Visual processing and interference performance influences on knee angular impulse in ACLR individuals: a cognitive-biomechanical analysis of drop-jumps

Abstract

Introduction: Visual processing speed and cognitive interference control are critical for athletic performance and Anterior Cruciate Ligament (ACL) injury risk. However, how these cognitive functions relate to biomechanical performance after Anterior Cruciate Ligament Reconstruction (ACLR) remains unclear. This gap is clinically relevant given persistent re-injury rates of 20–25% in young athletes returning to sport, suggesting that rehabilitation may insufficiently address cognitive demands. This study examined cognitive differences between ACLR individuals and controls during drop-jump tasks, and their relationship with knee angular impulse. Materials and methods: Thirty-two females (16 ACLR, 16 controls; 20 ± 1 years) completed cognitive assessments including the Stroop Color and Word Test, Trail Making Test, Digit Span Memory Test, and visual/auditory reaction time tests. Participants performed drop-jumps under four conditions: standard, choice, visual-cued, and audio-cued. Knee angular impulse was calculated for eccentric, concentric, and net phases. Binomial logistic regression identified cognitive predictors distinguishing groups, followed by factorial ANOVA to assess biomechanical differences. Spearman correlations examined relationships between cognition and knee angular impulse. Results: Three cognitive variables distinguished groups: cognitive interference score, visual simple reaction time, and visual complex reaction time (χ²(3) = 55.090, p < 0.001). The ACLR group demonstrated faster visual reaction times but impaired interference control compared to controls. Biomechanically, ACLR participants showed lower eccentric knee angular impulse (p = 0.003, d=-0.37), indicating persistent protective strategies. Audio-cued conditions elicited higher eccentric impulse than standard and choice conditions. Minimal correlations between cognitive variables and eccentric knee angular impulse suggest independent (parallel) adaptations. Conclusions: ACLR individuals exhibit distinct cognitive and biomechanical profiles characterized by enhanced visual reactivity, reduced interference control, and altered landing mechanics. The lack of association between domains indicates parallel adaptations, supporting rehabilitation approaches that independently target both cognitive function and biomechanical performance.