A new investigation in which 315 players from the Professional Football League (LFP) have participated has discovered the reason why the physical performance of some footballers is lower, they run less than their peers and are more likely to suffer muscle injuries. The person responsible for these effects, which can have such a negative influence on the career of these elite athletes, is the ACTN3 XX genotype, known as the ‘speed gene’.
The study that has analyzed the impact of the ‘speed gene’ in professional football has obtained first place in the Cajastur Foundation Sports Medicine National Research Awards convened by the University of Oviedo. Researchers have verified the incidence of injuries is higher in those players with a certain genotype in the ‘speed gene’ and who also have lower physical performance.
The finding may be relevant in order to individualize injury prevention programs, as well as in physical preparation plans or rotations in matches, according to Juan Del Coso Garrigós, professor at the Center for Sports Studies of the Rey Juan University. Carlos and first author of the work, who has highlighted the extra information provided by this study “not for the selection of players, but for individualized training.”
Identify players at higher risk of injury
α-Actinin-3, encoded by the ACTN3 gene, is a key protein for muscle contraction because it anchors actin filaments on Z discs, which function as fulcrums. This protein is only found in fast fibers, which is why it is considered essential for contractions performed with high values of strength and speed.
“The fact that they have a more fragile muscle does not mean that they are worse because it is very important to take into account that in a sport like football, the tactical and technical components are key, not everything is running”
The p.R577X (rs1815739) polymorphism in the ACTN3 gene renders individuals with the XX genotype deficient in α-actinin-3. Previous studies have shown that XX athletes are underrepresented in sprint sports, compared to athletes with RR and RX genotypes. That is why the ACTN3 gene is known as the ‘speed gene’. The RR genotype corresponds to that of those individuals who produce the α-actinin-3 protein in greater quantities, the RX with those who produce it in small quantities and the XX with those who do not produce it, that is, “the latter have a muscle less prepared to perform maximum intensity efforts.
The researchers selected 315 professional soccer players from La Liga and the ACTN3 rs1815739 genotype was determined through genomic DNA. They recorded physical performance during the La Liga matches of the 2021-2022 season using a validated camera system (Mediacoach), and the incidence of non-contact injuries was obtained by the clubs’ medical team following the consensus of the International Olympic Committee. .
The results showed that of the total cases analyzed, 116 (36.8%) RR players, 156 (49.5%) RX players, and 43 (13.7%) XX players were found. The incidence of injuries in general and those that occurred during matches was higher in the XX players than in the RR. The incidence of muscle injuries was also higher in XX players. The conclusion is that professional soccer players with the ACTN3XX genotype have lower physical performance during matches and a higher risk of injury.
“The fact that they have a more fragile muscle does not mean that they are worse because it is very important to take into account that in a sport like soccer, the tactical and technical components are key, not everything is running,” says the author of the work, although he adds: “We see that in actions such as dribbling, when the footballer is close to the ball or has to run to defend an action, the performance is lower because they run less distance throughout the game and, above all, they run less at high speed. Nor is it to say that they are fragile in general; We always talk about high-level athletes, but we do see a higher incidence of injuries in general and muscular injuries in particular in them”.
ACTN3 genotyping may be useful to identify elite soccer players at higher risk of injury and to develop individualized injury prevention programs. Juan del Coso highlights the error that trying to use this type of information in the selection of players would mean. “What it is very useful for is in the preparation and design of training sessions because performance can be worked on with more gym and preventive exercises in players with the XX genotype and thus counteract this greater propensity for injuries.”
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