Sports excellence often emerges for the first time during adolescence. Although their bodies are not yet powerful enough for most sports, they are very capable of performing perfectly coordinated movements. The bag of tricks on the football field is learned in this phase by endlessly practicing the movements and watching a lot of how others do it. The brain also plays an important role here. Motor neurons work to coordinate movements as best as possible. The brain cells in the motor cortex are not only active when you perform the movement yourself, but also when you watch someone making the movement and repeating the movement in your mind (imagination). The brain cells that carry out this mirroring are called 'mirror neurons'. The better the mirror neurons can imitate, the easier a person learns to perform the new movement. Given the speed at which adolescents pick up and execute new movements, their mirror neurons are probably very sensitive to them. Moreover, the brain areas that are important for risk and daring are overactive in adolescence. Adolescence could therefore be the sensitive period for exercise. In 1997, an article appeared in the Lancet, which for the first time contained indications that there is a link between a lot of exercise and better functioning of the prefrontal cortex. This study did not concern adolescents but very elderly people. One conclusion was that cognitive processes controlled by the cortex have a great influence on movement and, conversely, movement has a great influence on functions such as thinking and speaking. Another conclusion was that exercise is very effective in maintaining cognitive processes. Whether this also applies at a younger age requires further investigation.