It's an adage that a good martial artist gets better with age. This kendo blog has an interesting post about baseball skill and age. The data referenced are certainly interesting to look at, but the use of drugs masks its relevance. A question though: I don't think it's so much trickery as experience, so is baseball a good comparison to a martial art? Weightlifting would be another poor example. Loss of muscle with age is will understood. Archery I would imagine a good example, as would any skill where it's more brain than brawn.. This assumes brains are actually more important in martial arts than brawn.. I guess my lack of experience with baseball is a problem here, Yogi Berra did say 90% of the game is half mental. What does the curve look like for pitching? Wait.. indeed! sabernomics has a pitching analysis As I look at this, I see the following comment about the peak age:

It is a little higher for good pitchers, and a little earlier for lower quality pitchers. This is not surprising since high-quality pitchers will have more opportunities to pitch as they get older than low-quality pitchers.

The quote I started with is from Peter Urban, and it is incomplete. He actually says a good martial artist gets better with age, a mediocre one gets weaker with age, and a poor one gets smaller with age. Two thoughts from this: 1. pitching peaks later than hitting, which supports my theory that more mentally oriented skills peak later, even in physical activities. 2. This data cannot be graphed in two dimensions. the dependencies are immense. A good martial artist will have many opportunities to practice, will teach, will, in general, continue to improve. Lesser martial artists will not peak at a lower age merely due to less potential, but for many factors, the largest of which is probably quitting.