hamstrings

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

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Work-related musculoskeletal disorders (WMSDs) are prevalent among physiotherapists and occupational therapists due to the physically demanding and repetitive nature of manual therapy techniques. Stretching requires therapists to exert substantial force while holding static postures for extended periods. Assistive devices may mitigate these ergonomic risks. This crossover study evaluated postural risk factors for WMSDs during lower-limb muscle stretching (targeting the hamstrings, calves, iliopsoas, quadriceps, hip adductors, hip abductors, and gluteal muscles) and compared manual with device-assisted techniques among 32 healthy practitioners (highly trained students and licensed therapists). Postural risk was evaluated using the Rapid Entire Body Assessment (REBA), and perceived comfort via a five-point Likert scale. Data were analyzed using mixed-effects regression models. Device-assisted stretching significantly improved therapists’ posture (mean REBA score: 11.35 units lower, P < 0.001) and increased the odds of belonging to a lower WMSDs risk category by 69.17-fold. Furthermore, device-assisted stretching significantly enhanced participants’ comfort for nearly all muscle groups ( P < 0.010), with no period or carryover effects. These findings indicate that the assistive device can substantially reduce postural risk factors for WMSDs and improve comfort during lower-limb stretching. However, prospective clinical studies are needed to determine whether these postural improvements reduce the incidence of WMSDs.

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