Background Despite the link between jump landings and ACL injury risk, limited research has investigated the biomechanical and neuromuscular differences between successful and failed landings. Identifying the factors that lead to failed landings may provide specific targets for injury prevention programs.

Objective Identify which neuromuscular and biomechanical variables predict success or failure during unanticipated drop-jump landings.

Design Cross-sectional study.

Setting Controlled laboratory setting.

Patients (or Participants) Thirty-two healthy male (n=16; 15.9±1.87 yrs.) and female (15.7±1.7 yrs.) Ottawa area competitive athletes with no history of major musculoskeletal injury affecting functional performance.

Interventions (or Assessment of Risk Factors) Participants completed single-leg drop-jump landings from a platform aligned to their tibial plateau. The landing leg was randomly signalled during flight via a projector in front of the participant. The landings were then categorized as ‘successful’ or ‘failed’ (defined as any loss of balance forcing the participant to adjust their base of support during landing).

Main Outcome Measurements Sex, limb dominance, joint angles and excursions, and muscle excitation amplitudes during the flight phase of the drop-jumps were extracted. These variables were normalized, reduced and submitted to a logistic regression.

Results Twenty-nine variables were reduced to a seven variable logistic regression model that included trunk and pelvis lateral tilt, pelvis internal rotation, hip abduction, trunk and pelvis joint excursion, and biceps femoris muscle excitation. Using these variable the model correctly classified 74% of the landings. The same variables are present for both males and females.

Conclusions Regardless of sex, an athlete who presents the identified movement and control patterns during the flight phase risks a failed landing, potentially increasing the risk of injury. Typical prophylactic interventions focus on landing characteristics. This research indicates for the first time that modifying what occurs prior to landing is critical and must be addressed through training.