Low speed isokinetic knee extensors and flexors strength of soccer players is not predicting non-contact ACL injury

BACKGROUND: The ACL injury is a very serious injury and there are not many studies on how the muscle strength and strength asymmetry of the knee extensors and flexors affects it. The aim of the study was to analyse how maximum isokinetic strength and the strength balance of the knee extensors and flexors affect first-time, non-contact ACL injuries among male soccer players.METHODS: One hundred and six male professional soccer players participated in this study. The peak moment of the knee extensors and flexors was measured concentrically and eccentrically at an angular velocity of 60°/s before the beginning of the season. All the injuries experienced by players during the season were recorded by the medical staff of the teams. A Firth logistic regression for rare events was used to analyse how the strength parameters affected the probability of first-time, non-contact ACL injury.RESULTS: About 3.8% of players had a first-time, non-contact ACL injury during the season, and 80% of them in total suffered some sort of injury. Maximum muscle strength and strength asymmetry had no statistically significant effect on first-time, non-contact ACL injuries (P<0.05).CONCLUSIONS: Traditional indicators for the maximum strength of the isokinetic knee extensors and flexors do not predict the probability of a non-contact ACL injury.