The Influence of Concussion History and Progressively Increasing Cognitive Load on Jump Landing and Cutting Reaction Time, Biomechanics, and Task Demands.

Context:There is a 2-4x increased risk for musculoskeletal injury after concussion. A potential reason for the increased risk is aberrant biomechanics. The majority of prior research has focused on single-task biomechanics, but dual-task biomechanics may better represent athletic competition. Objective:To compare (1) jump landing and cutting biomechanics, (2) dual-task cost cognitive outcomes, and (3) perceived task difficulty/demands under single- and dual- task conditions (no-counting, serial 3s, serial 7s) between individuals with and without a concussion history. Design:Cross-sectional. Setting:Biomechanics laboratory. Participants:Twenty-three individuals with (age:20.2±1.9years, BMI:22.9±2.7kg/m2, 60.9% female, 44.7 months [95% confidence interval=23.6, 65.7] post-concussion) and 23 individuals without (age: 20.7±1.7years, BMI: 22.4±2.3kg/m2, 60.9% female) a concussion history participated. Main Outcome Measures:Jump landing and cutting trunk lower extremity kinematics and kinetics under single- and dual-task conditions. Cognitive accuracy and response rate during dual-tasking. NASA Task Load Index questionnaire. Results:During the jump landing, all participants exhibited a significantly faster reaction time during no counting versus serial 3s (p<0.001, Hedge's g=1.187) and serial 7s (p<0.001, Hedge's g=1.526). During the cutting, all participants exhibited a significantly faster reaction time during no counting versus serial 3s (p<0.001, Hedge's g=0.910) and serial 7s (p<0.001, Hedge's g=1.261), and serial 3s versus serial 7s (p=0.002, Hedge's g=0.319). All participants reported lower task demands during jump landing and cutting for no counting versus serial 3s (p<0.001) and serial 7s (p<0.001), and serial 3s versus serial 7s (p<0.001). Conclusion:Concussion history did not affect any of our outcomes, possibly because lingering biomechanical deficits may have resolved in our sample. Task demands did increase with increasing cognitive load, which may be beneficial for progressively manipulating the dual-task cognitive component during rehabilitation.