Zen's hit it on the nose. Or butt as the case may be.

I haven't pinned on a race number in a long time. But when I started doing lots of butt-type exercises to prepare for mountain climbing, my climbing power on the bike improved quite a bit.

Normally, when I come to a hill, I use shorter, faster strides to make it up (sort of like shifting to a smaller gear). However, I've started working on keeping my stride about the same length as when I'm running flats, but powering through the entire stride. It takes some focus (and some Social Distortion doesn't hurt), but it also seems to be improving my climbing ability on the bike. In particular, I have more noticeably more power on hills than I used to.