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Context: Induced mental fatigue negatively impacts sport performance and neurocognition. However, it is unclear how induced mental fatigue influences landing biomechanics. The purpose of this study was to examine the influence of mental fatigue on drop landing biomechanics in individuals with and without a concussion history. Design: Crossover design. Methods: Forty-eight (24 per group) recreationally active individuals were matched on age (±3 y), sex, and body mass index (±1 kg/m²). All participants completed an experimental (30-min Stroop task) and control (30-min reading magazines) intervention on separate days separated by a minimum of 24 hours. Drop landings were performed before and after both interventions. Outcomes included peak vertical ground reaction force (vGRF), vertical loading rate (VLR), knee flexion angle, knee abduction angle, external knee flexion moment, external knee abduction moment, and initial ground contact knee flexion and knee abduction angles. Separate 2 (group) x 2 (intervention) between-within analyses of covariance compared drop landing outcomes. Each group's average pre-Stroop and premagazine outcomes were covariates. Results: There was a significant interaction for vGRF (P = .033, ηp²=.097) and VLR (P = .0497, ηp²=.083). The vGRF simple effects were not statistically significantly (P range = .052-.325). However, individuals with a concussion history displayed a medium effect size for greater vGRF post-Stroop compared with their own postmagazine vGRF (mean difference (95% confidence interval [95% CI] = 0.163 (-0.002 to 0.327) bodyweight (BW), p =.052, ηp²=.081. In contrast, the control group displayed a small effect size (mean difference [95% CI] = 0.095 [-0.069 to 0.259] BW, p =.251, ηp²=.029). Individuals with a concussion history displayed greater VLR post-Stroop compared with controls (mean difference [95% CI], 26.29 [6.19 to 46.40] BW/s, P = .012, ηp²=.134) and their own postmagazine values (mean difference [95% CI] = 32.61 [7.80 to 57.42] BW/s, p =.011, ηp²=.135). Conclusion: Mental fatigue leads to greater VLR for individuals with a concussion history. Athletic competition and activities of daily living can increase mental fatigue. Training programs may seek to teach mental fatigue reducing strategies to athletes with a concussion history. [ABSTRACT FROM AUTHOR]