The effectiveness of the Copenhagen adduction exercise on improving eccentric hip adduction strength among soccer players with groin injury: a randomized controlled trial

Abstract

Introduction: Groin injuries are common in soccer players and often involve adductor muscle strains. The Copenhagen Adduction Exercise (CAE) is a targeted intervention whose effectiveness in rehabilitation for these injuries warrants investigation. Objective: To investigate the impact of a rehabilitation program, which includes the CAE, on eccentric hip adduction (EHAD) strength, hip joint range of motion (ROM), self-reported disability, and pain among soccer players with adductor-related groin pain. It was hypothesized that the addition of CAE to the rehabilitation program would yield greater improvements. Methods: Employing a randomized controlled trial with a two-group parallel design, thirty male soccer players with a mean age of 26.4 ± 3.9 years were randomized into an intervention group (IG) including CAE (n = 15) and a control group (CG) without CAE (n = 15), based on a power analysis to ensure 80% power to detect significant differences. Both groups engaged in their respective rehabilitation programs twice a week for eight weeks. The primary outcome measured was EHAD strength, while secondary outcomes included hip joint ROM, self-reported disability measured by the Copenhagen Hip and Groin Outcome Score (HAGOS), and pain levels. Results: Significant improvements within groups were observed across all measures (p < 0.001). The IG demonstrated a greater increase in EHAD strength (Mean Difference [MD] = 0.49 Nm/kg, 95% Confidence Interval [CI] [0.31, 0.66]), a more pronounced reduction in pain (MD = -1.60, 95% CI [−2.18, −1.02]), and betterment in all HAGOS subscale scores compared to the CG. There were no significant between-group differences in hip joint ROM. Conclusion: Incorporating the CAE into rehabilitation programs significantly improves EHAD strength, decreases pain scores, and reduces self-reported disability in soccer players with adductor-related groin pain. Registration: ClinicalTrials.gov identifier: NCT05589623.