Ask most people what physical activities you train in parkour, and most of the time you'll get the same answer: running, jumping and climbing. If you look at the training of most people, though, you'll see a whole lot of running and jumping, but not very much climbing. If you are one of those people who train parkour but doesn't climb very much, go out of your way to start climbing more.

My personal experience with climbing has been mostly in bouldering. I can't speak for top rope or lead climbing, but these are the benefits I've noticed since I started climbing.

Grabbing walls gets a lot easier. This might sound weird, but once you get used to grabbing small and oddly shaped climbing holds, the top of a wall seems a lot more generous than it used to be. You will also be better prepared to handle the top of wall if it is slick or angled back toward you.

Get a change of pace from your normal training. Climbing is like parkour's laid back cousin. If you approach climbing with the same pace and intensity you approach your parkour training, you'll probably burn out in about half an hour. When you go climbing, the pace is much slower because your hands and forearms can burn out fast if you just keep throwing yourself at walls. A lot of the time, you'll probably try a climbing route, then hang out and talk for a few minutes while you recover enough to start climbing again.

Develop climbing technique. Sometimes I wonder if people who do parkour realize how much technique there is in climbing. Having strong arms and a strong back will help you a lot, but there’s a lot of technique that you can only really learn from just climbing.>