analyzed the operative fifth metatarsal fractures in Major League Soccer (MLS) athletes for seasons 2013 to 2017. There were 21 fractures in 18 players. 95% of the cases returned to sport. Mean time to radiographic healing was 8.5 weeks. and mean time to return to play was 11.1 weeks. 22.2% of the players experienced re-fracture. Player performance characteristics showed small declines in the first year of return that improved by the second year.


3. Associations between maximal strength, sprint, and jump height and match physical performance in high-level female football players

Pedersen S, Welde B, Sagelv EH, Heitmann KA, B Randers M, Johansen D, Pettersen SA.

School of Sports Sciences, UiT The Arctic University of Norway

Scand J Med Sci Sports. 2021 Aug 6. doi: 10.1111/sms.14009

This study assess the association between one repetition maximum (1RM) half squat strength, 5-, 10-, and 15-m sprint times, countermovement jump (CMJ) height, and physical high-intensity match-play performance in 37 high-level female football players. No correlations were found between 1RM neither 5-m sprint time and performance. Conversely, strong correlations were found between 10-m- and 15-m sprint time, and CMJ with match peak speed, and a moderate correlation between 15-m sprint time and match peak acceleration.


4. Relationship between Training Load Management and Immunoglobulin A to Avoid Immunosuppression after Soccer Training and Competition: A Theoretical Framework Based on COVID-19 for Athletes’ Healthcare

Rico-González M, Pino-Ortega J, Clemente FM, Bustamante-Hernández N

Department of Physical Education and Sport, University of The Basque Country, Spain

Healthcare (Basel). 2021 Jul 6;9(7):856. doi: 10.3390/healthcare9070856

This systematic review studies the relationship between training load and salivary IgA, concluding that rest or moderate training sessions are suggested after official matches to ensure 16-18 h to recover IgA levels, while periods with multiple matches per week with limited recovery time should be avoided, and weekly training load should assume a small increment (<10%) to ensure IgA immune responses, that are important against upper respiratory tract viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).


5. Association of Field Position and Career Length With Risk of Neurodegenerative Disease in Male Former Professional Soccer Players

Russell ER, Mackay DF, Stewart K, MacLean JA, Pell JP, Stewart W

Institute of Neuroscience and Psychology, University of Glasgow, United Kingdom

JAMA Neurol. 2021 Aug 2:e212403. doi: 10.1001/jamaneurol.2021.2403

Comment in doi: 10.1001/jamaneurol.2021.2246

Neurodegenerative disease mortality is higher among former professional soccer players than general population controls. This cohort study used population-based health record linkage in Scotland to evaluate risk among 7676 male former professional soccer players born between January 1, 1900, and January 1, 1977, and 23 028 general population control individuals matched by year of birth, sex, and area socioeconomic status. 386 of 7676 former soccer players (5.0%) and 366 of 23 028 matched population control individuals (1.6%) were identified with a neurodegenerative disease diagnosis (hazard ratio for soccer players [HR] 3.66), being highest for defenders (HR 4.98) and lowest for goalkeepers (HR 1.83). Risk was highest among former soccer players with professional career lengths longer than 15 years (HR 5.20). While investigations to confirm specific factors contributing to increased risk of neurodegenerative disease among professional soccer players are required, strategies directed toward reducing head impact exposure may be advisable in the meantime.


6. Rating Player Actions in Soccer

Dick U, Tavakol M, Brefeld U

Machine Learning Group, Leuphana University of Lüneburg, Lüneburg, Germany

Front Sports Act Living. 2021 Jul 15;3:682986. doi: 10.3389/fspor.2021.682986

This study presents a data-driven model that rates actions of the players in the ball possession phases in soccer, according to a prediction model of the movements of the players and the outcome of these phases, deriving a set of aggregated players’ performance indicators.


7. Space and Control in Soccer

Martens F, Dick U, Brefeld U

Machine Learning Group, Leuphana University of Lüneburg, Germany.

Front Sports Act Living. 2021 Jul 16;3:676179. doi: 10.3389/fspor.2021.676179

In soccer, the ability to control and generate space in dangerous areas on the pitch is crucial for the success of a team. This study identifies the influence of the players on the pitch by tracking their movements and turn them into data-driven quantities that give rise to a novel space generation measure to visualize the strategies of the team and the player, which is useful in the context of game analysis.