Light-Emitting Diodes: Advances, Challenges and Applications in Musculoskeletal Pain

Musculoskeletal pain is a major cause of disability and long-term analgesic use, increasing interest in safe non-pharmacological interventions. This focused narrative review examines light-emitting diode (LED)-based photobiomodulation (PBM) for musculoskeletal pain, integrating molecular, mechanistic, clinical, and translational evidence. Red and near-infrared LED-PBM may act through mitochondrial and non-mitochondrial photoacceptors, modulation of ATP production, reactive oxygen species, nitric oxide, calcium signaling, inflammatory pathways, oxidative stress responses, and extracellular matrix repair. Clinical evidence suggests a potential benefit in selected conditions, particularly temporomandibular disorders, fibromyalgia, cervical and myofascial pain, tendon and plantar fascia disorders, knee osteoarthritis, and mild-to-moderate peripheral nerve compression, while findings for non-specific low back pain remain inconsistent. The reviewed literature indicates that therapeutic response depends less on emitter identity alone than on wavelength, irradiance, radiant exposure, treatment geometry, target depth, timing, disease phenotype, and protocol quality. LED-based PBM appears generally well tolerated and clinically promising as an adjunct to rehabilitation, but current evidence is limited by heterogeneous devices, incomplete dosimetry, variable comparators, and short follow-up. Future studies should prioritize standardized reporting, depth-aware dosing, phenotype-based recruitment, biomarker-linked outcomes, and direct laser–LED comparisons under dosimetrically matched conditions.