This randomized controlled trial found a significant increase of 36% in eccentric hip adduction strength (EHAD) and a 20% increase in eccentric hip abduction (EHAB) strength after a 8-week Copenhagen adduction exercise (CA) protocol in sub-elite football players. Increasing hamstring eccentric strength has been shown to reduce hamstring injuries. Thus, the CA seems a promising way of reducing adductor-related injuries in footballers.