Jump-Landing Movement Quality Predicts Future ACL Injury in Youth Soccer Athletes


Why did you do this study?

Soccer is the most popular sport in the world with over 265 million participants. Soccer is also one of the sports most commonly associated with sports-related injury, such as injuries to the anterior cruciate ligament (ACL).  Thus, there is a great need to prevent ACL injuries in youth soccer athletes.

LESS Scoring Sheet

LESS Scoring Sheet

For effective prevention, prospective risk factors for injury should be established prior to introducing preventive measures.  Prospective risk factors provide information for identifying individuals at risk for suffering an injury potentially years in advance of the moment of injury.  The Landing Error Scoring System (LESS) is a field assessment tool for identifying potentially high-risk movement patterns (“errors”) during a jump-landing maneuver. We have previously demonstrated that the LESS has concurrent validity using three-dimensional motion analysis and that good inter- and intra-rater reliability can be obtained.  However, there is limited research investigating the LESS as a prospective screening tool.  Therefore, the purpose of the study was to examine the validity of the LESS (total score and individual items) in identifying the subgroup of individuals at higher risk for future ACL injury. Our study population was elite youth soccer athletes.

Figure 1 - LESS Jump LandingWhat did you do and what did you find?

We tested a total of 829 elite youth soccer athletes, ages 11 to 18 years (25% under 13 years) at the beginning of their soccer season.  Testing for all participants consisted of a jump-landing task (3 trials) and landings were scored for “errors” in technique using the LESS.  A higher LESS score indicates a greater number of landing errors and consequently poorer jump landing technique.  Participants were then followed prospectively throughout their soccer season for diagnosis of an ACL injury.

Seven participants suffered an ACL injury during the follow-up period, all of whom suffered non/indirect contact ACL injury. Non-injured participants (4.4±1.8) had lower LESS scores than ACL-injured (6.2±1.8) participants (p<0.01).  Individuals who displayed a LESS score of 5+ were at 10.7 times greater risk compared to those who displayed a LESS score below 5 (Sensitivity = 86%, Specificity = 64%).

How do theses findings affect the public?

Our most important finding was that elite level youth soccer athletes with LESS scores of 5 or more were at greater risk of suffering a non-contact ACL injury compared to their counterparts with LESS scores of less than 5.  These findings suggest that the LESS may have screening potential for ACL injury in youth soccer athletes.  These findings may have implications for ACL injury prevention efforts in youth soccer, since the LESS is a field assessment of movement quality that requires no laboratory-based instrumentation.  Specifically, youth soccer athletes who score 5 or more on the LESS may be at risk for future ACL injury and should be targeted for ACL injury prevention training.  More information on developing an ACL injury prevention program can be found at: http://www.unc.edu/depts/exercise/peak/peak/Home.html