Enhancing eccentric hip adduction strength in soccer players: A systematic review and meta-analysis of randomized controlled trials

Abstract

Background: Groin injuries are common in soccer, accounting for 19% of all injuries, with an incidence rate of 0.1-2.1 per 1000 h of play. The Copenhagen Adduction Exercise (CAE) is proposed to increase Eccentric Hip Adduction Strength (EHADS), potentially reducing the risk of groin injuries. Objective: This systematic review and meta-analysis evaluated the effectiveness of CAE in improving EHADS among soccer players compared to no intervention or interventions without CAE. Methods: A systematic search was conducted in the Cochrane Library, Web of Science, PubMed, and PEDro for randomized controlled trials (RCTs) published between 2012 and 2024. Study quality was evaluated using the revised Cochrane risk of bias tool (RoB2). Results: Five RCTs involving 148 soccer players were included. CAE increased EHADS with a mean difference of 0.49 Nm/kg (95% CI [0.28, 0.70], P = 0.00001), compared to interventions without CAE or no intervention. Moderate heterogeneity was observed (I2 = 54%). The risk of bias was low, with minor concerns about deviations from interventions. Conclusions: CAE significantly improves EHADS in soccer players, suggesting its potential to reduce groin injury risk when incorporated into training. Study registration: PROSPERO (CRD42022327736).