Purpose: To investigate how hamstring injuries affect brain functional connectivity (FC) and identify potential biomarkers for injury assessment and rehabilitation. Methods: Brain activity was recorded during a rigorous motor task using electroencephalography in 129 footballers. Demographic, anthropometric, injury, and football-related data were also collected. Brain FC was calculated separately for the rest and activity periods. A 2-way mixed analysis of variance was conducted for group comparisons, and a partial correlation analysis examined links between FC and injury parameters. Results: The execution of the motor task led to a significant decrease in alpha-band FC during activity compared with rest (injured: P < .0001, n2p=.38; control: P < .001, n2p=.11). Injured players showed significantly lower FC during activity (P = .006, n2p=.07), as well as a greater decrease from rest to activity (P < .001, n2p=.13), particularly in the frontal (P < .001, n2p=.17) and temporal (P = .03, n2p=.08) regions. There were significant inverse correlations between the injury severity index and global (P = .003, r = -.58), frontal (P < .001, r = -.72), and parietal (P = .015, r = -.59) connectivity. Conclusion: Reduced FC in footballers with previous hamstring injury suggests an increased cognitive effort required for task execution, namely, in regions associated with motor planning and movement sequencing. The correlation analysis results point to a relationship between age and severity of the injury and the degree of this increase in cognitive effort.
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