Besides keeping the heels down and the butt back, the front rack position is one of the hardest foundational techniques for a new athlete. If you are unable to hold a secure front rack position, the all of your presses will suffer as a result, as well as your cleans and front squats. This inability is usually caused by tightness in the upper body which in turn is caused by things like hunching over a keyboard all day (you are doing it right now, open up your chest!) Some of the muscles that can be causing the tightness include the lats, posterior deltoids, and the triceps. The wrist flexors also play a big part in the front rack position, keeping them flexible will greatly improve your ability to rack the bar across your deltoids.
|CF Invictus has a great post on stretches for the front rack, view the rest of the photos here|
On the Mobility Wod, Starrett offers some easy ways roll out the triceps for an improved front rack. This is the same thing that happens when you roll out your quads. If you don’t have a barbell and rack handy, you can still do this stretch by lying on the ground and putting your outstretched arm across the top of a kettlebell, palm facing up. I have been having my trainees do this lately, with positive results.