1. Higher risk of ACL rupture in amateur football compared to professional football: 5-year results of the ‘Anterior cruciate ligament-registry in German football’
Szymski D et al
Department of Trauma Surgery, University Medical Centre Regensburg, Germany
Knee Surg Sports Traumatol Arthrosc. 2021 Sep 15. doi: 10.1007/s00167-021-06737-y
This study analyzes the ACL injuries registry in German Football – Professional (1st-3rd league), semi-professional (4th-6th league) and amateur leagues (7th league)- from 2014-15 to the 2018-19 season. 958 ACL injuries were registered. The incidence of ACL injuries was highest in amateur football (0.074/1000 h football exposure) compared to professional (0.058/1000 h) and semi-professional football (0.043/1000 h). At all skill levels, match incidence (professional: 0.343; semi-professional: 0.249; amateur: 0.319) was significantly higher than training incidence (professional: 0.015; semi-professional: 0.004; amateur: 0.005). Major risk factors were previous ACL injury (mean: 23.3%), other knee injuries (mean: 19.3%) and move to a higher league (mean: 24.2%).
2. Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise
Impellizzeri FM, McCall A, van Smeden M
University of Technology, Faculty of Health, Sydney, NSW, Australia
J Clin Epidemiol. 2021 Sep 11:S0895-4356(21)00287-0. doi: 10.1016/j.jclinepi.2021.09.007
The Nordic hamstring exercise (NHE) is strongly recommended to reduce hamstring injuries in previous meta-analyses. This study re-analysed under the random-effects model the findings of the meta-analysis of the 6 randomised control trials (RCT) using NHE. The point estimate (RR) was 0.59 (95%CI, 0.27 to 1.29). Thus, the evidence underpinning the protective effect of NHE so far remains inconclusive and mostly derived from high risk of bias RCTs. At best, only a conditional recommendation can be provided (for soccer) and future RCTs are warranted.
3. Muscle Fibre Typology as a Novel Risk Factor for Hamstring Strain Injuries in Professional Football (Soccer): A Prospective Cohort Study
Lievens E et al
Department of Movement and Sports Sciences, Ghent University, Belgium
Sports Med. 2021 Sep 13. doi: 10.1007/s40279-021-01538-2
This prospective cohort study was conducted over three seasons in professional football players competing in the Belgian Jupiler Pro League (n = 118) and in the English Premier League (n = 47). A total of 27 HSI were sustained during this period. Muscle fibre typology was non-invasively estimated using proton magnetic resonance spectroscopy and was characterized as a fast, slow, or intermediate typology based on the carnosine concentration in the soleus. Football players exhibited a wide variety of muscle typologies (slow 44.9%, intermediate 39.8%, fast 15.3%). Players with a fast typology displayed a 5.3-fold higher risk of sustaining an index HSI than slow typology players. So muscle fibre typology as measured in the soleus appears as a novel and potent risk factor for HSI.
4. Home advantage during the COVID-19 pandemic: Analyses of European football leagues
McCarrick D, Bilalic M, Neave N, Wolfson S
School of Psychology, University of Leeds, UK
Psychol Sport Exerc. 2021 Sep;56:102013. doi: 10.1016/j.psychsport.2021.102013
The home advantage (HA) is a robust phenomenon in football whereby the home team wins more games and scores more goals than the away team. One explanation is that the home crowd spurs on home team performance and causes the referee to unconsciously favour the home team. This study compared team performance and referee decisions pre-COVID (crowd present) and during-COVID (crowd absent) across 4844 games from 15 leagues in 11 countries. HA (goals scored and points gained) was significantly reduced during-COVID. Home teams created significantly fewer attacking opportunities and referee bias was diluted when controlling for the attacking dominance of teams, with a reduced number of fouls and yellow cards ruled against away sides.