The simple cerebellar lobule is involved in several neuromotor processes and it is activated during guided exercise. Although guided exercises are essential for motor rehabilitation, the plastic events that occur in the simple cerebellar lobule during motor training remain unknown. In this study, normal adult rats were intensely trained on a motorized treadmill during a period of four weeks (IT group) varying both the velocity and the slope of the moving belt, and they were compared to a mildly trained (MC) group and an intact control group (IC). Dendritic spine density and proportions of the different spine types on Purkinje cells was assessed in the cerebellar simple lobule, as was drebrin A expression. Both dendritic spine density and drebrin expression increased in the MC and IT groups. Stubby spines were more abundant in the MC animals, while there was an increase in both stubby and wide spines in IT rats. In addition, mushroom spines were more numerous in the IT group. Increases in stubby and wide spines could be related to regulation of the excitability in Purkinje cells due to the motor training regime experienced by the MC and IT rats. Moreover, the observed increase in mushroom spines in the IT group could be related with the motor adjustments imposed by training. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.