The front push-away is sometimes called the “Neider” or “neither” press because it’s neither a shoulder press nor a bench press. Its main function is to strengthen your capacity to hold the shoulder solid in the capsule.
It’s not a hypertrophy exercise, but it will strengthen the front deltoids, rotator cuff and even lats. It’s really more of an exercise to improve your capacity to keep the shoulder girdle rigid to avoid strength leaks. It can also be used with light weights and a slow tempo as an activation exercise prior to bench pressing or overhead pressing.
Focus on keeping the shoulder in the capsule; don’t bring it forward or up. Try to tense the lats. When you press out, attempt to compress your rip cage with your upper arms.
Sets of 8-10 reps with a fairly slow tempo and holding the finish position for 2 seconds per rep works best.