ACTN3 R577X polymorphism and muscle injury severity among professional Brazilian soccer players: a heightened impact on female athletes

BACKGROUND: This study aimed to analyze the incidence and severity of muscle injuries in male and female high-level Brazilian soccer athletes throughout one season, considering the impact of the ACTN3 R577X polymorphism and gender differences.METHODS: A total of 31 male and 28 female professional soccer athletes from the First Division of the Brazilian Championship were included in the study. Injury data from the medical records of the soccer club were assessed, and genotype analysis of the ACTN3 R577X polymorphism was conducted using saliva samples.RESULTS: A total of 94 non-contact muscle injuries were recorded for the entire cohort during the 2023 season. Female athletes exhibited a trend of higher incidence of muscle injuries per player compared to males (2.6 injuries/athlete in female and 1.8 in male, P=0.06), as well as a trend of more injuries per player compared to males (9.2±7 and 7.6±17, respectively, P=0.05). The presence of the ACTN3 X allele was associated with longer medical leave in the entire cohort (P=0.007), and particularly in females compared to males (P=0.01) and compared to females with the RR genotype (P=0.03). These results suggest an association between the X allele and the incidence and severity of injuries. The effect of ACTN3 R577X can be higher in women compared to men because of its lower average levels of testosterone, making other parameters, such as the influence of ACTN3, more significative in females. Besides that, gender differences in muscle force production and susceptibility to muscle injuries can be influenced by factors such as electromechanical delay, rate of force production, and other hormonal fluctuations, particularly estrogen levels during the menstrual cycle.CONCLUSIONS: The findings highlight the importance of considering both genetic factors and gender-specific differences in muscle injury research. Targeted injury prevention and rehabilitation strategies tailored to male and female soccer athletes are necessary to improve their health and performance outcomes.