Countermovement Jump and Quantitative Electroencephalography Assessment in Division I Football Athletes: An Exploratory Neurophysiological Study of Return‑to‑Play Readiness.

Background: The countermovement jump (CMJ) is commonly used to assess neuromuscular performance in athletic populations; however, force plate-derived mechanical metrics may not fully reflect central nervous system (CNS) contributions to persistent deficits following musculoskeletal injury. Quantitative electroencephalography (qEEG) offers cortical-level measures that may complement force plate assessments and provide additional insight into neuromuscular function. Purpose: To explore neuromechanical, movement quality, and cortical activation patterns during countermovement jump performance in previously injured and non-injured Division I football athletes using an integrated force plate, functional movement, and qEEG assessment approach. Study Design: Exploratory cross-sectional observational study. Methods: Ten male NCAA Division I football athletes were recruited for participation, five with history of lower extremity injury and five uninjured controls. All subjects completed a qEEG cognitive baseline then CMJ testing on a force-plate with synchronized qEEG. Outcomes included reactive strength index-modified (RSI Mod), jump height, peak landing force, reaction time, Stroop accuracy, and functional movement assessment (FMA) observations. Data were analyzed descriptively. Results: Compared with controls, previously injured athletes demonstrated lower RSI Mod (≈43% lower), reduced jump height (≈36% lower), and lower peak landing force (≈16% lower). Reaction times were modestly slower, with small interlimb differences. Stroop accuracy was comparable; however, injured athletes scored lower on sustained attention under task demands. FMA observations indicated greater single leg asymmetry and diminished step down control. qEEG sensorimotor rhythm (SMR) patterns showed greater asymmetry in motor related regions in the injured cohort, consistent with altered cortical activation. Conclusion: Medically cleared Division I football athletes with history of lower extremity injury demonstrated concurrent neuromechanical, movement quality, and neurophysiological differences during CMJ performance compared with uninjured controls. These descriptive findings suggest that a multimodal assessment approach may help identify potential CNS contributions to residual performance differences not captured by traditional musculoskeletal criteria. Given the small sample and cross sectional design, results should be considered hypothesis generating. Larger, longitudinal studies are needed before these measures can be considered for return to play (RTP) decision making. Level of Evidence: 3.