Results from a newly published crossover trial suggest that exercise training promotes white matter and hippocampal recovery after brain irradiation. Paediatric brain tumour survivors who had received radiotherapy were assigned to a 12 week period of group exercise followed by 12 weeks of no training, or vice versa. The participants underwent MRI and reaction time testing at baseline and at the end of the two 12 week periods. Exercise resulted in increased brain connectivity (as measured by fractional anisotropy) that was sustained over the 12 week off-training period. Moreover, exercise increased hippocampal volume and improved reaction times.