Originally Posted by Greg Everett
Some successful lifters do push their hips back slightly - but they also have really shitty jerk technique that's saved only by ridiculous strength. Every lifter who does this pushes the bar forward and must walk into it and muscle it back overhead. This is extremely difficult and is certainly not advisable.
The jerk is not a snatch or a clean - it's a jerk. That said, you'll notice that the ending positions of the snatch and clean have the lifter's body inclined backward in order to maintain the balance of the system because the bar is in front of the body. In the jerk, the bar can be centered over the base without a backward lean, but because it's forward of the spine, there's a moment on the back/hip that must be resisted during the dip/drive.
The hips should travel straight down and straight up. It will feel extremely awkward, and it will be nearly entirely quad and a little glute - virtually no hamstrings. But the movement is dictated by the position necessary. The athlete already has to drive the body forward through teh arms in order to reposition himself under the bar when receiving - if he pushes the bar forward as well it's unlikley he'll be able to cover the distance.
Finally, it's a pretty solid rule that if you can get away with pushing the hips back in the jerk, you're not jerking enough weight. Remember that any weight you can handle easily can be lifted with just about any technique - if that technique is more similar to other things you do (e.g back squat with hips back), it will feel "good" - but it won't hold up when you get to loads you can't fake.
Absolutely fantastic observation/advice.
Anytime I end up under a good load, when I'm jerking, I end up pressing it out and it's for the very reasons you've delineated above. The flaws show up when the limit is pushed.
All the best,