Cortical changes associated with an anterior cruciate ligament injury may retrograde skilled kicking in football: preliminary EEG findings

Abstract

Anterior cruciate ligament injuries (ACLi) impact football players substantially leading to performance declines and premature career endings. Emerging evidence suggests that ACLi should be viewed not merely as peripheral injuries but as complex conditions with neurophysiological aspects. The objective of the present study was to compare kicking performance and associated cortical activity between injured and healthy players. Ten reconstructed and 15 healthy players performed a kicking task. Kicking biomechanics were recorded using wearable inertial measurement unit sensors. Cortical activity was captured with a 64-electrode mobile electroencephalography. Multiscale entropy (MSE) analysis of biomechanics revealed increased variability in foot external rotation among injured players. Source-derived event-related spectral perturbations indicated significant differences in posterior alpha and frontal theta oscillations between the two groups. Furthermore, kick-related complexity of these regions as indexed by MSE was reduced in injured players at medium and coarse scales. Our findings suggest sensorimotor changes during kicking in injured players, which may necessitate compensatory strategies involving augmented attention at the cost of processing visuospatial information. This conflict may hinder the integration of task-relevant information across distributed networks. Our study provides preliminary insights into the neurophysiological implications of ACLi within football context and underscores the potential for prospective research.

Keywords: Anterior cruciate ligament injury; Electroencephalography; Football; Movement variability; Neurophysiology; Sports injuries.

Fig. 1

Entropy estimates of injured and healthy players computed for foot external rotation demonstrating statistically significant differences along 20 time scales (left) and the corresponding statistical parametric map (SPM, right). In SPM, the solid line displays computed t-values for each time scale, with critical t-values for both tails indicated by the dotted line. Areas where the computed t-value exceeds the critical threshold show time scales with statistically significant differences.

Fig. 2

Kick-related spectral perturbations in the right posterior cluster showing a stronger alpha desynchronization in healthy players (left column, top) compared to injured players (left column middle) with significant differences at 1750—2250 ms (left column, bottom). “0” ms indicates kick onset. The right column demonstrates the scalp map of the cluster (top) and the locations of allocated independent components (bottom).

Fig. 3

Kick-related spectral perturbations in the frontal cluster showing a more pronounced theta synchronization in injured players (left column, middle) compared to healthy players (left column, top) with significant differences at 750—1000 ms (left column, bottom). “0” ms indicates kick onset. The right column demonstrates the scalp map of the cluster (top) and the locations of allocated independent components (bottom).

Fig. 4

Channels indicating significant differences between healthy and injured players (shaded red) in the complexity of right posterior (orange-colored) and mid-frontal (yellow-colored) regions.

Fig. 5

Entropy estimates of Pz, P2, P4, P6 and P8 along 64 time scales (left column) and the statistical parametric mapping (SPM) of significant differences observed between injured and healthy players (right column). Injured players demonstrated lower complexity at medium and coarse scales with significant differences observed in a range between 40 and 56. For Pz, the lower trend reversed to higher complexity at fine scales yielding significant differences at scale 7. In SPM, the solid line displays computed t-values for each time scale, with critical t-values for both tails indicated by the dotted line. Areas where the computed t-value exceeds the critical threshold show time scales with statistically significant differences.

Fig. 6

Entropy estimates of PO4, PO8, Oz and O2 along 64 time scales (left column) and the statistical parametric mapping (SPM) of significant differences observed between injured and healthy players (right column). Injured players demonstrated lower complexity at medium and coarse scales with significant differences observed in a range between 36 and 46. In SPM, the solid line displays computed t-values for each time scale, with critical t-values for both tails indicated by the dotted line. Areas where the computed t-value exceeds the critical threshold show time scales with statistically significant differences.

Fig. 7

Entropy estimates of AFz, Fz, F2 and F4 along 64 time scales (left column) and the statistical parametric mapping (SPM) of significant differences observed between injured and healthy players (right column). Injured players demonstrated lower complexity at medium and coarse scales with significant differences observed in a range between 27 and 56. In SPM, the solid line displays computed t-values for each time scale, with critical t-values for both tails indicated by the dotted line. Areas where the computed t-value exceeds the critical threshold show time scales with statistically significant differences.