We are in some ways until we clearly decline because we know more. You're a musician. You know that some of the famous composers write things that stand alone shortly before their deaths.It seems to be a natural tendency to think of ourselves as a "new and improved" version of our younger selves.
However, in sports the physical is such a dominant factor that all the knowledge and growth in the world about how to win will not counteract aging for long. Apparently aging did not bode well for physicists either, who appeared to max out at around age 30.
Peak seems to be much later for very creative people. Stokowski was still an intimidating musical force in his 90s. Franck wrote his D Minor Symphony not long before he died. Then there is the strange case of Grandma Moses.