Rapid Re-activation of Functionally Inhibited Hamstring Muscles via Real-Time EMG Visual Feedback in an Asymptomatic Masters Sprinter: A Case Report.

Background: Masters athletes inevitably face age-related neuromuscular alterations, such as dynapenia, where the loss of muscle strength and power exceeds the loss of muscle mass. In sprinters, the selective loss of neural drive to the posterior chain impairs performance and increases injury risk. This condition often resembles a functional analogue of arthrogenic muscle inhibition, occurring even without structural damage. This case report highlights the application of real-time visual feedback (VFB) to overcome functional neuromuscular inhibition in a masters sprinter. Case Description: The 41-year-old participant had struggled with hamstring activation failure during Romanian deadlifts for two decades, a phenomenon resembling learned non-use despite the absence of structural injury. A wireless electromyography (EMG) system was used to provide real-time visual feedback of hamstring muscle activity. Outcomes: Following VFB intervention, the participant exhibited a dramatic increase in hamstring EMG amplitude compared to the control condition (without VFB). The muscle activity demonstrated a dramatic surge, rising from a negligible baseline (~ 0.014 mV) to ~0.574 mV. Conclusion: This 40-fold increase suggests that VFB can facilitate higher EMG output and re-recruit high-threshold motor units. These findings underscore the potential of VFB as a neuro-cognitive intervention to facilitate higher EMG output in aging athletes exhibiting functional inhibition. Level of Evidence: 4.