Physical activity preserves cognition in the aging brain, but the mechanisms remain obscure. In order to identify candidate genes and pathways responsible for the preservation of cognitive function by exercise, we trained mice that had been exposed to lifelong running or sedentary lifestyle for 16 months in the hippocampus-dependent water maze. After water maze training, we analyzed the expression of 24,000 genes in the hippocampus using Illumina bead microarray. Runners show greater activation of genes associated with synaptic plasticity and mitochondrial function, and also exhibit significant downregulation of genes associated with oxidative stress and lipid metabolism. Running also modified the effects of learning on the expression of genes involved in cell excitability, energy metabolism, and insulin, MAP kinase and Wnt signaling. These results suggest that the enhancement of cognitive function by lifelong exercise is associated with an altered transcriptional profile following learning.