Intrinsic risk factors for groin injuries among male soccer players: a prospective cohort study.

BACKGROUND: This study was conducted to determine if risk factors for groin injuries among male soccer players could be identified. HYPOTHESIS: Previous groin injuries, reduced function scores, age, findings on clinical examination, and low isometric groin strength are associated with increased risk of new groin injuries. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 508 players representing 31 amateur teams were tested during the 2004 preseason for potential risk factors for groin injury through a questionnaire on previous injury and function score (Groin Outcome Score [GrOS]) and a clinical examination of the groin. Generalized estimating equations were used in univariate analyses to identify candidate risk factors, and factors with a P value <.10 were then examined in a multivariate model. RESULTS: During the soccer season, 61 groin injuries affecting 55 legs (51 players) were registered. The total incidence of groin injuries was 0.6 injuries per 1000 playing hours (95% confidence interval [CI], 0.4-0.7), 0.3 injuries per 1000 training hours (95% CI, 0.2-0.4), and 1.8 injuries per 1000 match hours (95% CI, 1.2-2.5). In a multivariate analysis, previous acute groin injury (adjusted odds ratio [OR], 2.60; 95% CI, 1.10-6.11) and weak adductor muscles as determined clinically (adjusted OR, 4.28; 95% CI, 1.31-14.0) were significantly associated with increased risk of groin injuries. A multivariate analysis based only on acute time-loss injuries revealed the 40-m sprint test result (adjusted OR, 2.03 for 1 standard deviation change [injured group faster]; 95% CI, 1.06-3.88; P = .03) and functional testing of the rectal abdominal muscles (adjusted OR, 15.5 [painful in 19% of the players in the injured group compared to 16% in the uninjured group]; 95% CI, 1.11-217; P = .04) as significant risk factors. CONCLUSION: A history of acute groin injury and weak adductor muscles are significant risk factors for new groin injuries.