Muscle Asymmetry and the Incidence of Adductor Strains in Professional Soccer Players: A Systematic Review

Context: Soccer is a dynamic sport that consists of high-speed running, cutting, sudden stopping or changes in direction, and explosive movements. It is one of many unilateral sports that requires one leg to do most of the kicking and cutting. Adductor strains in professional soccer are among the most common injuries and are the most common groin and hip injuries in soccer at an incidence rate of 0.6 per 100 hours of exposure. The average time lost for an adductor strain is about 14 days, and there is about an 18% chance of reinjury. Evidence supports that a higher adductor-to-abductor asymmetry ratio is attributed to a higher incidence of adductor strains. This study aimed to compare the literature and critically evaluate the relationship between muscle asymmetry, adductor/abductor strength and its correlation to adductor injuries. Methods: Using PubMed and Cochrane Library, a database search was completed using the keywords adductor injuries AND soccer, groin injuries AND soccer, muscle asymmetry AND groin injuries, professional soccer AND adductor injuries, and adductor muscle asymmetry AND soccer. Prospective studies about muscle asymmetry and adductor injuries were included if they were published in the last 10 years, the full text was available, the article was in English, and the study included or was solely focused on professional soccer players of either gender. The initial search yielded 268 articles. 105 duplicate articles were removed leaving 163 articles to be screened. After reviewing the titles, 114 articles were removed, and 49 abstracts were left to be reviewed. 32 were excluded due to abstracts not including topics relating to muscle asymmetry or professional soccer players. 7 full article texts were left to be read and evaluated for any relativity for this systematic review. The references for the articles that had been selected were then combed through for any relevant studies that could be used as well. 1 article was then selected from the references. A total of 4 articles were selected for data collection. Results: The 4 studies included a total of 281 participants (35 female and 246 male). The mean age of the female participants was 23.2 years. while the mean age for the male participants was 24.1 years. Asymmetry between adductors and abductors was a predisposing factor for an increased risk of adductor injury. Decreased strength in adductors and abductor muscles were also risk factors for adductor injuries. Conclusions: There was a correlation between muscle asymmetry and incidences of adductor strains in professional soccer players. Studies have suggested adductor-specific strength programs to lower the rate of adductor injuries in professional soccer players. Studies have also suggested that regular testing of adductor/abductor strength can be used as a screening tool to further prevent adductor injuries