TrkB agonist is not able to mimic all the positive effects of treadmill exercise following peripheral nerve injury. Over activation of TrkB could have harmful effects in VGlut1 synapses. TrkB inactivation blocks the maintenances of synapses by treadmill exercise after axotomy. Physical exercise is better than pharmacological modulation of TrkB to attenuate the changes on axotomized motoneurons.