Bend the Bar
The term Bend the bar is used ubiquitously within the Powerlifting community and from my experience is misinterpreted and/or misapplied. Bending the bar or pulling the bar apart is a way of creating tension into the bar versus passively letting the bar sit in the hands/shoulders. Bending tightens and activates the upper back musculature, notably the upper lats and rhomboids.
To perform bending the bar, apply pressure from the outside of the hands twisting inward – right turns clockwise, left turns counter clockwise – with a firm, tight grip. When done properly, the elbow will rotate inward approximately 45 degrees with respect to the frontal plane; not flared out, a common pressing mistake leaving the shoulders in an unstable, vulnerable position . Bending the bar also engages the triceps to push down against the upper lats creating a spring-like tension to push off of and initiate the start of the overhead press.
Create a Nice Rack
The bar should be supported upon the shoulders/clavicles and hands in a firm, upright posture. This is the rack or shelf position. The majority of weight should be distributed through the upper chest and shoulders, not in the hands. The elbows should be raised up enough to create tension in the hands but allowing the majority of weight to be distributed along the upper chest and shoulders. To create a stable platform/rack, pull the shoulder blades together and down. This will create some lordosis (curvature of the lower spine) but also expand the upper chest for the bar to be supported upon.
The scapular retraction stabilizes the thoracic spine and creates tension throughout the upper body in addition to the tension created by bending the bar. The antithesis of this action is to "Gumby", having the bar passively sink into your upper chest, which creates a poor power position to transfer energy into the bar.
Handle the Weight with Authority
Take the bar out of the rack or from a clean with assertiveness, so your entire body is ready to handle the weight. A weak or poorly executed clean or set up out of the rack will result in a dismal performance and/or increase the chance of injury while attempting the press. If you’ve ever seen someone really struggle with the clean, more than likely they failed to press the weight, even despite being a very strong presser. More often you can tell if someone is going to successfully press the weight based on how well they take it out of the rack or perform a solid clean.
The front squat is often recommended as a way to improve the overhead press. Besides the overt increased leg/hip strength from squatting, the strength gained throughout the torso from having to stabilize the weight during time under tension provides the upper body strength for a robust pressing platform, and teaches the lifter how to handle increased loads on their shoulders compared to overhead pressing alone.
Create tension throughout the core region – rectus abdominis, obliques, lower erectors – with proper abdominal bracing/modified Valsalva maneuver. Grip the floor with your feet, creating stability, as this is your base from which you will transfer energy from the floor to locking the weight out overhead. When choosing footwear, pick a shoe that has a firm sole such as an Olympic weightlifting or powerlifting shoe (choose same footwear as a squat shoe). Soft sole shoes, like running shoes, displace energy (reduce kinetic transfer to the bar) and compromise balance.
The Bar Path
Press the bar throughout your center of gravity. Theoretically, this is your optimal groove and will garner the greatest leverages for pressing. In reality, depending on flexibility and individual-specific morphology of the lifter, the bar will travel in a subtle sigmoidal or J-shaped pattern from shoulders to fully locked out overhead (similar to a bench press pattern).
Fully locked out meaning that the weight is held out in front of you while the back is bent way back in extension. However, you want to try to think of pressing as if it occurs in a straight line, directly over your center of gravity (from a side view, picture a line that splits your body directly in half). Once the press is initiated, the head has to move out of the bar path and then return to its original position once the bar has ascended to lockout.
A miscue I often hear is to bring the head through during lockout. However, bringing the head through results in just that – pushing the head forward while leaving the rest of the body behind creating an extended "chicken neck" with the weight held forward of the center of gravity. Instead, cue to bring the bar back over your head, while maintaining a more neutral/stable spine allowing for the upper back to aid in the lockout of the press.
If flexibility is a concern and you aren’t able to rack the bar to your shoulders, widening the hands a small amount may help, but not to the point where it creates instability or discomfort in the shoulders, or a precipitous drop in strength.
Wrist and shoulder mobility exercises are beyond the scope of this article but the reader should confer such literature if need be. If lower back and/or hip flexor tightness is an issue, you can stagger the stance as this will allow the weight to be distributed over your center of gravity without having to significantly extend the lower spine. Staggered stance is especially useful for pressing implements that have a large diameter, such as a log or keg, which allows the lifter to better line up the center of mass of the implement with the center of gravity over your body.
Side Note: Many of the principles detailed here can be applied to any pressing movement.