Exercise-driven neuromuscular junction plasticity: integrating motor-neuron adaptation, synaptic remodeling, and...

The neuromuscular junction (NMJ) is a dynamic synapse whose structure and function change with activity. This review synthesizes evidence from molecular studies, in vivo imaging, computational models, and human exercise research to explain how exercise remodels the presynaptic motor neuron terminal, postsynaptic muscle endplate, perisynaptic Schwann cells (PSCs), and extracellular matrix (ECM). Three conclusions emerge. First, endurance, resistance, high-intensity interval training (HIIT), and neuromuscular electrical stimulation (NMES) produce partly distinct NMJ signatures: endurance training favors oxidative support and fatigue resistance, resistance training strengthens release sites and postsynaptic organization, and HIIT combines elements of both; NMES can preserve transmission when voluntary activation is limited but remains dose dependent. Second, muscle-derived neurotrophic factors and activity-dependent neuronal signaling converge on regulators such as PGC-1α, supporting motor-neuron excitability, axonal energy supply, and synaptic maintenance. Third, PSCs and the ECM act as an active glio-matrical unit rather than passive scaffolding. We use the term metabolic priming for exercise-induced enhancement of mitochondrial trafficking, local protein synthesis, and quality-control pathways that supplies the energy and components required for repeated remodeling. These mechanisms help explain how exercise can preserve NMJ integrity with aging and inform rehabilitation strategies, although evidence is stronger for structural adaptation than for modality-specific clinical prescriptions. Conceptually, this synthesis reframes the NMJ as an exercise-responsive, motor-neuron-centered network linking neural drive, muscle state, and glial support. Translationally, these mechanisms provide a rationale for individualized exercise and rehabilitation strategies, while underscoring the need for human studies to establish optimal protocols.