A Cognitive Dual Task Alters Dynamic Tibiofemoral Movements During Jump-Landing Assessments in Healthy Participants.

Background: Many sports situations impose high cognitive demands on athletes, requiring them to divide their attention across multiple tasks and leading to landing mechanics associated with an increased anterior cruciate ligament (ACL) load and injury risk.

Purpose: To investigate the influence of a cognitive dual task on dynamic tibiofemoral movements (ie, dynamic anterior tibial translation [ATTd] and dynamic internal tibial rotation [ITRd]) during jump-landing assessments in healthy participants.

Study design: Controlled laboratory study.

Methods: A total of 20 healthy participants performed the side hop for distance, single-leg hop for distance, and triple hop for distance. Each assessment was performed under 2 conditions: once with a dual task (serial subtraction) and once without a dual task, while jumping distance remained consistent across both conditions. ATTd and ITRd were measured using a 3-dimensional motion capture system from 0.25 seconds before initial contact (IC) to 0.75 seconds after IC. Additionally, dynamic knee flexion angle, knee valgus angle, maximal knee flexion moment, and foot angle at IC were measured.

Results: While performing a dual task during the side hop for distance, there was less ATTd during the flight phase and more ITRd during the landing phase (maximal difference [MD], 1.65 mm and 2.07°, respectively; P < .001), accompanied by a greater foot angle at IC (MD, 2.71°; P < .002), resulting in a more pronounced toe landing. During the triple hop for distance, there was more ATTd and less ITRd around IC while performing a dual task (MD, 1.92 mm and 1.42°, respectively; P < .001), accompanied by a decreased knee valgus angle (MD, 0.54°; P < .001) and a reduced foot angle (MD, 1.75°; P < .05), resulting in a flatter heel landing. No effects of the dual task were observed during the single-leg hop for distance.

Conclusion: Incorporating a cognitive dual task during jump-landing assessments had variable influences on tibiofemoral movements, depending on the assessment. The observed increases in ATTd and ITRd during the landing on certain assessments suggest an increased ACL load and injury risk.

Clinical relevance: The incorporation of cognitive dual tasks in ACL injury screening and prevention programs should be considered to potentially reduce the risk of injuries.