Effects of Cognitive Demands on ACL Injury-Related Knee Kinematics: A Systematic Review with Meta-Analysis

Interest in the relationship between cognitive demands and anterior cruciate ligament (ACL) injuries has increased, particularly during change-of-direction and jump-landing tasks. This study examined how different cognitive demands influence ACL-related biomechanical variables at initial ground contact. A systematic review with meta-analysis was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions and the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed, Scopus and Web of Science were searched up to 23 May 2025. Cognitive demands were classified into four groups: decision making, divided attention, perturbation and uncertainty. JASP software was used for the meta-analysis. A total of 6213 records were identified, and 59 studies were included. Significant differences were found only in the decision making group when analysing the female cohort, with greater knee flexion angles under anticipated conditions in the sagittal plane (SMD = 0.21, 95% CI = 0.01, 0.40, p = 0.039), whereas no differences were observed in the male cohort, the overall group or the frontal plane across any of the subgroups (p ≥ 0.163). No significant differences were found for divided attention, perturbation or uncertainty in either the sagittal or frontal plane. These findings indicate that cognitive demands modify knee kinematics only in the sagittal plane for females with a small effect size. While these laboratory-based insights offer potential hypotheses for neuromuscular training and assessment protocols (such as incorporating unanticipated and dual-tasks conditions) further clinical studies are required to confirm their effectiveness in actual injury prevention.