Two skinny J's
"When the pedal nears the forward horizontal position, your knee should be almost locked. Then let your body weight fall so the leg muscles aren't involved as much. Stand tall on the bike. Let your hips move up and down slightly as you shift weight from one leg to the other."
I never thought about what was actually happening when I stand to climb and I don't know if I do this or not but I'm going to try it on my next ride and see what happens.