You can't fix what isn't broken: eight weeks of exercise do not substantially change cognitive function and biochemical markers in young and healthy adults.

We provide evidence that a short-term course of moderate exercise does not improve cognitive function or change plasma biochemical markers concentrations in young and healthy adults, despite mild improvements in cardiorespiratory fitness. These results suggest that cognitive health may peak during early adulthood leaving little room for improvement throughout this period of the lifespan.