Why is smaller good for gymnastics? I'm sure there are physics reasons, but I don't know what they are.

When gymnasts hit puberty, it throws off their center of balance, which then screws with all the flipping and such they have to do. They have to relearn everything.

Such is my understanding... Kat would know more.

Well, I think it depends on the event. I think there's a bit of an advantage to being bigger on vault, but a huge advantage to being smaller on bars. For the men, shorter legs would seem to make pommel horse much easier.

Center of gravity is lower. Very important for balance beam, makes you a heck of a lot more stable. On the uneven parallel bars it means you don't have to make as many contortions to avoid the lower bar when circling the upper. Makes you spin faster, too.

When gymnasts hit puberty, it throws off their center of balance, which then screws with all the flipping and such they have to do. They have to relearn everything.

Same thing happens in most sports. Skating jumps feel really different with and without hips.

I think that this is a large part of the reason why the very young Olympians (from before the minimum age of 16 was put in) tended to not have a second Olympics, while a bunch who had their first Olympics around age 16 or 17 ended up going to a second and sometimes even a third. It's much easier to go through the body changes if you're not trying to keep your world title at the same time. If you get to that level after you've gone through puberty, you just have to work on staying there with pretty much the same body.

Article on WebMD discussing short bias vs. delayed puberty onset

Oh, interesting. Really a combination of reasons. The puberty body changes/having to relearn moves isn't something I'd have thought about. Makes sense.

Svetlana Boginskaya was a rare gymnast to perform in 3 Olympics. She competed in her first Olympics at 19. I remember she looked like a GIANT next to the others in 1996, her final Olympics, but was only 5'4".

Okay, really going to bed now.

Puberty is also a time of huge numbers of knee injuries for girls. My orthopedist explained it to me that, as the hips grow, the angle of the muscles and tendons holding the kneecap in place changes, and it takes a few years for the body to adjust and strengthen the muscles that hold it in. (I had one actual kneecap dislocation and several near-dislocations in middle school and the first year or so of high school, but that's calmed down by now to just twisting weirdly every once in a while and sometimes sliding precariously when I'm wearing heels for too long.)

Dominique Dawes was also in three Olympics. She was almost 16 at her first. (She was there in 1992, 1996, and 2000.)