Adaptations of the neuromuscular junction to exercise training

The neuromuscular junction (NMJ) is the synapse that enables proper function of the neuromuscular system. Like other synapses, the NMJ is sensitive to changes in its pattern of use and adapts accordingly. Exercise training stimulates the NMJ and elicits functional and morphological remodeling resulting in improved performance. Physiologically, exercise training increases quantal content, safety margin, alters spontaneous release of neurotransmitter, and improves resistance to fatigue during a train of stimuli. Structurally, exercise training leads to enhanced presynaptic nerve terminal branching, number of vesicles, along with a greater number of postsynaptic receptors. Generally, presynaptic to postsynaptic coupling is unaffected by exercise. Although the NMJ responds to both endurance training (e.g. running, swimming) and resistance training, it appears that the constant stimulus of endurance training imparts a more powerful stimulus to the NMJ. The plasticity of the NMJ is elegantly demonstrated with exercise training.