An Exploratory Proof-of-Concept Study of a Neuromuscular Timing Framework for Knee Stability in Elite Footballers

Abstract

This exploratory pilot study introduces the Gluteus-Vastus Temporal Coordination Model (GVTCM), a methodological framework for assessing dynamic knee stability through phase-based neuromuscular analysis in elite footballers. Five professional male footballers performed single-leg vertical countermovement jumps. Surface electromyography of the gluteus medius (GM) and vastus medialis (VM) was analyzed within a 100 ms pre-activation window preceding initial contact (IC), operationalized as a binary feedforward variable. Dynamic Q-angle, Rate of Force Development (RFD), and Clarke's sign were assessed concurrently. Four athletes demonstrated anticipatory co-activation of GM and VM, presenting dynamic Q-angles of 11.8–13.1° and RFD of 4,200–4,800 N/s with negative Clarke's sign. One athlete, lacking feedforward activation in both muscles, exhibited a dynamic Q-angle of 18.5° and RFD of 7,200 N/s with positive Clarke's sign. A negative correlation between GM feedforward activation and RFD was observed (ρ = -0.67, 95% CI: -0.89 to -0.21). The convergence of biomechanical, kinetic, and clinical findings provides preliminary descriptive coherence to the GVTCM framework. These exploratory, hypothesis-generating findings suggest that anticipatory neuromuscular activation may be a clinically relevant indicator of dynamic knee stability and warrant validation in larger prospective cohorts.