I was once an avid rock climber, but stopped for many years. One night on a surf trip in Indonesia I had someone hold my beer while I climbed a palm tree, which was only about 15 feet high, but that's still high enough that you don't want to fall.<p>I got to the top of the trunk and reached up to grab one of the branches, and it was like, 'oh man, I'm so out of condition, I can barely grip this'. But then, accidentally, my feet cut loose.<p>A jolt of adrenaline shot through me, and I managed to hold on one handed to this slippery, slopey palm tree branch as my body swung away from the trunk of the tree. This whole chain of muscles from my fingers down to my lower back fired at once. I used to use those muscles all the time when I climbed regularly, but on the tree I didn't have access to that strength until the adrenaline kicked in, and then it was all there like it had never left.<p>Of course, because I was out of condition I strained every muscle in that chain and I had to skip a few days of surfing. But it had me thinking about procedural memory, and how it relates to skills where raw strength is a factor. Strength is memory. There is physical conditioning needed to utilize that strength without hurting yourself, but how strong you are is about neural pathways in your muscles, and how they fire, not the muscle itself. Your muscles are actually strong enough to rip the tendons from your bones.<p>Now I'm back into climbing, but when I was first starting out I had this weird experience where a hold that I was too weak to latch at the beginning of a session became easy by the end. It's counterintuitive, if anything you should be getting weaker as you wear yourself out, but, after a decade of not climbing much at all, my finger muscles were remembering how to fire the way they needed to to stick that particular hold, and they got stronger. Now I'm at the point where my strength has mostly returned, but my tendons aren't yet resilient enough to handle the stress when I'm at my limit, so I've got to be really careful. This was all a big revelation for me.