Originally Posted by vision646

Actually according to a study (I'm not exactly sure which one, my bike fitter showed it to me) you shouldn't be pulling up. The study found that one of the biggest differences between pro and amateur racers is that in general pros don't pull up on the pedals. The theorize that this acts as a mini break for your legs. It can be used to increase power output for a short period of time but is not efficient enough to be doing all the time.